Deformation gradient in VUMAT of ABAQUS
Dear All,
In ABAQUS manual, it is said for hyperelastic material, it is better to define it by stretch tensor U. But if I need to use deformation gradient F in the material model directly, I need to rotate the stress back to corotational frame. How should I do that? Should I make a polar decomposition of F=R*U first, and then apply Rt*S*R? or I can use the relative spin increment already provided to do that? If so, how?