you can consult  "A Pian–Sumihara type element for modeling shear bands at finite deformation" very useful paper of colin mcauliffe

Thank you my freind NOUNOU !!!! Sahite hhhh

Perhaps it models shear bands more accurately than other element types.  A bit of study on you side might get to grips with this.  Perhaps there is the odd theoretical solution that you might model...

I think that this is due to the fact that PS element is a mixed element in which both the displacements and stresses are approximated. Thus, the stress field is more accurate. Furthermore the element is free of volumetric locking and less sensitive to mesh distortion.

Best regards,

Phu

Thanks a lot for your answer