Also, from the general expression for the Lagrangian and Eulerian finite strain tensors we have E ( m ) = 1 2 m ( U 2 m − − I ) = 1 2 m [ ( F T F ) m − − I ] ≈ ≈ 1 2 m [ { ∇ ∇ u + ( ∇ ∇ u ) T + I } m − − I ] ≈ ≈ ε ε e ( m ) = 1 2 m ( V 2 m − − I ) = 1 2 m [ ( F F T ) m − − I ] ≈ ≈ ε ε