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SweetPeasHub17-Peridot
17-Peridot
October 27, 2023
Solved

BOM center of mass repeat region - location according to top level default csy.

  • October 27, 2023
  • 2 replies
  • 3275 views

I have a table with a repeat region for a BOM with materials masses and COG information. The COG is being reported from the part level and is according to the part default CSY.

What is the best way to get the COG information tabulated according to the top level assembly default CSY?

 

When doing mass properties analysis this information is given and it is in the top level CSY and units, but it is not recursive and I don't know how to get this information according to the assembly CSY into a repeat region even for flat assemblies.

-------------------

MASS PROPERTIES OF COMPONENTS OF THE ASSEMBLY
(in assembly units and the XXXXXXXXX.ASM coordinate frame)

DENSITY MASS C.G.: X Y Z

-------------------

 

repeat region variables I have been using:

&rpt.index, &asm.mbr.name , &asm.mbr.PTC_MASTER_MATERIAL, &asm.mbr.pro_mp_mass[.7], &asm.mbr.pro_mp_cogx[.1], &asm.mbr.pro_mp_cogy[.1], &asm.mbr.pro_mp_cogz[.1], 

 

 

 

 

 

Best answer by Chris3

I don't know about repeat regions, but to get the analysis -> Mass properties to do this you have to turn on this config:

mp_calc_level all_models

Other configs you might want to consider:

mp_analysis_default_source assigned
force_upd_assem_mp_in_simp_rep yes

The way I do this is I have a repeat region that dumps level and descriptions and then I try and marry that with the mass property report. Its frustrating that PTC doesn't give you all of this information in one place. You can use PRO_MP_MASS but if your users didn't update that parameter at the time of release then it is going to be wrong.

2 replies

Chris3
Chris321-Topaz IAnswer
21-Topaz I
October 27, 2023

I don't know about repeat regions, but to get the analysis -> Mass properties to do this you have to turn on this config:

mp_calc_level all_models

Other configs you might want to consider:

mp_analysis_default_source assigned
force_upd_assem_mp_in_simp_rep yes

The way I do this is I have a repeat region that dumps level and descriptions and then I try and marry that with the mass property report. Its frustrating that PTC doesn't give you all of this information in one place. You can use PRO_MP_MASS but if your users didn't update that parameter at the time of release then it is going to be wrong.

    S
    SweetPeasHub17-PeridotAuthor
    17-Peridot
    October 27, 2023

    Thanks! This config option looks like a good solution for me. My question was too much down the road that the repeat region was the answer.

    mp_calc_level all_models

     I also use this option to keep mass up to date.

    mass_property_calculate automatic

     

    Chris3
    Chris321-Topaz I
    21-Topaz I
    October 27, 2023

    mass_property_calculate automatic is too heavy a performance hit on large assemblies for us. We also have lots of released parts that get modified using that config but then the users have no way of checking them in.

    tbraxton
    22-Sapphire II
    tbraxton22-Sapphire II
    22-Sapphire II
    October 27, 2023

    Would you see an advantage to calculating the mass props within the part with respect to the default assembly csys rather than in assembly mode? In general, I would do this calculation in part mode so that I do not have to have the assembly in RAM to get the results. Depending on how large your assemblies are this may not be an issue.

     

    If you see benefit to doing the MP calcs in part mode, then you can use the measure transform tool to place a csys in the part that is congruent to the default assembly csys when the part is in situ.

      S
      SweetPeasHub17-PeridotAuthor
      17-Peridot
      October 27, 2023

      Generally my assemblies are not that high of a component count unless someone puts a populated 3D PCB in.

      I do see a slight performance hit with the regenerations to keep mass up to date but not too bad. Maybe a mapkey could be used to initiate the update on demand. I used to use the measure transform matrices for getting secondary csy locations copied independently into subcomponents but there is an even easier way which is pretty cool if you want to know about that one I will snap a video which is the best way to show the simplicity of the process. I have also done csy that were the reverse transform that allows an imported model to be transformed so its default csy is correct for the overall assembly. (body coordinates) I guess I can say I am in automotive parts and the overall assembly is generally in the vehicle body coordinate system.

      tbraxton
      22-Sapphire II
      tbraxton22-Sapphire II
      22-Sapphire II
      October 27, 2023

      I am always interested to see alternate solutions to such problems. If you want to describe it in writing before taking the time to make a video, I will let you know if I grasp the methods or need clarification.

       

      In a past job, I designed mobile phones at Motorola and we did impact analysis of the entire phone in ABAQUS to predict drop test failure modes. For fidelity in the sim we used fully detailed product designs which did tax multicore compute servers dedicated to running simulation. It was not unusual for PCB assemblies to have 500+ parts on them with full mechanical geometry and properties to replicate the solder joints etc.  

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