meshing parameters

dendavis

I am trying to mesh this part to run a modal analysis. If it does mesh, the modal analysis runs out of memory.

Sergio

You must simplify all the small features as small radius, fillets, holes that don´t affect the results and complicate the mesh. Even small parts as washers or others must be eliminated.

Regards

dendavis

I have put a radius on all edges and the part meshed accordingly as per the attached jpeg. However, upon execution of the solver for Modal Vibration 3D, the following messages were provided:

00:00 Start 08:20:08
00:00 Allocating matrices
01:09 Assembling matrices .
02:33 Solving matrices
05:44 Error: -9
05:44 Failed

What is error -9?
Is there a source of definitions for error numbers in Mecway?

Sergio

When a say "simplify all the small features as radius" I meant delete the small radius and leave just the corners (and remove small holes and so on). Small features will not have big effect on modal results and will let you have a better mesh (less elements and better shape).

Victor

Error -9 from modal analysis can mean that density is 0. Make sure there are no red items in the outline tree. A zero density should be shown as the material name being red.

dendavis

Thanks for the recommendations as I work my way through this...Now, after having rounded all edges on the part, I was able to complete a Modal Vibration 3D simulation. Aluminum was used as the material. A snapshot of the results is attached. I have a few questions regarding this. First, I note that there are six modes associated with essentially 0 Hertz. Are these degenerate modes? Second, the other modes, starting at 59.9 Hertz, exhibit peak displacements that are unreasonable. At 59.9 Hertz, the peak displacement shown is 545 mm! What is wrong?

Victor

Yes. The 6 zero-Hertz modes correspond to the 6 rigid body degrees of freedom that a completely unconstrained object has.

Displacements and stresses are only relative to each other so the scale doesn't matter.