Micromechanical simulation of the failure of fiber reinforced composites

The strength of unidirectionally reinforced fiber composites is simulated using the three dimensional shear lag model of Landis, C. M., McGlockton, M. A. and McMeeking, R. M. (1999) (An improved shear lag model for broken fibers in composites. J. Comp. Mat. 33, 667-680) and Weibull fiber statistics. The governing differential equations for the fiber displacements and stresses are solved exactly for any configuration of breaks using an influence superposition technique. The model predicts the tensile strength of well bonded, elastic fiber/matrix systems with fibers arranged in a square array. Length and strength scalings are used which are relevant for elastic, local load sharing composites. Several hundred Monte Carlo simulations were executed to determine the statistical strength distributions of the composite for three values of the fiber Weibull modulus, m = 5, 10 and 20. Stress-strain behavior and the evolution of fiber damage are studied. Bundle sizes of 10 x 10, 15 x 15, 20 x 20, 25 x 25, 30 x 30 and 35 x 35 fibers of various lengths are investigated to determine the dependence of strength on the composite size. The validity of weakest link statistics for composite strength is examined as well. (C) 2000 Elsevier Science Ltd. All rights reserved.