The usual yield function proved in Eq. (42) does not produce precise physical response while linked with the phase-field model for crack growth. In the process of material failure, the damaged elastic reaction pulls the stress back within the yield surface and any further deformation up to complete failure is purely elastic.27 That is opposite to what is noticed physically for ductile materials where the deformation is controlled by plastic strain. To compensate for this behavior, plastic degradation function should take place in the yield surface. 46