On the evolution of energy dissipation in dispersed composite laminates under out-of-plane loading

In this paper, we present a novel model to predict the energy dissipation in composite laminates during out-of-plane loading based on experimental observations. Damage mechanisms and their sequences in composite laminates under out-of-plane loading were experimentally investigated and correlated with the energy dissipated during loading. The results showed that the energy dissipated during fiber breakage was around 3 times larger than that for delamination propagation. The first damage mechanism occurred during out-of-plane loading is matrix cracks and induced delaminations. Then, delamination propagated at different interfaces mainly at the lower half of the laminate dividing the laminate to sub-laminates. Once the normal tensile stresses due to bending at the lower plies reached the tensile strength of fibers, fiber breakage occurs causing large load drop and energy jump. The propagation of fiber breakage caused continuous load decrease and dissipation energy increase until complete perforation of the sample. Based on our experiments and others available in the literature, we concluded that the developed model is independent of the material type, stacking sequence, impactor size and boundary conditions. The model can be used as fast tool for designing composite laminates based on the energy dissipation and residual compressive strength.