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, σ is axial stress, δL is elongation due to axial load)

• A. \(\frac{{{P^2}{L^2}}}{{2AE\left( {\delta L} \right)}}\)
• B. Area under stress versus strain diagram of axially loaded bar
• C. \(\frac{\sigma }{2}\frac{{\left( {\delta L} \right)}}{L}\)
• D. \(\frac{{{P^2}L}}{{2AE}}\)