Effect of temperature and stacking sequence on the impact behavior of CARALL fiber metal laminates

The study evaluated the influence of operational temperature on impact energy absorption behavior of carbon fiber-reinforced aluminum laminates (CARALL) with different stacking sequences. Fiber Metal Laminates (FMLs) with three different stacking sequences, CARALL-SS 1, CARALL-SS 2, and CARALL-SS 3, were developed, and their impact absorption capacity was compared with carbon fiber-reinforced polymer (CFRP). The results from the Charpy impact test demonstrated a significant influence of operating temperature and stacking sequence on impact energy. An impact energy of 7.44 J absorbed by CARALL-SS 1 was significantly higher than the other two stacking orders explored in the study. The increased energy absorption by CARALL-SS 1 laminates is attributed to the inherent energy absorption capability of aluminum and CFRP plies and the strong interfacial adhesion between the metal-composite plies. Additionally, the impact energy absorbed by the FMLs was affected by operational temperature. Thermal softening at a higher temperature (180 °C) lowered the strength of aluminum and decreased the interfacial strength, thus lowering the impact energy absorption capacity of the FMLs by 19.2%–31.3% compared to room temperature. Moreover, a 9.3%–12.3% reduction in the impact energy absorption capacity was noted in FMLs subjected to a low-temperature atmosphere (−40 °C). At higher temperatures, the aluminum layers showed shear failure, while fibers were subjected to breakage, while at lower temperatures, both metal and composite layers were subjected to brittle failure. Exposure to a lower temperature reduced the adhesion strength between metal-composite layers, resulting in ply delamination and debonding.