Learning Forum

[Bahy209815]

Hi everyone,

I’m encountering a solver pivot warning/error in Ansys Workbench (2024 R2) while working on a static structural analysis. Below is the exact error message:

"A solver pivot warning or error has been detected in the UX degree of freedom of node 656799 located in Back Face Sheet; Back Face Sheet. This is usually a result of an ill-conditioned matrix possibly due to unreasonable material properties, an under-constrained model, or contact-related issues. Check results carefully. You may select the offending object and/or geometry via RMB on this warning in the Messages window."

Additionally, the solution takes an excessive amount of time, which might suggest further underlying issues. I've attached a screenshot for context

Any guidance or suggestions would be highly appreciated! Let me know if you need more details about my setup.

[peteroznewman]

It looks like you are making a honeycomb core sandwich panel and modelling individual cells. A much simpler way to create a honeycomb core sandwich panel is to use a rectangular solid to represent the core, mesh it with 6-8 hex elements through the core thickness, and assign an orthotropic material to the solid body. The orthotropic material, when populated with data from the honeycomb manufacturer’s datasheet, will create the correct stiffness so that the panel will behave like a honeycomb core sandwich.

The facesheets can be either sheet bodies and meshed with shell elements or solid bodies and mesh with hex elements with 4 elements through the thickness of each facesheet.

In SpaceClaim, on the Workbench tab, use the Share button to have the rectangular solid and the two surface bodies (or two thin solid bodies) share nodes so your model does not need any bonded contact.