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  • 1
    Electronic Resource
    Electronic Resource
    Strength of vibration-welded modified polyphenylene oxide structural foam butt joints (1992)
    Springer
    Journal of materials science 27 (1992), S. 5073-5083 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Tensile tests on 120 Hz vibration-welded butt joints of specimens cut from 6.35 mm thick plaques of modified polyphenylene oxide (M-PPO) structural foam have shown that 5% and 25% density reduction M-PPO structural foams weld well. This has been shown to be true for both foam-to-foam and skin-to-foam welds. The weld process phenomenology for these foams is shown to be identical to that for all neat resins: the penetration-time curve exhibits the four phases associated with vibration welding. The effect of weld pressure is not as significant as for solid M-PPO, for which increases in weld pressure are known to cause large decreases in weld strength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01105276
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  • 2
    Electronic Resource
    Electronic Resource
    Assessment of geometries for determining strengths of thermoplastic vibration welds (2000)
    Springer
    Journal of materials science 35 (2000), S. 2393-2403 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effects of weld geometry on the weld strength of thermoplastic resins, as determined by tests on vibration welds of bisphenol-A polycarbonate and poly(butylene terephthalate), are evaluated by tests on three weld geometries: butt welds, butt welds between specimens of different thicknesses, and T-welds. It is shown that only butt welds provide a true measure of the inherent weldability of resins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004788812627
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A comparison of rate sensitive constitutive equations under plane stress conditions (1980)
    Springer
    Acta mechanica 36 (1980), S. 231-246 
    Details
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Es werden numerische Lösungen für das dynamische Problem der Aufweitung eines Kreislochs in einer dünnen Scheibe, wobei eine konstante Beschleunigung am Lochrand vorgeschrieben wird, verwendet, um verschiedene, geschwindigkeitsabhängige viskoplastische Materialmodelle zu vergleichen. In den miteinander verglichenen Materialgesetzen ist der viskoplastische Teil der Verzerrungsgeschwindigkeit eine Funktion, die entweder exponentiell, linear, kubisch oder fünften Grades der Spannungszunahme gegenüber der statischen Spannungs-Dehnungskurve ist. Die Spannungsgeschichte und die Änderung der Plattendicke genommen am Lochumfang werden für verschiedene Belastungsgeschwindigkeiten und für einen weiten Bereich der Parameter des viskoplastischen Materialverhaltens berechnet. Die relative Brauchbarkeit der verschiedenen Modelle für komplizierte Spannungs- und Verformungszustände wird durch einen Vergleich der numerischen Lösungen abgeschätzt.
    Notes: Summary Numerical dynamic solutions of the circular hole enlargement problem for a thin plate, due to a constant acceleration imposed at the hole boundary, have been used for comparing different models for describing rate sensitive visco-plastic materials. In the constitutive equations that have been compared, the visco-plastic part of the strain rate is an exponential, linear, cubic and fifth power function of the overstress above the static stress-strain curve. Stress histories and the variation of the plate thickness, at the hole radius, have been computed for different rates of loading, and for a wide range of the parameter describing the visco-plastic behaviour of the material. The relative usefulness of the different models, for a complex state of stress and strain, has been assessed by comparing the numerical solutions for the different models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01214634
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  • 4
    Electronic Resource
    Electronic Resource
    On complex potentials in two-dimensional linearized elasticity with couple stresses (1969)
    Springer
    Acta mechanica 8 (1969), S. 304-322 
    Details
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Zur Lösung ebener Verzerrungsprobleme der linearen Elastizitätstheorie mit Momentenspannungen bei verschwindender Momentendichte wurde eine halbkomplexe Methode entwickelt. Zunächst wird eine Übersicht überMindlins undTierstens Herleitung [3] der Materialgleichungen der linearisierten Elastizitätstheorie mit Momentenspannungen undMindlins Theorie [4] den Spannungsfunktionen des ebenen Verzerrungszustandes gegeben. In Zusammenhang mit derMindlinschen Momentenspannungsfunktionψ werden zwei komplexe Potentiale eingeführt, die sich auf den Fall ohne Momentenspannungen reduzieren. Bei dieser Methode ist es nur notwendig, die Gleichungψ−l 2∇2 ψ=0 zu lösen. Die Ausdrücke für die zyklischen Funktionen des komplexen Potentials, die Verschiebungen und die Spannungsresultanten werden untersucht. Allgemeine Methoden zur Bestimmung des Potentials werden diskutiert. Lösungen verschiedener Probleme in Polarkoordinaten insbesondere für kreisförmige Löcher werden studiert.
    Notes: Summary A semi-complex-variable technique has been developed for solving planestrain problems in linear elasticity with couple stresses when the body moments are zero. In conjunction with theMindlin couple-stress functionψ, two complex potentials are introduced which reduce to those of the non-couple-stress case. With this technique it is only necessary to solve the equationψ−l 2∇2 ψ=0 forψ. Expressions for the cyclic functions of the complex potentials, displacements and stress resultants are investigated. General methods of determination of the potentials are discussed. Solutions of problems in polar coordinates and in particular for circular holes are studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01182266
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  • 5
    Electronic Resource
    Electronic Resource
    Local stiffness-density correlations for polycarbonate structural foams (2000)
    Springer
    Journal of materials science 35 (2000), S. 159-178 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Most studies on the mechanical properties of foams have focused on correlating pointwise, through-thickness elastic modulus and density variations. These local property correlations have then been used to predict the tensile and flexural moduli of foam bars. However, there is some question as to the meaning of a pointwise local density for a cellular material, and the dependence of local modulus on the local density is difficult to measure. This paper is concerned with correlating the density and tensile moduli of structural foams over a 12.7-mm scale. Data obtained from tests on 6.35-mm- and 4-mm-thick polycarbonate foam plaques, molded at nominal density reductions of 5, 15 and 25%, are used to show that the local average tensile modulus of the material correlates linearly with the local average density of the material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004717321666
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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Strength and bonding mechanisms in vibration-welded polycarbonate to polyetherimide joints (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 1667-1676 
    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: Under the right conditions, high strengths are shown to be achievable in vibration welded polycarbonate to polyetherimide Joints. While welding of thermoplastic interfaces of the same material can be understood in terms of interchain diffusion at elevated temperatures, this mechanism is severely limited in the case of dissimilar materials. Scanning electron microscopy is used to show that part of the bond strength in such dissimilar materials results from mechanical interlocking of the two polymers, which is caused by viscous mixing. The effects of the weld parameters on the weld morphology are considered in detail.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760292308
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  • 8
    Electronic Resource
    Electronic Resource
    Vibration welding of thermoplastics. Part IV: Strengths of poly(butylene terephthalate), polyetherimide, and modified polyphenylene oxide butt welds (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 998-1008 
    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 are the weld frequency, the amplitude of the vibratory motion, the weld pressure, and the weld time or weld penetration.; The effects of these parameters on weld quality were systematically studied by first butt welding thermoplastic specimens under controlled conditions, over a wide range of process parameters, and by then determining the strengths and ductilities of these welds by tensile tests. The three thermoplastics investigated are poly (butylene terephthalate), polyetherimide, and modified polyphenylene oxide. Changes in the weld pressure are shown to have opposite effects on the strengths of polyetherimide and modified polyphenylene oxide welds; Also, the weld frequency is shown to have a significant effect on the weldability of polyetherimide. The weldability data for these three thermoplastics are compared with data for polycarbonate. Under the right conditions, the strengths of butt welds in these materials are shown to equal the strength of the virgin polymer.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281509
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  • 9
    Electronic Resource
    Electronic Resource
    Steady melting of rectangular thermoplastic bars induced by hot contacting surfaces (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 1147-1162 
    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 steady melting of rectangular thermoplastic bars in contact with hot surfaces is analyzed by solving a simplified set of the momentum and energy balance equations, assuming a temperature and shear-rate dependent melt viscosity. A numerical model is developed for predicting the flow field and the temperature distribution in the solid and molten regions of the bar and the location of the solid/melt interface. Computer simulations show that the steady melting rate of the thermoplastic solid is mainly affected by the temperature sensitivity of the melt viscosity, by the pressure applied on the end of the bar, and by a balance between heat conduction and the convection of colder material into the molten region. For the amorphous and semicrystalline polymers considered, heat convection in the outflow direction of the molten material, viscous dissipation, and shear-thinning of the melt viscosity have a much smaller effect on the melting process. These results provide an insight into conduction-induced melting with forced melt removal caused by pressure-induced flow; they also provide a basis for developing a transient model for the hot-tool welding process.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760321612
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  • 10
    Electronic Resource
    Electronic Resource
    Vibration welding of thermoplastics. Part II: Analysis of the welding process (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 728-739 
    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 vibration welding process for thermoplastics is known to consist of four phases: (1) initial heating of the interface to the melting temperature by Coulomb friction; (2) unsteady melting and flow in the lateral direction; (3) steady-state flow; and (4) unsteady flow and solidification of the film after the vibratory motion is stopped. Simple analytical models are developed for the first three phases. These models are used for estimating the molten film thickness, the size of the heat affected zone, and the weld time as functions of the weld parameters: the amplitude and frequency of the weld motion, and the weld pressure. The steady-state film thickness and the heat-affected zone are shown to be very small.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281105
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