Strain energy U, in the case of axially loaded bar is expressed as. (where P is axial load, L is bar length, A is cross-section area of the bar, E is Young’s Modulus of the bar, $$\sigma$$ is axial stress, $$\delta L$$ is elongation due to axial load)

A

$$\frac{P^2L^2}{2AE(\delta L)}$$

B

Area under stress versus strain diagram of axially loaded bar

C

$$\frac{\sigma}{2}\frac{(\delta L)}{L}$$

D

$$\frac{P^2L}{2AE}$$