Low-velocity impact perforation response of titanium/composite laminates: analytical and experimental investigation

The low-velocity impact perforation behavior of fiber-metal laminates (FMLs) is evaluated by analytical modeling. Four different FML layups consisting of glass fiber/epoxy layers and titanium alloy Ti-6Al-4V sheets are fabricated, exhibiting the same thickness of total metal layers. The perforation behavior, threshold, and energy absorption mechanisms of FMLs are assessed using a mass-spring system. The results indicate that the elastic-plastic force history of FMLs up to maximum force predicted by both membrane and bending strain energy (M & B) and membrane strain energy only (M only) is found to be in good agreement with experiments, with M only matches closely than both M & B. The principal part of the total energy absorption of FMLs with both M & B and M only accounts for the energy absorption associated with global deformation of titanium and glass/epoxy layers, which is 67-71% and 65-69%, respectively. Here, a higher percentage of energy is absorbed by FML 4/3-0.3, succeeding by FMLs 3/2-0.3(O), 3/2-0.4, and 2/1-0.6. The predicted perforation threshold and overall energy absorption by various damage mechanisms of FMLs are in good comparison with experiments. The perforation response has also been predicted for aluminum-based FMLs, agreeing well with experiments. This insists on the robustness of the offered model. Also, the perforation resistance seems to be higher for titanium-based FMLs than aluminum-based FMLs. The overall energy absorption seems to be higher for titanium-based FMLs under low-velocity impact than high-velocity impact. This is also observed in the case of aluminum-based FMLs.