Load carrying characteristics of short fiber composites containing a heterogeneous interphase region

A micromechanics finite element model has been developed for the stress transfer in short fiber composites, incorporating a heterogeneous interphase region. The specimen consists of a single fiber under stress embedded in an epoxy matrix. Considering a heterogeneous and compliant interphase, a generalized computational procedure has been developed that enables imperfect adhesion or loss of interphasial strength simulations. Varying the global variables of the problem, parametric studies were performed to study the influence of the model parameters on the load transfer characteristics from the fiber to matrix. Numerical results of the stress distribution have been determined as a function of geometric and material variables. The effect of both the imperfect adhesion between the fiber and the matrix, and the loss of interphase compliance on stress state were demonstrated and discussed. The results showed that the interphase plays a significant role in stress transfer characteristics of fibrous composites, and extension of the load transfer zone is restricted very close to the loaded fiber end.