Hello everyone,

I am writing UMAT subroutine in ABAQUS to analyze the damage of the microscale RVE model(Fig.1 including fiber and matrix).However, the calculation to the damaged part doesn't converge or no results are output, even the DSTRAN appears NAN(Fig.2).

The UMAT.for has been judged by adding " IF...THEN END IF " statements of multiple materials according to the Abaqus help documentation(Fig.3). The two subroutines, including Fiber damage & Matrix damage, have been verified to work. I'm not quite sure if this flow is correct.

Could someone please tell me how to use one UMAT subroutine to correctly analyze the damage of the different components of the RVE model ? Or please provide some relevant solutions about realization of multiscale analysis of composites. Thanks all for your help.