Modeling of Progressive Damage in High Strain–Rate Deformations of Fiber-Reinforced Composites

We use the theory of internal variables, or equivalently of continuum damage mechanics, to develop a mathematical model involving three variables to describe the evolution of progressive damage in high strain–rate deformations of fiber-reinforced composites. The degradation of material parameters with the damage is considered. Values of material parameters in the postulated evolution laws of internal variables are determined from the test data. The delamination mode of failure is simulated by hypothesizing a damage surface in terms of transverse normal and transverse shear stresses acting on an interface between two adjoining layers. When the stress state at a point on an interface lies on this surface, delamination is assumed to ensue from that point. Initial-boundary-value problems are numerically solved to validate the mathematical model by comparing computed results with test findings. A Figure of Merit, equal to the percentage of work done by external forces dissipated by all failure mechanisms, is introduced to characterize the performance of laminated composites under shock loads.