COSMOS modelling of sheet metal assemblies

[CalculatorDave]

Hi all,

I am trying to model a multiple-part sheet metal assembly in COSMOS/Works. I am attempting to build the entire model with surfaces (instead of with solids), to make it easier to select surfaces for shell-meshing. That is to say, if I WERE to build the sheet metal structure from solids, it would be very time-consuming to select the surfaces that I want to mesh (I don't want to mesh both sides of the sheet metal!). Anyway, this method makes it easy to mesh (although the meshes between adjacent sheet metal parts do not match), but, when I run the actual analysis, I get messages saying that there are "not sufficient constraints". This mystifies me, as I have restrained the model. Any advice on modelling multiple-part sheet metal assemblies in COSMOS?

David

 

[gelu]

I think you have one or more nodes unconnected.
I never use Cosmos, but you must have the option of merge nodes (check help).
I remember about a discussion with Solid Works representative, he says me about a feature of extracting mid-faces from solid automatically.
Regards

 

[JGalliera]

To make sure that your mesh from one surface to the next matches exactly, you must use the Split Line tool in SolidWorks. If done correctly, this will solve your problem of insufficient constraints. What I mean by that is if the mesh does not match (and thus the nodes on adjacent surfaces do not get merged) then the restraints do not get transferred to the entire model.

You can find out why the model is insufficiently constrained by this method: in the study properties, choose the "soft spring" option for either the Direct Sparse or FFEPlus solvers. This will allow the model to be sufficiently constrained enough to run all the way through. Then you can animate the results to find out what is going on. Using that information, fix your model (like I suggested above) and run again. But make sure you turn off soft spring before making your final run.