Part COG in Assembly

[uh60rascal]

Hi all,

I am getting a major headache trying to calculate the COG of a part relative to a reference coordinate system in an assembly. I activate the part, go to mass props, uncheck default CSYS and select my reference. But when it performs the analysis, although it uses the origin of my reference coordinate system, it changes the orientation! So the individual COG's (x,y,z) for each part are not consistent with one another. It is with about 50% of the parts that I encounter this problem.

Something else interesting that I found is if I create a coordinate system at the COG as a feature of the analysis and then use that COG as my reference CSYS and perform the analysis again, the calculated COG is NOT at the origin. Yet if I now create COG2 as a feature and measure the distance between it and the previous COG feature, the result is 0.

Does anyone have an idea what the problem is or could maybe shed some light on how Pro/E (WF 5.0) performs this calculation?

Thanks,

uh60rascal

 

[uh60rascal]

Not completely solved, but I have noticed that I get the correct answer (and orientation dictated by my chosen ref CSYS) if I do not activate the part, but instead suppress every other part except the one I want. This will be problematic when I need to measure the COG of a part whose placement is dependent on external geometry since I won't be able to suppress the other parts without suppressing the part I need to measure.

Another interesting bit I've noticed about trying to perform the analysis while the part is activated is that despite specifying my reference CSYS (it even confirms it by name in the analysis itself) a white coordinate system is created elsewhere in the model. It seems like Pro/E is using this dummy coordinate system as the reference to perform calculations.

 

[uh60rascal]

Well, I have figured out how to obtain my part COG's.

Apparently the full output text of the Mass Analysis contains the density, mass, and COG (X,Y,Z) for each part or subassembly in the assembly.

Just need to scroll down. Hope this helps if someone else ever finds themselves in a similar situation.