Hi Md_Salem
You will need to show your work and prove this. I just tried with Verfication Manual model 61 using version 2023R2 of Mechanical APDL and PhiTMPhi was the identity matrix with off diagonal terms on the order of 1E-12 which is close enough to zero for engineering needs (diagonal terms exactly 1).
Mike
You are navigating away from the AIS Discovery experience