Toughness

The toughness of a material measures the energy absorbed to the point of fracture. This quantity is dependent upon the strain rate, the temperature, and the geometry of the sample. Toughness is, therefore, test condition dependent.

For a constant strain rate tensile test, toughness is the area under the stress strain curve to the point of fracture.

In an impact test, the energy adsorbed by the sample is measured in terms of the energy loss experienced by the impacting hammer.

As the temperature of the sample is changed it may go from high toughness (large energy absorption) at elevated temperatures to brittle (low toughness) behavior at low temperatures. The ductile-brittle transition temperature is an important property.