Finite element analysis of thermoelastoplastic stresses in composites

A new formulation has been developed for finite element analyses of thermoelastoplastic stresses in continuous fiber-reinforced composites. The formulation computes stresses at the micromechanics level, in other words stresses occuring in fiber and matrix of a composite. Thermoelastic deformation of fiber and thermoelastoplastic deformation of matrix are considered in the formulation because the yield strength of matrix is, in general, substantially lower than that of fiber. If matrix is assumed homogeneous and isotropic, the von-Mises yield criterion is used for plastic yielding. As numerical examples, thermal stresses at the micromechanical level are computed for unidirectional and symmetrically laminated composite plates with various fiber orientations and fiber volume fractions.