Toughness:

A quality called as toughness defines the way a material reacts under sudden impacts.  It is described as the work required deforming one cubic inch of metal until it fractures. Toughness is measured through the Izod test or the Charpy test.

Both of these tests use a notched sample. A location and shape of the notch are standard. The points of support of the sample, as well as the impact of the hammer, have to bear a constant relationship to the location of the notch.

Figure: Charpy Test Equipment

The tests are conducted through mounting the samples as displays in Figure and  permitting a pendulum of a known weight to fall  from a set height. The maximum energy established through the hammer is 120 ft-lb in the Izod test and 240 ft-lb in the Charpy test.  Through properly calibrating the machine, the energy absorbed through the specimen might be measured from the upward swing of the pendulum after it has fractured the material specimen as display in Figure.