Hello everyone.
I am trying to do something with the deformation gradient in UMAT. I used F=DFGRD0 as the gradient. but i found that it always comes to be a identity tensor not only for the case of a 3d isotropic elastic material but also for the ramberg osgood model. it was very surprising for me so i also tried to print DFGRD1 it was also identity tensor.
I have used a C3D8 single element and was doing the uniaxial test. Please help me out with this.
For one element under
For one element under uniaxial, you may not have shear. You can either try your model with more elements or do a simple shear simulation.
Read the documentation.
Is that simple.