Hi,

I want to write a UMAT for elastic material based on continuum damage mechanics. It is simply to incorporate a scalar damage variable in the stiffness matrix (DDSDDE) which makes it look like

dsigma = (1-D(epsilon + depsilon)) E depsilon

Here epsilon is the strain at the beginning of the time increment that is stored in STRAN. So in UMAT we just need to provide a functional form of D(epsilon + depsilon) and then this nonlinear equation group will be solved automatically in the ABAQUS solver with Newton-Raphson scheme for example, right? Thanks!