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How to maintain COG and inertias with dummy assembly?

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How to maintain COG and inertias with dummy assembly?

Hello All,

I have an assembly with 40-50 parts.  A customer is asking for a 3D model that retains all the correct inertias and center of gravity for the assembly.  Of course, I cannot give them our actual Creo model for intellectual property reasons.  When I give customers 3D models, I typically use a cut in the assembly to remove all the guts, then create a shrinkwrap, then export as a step file.  

 

Is there anyway to efficiently create a dummy 3D model that does not give away the farm, but still possesses the COG and inertias?

 

Thanks.

1 ACCEPTED SOLUTION

Accepted Solutions

Re: How to maintain COG and inertias with dummy assembly?

So with Mass properties you should be familiar with the options in File/prepare/model properties/mass properties and probably have assigned material or know your material density.

 

In the mass properties screen at Model properties there is 'change'

 

Define properties by

 Options are Geometry and density, Geometry and parameters and fully assigned.

 

Before removing geometry make sure the MP has been calculated then save as ( file to a reasonable location). Now change to fully assigned and open the .dat file this will pull in all the MP content. Now you can delete the geometry and the mass properties are carried over. ( or save to other file to preserve geometry) I would also create a cog coordinate system from the pro_mp_cogx, pro_mp_cogy and pro_mp_cogz 

 

You would need to do this for all of your components or if only required at assembly level you can just do the whole assembly in the same way.

4 REPLIES 4

Re: How to maintain COG and inertias with dummy assembly?

Create a "dummy" model of a mass and assign density to replicate the mass props of the assembly. I have done this by modelling a sphere and creating an arbitrary material with density to give me the mass needed. If you calculate the mass props of the assembly then you should be able to locate a sphere at the center of mass and assign a density to get equivalent mass props with a single solid feature.

 

Depending on your frame of reference for MMI calculations you may need more than one dummy model in the assembly to get what you need.

Re: How to maintain COG and inertias with dummy assembly?

So with Mass properties you should be familiar with the options in File/prepare/model properties/mass properties and probably have assigned material or know your material density.

 

In the mass properties screen at Model properties there is 'change'

 

Define properties by

 Options are Geometry and density, Geometry and parameters and fully assigned.

 

Before removing geometry make sure the MP has been calculated then save as ( file to a reasonable location). Now change to fully assigned and open the .dat file this will pull in all the MP content. Now you can delete the geometry and the mass properties are carried over. ( or save to other file to preserve geometry) I would also create a cog coordinate system from the pro_mp_cogx, pro_mp_cogy and pro_mp_cogz 

 

You would need to do this for all of your components or if only required at assembly level you can just do the whole assembly in the same way.

Re: How to maintain COG and inertias with dummy assembly?

rcrerar-2,

 

I tried your method by assigning the mass properties .dat file to my dummy model.  That method worked great within Creo.  I then tried to open my dummy file with assigned mass properties in Solidworks, the file imports fine, but the assigned mass properties are missing.  I need a way for Solidworks to have the same mass properties.

Re: How to maintain COG and inertias with dummy assembly?

Sorry I don't do Solidworks at all. Thinks i answered your question about how to capture the data must be to do with step export or import settings, are you passing parameters/attributes or just geometry.