Numerical analytical method of predicting the durability of fibrous composite materials under conditions of biaxial cyclic loading

Abstract

A combined numerical-analytical method for predicting the durability of fibrous composite materials under conditions of biaxial cyclic loading is proposed. The model of nonlinear elastic behavior of random composites is used. The mechanics problem of determining the stress-strain state in the matrix and fibers is solved within the framework of the physically nonlinear theory of elasticity with the use of numerical methods. To predict the durability of an anisotropic composite in the macro volume, the matrices strengthening effect were used. The method of determining the equivalent stress used for asymmetric two-dimensional loading is considered. The influence of the average stress on the fatigue characteristics of the matrix with nonlinear strengthening is shown. Examples are given that illustrate the importance of the mutual influence of nonlinear elastic and anisotropic properties of the composite on the redistribution of stresses in the fibers and the matrix. As a practical result, we can note the possibility of predicting the long-term strength of the material when the field of cyclic stresses is determined in the vicinity of the inclusions. For a detailed analysis of local stress fields and specification of the type of complex load in structural elements, a numerical analysis was performed using finite element programs for a single, forming cell in the context of random homogenization.