topic Re: Mass/Weight calculation in Fusion Support Forum

Mass/Weight calculation

oyvindTMNSU — Thu, 31 Oct 2019 12:13:18 GMT

How is the mass calculated in Fusion?
Apparently it's not the volume x density. Because that gives another number than fusion shows as the mass.

If I times that with the gravity acceleration, it still does not match perfectly. So what's the logic behind the calculation, and what numbers should be used to get the actual weight of the component?

Re: Mass/Weight calculation

TheCADWhisperer — Thu, 31 Oct 2019 12:36:24 GMT

File>Export unit cube, attach the *.f3d file here and indicate discrepancy found.

Re: Mass/Weight calculation

skylord73 — Tue, 12 Jan 2021 15:31:58 GMT

Hi,

I'm finding a huge difference (hoping a bug) in mass calculation

Here is the property output

Bodies (1)
Area 1.021E+04 mm^2
Density 1.420E+07 g / mm^3
Mass 2.817E+11 g
Volume 1.984E+04 mm^3
Physical Material Delrin

I checked the delrin density in fusion and it's 0.025 g / mm^3

If you make the calculations: 19.840mm^3 x 0.025g/mm^3 = 496g that is correct, while the reported mass is: 2.817E+11 g or 281,700 tons... 🤔

Any ideas?

Re: Mass/Weight calculation

TheCADWhisperer — Tue, 12 Jan 2021 17:06:12 GMT

I can't find Delrin in Fusion 360.

Can you post screen capture of where you found that material?

Re: Mass/Weight calculation

skylord73 — Wed, 13 Jan 2021 09:37:56 GMT

The material was imported with the STEP file.

Making your screenshot I found the problem:

the BASIC density property was correct 0.025g/mm^3

the ADVANCED Mechanical -> Density was incorrect

The system used the incorrect one as you can see in the screenshots, once aligned the two, the mass is now correct.

Probably the is a bug in the import process of materials...