Original: Resilience is the property of a material to absorb energy when it is deformed elastically and then, upon unloading to have this energy recovered.
Simplified: Modulus of Resilience, U_r, can be calculated using the following formula: U_r = frac {sigma ^ 2} {2E} = 0.5 sigma epsilon = 0.5 sigma (frac {sigma} {E}), where sigma is yield stress, E is Youngs modulus, and epsilon is strain.