point mass guidelines...

[PAULKORENKIEWIC]

Guru's,

I need to run an analysis of a part that has a fairly complicated
assembly bolted up to it. I don't want to run the assembly in the
analysis due to complexity, but I want to capture it's effect on the
part in question. I believe I can do this by modeling a "point mass
load" at the assemblies CG with the load equal to it's weight and then
connecting this with rigids to the bolt holes. I'm not sure if this is
the best approach. Anyone have any guidelines, recommended practices?

Thanks...

Paul Korenkiewicz
FEV, Inc.
4554 Glenmeade
Auburn Hills, MI., 48326


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[RodGiles]

Paul

This approach works well if the part that you are replacing with the point mass is rigid compared to the mounting structure. If it's not, or you want to see what effect a compliant part has, then you can use the 'weighted-link' option. If you know what the local stiffness is at the mounting locations, then you can use a beam model (with stiff-light beams) to connect the cg to the mounting points, then put springs between the centre of the mounting hole and the end of the beam.

If you use the rigid link method it's worth putting beams from the mounting points to the cg so that the deflection of the cg is shown in the plots.

Hope this helps,

Rod
Rod Giles
Senior Design Engineer
Polaris Britain Ltd.