Charpy impact test

A pendulum impact test in which a notched specimen is clamped vertically as a cantilever and struck by a swinging hammer, with the energy absorbed in breaking it recorded as a measure of toughness. The plastics versions are standardised in ISO 180 and ASTM D256.

The ability of a material to absorb energy and deform without fracturing, combining strength with ductility. Tough materials resist impact and flaw growth, whereas strong but brittle materials can fail suddenly.

A composite damage-tolerance test in which a laminate panel is first subjected to a controlled impact and then loaded in compression to failure to measure its retained strength. It matters because barely visible impact damage can markedly reduce compressive strength; ASTM D7137 is a widely used method.