Plastic criteria

The PlasticCriterion class manages the possibility to replace the default Von Mises plastic criterion by another one, described below.

Plastic criterion for orthotropic composite plies with unidirectional fibers. Also used with woven fibers.

$$ \overline{\sigma} = \sqrt{\sigma_{12}^2+\sigma_{13}^2+\sigma_{23}^2 +a^2\, \sigma_{22}^2 +b^2\, \sigma_{33}^2} $$