Solid bodies and surface bodies

[rgrayclamps]

Hi,

I am a new user doing a FEA analysis on an assembly using Cosmosworks 2007. I am just wondering what is correct way to analyze an assembly with solid bodies. Do I have to model and mesh all the solid bodies together with othe elastic compoments, or can I use surface bodies to represent solid bodies? I tried surface bodies, but it did not work. Modelling and meshing solid bodies seems a waste of computational power.

Thanks,

Alex

 

[jmagri]

I see that no one has responded to this post.

In general you have to mesh all of the solid bodies in an assembly as solid bodies. Mixed meshes are possible but are used when sheet metal and solid bodies are combined in the assembly. As you point out this does cause a lot of computational time to be used up in areas that are not of interest. One of the ways to handle this is to experiment with the largest element size that the model will mesh with. Once you have established that then use the mesh controls feature in the mesh command to reduce the mesh in the spots of interest.

Another way to control the mesh is to remove as many of the features that have little bearing on the results as possible. Usually in an assembly this means holes or radiused edges.

 

[rgrayclamps]

Hi, JMAGRI:

Thanks a lot for your reply!

Does Cosmosworks 2007 have capability of meshing surface bodies in Cosmosworks 2007?

Alex

 

[jmagri]

Yes I have meshed surfaces, but I believe they must be meshed as shells because they have no thickness. This can be done by when the study is created by asking that the study use shell elements. When you open the part or assembly the shell is meshed by picking the surfaces individually. This can be tedious but it gets the job done. You then generate the mesh and look at it carefully. All of the "active" mesh surfaces, the ones in orange, need to be meshed to each other. If not flip the shell elements so that they are. When that is done look at the elements themselves particularly where they come together with other defined surfaces on other parts of the assembly. The element lines of different surfaces should meet at the intersection of the surfaces or the nodes. If this doesn't happen the parts will not be connected to one another and the results will not be valid. If there is no connection it may mean that you need to mesh the edge surfaces of the shell so that adjoining shells become joined in the FEM model.

If I get the chance I use the solid model whenever I can. But since we use a lot of sheet metal parts in large assemblies I am forced many times into using shells. They can be a pain to work with but the results are good with less processing time.

Hope this helps.