Hi @andrea_pinato
If your question is "how to know what direction is X and Y for shells", the answer is in this article on knowledge.autodesk.com: "Shell X-Normal and Y-Normal Stress results are wrong in Autodesk Nastran In-CAD". (A better title would have been "How to define the X and Y directions for shells", but that is not the title created. 😊 You have a 50/50 chance that the X axis and the X-Normal stress would align with the length, and it looks like that is how it worked out.)
After you define the material/axis orientation, you will be able to display the element X axis.
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.
