Experimental study on the impact resistance and damage tolerance of thermoplastic FMLs

Abstract

This study aimed to enhance the impact resistance of fiber metal laminates (FMLs) and achieve lightweight optimization by incorporating a new thermoplastic resin, a titanium alloy and ultra-high-molecular-weight polyethylene (UHMWPE) fiber to produce a novel type of FMLs (PEFMLs). The impact resistance of PEFMLs was analyzed through low-velocity impact tests conducted at different energy levels. Subsequently, the residual compression-after-impact (CAI) strength of the PEFMLs was evaluated through compression tests on the impacted specimens. The experimental findings revealed that PEFMLs exhibited subcritical failure when subjected to impact energies less than 35 J, with a penetration energy threshold of 55 J. Higher impact energies resulted in larger damage areas and increased plate buckling of PEFMLs, consequently leading to reduced CAI strength. The presence of metal, thermoplastic resin and UHMWPE in the PEFMLs effectively dissipated a substantial amount of impact energy while maintaining their structural integrity during both the impact and compression processes.