How can I change iproperty density via parameter

[JBEDsol]

I have a block representing a cable run.  I want the density to calculate so that I can get a decent weight report.  I have a notional width based on the radius of the cable.  This number might change.  I know the lbs/foot per cable but want to have the weight/cg calculated based on the density.  However the lbs/foot doesn't change just because I have better numbers on the cable diameter.  This is further complicated by the fact I have various numbers of cables in a run.  If I could get the density to function as a product of a custom property (lbs/foot) and the cable diameter this would work fine.  I've tried to do this using illogic but I can't seem to find the material density nor know how to change it.  Is there a way to do this?

[leowarren34]

I believe if you create a new custom material and then you can more easily customise it's density. I reckon in the density section is where you can enter the parameter.

[frankstardelux]

Ladies and gentlemen, we can now change the density and therefore mass per length (pounds/foot etc) of a cable harness! Ok, I had such an uphill battle trying to solve this and I don't think it works for individual wires with different densities in a single harness, so you might need a separate harness for each density, if that makes sense. The version of Inventor at the time of writing is 2021.

The main thing that threw me for ages is, you have document materials and you have library materials. Usually for a part, you assign a material from a library and it basically adds a copy of it to the Part (otherwise known as a Document Material) which you can edit and this doesn't affect the original library material.

You can assign library materials to a Harness and the densities of those materials will be used to control the mass of the wires within. So the first step is to make sure that a material within the library you use (as specified under the Project settings) has the density that you want to use.

For me the density was obtained by a combination of: 100m of tube weighs 6.99kg, so you can work out a mass/length, and by using the current mass and density combination which was 1g/cc and 24.249g, and measuring the length of the wire which was 187.064mm, smash some numbers together and you should get 0.539 g/cc for my particular tube. If 100m weighs 6.99kg, then my 187mm should weigh 13.075g. If 1g/cc gives us 24.249g then (13.075g/24.249g)*1g/cc gives us 0.539 g/cc.

Next edit your harness:

R-Click on the upper Harness and choose Harness Settings. There should be a check box for "Use Surfaces for All Segments and Wires. This should be unchecked so that the wire is treated as a solid. Close that dialogue box.

R-Click again on the upper Harness and choose Bill of Materials (or go Manage tab -> Bill of Materials). Here, simply double click the material for the *.Harness1 and the field should change to a drop down menu. Select your material and then click off and you should see the mass update.

And that's it. Check the iprops of the Harness (either when editing the harness or at the top level) and the mass should now be correct for the density you set.

Really hope that helps you guys.

Cheers,

Frank.