Unlike metals, composites don’t always fail in a single, visible way. Instead, they absorb energy through mechanisms like matrix cracking, delamination, and fiber breakage, which can reduce structural performance without immediate failure. Standardized tests like Charpy, Izod, and drop-weight impact help quantify how energy is absorbed, but understanding real-world performance requires looking beyond a single number. For composite sheets, both impact energy and post-impact behavior play a critical role in how the material performs in service.