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  • Articles: DFG German National Licenses  (17)
  • Engineering  (8)
  • mesophase  (8)
  • Classical period  (1)
  • 1
    Electronic Resource
    Electronic Resource
    On the evaluation of adhesion between phases in fiber composites (1984)
    Springer
    Colloid & polymer science 262 (1984), S. 929-938 
    Details
    ISSN: 1435-1536
    Keywords: Fibrous composites ; mesophase ; unfolding models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A theoretical model was introduced for the evaluation of the boundary layer developed between the main phases during the preparation of unidirectional fiber composites. It has been shown that this thin layer influences considerably the physical properties of the composite. It was assumed that the physical properties of themesophase unfold from those of the hard-core fibers to those of the softer matrix. Thus, a multicylinder model was assumed improving the classical two-cylinder model introduced by Hashin and Rosen for the representative volume element of the composite. Based on thermodynamic phenomena appearing at the glass transition temperatures of the composite and concerning the positions and the sizes of the heat-capacity jumps there, as well as on the experimental values of the longitudinal elastic modulus of the composite, the extent of the mesophase and the mechanical properties of the composite may be accurately evaluated. This version of the model is based on a previous one concerning a multilayer model, but it is considerably improved in order to take into consideration, in a realistic manner, the physical phenomena developed in fiber reinforced composites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01490025
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The influence of the mesophase on the transverse and longitudinal moduli and the major poisson ratio in fibrous composites (1986)
    Springer
    Colloid & polymer science 264 (1986), S. 561-569 
    Details
    ISSN: 1435-1536
    Keywords: Fibrous composites ; mesophase ; longitudinal elastic modulus ; transverse elastic modulus ; major Poisson ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Expressions for the evaluation of the transverse and longitudinal elastic moduli and the major Poisson ratio of unidirectional fiber composites are derived. The model described is based on the correct version of Kerner's model, which in our case is conveniently modified by introducing a mesophase layer between the fiber and the matrix in the representative volume element surrounding the typical fiber. The expression for the longitudinal elastic modulus derived in this paper, and the law of mixtures already presented in previous papers, give concordant results. Therefore, the law of mixtures, taking the mesophase also into account, and the two-term unfolding model for the mesophase are used for the evaluation of its extent and its properties. The model was applied to a glass filament-epoxy resin composite and its predictions were found to be in good agreement with the experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412593
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Phase transformation, at the boundary layers between polymers, and solid surfaces (1985)
    Springer
    Colloid & polymer science 263 (1985), S. 863-872 
    Details
    ISSN: 1435-1536
    Keywords: Composites ; mesophase ; unfolding models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The size of the mesophase, which constitutes a boundary layer between fillers and matrix in composites, has been efficiently evaluated by the modified two-term unfolding model, which was based on delicate DSC measurements of the heat capacity jumps at the glass transitions of the composite and its constituent phases [1,2]. This model is now used to evaluate the mesophase along the whole viscoelastic spectrum of the composite, by making measurements of the storage and loss compliances or moduli of the composite and matrix and without making recourse to any other type of special measurement at the glass transition temperature of the substances. By applying this model the following important results were derived: i) Lipatov's empirical formula for defining the mesophase atT g was shown to yield reasonable results and ii) the evaluation of the size of mesophase over the entire viscoelastic spectrum was shown to remain almost constant and in conformity with the values defined by the other versions of the model. Extensive application of the experimental results of the literature indicated the mutual proof of the validity of these affine models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01469622
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  • 4
    Electronic Resource
    Electronic Resource
    Accurate evaluation of the transverse shear modulus in unidirectional fibrous composites (1987)
    Springer
    Rheologica acta 26 (1987), S. 182-192 
    Details
    ISSN: 1435-1528
    Keywords: Transverseshear modulus ; unidirectionalfiber composite ; mesophase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A new relation for the prediction of the transverse shear modulus in unidirectional fiber composites has been derived. The theoretical results of this relationship are in better agreement with the experiments than those of other relations, existing in the literature. The discrepancies, which are observed among the theoretical predictions and the experimental values, are explained by the consideration of the boundary layers existing between the matrix and the fibers of the composite. A new model, which includes the intermediate phase between the matrix and the fiber, called the mesophase, is considered in order to take into account the above-mentioned layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01331976
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  • 5
    Electronic Resource
    Electronic Resource
    Geophysical prospection, archaeological excavation, and dating in two Hellenic pyramids (1996)
    Springer
    Surveys in geophysics 17 (1996), S. 593-618 
    Details
    ISSN: 1573-0956
    Keywords: Pyramid ; magnetics ; electromagnetics ; archaeology ; pottery ; Helladic ; Hellenistic ; Classical period ; excavation ; thermoluminescence (TL) dating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Geophysical prospection employing magnetometry and electromagnetic measurements has been applied in and around two small sized pyramids of Hellenikon and Ligourio in Argolid, Greece. The magnetic anomalies appropriately assessed were interpreted as possible archaeological targets. Subsequent test excavations revealed the presence of room foundations and parts of walls, as well as a plethora of ceramic ware. Typological study of the ceramics classified them to as early as the proto-Helladic period and to as late as the first centuries A.D. The earlier periods have been also confirmed by a novel application of thermoluminescence (TL) dating of ceramics and the megalithic stones themselves. The present results question earlier attempts classifying these pyramids at the Classical period and favour much earlier periods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01888980
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The exact shear modulus of particulates based on the concept of mesophase (1990)
    Springer
    Colloid & polymer science 268 (1990), S. 1118-1130 
    Details
    ISSN: 1435-1536
    Keywords: Particulatecomposites ; Kernermodel ; Christensenfield ; mesophase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An accurate relationship for the shear modulus of particulates is derived based on the Kerner model, but not using its approximate relations. Furthermore, the model takes into account the existence of the mesophase layer between the inclusions and the matrix, which acts as a smooth transition boundary layer between constituent materials. By applying Christensen's field to the Kerner model, modified by introducing the mesophase, the new model is liberated from any inconsistencies. Experimental evidence and application to a glass particle-epoxy resin-matrix composite indicated the superiority of the model over previous ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410677
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  • 7
    Electronic Resource
    Electronic Resource
    Diffusion-based adhesive bonds between phases in fibrous composites (1990)
    Springer
    Colloid & polymer science 268 (1990), S. 414-425 
    Details
    ISSN: 1435-1536
    Keywords: mesophase ; fibrouscomposites ; diffuseboundary ; polymer-polymer adjacent phases ; diffusion reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper the mesophase developed between main phases in fibrous composites was studied assuming that it constitutes a diffuse boundary. This type of mesophase is normally developed in polymer-polymer adjacent phases and it it useful for the study of modern composites disposing a coupling agent between main phases. At the high temperature of reaction of phases during the casting process both neighboring phases are partly liquified, allowing a two-way movement of elements of either phase whose intensity and extent depends on the particular diffusion characteristics of either phase and the affinities between them. The characteristics of this diffusion reaction were studied and their influence on the development and the properties of the adhesion between phases were established, especially for fiber composites. Interesting results were derived concerning the extent of the diffusive mesophase and its mechanical properties, as well as its contribution on the global mechanical behavior of the composite. Finally, the results were found to be in agreement with previously established models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411000
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    The shear modulus in the fiber direction of unidirectional fiber composites based on the concept of mesophase (1987)
    Springer
    Rheologica acta 26 (1987), S. 322-327 
    Details
    ISSN: 1435-1528
    Keywords: Shear modulus ; fiber composite ; mesophase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A new and accurate relationship for the shear modulus in the fiber direction of unidirectional fiber composites is derived, based on the Kerner model concepts but not using its approximate relationships. Furthermore, this model is extended by taking into account the mesophase between the fiber and the matrix accomodating smoothly the mechanical properties between neighbouring phases. The introduction of the mesophase results in an improvement of the theoretical predictions, which now approach close to experimental values for the moduli of different fibrous composites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01332249
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    The elastic modulus of particulate composites using the concept of a mesophase (1986)
    Springer
    Rheologica acta 25 (1986), S. 350-358 
    Details
    ISSN: 1435-1528
    Keywords: Composite ; elastic modulus ; mesophase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A theoretical model for the evaluation of the elastic modulus in particulate composites has been developed. The method takes into account the existence of a mesophase between main phases, which constitutes an important parameter influencing the behaviour of a composite material. This layer between the matrix and filler develops different physico-chemical properties from those of the constituent phases and variable ones along its thickness. The effect of the progressive variation of the elastic modulus of the mesophase on the modulus of the composite was estimated by applying various simple laws of variation. Convenient laws of variation were introduced, varying from a simple one, assuming a linear law, to a more refined one using a parabolic law. Experimental results with particulates, based on iron-filled epoxy composites, compared satisfactorily with other models. However, the model based on a parabolic law was superior to all others on physical grounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01331505
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  • 10
    Electronic Resource
    Electronic Resource
    A relaxation technique for evaluating stress intensity factors by the finite element method (1983)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 19 (1983), S. 17-26 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A simple two-step corrective technique is presented in this paper for evaluating stress intensity factors in crack problems. In the first step an approximate evaluation of the stress intensity factor was made by considering the cracked plate to be of infinite size. The stresses of the problem were relaxed by the stresses of the infinite body which corresponds to the approximate value of the stress intensity factor. The expected discrepancy in the value of SIF by the infinite plate approximation was corrected in the second step where the existing residual stresses are equilibrated at the cracked plate by using any of the conventional finite element techniques and the corrective value of the stress intensity factor is calculated by using an appropriate collocation formula. The method was applied to three typical plane problems of cracked plates with satisfactory results.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620190104
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    Paper (German National Licenses)
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