DSTRAN in UMAT with nonlinear geometry
Dear Colleagues,
I have done some analysis with nonlinear geometry. I use quadratic 3D solid elements. I have learned the way to calculating DSTRAN and DROT from ABAQUS documentation as follows:
ΔF*F (t)= F (t+dt)ΔF=ΔV*ΔR
DSTRAN=ln(ΔV)
DROT=ΔR