Creating part with specific properties

[compujas]

I'm trying to create a "brick" part that accurately represents the mass, three principal moments, and three Cg's of an assembly. Basically, take an assembly of parts and create a replacement part that can be used for analysis without revealing the inner parts. I'm currently trying to use a feasability study to do this. I created severalholes in various locations and directions on the outer surfaces and two-sided holes from the inside. ThenI create an analysis feature of the properties that need to be checked, and assign them values in the feasability study as constraints, and then select all of the dimensions of the holes as variables. Essentially this all comes down to, I made several features in different places for the study to remove material and shift the holes to obtain the properties required. Unfortunately, this doesn't seem to be working. So my question is, has anyone ever had to do this before, and how could it be done without spending 2 solid weeks tweaking all of about 100 dimensions until I get what I need. Thanks in advance.

 

[dsergison]

shrinkwrap


you save as, select file type shrinkwrap. the new, (non associative), xxx_sw0001 model will look like the origional part, but only the exterior shape. the internals and any fine details are omitted. it retains the same mass props.

 

[compujas]

Thanks for your reply. Will this create a part that can be assembled into the rest of the model and is good for analysis purposes (analysis is not done within Pro/E, but exported to a 3rd party software package)?
Edited by: compujas

 

[compujas]

Now that I tried it, it appears that mass properties are not preserved when I shrinkwrap the model. And before I get the obvious question, yes I checked Assign Mass Properties. If I use a faceted solid (which would be preferable as most of the geometry is external) the mas properties are not even close, and if I use Surface Subset, every mass property is zero. Any other ideas? Thanks.

 

[dsergison]

when you go to analasys, model analasys to check the mass props of the new shrinkwrap model there is a check dot for COMPUTED, or ASSIGNED.


you need to check ASSIGNED. then it will tell you the old mass props.


I don't know how/if this will be used by external analasys packages.


---an oddity I observed. I just shrunk a metric (mm)part and the shrinkwrap.prt created was in inches. -this scaled up the offsets of the CG csys by 25.4


setting the part back to mm fixed the CG placement. -weird.






Edited by: dsergison

 

[compujas]

Ok, I see it now. Unfortunately, since it is an external analysis package and the parts are converted, I'd imagine that it probably abandons the assigned values and recalculates them based on geometry. Luckily though, it didn't take as long as I'd expected to create the part with reasonably accurate values, though I wouldn't like to do it again. Thanks a lot for the help.