Hello everyone,

i have some fundamentel question about a low cycle fatigue analysis with ABAQUS. I want to use the direct cycle step, which seems to be suitable for this problem.

The aim of my analysis is a numerical investigation of experimental LCF Test. So i have material data and experimental data to compare my numerical results.

I have some issues with understanding the direct cycle step.

If i ran the simulation with a material model without a plastic model (I provided only the youngs Modul and the Poisson' ration) the analysis was stable.

Then i put a plastic model in my material model. Even a simple one with ideal plastic behaviour i have got the problem:

THE FORCE CONVERGENCE NOT ACHIEVED WITHIN TOLERANCE FOR THIS ITERATION

and direct cycle step tries to find a solution but did not find any. Even not after hunders of iterations.

Is it not possible to run a direct cycle step with a plastic model?

Part two of my question:

Abaqus provides a damage model for LCF test

The damage intiation is defined with:

N0 = c1 *w^c2

N0 = Number of cycles at which damage starts

c1 and c2 material parameter

and w is called the accumulated inelastic hysteresis energy per cycle

If i cant run a simulation with an plastic modell i cant have inelastic energy, am i right?

And could anybody tell how to get the value of w from abaqus. I cannot find any output Variable

I hope anybody could help me