Micromechanical analysis of transversal strength of composite laminae

Abstract

The paper presents analysis of several micromechanical models for estimating transversal strength of composite laminae and comparing theoretical results with the available experimental data. The tensile, compressive and shear transversal strengths are analyzed. For a load transversal to the fiber direction, micromechanical analysis becomes complicated due to stress concentration. In order to deal with it, an elasticity-based solution is used to obtain stress around single inclusion in infinite matrix. In addition, the finite element simulations are carried out to derive approximation functions for actual values of fiber volume fraction. For tensile transversal strength, the density of dilatational energy is assumed to be the dominant failure mechanism, while for the compressive transversal strength, the interface failure is modeled. Since the critical dilatational energy and interface strength are commonly unavailable in literature, average values are obtained based on the experimental data. Alternatively, a semi-empirical modification of Chamis model is also proposed. For transversal shear strength, the results indicate that the matrix shear strength provides a good approximation. It should be noted that closed-form expressions are obtained, resulting in simple and efficient implementation for engineering applications and design optimization. Results are compared with other micromechanical models and with 58 experimental data from the literature. In general, elasticity-based models and modified Chamis model present a considerable advancement in transversal strength estimation with the small average errors.