Micromechanical modeling of tensile behavior of short fiber composites

A simple micromechanical constitutive model is developed for short fiber reinforced composites (SFRC) undergoing damage. The model is based on the Carman and Reifsnider approach for the prediction of mechanical properties of discontinuous fiber reinforced composites. The composite is modeled by a distributed representative element composed of concentric circular cylinders using a general 3D configuration. The micromechanical model is used to evaluate the elastic properties of SFRC, by varying the orientation distribution of the fiber, the length distribution of the fiber and the fiber-fiber interaction phenomena. The composite is assumed to behave as linearly elastic in absence of any debonding of fiber from the matrix and in the fully debonded stage. The stress-strain behavior of molded composite materials and the debonding are modeled using the Hsueh model to estimate the debonding stress for misaligned fibers. A good agreement between calculated and experimental data was achieved.