Problem with UMAT for clay hypoplasticity. Program exiting.

Ashesh Choudhury|30.6.2023|Constitutive Modelling|0 |

Whenever I am running the umat for clay hypoplasticity, it is getting exited in ABAQUS by fulfilling the criteria testnan=1. It is failing the check – “check whether the strain rate from the ABAQUS is not NAN “. How can I resolve the issue? I am able to run the umat for sand hypoplasticity successfully though!