Izod impact strength test

A pivoting arm is raised to a specific height (constant potential energy) and then released.

Everyday engineering structures are subjected to it and may develop cracks that, over time, propagate to a point where catastrophic failure would result.

A material's toughness is a factor of its ability to absorb energy during relatively slow plastic deformation, though the rate at which strain occurs matters.

Brittle materials have low toughness as a result of the small amount of plastic deformation they can endure at any rate.

Alternatively, the results may be reported as energy lost per unit cross-sectional area at the notch (J/m2 or ft·lb/in2).