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  • 1985-1989  (3,047)
  • 1988  (3,047)
  • Life and Medical Sciences  (1,786)
  • Chemical Engineering  (691)
  • Engineering General  (570)
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  • 1985-1989  (3,047)
Year
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  • 1
    Electronic Resource
    Electronic Resource
    Masthead (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280701
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  • 2
    Electronic Resource
    Electronic Resource
    A boundary element simulation of compression mold filling (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 413-420 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper presents the development of the boundary element equations for the compression molding process of isothermal Newtonian fluids. It shows the numerical implementation of the boundary element equations and presents a simple method of carrying out the domain integral present in the governing equations. The results and accuracy of a boundary element simulation are discussed, and the numerical results compared to experimental values.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280703
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  • 3
    Electronic Resource
    Electronic Resource
    Fracture behavior of coated/uncoated graphite-epoxy composites (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 605-609 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The static delamination behavior of graphite/epoxy composite specimens subjected to mode I tensile opening (using UDCBUniform double cantilever beam. specimens), and pure mode II shear loading (using ENFEnd-notched flexural. specimens) were studied. The graphite epoxy composites for the study were made from commercially treated fibers, with and without an electropolymerized interlayer. The mode I fracture energy (GIC) was found to be significantly higher (more than 50 percent) for the coated fibers. However, this improvement was accompanied by a high reduction (more than 3 times) in the mode II fracture energy (GIIC). This effect is apparently related to poor adhesion between the interlayer and the epoxy resin, which may be corrected by use of a “top layer” of appropriate composition to form chemical bonds between the phases. The fracture toughness (KIC) of composites made with commercially treated fibers was also evaluated, using double side-notched specimens.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280909
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  • 4
    Electronic Resource
    Electronic Resource
    Heat transfer effects on the processing-structure relationships of polyetheretherketone (PEEK) based composites (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 583-591 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An analytical methodology was developed capable of describing interrelations between thermal processing and polymer structure for thermoplastic based composite laminates. Specifically, this modeling methodology was used to describe experimental results generated with a specially designed match die quench mold by processing both neat PEEK polymer and carbon fiber reinforced laminate samples at different cooling rates. The developed model accurately predicted temperature profiles for PEEK laminates of different thicknesses, under normal as well as extreme quenching conditions of 114°C/s. surface cooling rates that are possible to generate with the quench mold. In general, the modeling methodology is capable of predicting a part's thermal profile during processing in terms of the composite's microscopic intrinsic properties (fiber and matrix), composition, and lamina orientation. Furthermore, by coupling to the thermal profile description, a previously developed crystallization kinetics model for PEEK polymer and its carbon reinforced composite, a quantitative description of structural development during processing was obtained. Thus, with this analytical methodology, a skin-core crystallinity profile, where the crystallinity varies with part-thickness as a result of uneven cooling experienced during processing, was predicted both for the neat PEEK polymer and its carbon reinforced laminate forms. Finally, the developed methodology clearly established the interplay of both microscopic heat transfer and kinetics of crystallization/solidification of the matrix that must be accounted for in predicting the final structure of a carbon fiber reinforced laminate that will, in turn, govern microscopic and macroscopic performance.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280907
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  • 5
    Electronic Resource
    Electronic Resource
    Fluid sorption characterization of PEEK matrices and composites (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 634-639 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Neat poly(ether-ether-ketone) (PEEK) and carbon fiber reinforced PEEK (APC-2) specimens were prepared using a variety of cooling rates to achieve a range of crystallinities. Amorphous specimens were exposed to a variety of fluids to determine the penetrant types which are able to strongly influence the material. This allowed the estimation of the solubility parameter and hydrogen bonding index for PEEK to be 9.5 and 3.1, respectively. Methylene chloride was used to investigate the kinetics of penetrant sorption. The data demonstrated Case II behavior, with the initial crystallinity having a pronounced effect on both the kinetic and equilibrium data. Accordingly, a model was proposed capable of describing the sorption level and penetration depth as a function of time given the sample crystallinity and sorption temperature. With Case II behavior there was no difference in the sorption kinetics of neat and fiber reinforced PEEK. Finally, the dynamic mechanical properties measured during sorption were found to be dependent on the sorption process.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280912
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  • 6
    Electronic Resource
    Electronic Resource
    Morphology and rheological properties of polypropylene-linear low density polyethylene blends (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 670-678 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dynamic shear viscosity and the morphology of polypropylene homopolymer and copolymer blended with linear low density polyethylene are studied. A maximum in the dynamic shear viscosity vs. blend composition is reported for the polypropylene copolymer, linear low density polyethylene system. The increasing dynamic shear viscosity is in accordance with the occurrence of a morphology of polyethylene inclusions in rubber surrounded by a polypropylene matrix. Comparing calculations of the dynamic shear viscosities - based on a shell model with interlayer - and experimental results supports this view.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281006
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  • 7
    Electronic Resource
    Electronic Resource
    Properties of segmented block copolyurethane II. Adhesion between PET cord and rubber by poly(styrene-b-butadiene) polyethylene terephthalate block copolyurethane (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 684-687 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Hydroxy-terminated copoly(fstyrene-b-1,2-butadiene) (HPSB) containing rubber-affinitive vinyl side chains and having a molecular weight of 2000 to 4000 were prepared, and block copolyurethanes were synthesized by using a low molecular weight hydroxy-terminated poly (ethyl en e terephthalate) as a PET-affinitive component and 4,4′-diphenylmethane diisocyanate as a chain extender. The relationships between the molecular weight of HPSB, copolymerization ratio of styrene to butadiene and the adhesive strength of PKT/rubber in high temperature atmospheres were examined. A peak of adhesive strength was observed at styrene copolymerization ratio of 20 wt percent and a HPSB molecular weight of 3000. The adhesion mechanism was estimated from the behavior of the characteristic infrared absorption of block Copolyurethane in heating.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281008
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  • 8
    Electronic Resource
    Electronic Resource
    Vibration welding of thermoplastics. Part I: Phenomenology of the welding process (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 718-727 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In vibration welding of thermoplastics, frictional work done by vibrating two parts under pressure, along their common interface, is used to generate heat to effect a weld. The main process parameters in vibration welding are the weld frequency, the amplitude of the vibratory motion, the weld pressure, and the weld time. How these parameters affect weld quality, the conditions that result in the best welds, the weldability of dissimilar plastics, and the effect of fillers such as glass are of interest. To address these issues, a research vibration welding machine in which all the parameters can be independently and accurately controlled and monitored was designed and fabricated. The phenomenology of welding, as determined by experiments on the four thermoplastics polycarbonate, poly (butylene terephthalate), polyetherimide, and modified poly (phenylene oxide), is described.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281104
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  • 9
    Electronic Resource
    Electronic Resource
    A study on the reactive extrusion process of polyurethane (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 743-757 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An engineering analysis of the reactive extrusion process of a thermoplastic polyurethane was made through numerical simulation and actual experiment. The reactants used in this system were 4,4′diphenylmethane diisocyanate, polycaprolactone diol (M.W., 824), and 1,4-bu-tanediol with equivalent weight ratio of 2:1:1. As a catalyst, dibutyltin dilaurate was used. The reaction kinetics and the viscosity function were obtained through experiments, and the mathematical model which includes the conservation equations of mass, momentum, energy, and chemical species was solved numerically to obtain the velocity, concentration, temperature, viscosity, and pressure profiles. The actual experiments were performed in the laboratory scale extruder to compare the experimental results with those of the numerical simulation.
    Additional Material: 30 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281107
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  • 10
    Electronic Resource
    Electronic Resource
    Interpenetrating polymer network from blocked isocyanates. I. Structure and properties of polyurethane-urea polyvinyl simultaneous interpenetrating networks (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 775-784 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of polyurethane-urea/polyvinyl simultaneous interpenetrating polymer networks (SINs) were prepared starting from a mixture of isocyanate prepolymer blocked with N-(1-1′-dimethyl-3-cxobutyl) acrylamide oxime, chain extender, vinyl monomers, and catalysts. Their physical properties and morphology were investigated using differential scanning calorimetry, dynamic mechanical measurements, and small-angle X-ray scattering. The polyurethane-urea networks examined were two-phase in nature. The vinyl network was formed with diacetone acrylamide oxime, trimethylolpropane trimethacrylate, and N-vinyl-pyrrolidone. Calorimetric analyses revealed that the polyether soft segment phase separated within the SINs. At higher temperature, dynamic mechanical measurements demonstrated the presence of only one glass transition temperature (Tg) intermediate in temperature to the Tg of the vinyl network and the Tg of the urethane hard phase. This is indicative of chain entanglement (interpenetration) between the vinyl network and the polyurethane hard segments resulting in a two-phase morphology. Small-angle X-ray scattering analyses provided measurements of diffuse phase boundary thickness, phase mixing, and domain size distribution. Appreciable interfacial thickness was not observed and thus phase mixing occurred within the phases. Domain size distribution indicated that high network constraints hindered the development of domains and limited the phase segregation.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281203
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  • 11
    Electronic Resource
    Electronic Resource
    Masthead (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281301
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  • 12
    Electronic Resource
    Electronic Resource
    Thermal degradation of high nitrile barrier polymers (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1152-1155 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Effects of absorbed moisture on degradation behavior of high nitrile barrier polymers were monitored using thermogravimetric analysis techniques. Non-modified and 10 percent rubber modified samples were heated isothermally at nitrile processing temperatures (200°C to 240°C) in air and nitrogen environments. Degradation was evaluated in terms of weight loss as a function of heating time and sample coloration. It was determined that complete removal of moisture, as well as high moisture concentration, contribute to increased degradation at the temperatures evaluated. Moisture levels in the range of 0.15 to 0.5 percent were found to minimize degradation. Heating environment, time, temperature, and rubber modification were also found to influence thermal stability.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281803
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  • 13
    Electronic Resource
    Electronic Resource
    Chlorinated high density polyethylene. I. Chain characterization (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1167-1172 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: High density polyethylene has been chlorinated by three different methods: in suspension and in solutions of two different solvents. Carbon-13 NMR and infrared analysis show that chlorination in chlorobenzene solution leads to statistically random distribution while chlorination in suspension gives highly blocky substitution. An intermediate distribution was obtained by chlorination in tetrachloroethane solution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281806
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  • 14
    Electronic Resource
    Electronic Resource
    Stored energy of cold work in polystyrene (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1198-1202 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The energy stored in polystyrene after plastic deformation is measured by the differential scanning calorimetry (DSC) technique. Similar to metals, the stored energy increases with plastic straining, first rapidly, and then more slowly, and finally the stored energy seems to approach a saturation value (about 1 cal/gram). By comparing to the plastic work done, the fraction stored ranges from 30 percent after 10 percent compression to 10 percent after 60 percent compression. The fraction is about twice as large as that of copper. The release of stored energy has two distinct parts, one below Tg and the other above Tg. Most of the strain recovery seems to accompany the second part. By using the Kissinger plot, the second part has an activation energy, of 142 kcal/mole which is about 10 percent larger than that of compressive strain recovery.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281810
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  • 15
    Electronic Resource
    Electronic Resource
    Moldability diagrams for the reaction injection molding of a polyurethane crosslinking system (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1219-1226 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A trial and error approach reflects the state of the art in reaction injection molding. Material and process parameters determine the “moldability” of a specific system in a particular application. The concept of “molding areas” on the critical parameters plane can be extended form thermoplastic injection molding (TIM) to reaction injection molding (RIM).In this work moldability diagrams for the filling and curing stages of a RIM process are obtained based on a simplified engineering approach. The key process parameters chosen for the filling stage are initial material temperature and filling time. In the curing stage, the critical parameters are considered to be mold wall temperature and demold time. Experimental results obtained on a laboratory-scale RIM machine on a Crosslinking polyurethane system are used to check the validity of the predicted molding areas. The agreement obtained is satisfactory considering the broad range of processing parameters used.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281903
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  • 16
    Electronic Resource
    Electronic Resource
    Microstructure in injection molded samples of liquid crystalline poly(P-hydroxy-benzoic acid-Co-ethylene terephthalate) (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1248-1259 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The microstructure of injection molded bars (2.9 and 5.8 mm thick) of thermotropic liquid crystalline poly(p-hydroxy-benzoic acid-co-ethylene terephthalate) has been studied by SEM on samples etched with n-propylamine, SEM fractography, DSC, IR, ESCA, WAXS and polarized microscopy. The 2.9 mm bar consists of three different layers: a highly oriented surface skin, an oriented intermediate layer and a non-oriented core. The 5.8 mm bar has a more complex microstructure and is composed of five different layers: a highly oriented surface skin, an oriented layer just beneath, a non-oriented layer, another oriented layer and a non-oriented core. The thicknesses of the different layers vary, significantly, with distance from the mold gate. The thickness of the core increases, significantly, with increasing distance from the mold gate at the expense of the oriented layers. The structure within the different morphological layers is not perfectly uniform. Tensile testing demonstrated the mechanical anisotropy of the surface material (a ratio of almost 20 between the longitudinal and transverse moduli) and the isotropy of the central core material.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281906
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  • 17
    Electronic Resource
    Electronic Resource
    Molecular orientation of polypropylene by rolling-drawing (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1264-1269 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Rolling-drawing is a simple, effective, solid state processing technique for manufacturing high strength and high modulus oriented polymer sheet products. The process is capable of increasing the tensile modulus and strength of polypropylene by more, than an order of magnitude with inexpensive equipment and straight forward controllable techniques. This paper gives an overview of the rolling-drawing of polypropylene. It is intended to answer the following questions. What is rolling-drawing? What changes in tensile properties can be expected as a result of this process? What deformation processes occur during rolling-drawing? What are the processing variables and how do these variables relate to the deformation ratio achieved by rolling-drawing? A tensile flow stress relationship was formulated from experimental data for oriented polypropylene. This constitutive equation, estimates the flow stress (or yield stress) of the polymer as a function of deformation ratio, strain rate and temperature. Since stretching was found to provide a significant portion of the deformation during the rolling-drawing process a Hoffman-Sachs computer analysis was written to predict plastic deformation and drawing forces in the stretch zone. The results of experimentation and the analysis are briefly compared in this paper.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281908
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  • 18
    Electronic Resource
    Electronic Resource
    Molecular structure, crystallization behavior, and morphology of fractions obtained from an extrusion grade high-density polyethylene (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1289-1303 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An extrusion-grade of high density polyethylene (HOPE) (3 ethyl groups per 1000 carbons) has been divided into 16 fractions by preparative GPC and selective p-xylene extraction. The fractions, with molecular weights ranging from 900 to 1,000,000, have been studied by IR spectros-copy, DSC, WAXS, polarized microscopy, and small-angle light scattering (SALS), The average degree of chain branching (percent C2H5) is 0.5 percent for the part of the sample having a molecular weight lower than 10,000 and it decreases monotonically with increasing molecular weight, finally approaching 0.1 percent C2H5. A crystallinity depression with respect to linear PE equivalent to 20 percent/(percent C2H5) is recorded for all samples except for the very low molecular weight samples for which the crystallinity depression is much larger (30 to 35 percent/ (percent C2H5)). The unit cell volume increases with increasing percent C2H5, presumably due to the inclusion of ethyl groups in the crystals as interstitlals at 2gl kinks. The concentration of ethyl groups in the crystals (∊c) unanimously follows the relationship: ∊c(percent) = 0.32 + 0.25 log(percent C2H5) except for the low molecular weight fractions which have significantly lower values for ∊c. Our admittedly speculative explanation for this major discrepancy between high and low molecular weight samples is based on the idea that segments with ethyl groups close to chain ends have a greater difficulty in crystallizing than segments containing ethyl groups located at positions far from the chain ends. The fractions obtained from the extrusion-grade HDPE show a solidification temperature depression with respect to linear PE which can only be explained by the presence of chain branches in these samples. The depression is particularly pronounced for the low molecular weight samples as is expected from the data on molecular structure. Well-developed non-banded spherulites are observed in rapidly cooled (crystallized at about 35 K supercooling), low molecular weight samples (6,000 〈 Mw 〈 8,000)from the extrusion-grade HDPE in contrast to the axialites observed in linear PE of the same molecular weight and thermal treatment. This discrepancy in morphology has been related to the presence of ethyl groups in the extrusion grade HDPE fractions. Higher molecular weight samples (20,000 〈 Mw 〈 1,000,000)from the extrusion-grade HDPE and linear PE both display well-developed banded spherulites of similar nature as is expected due to the similarity in molecular structure of the two sets of sample.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282003
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  • 19
    Electronic Resource
    Electronic Resource
    Application of a concept of distributed damage to creep induced buckling of high density polyethylene specimens (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1066-1070 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this work, a concept of distributed damage, including its inception and propagation, was applied to creep induced buckling of specimens prepared from high density polyethylene (HDPE). Using a kinetic relationship for damage accumulation, an integral equation for the front of the damage zone was derived. A time parameter associated with the inception of the damage front was obtained. The motion of the front was approximated for small times. Long time estimation was obtained using an assumption for a shape of the damage distribution. These results enabled us to review reported experimental results on creep induced buckling using a new insight into the relationship between applied load and time to buckle.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281609
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  • 20
    Electronic Resource
    Electronic Resource
    Characteristics of hydroxybenzoic acid-ethylene terephthalate copolymers and their blends with polystyrene, polycarbonate, and polyethylene terephthalate (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1095-1106 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We present a basic study of the thermal, dielectric, Theological, and mechanical properties of hydroxybenzoic acid-ethylene terephthalate copolymers (PHB-PET). It is argued that they have two-phase structures, one rich in ethylene terephthalate (PET) and one rich in hydroxybenzoic acid (PHB). Polystyrene (PS) is immiscible in 60% PHB-PET (60-PHB-PET) blends. Polycarbonate (PC) is partially miscible with the high PET phase of 60-PHB-PET. PET seems completely miscible with this high PET phase. Shear viscosity measurements on blends indicate that 60-PHB-PET gives rise to large reductions of viscosity. Extrudates and melt-spun fibers have been prepared. The phase morphologies of low PHB-PET blends as determined by scanning electron microscopy indicate ellipsoids or long fibrils of the, 60-PHB-PET in PS or PC matrices. High extrusion rates and melt spinning produce fibrillar structures. The mechanical properties of films, extrudates, and melt-spun fibers were studied. Blends with 10% 60-PHB-PET exhibited significant increases in Young's modulus and tensile strength.
    Additional Material: 29 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281704
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  • 21
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    Electronic Resource
    Masthead (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281801
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  • 22
    Electronic Resource
    Electronic Resource
    Kinetic studies of the polymerization of nylon-6 block copolymers (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1145-1151 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetics of the activated anionic polymerization of caprolactam to nylon-6 and its copolymers has been studied. Nylon-6 block copolymer and nylon-6 were prepared at various initial reaction temperatures (140°C to 165°C) by anionic polymerization in an adiabatic dewar flask. Different concentrations of poly(ethylene oxide) (PEO) in 4,4′-diphenyl methane diisocyanate (MDI)-capped PEO and 1 mole percent MDI, in a caprolactam solution, were used as the activators with the catalyst, the sodium salt of caprolactam. The kinetics of the reaction were analyzed from an adiabatic temperature rise. A new method was applied to determine the rate parameters. The activation energy, Ea, of nylon-6 and nylon-6 block copolymers were found to be 22 kcal/mole. The collision frequency factor, Ao, steadily decreased and the autocatalytic constant, Bo, decreased to a constant value of 16 with the introduction of PEO. However, it was found that the order of reaction, n, was almost a constant value at the second order for all experiments.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281802
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  • 23
    Electronic Resource
    Electronic Resource
    Chlorinated high density polyethylene. II. Solid state structure (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1173-1181 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Chlorination of high density; polyethylene results in polymers which consist of unmodified methylene units and chlorinated methylene co-units. The effect of the concentration and distribution of chlorinated units on the solid state structure has been examined by thermal, wide angle X-ray diffraction and dynamic mechanical analysis. As the substitution becomes more random, the crystallinity, crystallite size, and crystalline perfection decrease for a given chlorine content. The chlorinated units are shown to be capable of co-crystallizing, and the concentration of chlorine in the crystalline phase increases as the distribution is made more random. Concurrently, the chlorine concentration of the amorphous phase decreases. Segregation of chlorine into the amorphous regions is most efficient when the substitution is blocky.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281807
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  • 24
    Electronic Resource
    Electronic Resource
    Masthead (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281901
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  • 25
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    Electronic Resource
    An efficient algorithm of computation of molecular weight distributions and its moments for reversible step growth polymerization in homogeneous continuous flow stirred tank reactors (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1240-1247 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The reversible step growth polymerization in homogeneous continuous flow stirred tank reactors (HCSTRs), in which the condensation product (W) leaves the reactor through flashing, has been analyzed. The molecular weight distribution (MWD) of the polymer formed is governed by nonlinear coupled algebraic relations to be solved simultaneously. To find the MWD numerically a large number of these are normally solved simultaneously using a suitable iterative procedure. In this paper, these have been decoupled using the technique proposed in our earlier works (1, 2) and the MWD can now be obtained sequentially without any trial and error. This leads to considerable saving in computation time compared to methods currently used. To demonstrate the efficacy of the algorithm, the polycondensation step of the poly(ethylene terephthal-ate) (PET) formed in HCSTRs has been analyzed. The MWD, the average chain length and the polydispersity index of the polymer have been computed and it takes 0.1 CPU seconds on a DEC 1090 as opposed to the earlier method which would take seventy minutes for similar computations. The simple model of the HCSTR for the PET formation gives the effect of reactor temperature and pressure and the quantitative results have been presented in this paper.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281905
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  • 26
    Electronic Resource
    Electronic Resource
    Adhesive processing by electromagnetic irradiation (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1270-1274 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A mathematical model is presented which describes the degree of cure in a thermosetting adhesive used to bond sheet molding compound (SMC) components. The model allows computer aided optimization of the thermosetting process for any type of electromagnetic heating of the various layers of the structure (e.g. dielectric, microwave or induction), arbitrary material properties and arbitrary layer thickness. Computer simulated results are given for the particular case when the cure of the thermosetting material is initiated by its exposure to a high-power radio-frequency electric field (dielectric heating). These results indicate a strong sensitivity of the process to the thickness of the adhesive layer and the degree of coupling with the electromagnetic field. The analysis demonstrates that substantial heat losses from the relatively thin adhesive layer to the structural members of the joint by diffusive heat flow can be counterbalanced by additional electric power dissipated either in the adhesive or the structural members of the joint. Although derived for dielectric heating, those results are general, being independent of the type of electromagnetic heating employed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281909
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  • 27
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    Electronic Resource
    Flat die geometry - A note (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1275-1275 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Linearly tapered coat hanger dies or T-dies are widely accepted. Nevertheless a newly proposed curvilinearly tapered coat hanger die has been shown to perform much better. It costs about the same as the other types of dies. This contribution is considered in terms of the recent literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281910
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  • 28
    Electronic Resource
    Electronic Resource
    Masthead (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282001
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  • 29
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    Electronic Resource
    Rheological properties of the liquid crystalline poly(γ-benzyl α, L-glutamate) gels in benzyl alcohol (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1304-1312 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We have determined the degree of stiffness of a poly(γ-benzyl α, L-glutamate) (PBLG) chain in benzyl alcohol by measuring the intrinsic viscosities of dilute Solutions with differing molecular weights. Viscoelastic properties in oscillatory shear flow have been studied and the dependence of the loss and storage moduli on temperature, composition, and frequency are reported. We have also studied the transient shear stress relaxation behavior of the PBLG gel at different temperatures and concentrations. A comparison has been made between these gels and a classical poly(dimethyl siloxane) (PDMS) network, as well as, typical glassy polymers. Shear creep and recovery measurements have been made for this system. Some extensional step strain experiments using lubricated squeezing have been investigated. Tensile experiments have been made to determine stress-strain relationship during elongation. Preliminary experiments using the impulse approach to viscoelasticity further indicate the high elastic contribution in the gel.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282004
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  • 30
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    Electronic Resource
    Corrections (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1342-1342 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282009
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  • 31
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    Liquid-liquid phase behavior of mixtures according to the Simha-Somcynsky theory (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1347-1354 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is well known that equilibrium, thermodynamic properties are governed by different functional derivatives of the thermodynamic functions of state. For example, the phase behavior of mixtures of low and/or high molar mass components is determined by the compositional derivatives of the free energy. In this contribution, the merits of the Simha-Somcynsky theory in describing and predicting the phase behavior of mixtures are considered. The influence of temperature and composition on the miscibility behavior for practically binary polymer solutions are studied. Furthermore, the important aspect of polydispersity, inherent to synthetic polymer systems will be addressed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282103
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  • 32
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    On the role of coupling agents in zirconia-polypropylene suspensions for ceramic injection molding (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1572-1577 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of titanate, zirconate, and zircoaluminate coupling agents on the viscosity of zirconia-polypropylene injection molding blends was investigated. The zircoaluminate did not influence viscosity while the two former additives effected a considerable reduction. The titanate coupling agent also reduced the viscosity of the polymer in the absence of ceramic powder, and was more efficient in this respect, as a flow modifier than dioctyl phthalate. A comparable effect on the ceramic suspension was obtained by adding a species similar in molecular structure to the titanate coupling agent but without coupling ability.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282308
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  • 33
    Electronic Resource
    Electronic Resource
    Dielectric properties of medium thermal black-polyethylene systems (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1581-1585 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dielectric properties of thermoplastic and cross-linked polyethylene compounds with a low structure medium thermal carbon black are described in the frequency range between 30 and 8000 kHz as a function of frequency, temperature, and carbon black loading. Very high values of the dielectric constant were obtained for the conductive samples. The systems investigated are shown to follow percolative type models with experimental critical exponents in good agreement with the predicted values. The dielectric constant increases slowly with the carbon black concentration up to roughly the percolation concentration, then increases rapidly, and subsequently decreases at the higher black loadings. The dissipation factor-concentration curves show maximum values in the vicinity of the percolation concentration. The dielectric properties of these systems are discussed in terms of interfacial Maxwell-Wagner polarization effects.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282402
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  • 34
    Electronic Resource
    Electronic Resource
    Cure analysis of printed wiring boards containing reactive adhesive layers (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 372-376 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper presents a method for analyzing the cure of multilayer circuit boards containing chemically reactive adhesive interlayers. The cure kinetics of the adhesive are first quantified by differential scanning calorimetry, using the method of Freeman and Carroll to obtain the numerical kinetic parameters. These parameters are then used in a finite-element model of the circuit board which solves the heat and species transfer equations simultaneously. It is then possible to predict the temperature and extent of reaction at any time and position within the laminate, enabling the curing program to be optimized.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280605
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  • 35
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    Correction (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 403-403 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280610
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  • 36
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    A method for estimation of polymer melt temperature fluctuation in a single screw extrusion process (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 429-433 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A method for estimating the polymer melt extrudate temperature fluctuation in the single screw extrusion process is proposed. Predictions of the melt temperature fluctuation is feasible if the extrusion process parameters are known. The method is superior to these in the literature because it incorporates effects of the melting process on the temperature fluctuation. The method has been verified experimentally.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280705
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  • 37
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    Extrusion behavior of filled polymeric systems exhibiting an apparent yield stress (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 453-459 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An investigation was undertaken to study the extrusion behavior of composite systems. A compound made up of approximately 50 percent ceramic particulates by volume dispersed in a high molecular weight thermoplastic polymer was characterized by measuring the shear viscosity on an Instron capillary viscometer. The experimental data indicated that the ceramic composite exhibited an apparent yield stress. As a result, an expression that was previously shown to provide flexibility for describing a yield stress at low rates of deformation could explain the viscosity of the ceramic composite. The expression was then applied to the flow analysis of both a “rod” and a “slit” die in an extrusion process, and the derived equations adequately correlated experimental volumetric flow rate us. Pressure drop data obtained on a laboratory extruder.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280708
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  • 38
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    Molding by reactive injection of reinforced plastics (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 485-490 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A model for the molding by reactive injection of reinforced plastics for systems in which fiber glass reinforcements are placed into the molds, is proposed. It allows for the determination of processing parameters and their influence on dependent variables: conversion, temperature, and pressure. Moldability areas, where premature gelling is avoided, are defined. Operating conditions are selected to reduce cycle time, produce small load losses, and provide a fairly uniform curing stage throughout the product.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280712
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  • 39
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    Characterization of linear copolymers by methods sensitive to the refractive index increment (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 510-516 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: For linear copolymer molecules, the refractive index increment depends on the chemical composition of the molecules. However, the polydispersity in chemical composition of the sample introduces a great complexity in the data analysis in order to obtain a true molecular weight distribution. Even when the mean chemical composition does not depend on the molecular weight, a correction has to be applied when the output of an instrument depends quadratically on the refractive index Increment of the sample, such as in a light-scattering measurement. For that purpose, the light-scattering expressions are written in terms of polydispersity in chemical composition, which in turn is modeled using linear copolymerization equations. The microstructure effects, which are related to the order in which two different kinds of monomers appear along the chain, are not as yet taken into account in this approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280804
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  • 40
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    Electronic Resource
    Creep induced buckling of plastic materials (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 506-509 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this work, creep induced buckling was studied for a number of thermoplastic materials. The effect was observed by monitoring top displacements of thermoplastic bars as a function of time under static loading conditions. The recorded times to failure were averaged and correlated with the applied loads. The experiments, conducted for different materials, established an exponential dependence between the critical time and the load. The evolution of the buckling eigenvalues was modeled numerically. The simulations of eccentric columns behavior under compressive loads were coupled with the eigenvalue analyses. The correlation of the time-load predictions obtained from the numerical simulations followed the experimental results within acceptable limits. The observed phenomenon of creep induced buckling was explained by damage accumulation leading to an effective reduction of the load carrying capability.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280803
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  • 41
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    Comments and recommendations on the use of the Avrami equation for physico-chemical kinetics (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1042-1045 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Over the last four decades, numerous reports have appeared on the physico-chemical kinetics, especially crystallization kinetics, based on the Avrami equation, φ = exp [-Ktn] where φ is the fraction of material unchanged at time t, K is an overall rate constant and “n” is the Avrami exponent indicative of process mechanism. The usage of the Avrami equation has been limited to the determination of “n” and its temperature dependence. It is shown that the evaluation of K and the activation energy (E) using this equation is erroneous since K and E are both influenced by “n” although such would be unexpected from the Avrami equation. On the other hand, if one uses a modified expression, φ = exp[-Kt]n, then in addition to the value of “n”, correct values of K and E are obtained. This retains the original correspondence of the Avrami equation to nuclea-tion and crystal growth processes but extends its applicability to (i) correctly evaluate K and E parameters, and (ii) correctly compare transformation rates when the systems differ in their n values. Experimental data are presented to support these conclusions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281605
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  • 42
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    Chemorheological characterization of thermoset cure (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1071-1075 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Thermosetting resin/glass cloth composites find extensive use in the packaging of electrical circuits into multi-layered circuit boards. To determine optimum processing conditions, it is necessary to understand the rheology of the resin as it cures. In this study, a squeezing flow geometry was used to determine the shear viscosity of a high performance epoxy resin during cure; Viscosity profiles were obtained during rising temperature cure. The results were compared with the complex viscosities obtained using the dynamic oscillatory parallel plate geometry. A numerical optimization algorithm was used to obtain the dual Arrhenius viscosity model parameters from the experimental viscosity data. The sensitivities of the model parameters and their effects on the predicted viscosity profiles were also determined.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281610
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  • 43
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    Masthead (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281701
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  • 44
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    Blends of a chlorinated poly(vinyl chloride) compound and a thermotropic liquid crystalline copolyester: Some rheological behavior and spiral mold flow (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1107-1114 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Rheological and spiral mold flow measurements were made on blends of a chlorinated poly (vinyl chloride) (CPVC) compound and a thermotropic liquid crystalline copolyester of p-hydroxybenzoic acid/poly (ethylene terephthalate) (60/40), hereafter referred to as LCC, at 210°C. Several interesting flow phenomena have been observed. While the shape of the flow curve (i.e., G′ vs. ω; G″ vs. ω) of LCC is solidlike, those of the blends are pseudoplastic. The dynamic viscosity of the blends increases as the concentration of LCC increases. However, the shear viscosity of the blends is reduced with LCC and may be described using the relationship of additivity of fluidity. Although the melt elasticity of the blends is increased with the concentration of LCC, the extrudate swell of the blends after extrusion from a capillary is decreased. This phenomenon, however, is complicated. A Theological analysis based on an idealized runner system is used to describe the spiral flow length as a function of the Theological properties of the molten polymers and also the operating conditions. The relative improvement of the spiral flow length of the CPVC compound due to blending with LCC could be correlated with the power-law fluid model at high shear rates.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281705
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    Tg-Composition analysis of miscible polymer blends (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1355-1361 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Several authors have suggested a monotonic variation of the glass transition temperature (Tg) of miscible polymer blends as a function of composition. They usually express the results in terms of equations proposed by Couchman-Karasz, Gordon-Taylor, Fox, and several others. However, we have noticed that numerous systems exhibit a cusp when Tg is plotted as a function of composition (after correction for the presence of crystallinity when semi-crystalline polymers are involved). This cusp cannot appear when the Tg's of the two homopolymers involved are separated by less than about 52 degrees., It will be shown that this observation is quite general since it has been observed with several polyester/chlorinated polymer blends, polycaprolactone/nitrocellulose blends, and polystyrene/poly(vinylmethylether) blends; It will also be shown that this behavior is predicted in the framework of the free volume theory, with equations derived by Kovacs. According to this theory, above a critical concentration φc (relative to the plasticizer) and below a critical temperature Tc, the high-Tc, polymer no longer contributes to the free volume of the mixture whereas it does above Tc. This difference leads to a Tg-composition variation which has to be expressed by two different equations, one below Tc and the other above Tc, the cusp defining the limit of applicability of each equation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282104
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    Viscoelastic behavior of polymer blends (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1401-1404 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: There is a reciprocal relation between flow and structure in multiphase systems such as polymer blends or composites. For this reason characterization of these materials must be carried out under conditions which guarantee minimum modification of structure. Capillary rheometry is particularly ill suited as a test tool, but the small strain dynamic oscillatory method may provide the true material responses, Most frequently these are expressed as frequency, ω, dependent storage and loss shear moduli, G′ and G″, or real and imaginary viscosities, η′ = G″/ω and η″ = G′/ω. However, two other methods of data presentation seem to be more sensitive to melt structure. They are the Cole-Cole plot of η″ vs. η′ and the relaxation spectrum. Frequently, both of them indicate a binomial response. Various mechanisms leading to such behavior will be discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282109
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    Processing-morphology relationships of compatibilized polyolefin/polyamide blends. Part I: The effect of an lonomer compatibilizer on blend morphology (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1416-1426 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The morphology of compatibilized polyolef in/polyamide blends was found to be significantly dependent on the concentration of an ionomer compatibilizer (polyethylene-methacrylic acid-isobutyl acrylate terpolymer) in the blend. For a dispersed phase content of 10% by weight, a maximum reduction in phase size was observed when only 0.5% by weight of ionomer was added to the blend, A more significant reduction of the dispersed phase size was observed when the minor phase was nylon, due to interactions which exist between the ionomer and the polyamide. These interactions have been confirmed by Fourier transform infrared spectroscopy. At high concentrations of the ionomer, flocculation of the nylon dispersed phase was observed. In comparison to one-step mixing, blends prepared by two-step or batch mixing were characterized by a smaller dispersed phase when nylon was the matrix, and a larger particle size when nylon was the minor phase. The results observed are explained in terms of a speculative model of the interactions occurring across the nylon-polvolefin interface.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282111
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    Determination of the nature and content of antioxidant and antioxidant synergist in polyethylene and crosslinked polyethylene used in cables (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1445-1449 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is shown that polyethylene and crossllnked polyethylene resins used for cable applications contain an antioxidant synergist in addition to an antioxidant. Their nature and content have been determined by a combination of ultraviolet and Fourier transform infrared spectroscopy and neutron activation analysis measurements. The results thus obtained suggest that part of the antioxidant compound is grafted to polymer chains during crosslinking.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282202
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    The effect of cryogenically ground rubber on some mechanical properties of an unsaturated polyester resin (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1455-1461 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of Cryogenically Ground Rubber (CGR) from old tires on some mechanical properties of an unsaturated polyester resin is presented. A delay in the free radical cure reaction of the unsaturated polyester resin was observed upon the addition of ground rubber. This delay in the cure reaction could be overcome with the further addition of the free radical initiator. The particle size, surface chemistry, and the chemical composition of the rubber had an effect on the cure and on the final properties of the rubber-filled composites. It was also found that the rubber particles decreased the tensile, flexural, and storage shear modulus of the unsaturated polyester. Composites made from silane-treated ground rubber showed better mechanical properties than composites made from untreated CGR. Finally, the particle size of the ground rubber was apparently too large to produce a toughening effect on the filled materials.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282204
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    Computer-aided analysis of a linearly tapered coat-hanger die (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1517-1526 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We describe the computer-aided engineering analysis of a linearly tapered coat-hanger die in this paper. The general governing equation for flow distribution inside the die was derived first. On the basis of this equation, we have developed the design formula for a die to deliver uniform flow. In addition, we have also examined the variations of lateral flow uniformities and residence time distributions of polymeric liquids under several different design and operating conditions: (1) using manifolds with non-circular cross-sections, (2) adjusting production widths, (3) delivering fluids with different viscosities, and (4) enlarging manifolds for practical production considerations.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282302
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    The pressure drop/flow rate equation for non-Newtonian flow in channels of irregular cross-section (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1559-1564 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The pressure drop/flow rate equation for non-Newtonian fluid flow in channels of irregular cross-section is determined theoretically by two numerical methods. Two representative non-Newtonian fluid models, the Ellis and the Herschel-Bulkley models, have been studied for several commonly encountered non-circular channels. The empirical methods proposed by Kozicki, et al, and Miller have been analyzed. The validity of their methods is discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282306
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    Memory effects in polymers. II. Processing history vs. crystallization rate of nylon 6 - observation of phenomenon and product behavior (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1600-1606 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The observation of a novel phenomenon is reported whereby the processing history of a nylon 6 leads to a memory effect which in turn affects its crystallization rate from the molten state. Differential scanning calorimetry (DSC) and optical microscopy are the primary techniques used to demonstrate that the melt-crystallization behavior of nylon 6 can be controlled by processing variables. Characterization data is presented to show that obvious parameters such as molecular weight, impurities, monomer and oligomers, etc. are not responsible for the observed changes in crystallization behavior upon processing. It is shown that the mechanical properties and/or morphology of a nylon 6 article can depend upon the processing technique (e.g., compression or injection molding) as well as the processing history of the nylon 6 resin itself.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282405
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    A study of bubble nucleation in a mixture of molten polymer and volatile liquid in a shear flow field (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1616-1627 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Bubble nucleation in a mixture of volatile liquid and polymer melt under shear flow conditions was investigated, using a light scattering technique. In the study, a mixture of polystyrene and trichlorofluoromethane was extruded through a slit die having glass windows and bubble nucleation in the flow channel was observed optically. A He-Ne laser was used to illuminate the nucleating and growing bubbles. The light flux scattered by the growing bubbles at a fixed angle was detected by a photomultiplier with the aid of a high-voltage power supply. The bubble nucleating site in the flow channel was located using a computer controlled tracking system, which was designed to move the entire optical system automatically in the three dimensional space, and also had the ability to follow the software control command and cooperate with the data acquisition system. When the site of bubble nucleation was located, the coordinates of this site in the flow channel and the experimental conditions were automatically recorded on a floppy diskette by entering a software command. The pressure profile along the flow channel was measured by pressure transducers, with the aid of a microprocessor-based pressure reading system. It has been found that the site of bubble nucleation varies with the position in the direction perpendicular to the flow direction, which is attributed to the nonuniform velocity and stress distributions in the slit flow channel. The present investigation suggests that bubble nucleation can be induced either by flow and/or shear stress; specifically, flow-induced bubble nucleation is the dominant mechanism at positions near the center of the die opening, and shear-induced bubble nucleation is the dominant mechanism at positions near the die wall. It should be mentioned that the bubble near the die wall may also be generated by cavitation brought about by the surface roughness of the wall and also by thermal fluctuations due to the heat transfer between the metal (die wall) and the mixture of polymer and volatile component. The present study indicates that bubble nucleation in a shear flow field can occur at an unsaturated condition. This is in contrast to bubble nucleation under static conditions, where supersaturation is necessary.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282408
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    Torsion Impregnated Cloth Analysis for resin rheological studies (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 578-582 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper describes the utility of Torsion Impregnated Cloth Analysis, a very versatile technique to characterize resin behavior during cure or after repeated thermal and environmental treatment. Multi-frequency scan data have been shown to help tremendously in interpreting the behavior during experimentation. The technique is also very useful in defining the cure conditions for new resin chemistry/systems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280906
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    Characterization and role of an elastomeric interphase on carbon fibers reinforcing an epoxy matrix (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 568-577 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Oxidized carbon fibers were coated using an on-line filament winding process with an elastomeric adduct crosslinkable and compatible with an epoxy matrix. The coating and modifications of the epoxy network were studied by dynamic mechanical measurements. Assuming that apparent activation energies of the secondary relaxation βe of the epoxy network and main relaxation αa of adduct are very different, it is possible at low frequencies to separate the two peaks. The composite material can be described as a three phase system: an epoxy network as matrix, carbon fibers, and a soft interlayer. The mechanical behavior of unidirectional composite materials studied by impact and bending tests is strongly dependent on the presence and the thickness of the coating at the carbon fiber surface.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280905
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    Crack propagation modes in fiber and particulate composites in the microstructure (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 610-625 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The influence of the hard or soft inclusions and the mesophase layers in either a soft-hard-soft or hard-soft-hard combination of biphase plates submitted to dynamic tensile loads on the fracture mode and bifurcation process in both phases was investigated in this paper. It was assumed that the soft or hard matrix is infolding the hard or soft inclusion of the plate, so that the plate constitutes a meridional section of the representative volume element of a unidirectional fiber composite, or a principal section of a particulate. The influence of the mechanical properties of either phase on the crack propagation velocity and the initiation of crack bifurcation was studied by using high-speed photography and dynamic caustics. The results showed that the propagating crack tended to bifurcate either in the brittle or in the mesophase layer under certain conditions of propagation velocity. It was shown that bifurcation of a propagating crack depends on the elastic moduli and Poisson's ratios of the phases, as well as on the extent of the mesophase layer, which depended on the adhesion quality of phases.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280910
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    Masthead (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281001
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    Masthead (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988) 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250101
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    Error estimation and adaptivity in flow formulation for forming problems (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 23-42 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A very simple and reliable error estimator has recently been developed for problems of linear elasticity.1 This leads naturally toa predication of an h-mesh refinement required for a given accuracy and with a suitable mesh generator2 for an efficient adaptive process. In this paper we extend the methodology developed previously to incompresible plastic flow of metals or polymers using the ‘flow formulation’ approach.3The examples of application include steady state extrusion problems for which exact solutions are available and hence allow the efficiency of the error estimates to be tested as well as more complex problems of upsetting in which the mesh is updated. It is found that the estimator performs well under various circumstances and provides an economical adaptive process.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250105
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    Ignition phase transition of a polymer: Convective exposure (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 373-386 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The ignition of a semi-infinite solid polymer under convective exposure is investigated. A quasi-steady approximation is used for the gas phase and the transient effect is accounted for in the solid phase only. Both surface and gas phase chemical reactions are included simultaneously. The ignition mechanism is studied in terms of the concurrent heat transfer, mass transfer, mass transfer and chemical processes at the surface as well as in the gas phase. The gas phase governing equations are integrated independently from the solid phase energy equation using the Adams-Moulton subroutine. Corrections to the iterative procedure are carried out by establishing a set of perturbation equations and using the Newton-Raphson and least-squares methods. The results indicate that ignition occurs in the heterogeneous mode within a narrow range of low flow velocities and high temperatures. An ignition phase transition point exists, and within a wide range of high flow velocities, ignition switches to the homogeneous mode.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250208
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    Shape design sensitivity analysis for non-linear anisotropic heat conducting solids and shape optimization by the BEM (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 109-120 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Shape design sensitivity analysis (SDSA) expressions have been derived for non-linear anisotropic heat conducting solid bodies by following the material derivative concept and adjoint variable method of optimal shape design given in the literature. The variation of a general integral functional has been described in terms of primary and adjoint quantities evaluated at the varying boundaries. As an example problem in shape optimization, optimal outer boundary profiles of an orthotropic solid body are obtained by the boundary element method (BEM), after reformulating the SDSA equations in a form which is most suitable for the BEM.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260108
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    Analyses of steady-state visco-elastic fluids using the penalty function method (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 43-54 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The application of the penalty-function formulation of the finite element method is made possible for analysing visco-elastic fluid flows by the method which decouples the momentum and continuity equations from the constitutive equation. An upwind finite element scheme is combined with the method in order to solve the constitutive equation. As visco-elastic fluid models, Jaumann derivative, upper and lower convected derivatives are considered. The Poiseuille flow and the flow through a plane converging channel are analysed.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250106
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    Approximate methods for analysing the cold drawing of polymeric fibres and films (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 99-112 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Approximate methods for analysing steady-state cold drawing processes in polymer forming are discussed. These methods are applied to both axisymmetric and plane-strain drawing. The cold drawing process is associated with steady-state neck propagation along the specimen. Modifications are introduced in the approximate steady-state analysis which reflect the neck initiation and localization phases prior to steady-state drawing. This is accomplished without resorting to an analysis of the entire load-deformation history of the process. Finite element results are also presented and compared with those of the proposed approximate analyses. These comparisons show the approximate analysis to be an extremely efficient and quite accurate computational scheme for the analysis of steady-state cold drawing processes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250110
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    Analysis of stress and strain distributions in slab rolling using an elastic-plastic finite-element method (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 55-66 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The cold rolling of rectangular section slabs is analysed for a range of width-to-height ratios (one to three) for which spread of the workpiece is appreciable. This necessitates the use of a three-dimensional model. An elastic-plastic finite-element method is used to provide a complete description of the slab rolling process.The pressure distribution at the workpiece/roll interface is found to show the typical ‘friction-hill’ observed in near-plane-strain experiments, but the pressure varies across the width of the interface. The shear-stress distribution at the roll interface provides detailed information about the ‘neutral line’ which is usually assumed to occur where the shear stress changes direction. The 3-D analysis shows clearly that there is a flow divide in both longitudinal and transverse directions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250107
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    Numerical simulation of the densification behaviour of metal powder during hot isostatic pressing (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 213-225 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A numerical method is introduced which is based on metal flow theory and simulates the densification of metal powder during hot isostatic pressing.The method, in which nodal velocities are variables, takes into consideration the dependence of flow stress on the temperature, strain rate and relative density of the material. The compressibility of porous metal as well as the incompressibility of fully dense metal are also taken into account.Porous specimens of the superalloy MERL76 were subjected to uniaxial compression tests at high temperature in order to determine the parameters of the equations on which the method is based. The densification behaviour of a turbine disk and two cylindrical components was numerically simulated and compared with experimental results.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250117
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    Preface (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. i 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250202
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    Coarse-fine mesh method for heat and mass transfer in locally complex flows (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 347-355 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Combined forced and free convective flows having locally complicated geometries or boundary conditions were numerically studied with a finite difference method of coarse and fine meshes. The coarse-and-fine mesh method developed can be used for numerical calculations of both unsteady and steady processes of heat and mass transfer in convective and diffusion flows which are strongly influenced by locally fine flows. The method was applied to a numerical calculation of the steady flow field of a CVD (chemical vapour deposition) reactor which has locally complicated flows caused by small inlet nozzles. The results of the calculation showed a considerable contribution of locally fine flows to the overall flow field, which is well predicted with the present method.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620250206
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    Thermal analysis of human body-clothing-environment system (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 357-371 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: For the solution of thermal comfort problems a coupled model is presented consisting of the thermal model of the human body and of the clothing, with boundary conditions of the third kind.For thermal modelling the human body is divided into 16 parts according to the special character of the internal heat generation, of the blood vessel system and of the sweat secretion mechanism. Part models are connected by the flow paths of arteries and veins.Transport phenomena in the clothing are treated by a coupled heat and mass transfer model which permits various kinds of clothing for the different parts of the body.The equation system of the full model has been solved numerically by using time stepping schemes. As the results of the computations an approximative temperature field of the human body is produced.Calculated results have been compared with Experimental data.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250207
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    Finite element simulation of hot isostatic pressing of metal powders (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 191-212 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Rate form constitutive equations of elasto-viscoplastic type are expressed in a manner similar to that of classical metals, but the viscoplastic part, which is no longer incompressible, is related to the rate of variation of porosity. An incremental and implicit algorithm has been implemented in a finite element program in order to simulate hot isostatic pressing of an Astroloy powder. Temperature distributions are shown to induce strong density variations in real parts during hot isostatic pressing (HIP). For one particular turbine disk, we tested the sensitivity of the final shape to different processing parameters. Computed final shapes compare well with experimental ones.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620250116
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    Analysis of bending effects in sheet forming operations (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 253-267 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The majority of work in numerical analyses of sheet metal forming operations is based on the simple membrane-shell theory which neglects the effect of sheet bending. While useful information can be extracted from these analyses, especially for stretch-dominated operations, the membrane theory is basically inadequate for analysing the draw-type operations where sheet metal bends, slides and unbends over a draw radius.This paper presents axisymmetric and plane-strain finite element analyses of stretch/draw of sheet metal over a die corner radius. Numerical solutions obtained from a total Lagrangian formulation of a finite-strain thin shell theory are used to indicate the relative significance of including the bending effects in various simple forming operations. Comparisons of the calculated results with available experimental data are also given.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250119
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    A finite element simulation of the sheet metal forming process (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 283-292 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A finite element simulation code of the sheet metal forming process has been developed. This simulation code plays an important role in the computer aided engineering (CAE) system for an automobile parts forming process, which includes the pre- and post-processes. The paper presents the development of an updated Lagrangian type finite element modelling, based on the elastic-plastic (J2 flow law) membrane shell theory. An attempt is made to calculate the strain distribution incurred by peripherally clamped or non-clamped square plates when impressed by rigid punches. These are the cases of square box-shape punch drawing and arbitrary shaped panel stretch forming.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620250121
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    Punch stretching of sheet metal and differential equations on manifolds (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 269-282 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The goal of mathematical modelling of sheet metal forming processes is to provide predictive tools for use in the design of stamping processes and the selection of sheet materials. Most current approaches to finite element modelling of large deformation, elastic-plastic sheet metal forming problems use a rate form of the virtual work (equilibrium) equations, and a single-field finite element representation of the displacement components. Called the incremental method, this approach does not produce approximations which satisfy the discrete equilibrium equations at all times, and consequently it demands small time steps to insure stability and numerical accuracy. This paper describes a variant of the mixed method in which displacements, stresses, effective strain and pressures are all given separate finite element representations. The equilibrium equations in non-rate form are discretized to produce a system of algebraic equations which are coupled with the constitutive equations and then integrated using state-of-the-art numerical software. When used to model rate sensitive sheet materials in hydrostatic bulging, plane strain punch stretching and hemispherical punch stretching, the new approach proved to be between 6 and 26 times as fast as the old incremental method.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620250120
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  • 73
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    Buoyant flow calculations with non-orthogonal curvilinear co-ordinates for vertical and horizontal parallelepiped enclosures (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 331-345 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A control-volume-based finite-difference formulation is developed for heat transfer and fluid flow in arbitrary three-dimensional parallelepiped enclosures. The governing equations in Cartesian co-ordinates are first transformed to those in non-orthogonal curvilinear co-ordinates by tensor transformations. After introducing the properties of the parallelepiped geometry, equations are obtained in the primitive variables for which all vectors and tensors are based on the curvilinear co-ordinates. With proper treatment of the heat flux and stress tensor terms, the finite-difference equations, analogous to those in the Cartesian coordinates, are formed. Examples are utilized to show the validity of the methodology and the results are found to compare well with existing experimental data. The differences in heat transfer and fluid flow inside parallelepiped enclosures and rectangular enclosures are delineated and discussed from a physical point of view.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620250205
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    Finite element analysis of turbulent forced convection in lid-driven rectangular cavities (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 313-329 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Turbulent fluid flow and heat transfer in lid-driven rectangular cavities are analysed by a finite element procedure for the prediction of the turbulent forced convection in two-dimensional recirculating flows. The (k-ε) model is used to compute effective viscosities and thermal conductivities. The fluid flow and turbulence model parabolic equations are solved sequentially, one after the other. Then, the calculated velocity distribution is used in the solution of the steady state energy equation to yield the temperature field. Aspect ratios e=0·75, 1·0 and 1·5 and Reynolds numbers ranging from 5 × 104 to 4 × 105 are considered in the numerical examples.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620250204
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    Non-linear simulation of dendritic solidification of an undercooled melt (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 415-444 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Two-dimensional finite element simulations of solidification for quiescent undercooled pure metals are presented. The full non-linear, transient heat equation is used with phase front tracking which is subject to local curvature and interfacial kinetics. During early stages of the waveform instability the simulated solutions match the linear stability analysis with fidelity. Beyond the valid range of that analysis the numerical solution continues to demonstrate the physically observed exponential growth behaviour and characteristic spacing between fingers. Whereas the simulations show the sensitivity of dendritic growth to initial conditions, as expected for an unstable process, the overall pattern formation preserves the characteristic spacing. The simulations are terminated after the onset of bifurcation. Thereafter, the numerical model is inappropriate for physical comparison owing to the planar, two-dimensional limitation.
    Additional Material: 24 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620250211
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    A regular indirect boundary element method for thermal analysis (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 495-515 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A Regular Indirect Boundary Element formulation is developed following a weighted residual approach. In this formulation, the fictitious source density, which appears in the integral equations of the method, is distributed on a surface which is exteriorly separated from the physical field boundary of the problem. This approach does not require the evaluation of singular integrals and produces undeteriorated solutions at geometric discontinuities. The formulation is presented here as applied to two dimensional and axisymmetric thermal problems. It includes a different subregioning scheme which treats each subregion, of a multidomain problem, separately, thereby eliminating the need for a sophisticated reduction scheme.
    Additional Material: 24 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620250214
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    Warping torsion in thin-walled open section beams using the semiloof beam element (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 231-243 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Many structural members including metallic, reinforced polymer and concrete members must be modelled, in the simplest approximation, as thin-walled beams whose cross-sections exhibit significant, out-of-plane warping owing to torsion. The elastic capabilities of the semiloof beam element are extended to include warping torsion of thin-walled open section beams. The performance of the extended element is compared with that of the original formulation.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620260116
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    Partial eigensolution of damped structures by non-linear optimization (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 143-152 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The partial solution of damped structures involves the determination of only a few of the resonant frequencies and corresponding damping characteristics and mode shapes. The procedure outlined here uses a modification of the variable metric solution algorithm, in which the dicision variables are elements of the complex eigenvector and the eigenvalue. The quadratic eigenvalue problem is reformulated as a sequential unconstrained minimization problem. Both normality and orthogonality constraints are incorporated in the objective function. The method is compared to an adaptation of the subspace iteration technique, also applicable to the quadratic eigenvalue problem.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/nme.1620260110
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    An element-by-element method for heat conduction CAE including composite problems (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 199-215 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Mechanical computer aided engineering (CAE) implies large finite element problems due to the geometric complexity of the ‘true’ 3D designs. Application of the standard finite element technique is not practical for such problems because the direct solution of the global matrix equations is too costly. This paper considers the element-by-element implicit algorithm for the CAE application of transient heat conduction. The direct solution is avoided by an operator splitting or approximate factorization technique. This results in both the execution time and storage requirements for each time step being linearly proportional to the number of elements while retaining unconditional stability. However, the approximate factorization introduces additional truncation error and incorrect jump conditions at material interfaces. Detailed analyses and numerical experiments are carried out in one dimension to assess the nature and mechanism of these inaccuracies. A three dimensional implementation is then compared with one dimensional results. The need for an additional predictor-corrector element-by-element algorithm for 3D composite problems is also presented.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620260114
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    Letters to the editor (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 281-282 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260119
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    Conference diary (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 291-292 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260124
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    Plastic design. An imposed hinge-rotation approach, P. Zeman and H. M. Irvine, Allen & Unwin, London, 1986, 86, pages (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 290-290 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260123
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    Finite elements and solution procedures for structural analysis. vol. I: Linear analysis. M. A. Crisfield, Pineridge Press, Swansea, 1986. No. of pages: 272 (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 289-289 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260122
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    Hybrid finite element-Monte Carlo method for coupled conduction and gas radiation enclosure heat transport (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 361-378 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A hybrid two-dimensional finite element-Monte Carlo numerical solution method has been developed for solving complex transient non-linear gas radiation enclosure problems. Solid conducting media are coupled to conducting gaseous or particulate participating media and both may be internally energy generating. Bilinear isoparametric elements are used, allowing geometrically complex enclosures with internal objects to be present. Radiative energy transport within the gaseous enclosures is accounted for using a Monte Carlo method which permits a broad range of complexities. Included here are: diffuse-grey and specularly reflecting walls with temperature and spectrally dependent, and non-homogeneous emissivities or absorptivities; absorbing/emitting gases with temperature and spectrally dependent, and non-homogeneous emissivities or absorptivities; and isotropic or anisotropic scattering gases or particles. This method was verified by solving several standard steady state problems and comparing the solutions to those found using the conventional finite element, the P-N and the exchange factor methods. Solution times are comparable to those of the finite element method. A more complex transient problem solution is then given to demonstrate the versatility and power of the method.
    Additional Material: 17 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620260206
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    Derivatives of eigenvalues and eigenvectors of a general complex matrix (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 293-311 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A survey of methods for sensitivity analysis of the algebraic eigenvalue problem for non-Hermitian matrices is presented. In addition, a modification of one method based on a better normalizing condition is proposed. Methods are classified as Direct or Adjoint and are evaluated for efficiency. Operation counts are presented in terms of matrix size, number of design variables and number of eigenvalues and eigenvectors of interest. The effect of the sparsity of the matrix and its derivatives is also considered, and typical solution times are given. General guidelines are established for the selection of the most efficient method.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620260202
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    Convergence of curved shell elements based on assumed covariant strain interpolations (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 329-347 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A C0 9-node shell element based on assumed interpolations of covariant strain components defined with respect to the element natural co-ordinate system has recently been proposed. In this formulation, the covariant strains are obtained directly from the Cartesian strains by tensor transformation without any need to compute laminar co-ordinate based strains. In the present work, the interpolated covariant strains used in this element are analysed to determine their satisfaction of the basic requirements for successful strain interpolation. These basic requirements are stated as invariance to rigid body motions and ability to represent constant and linear strain states. In the finite element formulation, the weak form of momentum balance is expressed in terms of covariant strains and contravariant stresses. The corresponding elasticity tensor is a function of the components of the metric tensor associated with the element natural co-ordinate system. The invariance properties of the metric tensor in the context of the finite element approximation are also discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620260204
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    Spline collocation in the flow of non-Newtonian fluids (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 413-421 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Natural convection flow of a non-Newtonian fluid between two vertical infinite parallel flat plates forms the case study of the present work. Velocity profiles for the Prandtl-Eyring and Powell-Eyring fluid models are obtained through the method of spline collocation.The applicability and reliability of the techniques employed here are discussed in detail with a suggested error estimate and analysis. Accuracy in the successive iterations in the results is of the fourth order. To maintain this accuracy the help of a computer is not required for carrying out the calculation of velocity profiles. Thus the simplicity of the spline collocation technique is demonstrated in its application to flow problems.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620260209
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    Computation of hybrid element matrices by elimination techniques (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 423-435 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Three functionals, the modified forms of the Hu-Washizu, Hellinger-Reissner, and complementary energy principles, as developed by Pian, Chen, and Kang1.2 are stated. Finite element discretization of each is presented and the ensuing computations developed, resulting in the element stiffness matrix, with displacement degrees-of-freedom only, and the stress recovery matrices. Subroutines are presented for this purpose where the close relationship of the three principles is exploited to result in a compact hybrid element technique. The techniques herein reviewed are assumed applicable at the individual element level. The usual summation over all elements in the model is implied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260210
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    Accuracies of numerical solution methods for the pressure-modified von Mises modelThe paper was presented at Tenth U.S. National Congress of Applied Mechanics, June 16-20, 1986, Austin, Texas, U.S.A. (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 453-465 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The accuracy of three numerical algorithms - the tangent-stiffness radial-return, secant-stiffness radial-return and simple radial-return methods - is analysed against exact solutions for the pressure-modified von Mises yield criterion with the associated flow rule. The governing equations of the exact solutions are derived using a simple and innovative geometrical approach, in terms of a pair of non-linear, first order differential equations, in rate change of the deviatoric radius and in rate change of angular locations on the deviatoric plane. For both accuracy and efficiency, and for small and large time steps, the secant-stiffness radial-return method is the best of all.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620260212
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    Three-dimensional elastic finite element study of the skid resistance of grooved pavement (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 437-452 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A three-dimensional finite element model has been developed to simulate the sliding of a rubber block over a grooved road surface. The model makes use of the symmetries of the problem to simplify the analysis, so that two-dimensional isoparametric elements of both rectangular and triangular configuration have been extended into the third dimension. A procedure for analysing the behaviour of any one groove to groove unit of the pavement is also developed, and this is extended so that the contact between the sliding rubber block and the leading edge of each raised pavement section is analysed. Preliminary comparisons between theoretical calculations and experimental measurements indicate that the finite element procedure provides an accurate and economical estimate of the behaviour of the rubber slider as it is pressed into a grooved pavement. Elastic predictions of sliding resistance seem reasonable at low sliding speeds, but viscoelastic rubber analysis appears necessary if higher speed skid resistance is to be predicted.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260211
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  • 91
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    Analysis of steady free convection from an axisymmetric heat-generating body embedded in a semi-infinite porous medium (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 467-487 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An analysis is presented for the steady state free convective flow and heat transfer from an axisymmetric heat-generating body that is embedded in a fluid-saturated, semi-infinite, porous medium. The porous medium is assumed to be rigid, homogeneous and isotropic, and be in thermal equilibrium with the fluid. The fluid is assumed to be incompressible, with the density changes contributing only towards the buoyancy forces via the Boussinesq approximation. The governing equations for the fluid consist of the equation of continuity, Darcy's law and the equation of energy. After introducing the stream function concept, the equations governing the stream function and pressure are derived. Using the non-dimensional variables, the non-dimensional equations governing the non-dimensional forms of the temperature, stream function and pressure are dervied and the appropriate boundary conditions are stated. The mathematical formulation contains two parameters; D, the non-dimensional depth of the body from the surface of the porous medium, and a product Raθs of Rayleigh number (Ra) and the non-dimensional surface temperature of the body (θs). The Galerkin finite element method, with linear, isoparametric, quadrilateral elements, is used to reduce the mathematical formulation into a set of algebraic equations. The expressions to calculate the non-dimensional surface temperature and Nusselt number of the body, and the non-dimensional velocity of the fluid, are derived. A computer code has been developed to solve the algebraic equations, using Gauss elimination procedure, in a banded matrix form. The computer code, in addition to the non-dimensional temperature, stream function and pressure, calculates the isothermal lines, non-dimensional surface temperature of the body, Nusselt number of the body, velocity field and isobars.To demonstrate the application of the code, a spherical heat-generating body is considered as an example. Numerical results are obtained for D = 3 and 6, and Raθs = 0.001, 0.1, 1 and 5, and presented.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260213
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  • 92
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    Masthead (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988) 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260301
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  • 93
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    Announcements (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 527-530 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260217
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  • 94
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    An integrated approach to the synthesis of geometrically non-linear structures (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 555-570 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An integrated approach to the minimum weight design of geometrically non-linear three dimensional truss structures with geometric imperfections, subject to inequality constraints on static displacements, stresses, local buckling and cross sectional areas, is investigated. The integrated structural synthesis problem involves design and response quantities as independent variables and equilibrium equations, describing the finite element model, as equality constraints. The non-linear structural analysis and the optimization are thus merged together into a single process. A computer program developed to compute the contraint values and analytical gradients is coupled with a generalized reduced gradient algorithm to solve the integrated problem. Numerical results for a geometrically non-linear shallow dome example problem are presented for various types of imperfections. Furthermore, it is found that the algorithm is capable of detecting and guarding against system as well as element elastic instability using equilibrium information only, that is, without imposing system and local buckling inequality constraints.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260304
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  • 95
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    Theoretical basis of the finite element iterative method for the eigenvalue problem in stationary cracks (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 531-539 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In a recently published paper a finite element based iterative method was introduced for the solution of the eigenvalue problem of stationary cracks.1 In this paper we give the theoretical basis of this iterative method and we show why it converges and how it could be extended to more complex fracture problems. The cases of cracks at interfaces are illustrated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260302
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  • 96
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    Application of the finite element iterative method to the eigenvalue problem of a crack between dissimilar media (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 541-554 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The finite element iterative method is applied to the eigenvalue problem of a crack between dissimilar media. In this case the transfer matrix is non-symmetric, which leads to complex eigenvalues. The singularity obtained agrees with the analytical results of r(-1/2+ie). The method of evaluating the eigenfunctions is general and can be applied to more complex cases of material and geometry, which are frequently encountered in composite materials. A powerful method for evaluating stress intensities in dissimilar media is given in the Appendix. The method is also reduced for homogeneous media to give stress intensity factors for modes I, II and III.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260303
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  • 97
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    Elasto-plastic large deformation analysis of space-frames: A plastic-hinge and stress-based explicit derivation of tangent stiffnesses (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 589-615 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper deals with elasto-plastic large deformation analysis of space-frames. It is based on a complementary energy approach. A methodology is presented wherein: (i) each member of the frame, modelled as an initially straight space-beam, is sought to be represented by a single finite element, (ii) each member can undergo arbitrarily large rigid rotations, but only moderately large relative rotations; (iii) a plastic-hinge method, with arbitrary locations of the hinges along the beam, is used to account for plasticity, (iv) the non-linear bendin-stretching coupling is accounted for in each member, (v) the applied loading may be non-conservative and (vi) an explicit expression for the tangent stiffness matrix of each element is given under conditions (i) to (v). Several examples, with both quasi-static and dynamic loading, are given to illustrate the accuracy and efficiency of the approaches presented.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260306
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  • 98
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    Multi-grid solutions to the elastic plastic torsion problem in multiply connected domains (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 631-646 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The elastic plastic torsion problem for an elastic, perfectly plastic cylinder with multiply connected cross section twisted around its longitudinal axis is formulated as an obstacle problem for an associated stress potential, the obstacle being defined in terms of a generalized distance function. Based upon the reformulation of the obstacle problem as an equivalent linear complementarity problem, the latter is discretized by means of finite difference techniques, and a monotonically convergent iterative scheme for its numerical solution is developed. At each step of the iteration the solution of a reduced system of discrete Poisson equations is required which is done by applying multi-grid techniques with respect to a hierarchy of grid-point sets. Combined with a suitably chosen nested iteration process this results in a computationally very efficient algorithm for the approximate solution of the elastic plastic torsion problem.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260308
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  • 99
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    Application of spline strip method to analyse vibration of open cylindrical shells (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 663-676 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper deals with the vibration of open cylindrical shells by the spline strip method based on Novozhilov's shell theory. Convergence of the solutions is investigated in a few examples and is found to be satisfactory. The accuracy of the results is compared with those calculated by other numerical methods and found to be in good agreement.The effect of inlcuded angles and inplane constraints on vibrating characteristics of simply supported cylindrical shells is shown.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260310
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  • 100
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    A quadrilateral finite element including vertex rotations for plane elasticity analysis (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 717-730 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A finite element of arbitrary quadrilateral shape is presented for plane elasticity analysis. The element is derived from triangular fields of compatible quadratic displacements with vertex connectors which include rotations. All rigid body movements and constant strain states are recovered exactly. Results from several test problems demonstrate that very good numerical accuracy is obtained for both displacements and stresses, even for quite coarse finite element meshes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620260314
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