Modeling of residual stress-induced stress-strain behavior of unidirectional brittle fiber/brittle matrix composite with weak interface

To describe the residual stress-induced interfacial debonding and stress-strain behavior of unidirectional brittle fiber/brittle matrix composite with weak interface, a simulation method, based on the modified shear lag analysis which can take residual stresses into account and Monte Carlo procedure, was presented, and was applied to a model composite similar to polymer-derived SiC/ceramic glass system. Main results are summarized as follows. (1) It was shown concretely that the broken component-induced debonding is encouraged and discouraged when the corresponding component has tensile and compressive residual stresses, respectively. (2) The feature of the damage-(breakage of fiber, breakage of matrix and interfacial debonding)-accumulation process and its influence on the stress-strain curve could be realized in the computer; the damages are accumulated intermittently, resulting in a serrated stress-strain curve of composites. In such a damage accumulation process, the existence of residual stresses change the order and location of occurrence of damages and therefore the stress-strain curve and strength of the composite. (3) The dependence of the composite strength on the matrix strength in the presence of residual stresses was clarified; the composite strength increases significantly with increasing matrix strength when the fiber and matrix have compressive and tensile residual stresses along the fiber axis, respectively, but only marginally when they have reversed residual stresses. (C) 2003 Elsevier Science Ltd. All rights reserved.