EFFECT OF FIBER RUPTURE ON TENSILE PROPERTIES OF SHORT-FIBER COMPOSITES

A probabilistic-based micromechanical model has been developed for the postcracking behavior of a brittle matrix reinforced with short, rand omly distributed fibers. The model that predicts the composite bridgin g stress crack-opening displacement (GOD) relationship, accounts for f iber pullout, fiber tensile rupture, and a local frictional effect cal led snubbing, However, it does not account for fiber bending rupture, and the possible effect of matrix spalling at the exit points of incli ned fibers from the matrix. The model assumes a fiber/matrix interface that is controlled by a constant frictional bond stress. The model is used to predict the composite tensile strength and fracture energy. C omparisons of model-predicted bridging stress-GOD relationship with ex perimental data, where fiber rupture has occurred, show reasonable agr eement supporting the validity of the proposed model. The model is the n used to perform a parametric study to evaluate the effect of the mic romechanical parameters on the composite tensile strength and fracture energy. The study suggests that this model can be used to design the composite for optimum performance.