Hi,
I have start to search about Creep and I have recently found a very interesting explanation of why convergence could be difficult with Calculix in some cases. The origin could be the Creep LAW=NORTON formulation itself. (Explained in the first two minutes of the vid).
According to the manual the stress is not normalized in Calculix, and it could lead to a tiny A parameter which further leads to rounding/convergence issues. Reviewing the example shown in the previous posts of ZFDong , I can see he is using an A parameter of A=2.5E-27. That seems a bad starting point for any numerical analisys. Maybe other unit system for the model would help to reduce that A value.
¿What do you think? ¿Or maybe directly normalizing the NORTON LAW and changing A by the initial Strain rate parameter in Calculix?
Regards,