Strain Energy: When an elastic member is deformed under the action of an external loading the member is said to have possessed or stored energy which is called the strain energy of the member or the resilience.

Strain energy due to bending: $\int_{}^{} \frac{M^{2}}{2EI} dx$

Strain energy due to S.F : $v=k\int_{0}^{L} \frac{V^{2}}{2GA} dx$

Strain Energy due to twisting moment:$\int_{}^{} \frac{T^{2}}{2GJ} dx$