2007 Volume 1 Issue 1 Pages 102-113
This study deals with analytically evaluating the stress concentrations near loaded and initial fiber breaks in unidirectional composites with matrix yielding and interfacial sliding. To this end, by performing a detailed 3D finite element analysis, it is demonstrated that significant nonproportional straining occurs in the matrix near loaded fiber breaks in contrast to initial breaks, and that such nonproportional straining induces almost elastic developments of matrix shear stress near loaded fiber breaks. Then, the 3D shear-lag closed-form solution derived by the present authors, which is modified so as to be effective over a wide range of fiber volume fractions, is shown to be applicable to loaded, as well as initial, fiber breaks, provided the matrix shear modulus in the solution is prescribed by taking account of the nonproportional straining. It is thus demonstrated that the nonproportional straining in the matrix can lower the stress concentrations near loaded fiber breaks in the presence of matrix yielding.
