I have an assembly that keeps giving me an error, "The Iterative Solver stopped. Numerical difficulties. (Preconditioning failed) Please check model boundary conditions. No results saved."

I'm not sure what to do to "check model boundary conditions". How do I solve this?

Hi Richard,

Like Siavash Khajehhasani outlines, there are many ways to diagnose an unstable study. In my experience this one works 9 times out of 10:

1. Go into the study 'Properties'

Turn on 'Use soft springs to stabilize model'

Turn off 'Compute free body forces'

Turn off 'Large displacement mode'

2. Suppress all loads and apply only gravity

3. Mesh/Run the study

4. When the solver stops due to large displacements and prompts to put the study into 'Large Displacement mode' declined this offer. The solve will dump what results it has so far

5. Inspect the displacement plot in the results to find the unrestrained body

6. Add bonded contacts as appropriate to restrain these bodies