OOF2: The Manual

Name

Mechanical:Elasticity:LargeStrain:Isotropic — Isotropic large-strain elasticity.

Details

Discussion

The isotropic large strain elasticity Property specifies that the Stress depends nonlinearly on the gradients of the Displacement, \(u\):


      \[ \sigma_{ij} = C_{ijkl}\epsilon_{kl} \]
    (6.19)

where \(\sigma_{ij}\) is the Stress, \(C_{ijkl}\) is an isotropic fourth rank tensor given by the modulus cijkl, and \(\epsilon\) is the nonlinear geometric strain,


      \[ \epsilon_{ij} = \frac12\left(
      \frac{\partial u_i}{\partial x_j}
      + \frac{\partial u_j}{\partial x_i}
      + \frac{\partial u_k}{\partial x_i}\frac{\partial u_k}{\partial x_j}
      \right). \]
    (6.20)

This form of the geometric strain is invariant under rigid rotations, unlike its linear variant, Eq. (6.2).