Over-ride the weight of a part or product for "Measure Enertia" 3

[gcpdesign]

Hello All,
Problem:
I have a product with many supplier items. most of these items are just dumb block solids which does not reflect the true volume of the item. eg. a pneumatic cylinder is hollow with a piston & rod. it also has mildsteel & aluminum parts. the supplier models most times dont come with the "guts". So, when we check the properties of these items they weight eiter much more or less. As i'm sure you'll understand that we don't have the time to go and re-model these items so it is correct.
Question:
Can one somehow over-ride the weight of these items, eg. in properties or even a parameter which would assist in weighing these item used in an assembly so one can get the proper COG, weight, etc?

Thank you in advance!!!!

 

[Solidkat]

With a volume and a known weight you should be able to make a custom materials database based on supplier parts instead of just the materials.

The only problem with this method is that the COG might not always be correct.

 

[DBezaire]

To remove the part from inertial measurement.

In the property page of the part - turn on Only Main Body
Inside the part - Create a new body, contextual menu new body -- Change Part Body

Regards,
Derek

 

[ferdo]

Hi,

First you have to find your specific density for your cables (easy to do since you have all the data for the them).

Be careful to use same units like in CATIA (lets say ISO standard). By default, CATIA density is 1000. Lets suppose your part has density 7800.

Now check the attached file. As you can see in the attached file, all data you usually want are linear.

All you have to do is to create a macro to write in your CATPart properties what you want to have to help your gravimetry guys...and eventually write a text file with these properties for them.

This can be done by taking the data from measure inertia command and multiply (in our case) with 7.8 ......

Regards
Fernando

 

[ferdo]

I forgot to tell that the data in the excel files were coming from a cube with an edge of 1000 mm, with the axis system in a corner, everything measured with measure inertia command and checked under check line.

Regards
Fernando

 

[ferdo]

Hi,

It was a question on a Spanish forum somehow related with this, so I guess with whole explanations given here and the attached CATScript should be clear enough how to do it.

Regards
Fernando

 

[gcpdesign]

Thanks guys, i learnt something new from all your posts. I just went with Dereks solution at the time.

 

[gcpdesign]

Question: (Fernando )
Where can one change the catia default density 7800? this whay we are closer to the real weights on parts as generaly most of our parts are made of "mild steel" (7800)

 

[oakmanrich]

To answer the first question, the best way to overide mass props is to use equivalents, import a text file (use below)into your parameters and fill out mass, CoG etc. see attached pdf or search the catia help for equivalents.

Equivalent_IsSurface false
Equivalent_IsVolume true
Equivalent_Area 6m2
Equivalent_Volume 1m3
Equivalent_Mass 1000kg
Equivalent_COGx 75mm
Equivalent_COGy -10mm
Equivalent_COGz -25mm
Equivalent_MatGxx 50000gxmm2
Equivalent_MatGyy 50000gxmm2
Equivalent_MatGzz 50000gxmm2
Equivalent_MatGxy 0gxmm2
Equivalent_MatGxz 0gxmm2
Equivalent_MatGyz 0gxmm2