Dear Irene,
I am not sure if I understand your question. I assume you have already read the related sections of the ATENA Troubleshooting Manual, sections
2.2.2 I get the message "The execution is killed due to violation of stop iteration criteria", what does it mean?
and
2.2.5 Floating point problems - Division by zero, Loss of >7 digits on the matrix diagonal, Floating point exception: Multiple floating points traps, Zero or negative jacobian, InvertA: zero determinant, CCMaterials Extended AExc: CC5ParamYield F: project_stress_on_f_division by zero, and similar
and
2.2.6 I get the warning "Convergence criteria (within line search) not satisfied due to eta limit, continuing super-ordinate iteration" during analysis, what does it mean?
- you can find detailed explanation about the convergence measures, including the definition formulas of the 4 criteria being used, in the ATENA Theory Manual, section 4.2 Full Newton-Raphson Method.
In general, if there are errors >10% in several steps in a row, the results are most likely just numerical noise. On the other hand, a single step with error about 2% is absolutely no problem in most cases.