Standardization of the refund rate G
======================================


2D plane stresses and plane deformations
--------------------------------------------

In dimension 2 (plane stresses and plane deformations), the crack bottom is reduced to one point and the value :math:`G(\theta )` from the CALC_G command is independent of the choice of field :math:`\theta`:

     :math:`G=G(\theta )\forall \theta \in \Theta`


Model symmetry
------------------

If we only model half of the solid in relation to the crack:


* or specify the keyword SYME =' OUI 'in the commands concerned;


*or do not forget to multiply by 2, the values of the energy recovery rate :math:`G` or :math:`G(s)` and by 4 those of :math:`{G}_{\mathrm{Irwin}}`*.* In addition, the values of the stress intensity factors corresponding to the mode of symmetry must also be multiplied by 2.