Currently I am using NX 8.5 (advanced simulation with sol 103_response simulation). I try to find the mode shapes and FRF for a flat panel with three simple boundary condition cases (which all the edges either are clamped,simply supported or free)
1. What are the BC condition for free case since if i put all the edges free (all the 6 DOF are free), the simulation cannot be run?
2. Any advices/reviews should I consider/check again to increase accuracy since my FEA results for clamped and simply supported are different with the theoritical results? ( I have taken consideration on the material choice/properties and refining the mesh)
Define no constraints on the model if you want to perform a free-free analysis. By default, if no constraints are defined, the structure will be free to move rigidly. For your flat panel example, the panel will be free to move in 6 degrees of freedom. You can create a new normal modes solution, specify the modes that you want to recover, and then solve.
My only comment regarding comparisons to theoretical results would be that NX Nastran is tested against verification examples, including some from NAFEMS. Perhaps you can contact our GTAC support staff to help you with your specific example.
Mark Lamping Simulation Product Management Product Engineering Software
Siemens Industry Sector Siemens Product Lifecycle Management Software Inc. firstname.lastname@example.org www.siemens.com/plm