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?
This could happen because the model is not fully constrained.
To troubleshot you can follow these steps:
1) Use contact visualization plot
2) use find unconstrained bodies
3) Run frequency analysis with the same setup using FFEPlus solver to find if there is any rigid body mode.
4) Run a static simulation using soft spring option
5) Use FFEPlus solver instead of Direct Sparse
6) Update all components in simulation, remesh.
If still experiencing the same issue, please upload your model for further investigation.
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
Thanks, all! I got it to work.
I have a force on four arms, going at an angle. How do I create those forces?
Thanks,
Before defining the force itself create a sketch with a line in it that points in the direction that you wish to apply the force. If you already have a sketch entity or model edge that points in that direction you don't need to duplicate it; you would just use the existing model edge or sketch entity. You would then define your force load and use the 'Selected direction' option to apply the force in the direction of your edge/sketch.
Cool! It looks like it is working. Thanks, for all your help!
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