Hi @waltertulin
Let me elaborate your question to make sure that I (and everyone else) understand. It sounds like your model has a sharp, internal corner like the inside of an "L" shape. Because of the mathematics of FEA (simulation), the calculated stress is high at sharp corners. If you refine the mesh in the corner, the stress just goes higher and higher (usually at the 1 element right at the corner) which is the telltale indications of a singularity.
These are the options that come to my mind. Of course, these suggestions are only valid if you are confident that the result is a singularity.
- Ignore the high stress. Change the maximum legend value to a more reasonable scale. More of the model will appear in the red region of the scale, and the appearance of the singularity is minimized. (If the high stress does occur in reality, the material will yield at a small volume and usually is not a problem.) If the stress in the corner is needed, then use nodes 2, 3, or 4 elements away to extrapolate the stress result to the corner.
- Model a small radius fillet. This then requires a fine mesh on the fillet in order to get 3 or 4 elements along the fillet to allow for a smoother transition.
- When presenting results to co-workers or your customer, be prepared to explain what a singularity is and why the magnitude reported by the software can be ignored.
John Holtz, P.E. Global Product Support
Autodesk, Inc. If not provided, indicate the version of Inventor Nastran you are using.If the issue is related to a model, attach the model! See What files to provide when the model is needed.
