what are the errors that you got in the solver output? can you post images of convergence plots?
Please try searching for the convergence error and see if you find anything useful on the forum, if you don't you can paste the error here.
From description of the model it seems like foam material is too soft to bear the loads of bolt pretension, you can test the capacity of material in a single element model to see how much load that model can bear.
-Aniket
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