The impact test is done to test

Toughness:Toughness is defined as the ability of the material to absorb energy before fracture TAKES place.This PROPERTY is essential for machine components that are required to withstand impact loads.Tough materials have the ability to bend, twist or stretch before failure takes place.Toughness is MEASURED by a quantity called modulus of toughness. Modulus of toughness is the total AREA under the stress-strain curve in a tension test.Toughness is measured by Izod and Charpy impact testing machines.When a material is heated it becomes DUCTILE or simply soft and thus less stress is required to deform the material and the stress-strain curve will shift down and the area under the curve decreases thus toughness decreases.Toughness decreases as temperature increases.