Papers by Keyword: Effective Moduli

Abstract: Theoretical and experimental estimation of elastic properties of two-phase composites containing matrix material and arc-shaped cylindrical fibers is given. Theoretical aspect consists in hybrid micro-macro formulation of problem with consideration of two associated subproblems –nume­rical simulation of fiber influence on the representative volume element and effective strain-stress field approximation by the averaging procedures. Boundary element method is applied for the solution of micro-level subproblem as well as Mori-Tanaka model is adopted for the overall description of composite properties at the macro-level. Then interfacial displacements are involved into solution scheme only. The effective elastic moduli of arc-fiber-reinforced composites are analyzed for the different materials combinations and fiber fractions. For the validation of numerical results, the prismatic concrete specimen filled by the curvilinear shaped cylindrical steel fibers under compression is investigated experimentally. Comparison of theoretical and experimental data is made.

Abstract: The problem of determining the effective properties of composite materials is actual problem for deformable body mechanics. The model, proposed by Crisher for modeling effective values of the coefficient of thermal conductivity, has been considered. Modifications of this mathematical model for two-component elastic composite were built. Model of Hill-Budiansky compresses classic fork of Voigt-Reuss, if it is added by Voigt component. Expressions of hybrid effective characteristics through the use of effective Hashin-Shtrikman moduli are built. The accuracy is estimated depending on the type of modification of the effective characteristics for the calculation of the stress-strain state of bodies (two-layer shell and three-layer plate) made from composite materials. The results are compared with the exact classical solutions, and admissible concordance is achieved.

Abstract: Elastic wave scattering of single spherical particle and the multiple scattering in particle-reinforced composite with imperfect interfaces are studied by the use of wave function expansion method. Four typical interfaces are obtained by appropriate selection of spring constants in the classical spring interface model, i.e. perfect interface, slide interface, rough interface and unbonded interface. The jump and continuous conditions of displacement vector and traction vector are used to derive the equation which the unknown expansion coefficients of the scattered wave field satisfy. Furthermore, the multiple scattering in composite reinforced by random distributed spherical particles is investigated. The effective velocity and attenuation of coherent waves and the dynamic effective moduli of composites are evaluated. The numerical simulation is performed for the SiC-Al composite. The influences of interface parameters on the scattering cross section, the effective velocity, the effective attenuation and the effective elastic moduli are discussed.