The strain energy due to torsion is (torsion = T; modulus of elasticity = E; moment of inertia = I; shear modulus = G; polar moment of area = J)
1
\(\int\frac{T^2 dx}{2EI}\)
2
\(\int\frac{T^2 dx}{2GJ}\)
3
\(\int\frac{T dx}{2EI}\)
4
\(\int\frac{T dx}{2GJ}\)