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Calculation of CG from asserted weights of sub-assemblies

Creator
Creator

I searched through the discussions and could not find one that answers my issue.  I am trying to determine the c.g. of an assembly consisting of homogenious parts and eom assemblies.

 

I can assign a material to the homogenious parts.  The oem assemblies consist of several parts in the model and I can assert a weight for the oem assembly model.

 

Now the problem is how do I find the c.g. of the entire assembly?  If I use the Measure Bodies tool I can only select the bodies in the assembly and not the oem assemblies with the asserted weights.  I cannot not select the sub-components of the oem.  Thus the tool is including the volumes of the oem components.  I am just using the volumetric center of the oem assemblies as their size is small relative to the parent assembly.

 

Anybody have a solution?

6 REPLIES

Re: Calculation of CG from asserted weights of sub-assemblies

Siemens Phenom Siemens Phenom
Siemens Phenom

Have you looked at the Advanced Weight Management command?

 

It allows much more control over assemblies and components.

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Re: Calculation of CG from asserted weights of sub-assemblies

Creator
Creator

Yes, I used the Advanced Weight Management to assign a weight to the sub-assembly.  Now the issue is when I want to then determine the resulting weight and cg of the parent assembly how do I do that knowing that the parts in the sub-assembly are ignored and the assigned weight and location of the sub-assembly is used?  The parent assembly is quite large and selecting or de-selecting piece parts would be pretty tedious and time consuming.  Are there some functions in the Advanded Weight Management command I'm overlooking?

Re: Calculation of CG from asserted weights of sub-assemblies

Siemens Phenom Siemens Phenom
Siemens Phenom

You may want to consider the use of reference sets, assigning components or subassemblies to a 'weight' reference set. This ensures that only members of the reference set are used in the calculations.  Another option is to create component groups. Again, you can choose which component group to use in the calculations. 

Re: Calculation of CG from asserted weights of sub-assemblies

Creator
Creator

So if I create "weight" reference sets for the sub-assemblies will I need to create a "weight" reference sets also for the rest of the parts not contained in the sub-assemblies?  How about for the component groups?

Re: Calculation of CG from asserted weights of sub-assemblies

Siemens Phenom Siemens Phenom
Siemens Phenom

Any subassembly or component that you want to use in the calculations would have to be a member of a 'weight' reference set.

 

Alternatively, if you create component groups, you could create one called 'weight'. Any component or subassembly that is a member of the component group would be used in the calculations.

 

Any component or subassembly that is NOT in the specified component group or does NOT have a 'weight' reference set is not used in the calculation

Re: Calculation of CG from asserted weights of sub-assemblies

Creator
Creator

I created a test assembly with a couple of homogeneous parts and two sub-assemblies. I specified the material of the homogeneous parts and asserted the weight of the sub-assemblies. I used the Advanced Weight Management and selected "Work Part" in the calculation section. The result agrees with what I find by adding up the weights of the parts by hand. So it appears to ignore the sub-assembly children when I assert the weight of the sub-assemblies. 

If this is working like I think it is, it is a great deal less work than creating a reference set or component groups.  I am working with an assembly with many parts and sub-assemblies. 

Do you see anywhere that I am missing something?