Models for Analysis of the Effective Properties of Hybrid Composites

摘要

Hybrid composites have been studied and used for several decades. When differentrnlayers are used for the creation a hybrid composite, classical laminating theory isrnusually applicable. For in-layer hybridization the prediction of longitudinalrnproperties using mixture rules gives practically acceptable results. The mainrndifficulties appear in the transversal properties prediction. A majority of knownrnapproaches use the results of theoretical modeling of usual unidirectionalrncomposites in combination with some additional assumptions. Most of the formulaernrepresent the additive contribution of two or more sets of fibers. However, thernconcentrations of fibers participate in these formulae in a nonlinear way andrnsuperposition in such a situation is incorrect (or it can be acceptable if concentrationrnof one set of fibers is small). This report presents a short review of the approachesrnpublished until now and discusses some new models based on differentrnmathematical techniques. One technique is using double periodicity of the hybridrnstructure with a complicated unit cell. Another technique is using the idea of thern“anisotropic matrix” created by matrix and one set of fibers and reinforced byrnsecond set of matrix. One more technique is based on Rayleigh’s idea about directrnsummation of the fields disturbances created by the presence of neighborrninclusions. The results of the prediction of transversal characteristics are illustratedrnby numerical examples demonstrating some common tendencies and somerndifferences. Longitudinal strength drop due to mismatch of ultimate strains of fibersrnand first ply failure are discussed.