Hi!

The convergence of the computational procedure depends on the boundary conditions at the pile-ground contact.

Valery A.

Dear Aptukov; First of all, thank you for your interest. I defined a surface-to-surface friction contact between the pile and the ground. I defined a surface-to-surface friction contact between the pile and the ground. I didn't define any boundary conditions for this region. Only the soil base is retained.

Best regards...

For Soil structure interaction, you need to use Mohr-Columb or Druckerprager material model. If you use regular yield models based on von mises kind of thing, the solution shall not converge or even if it converges, it shall give absurd results. Again to use the relevant material model, you need to have the correct and relevant material data as applicable.

I have used Drucker Prager model, no such issue of convergence occurred to me.

Addressing to your question directly, time increment errors might get solved by taking smaller increment size. However it rarely helps, and I'm sure that you might have already tried it.

Hence you might wanna look at the cause of non-convergence, for e.g. look at the contacts defined in your model. Most of the time, I have faced that un-converged models are getting fixed with this. In case if you're using frictional contact, tr converting it into bonded (just to check if that's what preventing model from getting converged).

Dear Mishra; First of all, thank you very much for your comments. I used the Mohr columb material approximation method for the soil environment. I noticed that because the cohessive yield stress value is zero, it gives this error. Increasing this value a little bit solved the problem.