just wanted to know if anyone here can give my team and I some insight on how to run an FEA structural analysis in NX Nastran for assembly files. We've been running some FEA's for single parts, but we can't quite figure out how get an assembly file fully analyzed. Can someone please describe how setting up the mesh, loads, and constraints are different for an assembly from a single part?
We're currently running NX 10, but also have access to NX 11.
exactly the same way as part!
your assy (.afm) is made of all your meshed parts (.fem)
you attache (connect) them together as appropriate (in the .afm)
in the .sim apply all LBCs as normal and run the analysis as normal
There are actually 2 workflows:
Hey, I guess the question I'm interested in from that, is how do I set the right constraints for the assembly? I've used constraints on a single part, but I guess I'm having the most trouble with getting everything constrained correctly. I'm sort of new to this, so is it just exactly the same as constraining a single part?
Yes, the process to follow to apply constraints, loads, sim objects to an assemby FEM is exactly the same as the process when using a single FEM.
As an example, I've attached a zip file that contains a simulation to a single FEM containing 3 polygon bodies and the exact same simulation to an Assembly FEM that points to 3 FEMs each with 1 polygon body.
The associated parts for the simulation connected to the single FEM:
OpticalAssembly.2_i_fem1_sim1.sim > OpticalAssembly.2_i_fem1.fem > OpticalAssembly.2_i.prt
The associated parts for the simulation connected to the Assembly FEM:
OpticalAssembly_afem1_sim1.sim > OpticalAssembly_afem1.afm
The example was created using NX10.
I finally got the Assembly file run today while doing similar constraints to what you used! I've either used a glue to connect two parts together or I use a fixed constraint. I can't seem to get the assembly to simulate without a fixed constraint somewhere. Is that typical?
Also, I want to use a pinned constraint on a part where a bolt is screw is used to hold two parts together, but I can't really use the same pinned constraint to connect both parts. I'm never able to use a pinned constraint though, because NX wants me to either use a fixed constraint or glue that part to another which has a fixed constraint. Does this sound right or am I missing something?
Thanks to everyone who has replied by the way, you've all been massively helpful to my group!