When measuring " Mass Properties" on an assembly, the coordinates of the center of gravity are obtained, and if the " Create Center of Mass function" checkbox is selected, the center of mass point is created after closing the " Mass Properties" measurement.
If I measure the coordinates of the center of mass and compare it to the values of the coordinates of the center of gravity obtained during the measurement in " Mass Properties"; I get different coordinates.
Why do we have different coordinates for the center of gravity and the center of mass?
Why doesn't SolidWorks provide a function to create the center of gravity?
During the measurement of " mass properties" we obtain the center of gravity, yet we do not make any parameterization for the gravitational field (direction, value, etc.), so what is this calculation based on?
The center of gravity is defined by the gravitational field. This gravitational field is linked to mass, of course, but the center of mass can be off-center with respect to the center of gravity. See article pointed out by @Sylk
Indeed, when we click on <Replace Mass Properties> the XYZ coordinates correspond to the coordinates of the center of gravity. ==> misuse of language or vagueness
And in English, what does it say? I say this because I've seen so many screwed-up translations made in France by badgers who don't understand what they're translating. In movies typically. Translating " 10% of the speed of light " as " 10% of a light-year " in a Transformers... When we translate units of speed by units of distance, we hit rock bottom... Long live France.
I have to check on my side but it seems to me that: The coordinates of the center of mass are relative to the origin of the assembly As for the coordinates of what Solidworks call center of gravity is relative to the center of the bounding box. Unless it's just a problem of reconstruction...
After some tests, it appears that the difference in coordinates between the two " centers " is due to the reconstruction. The center of " gravity " requires reconstruction. Whereas the center of mass seems to be recalculated with each change. => Solidworks 2022
That's @Maclane our big winner of the day I think. SW only manages centers of mass (because we never talk about gravity in SW unless we go into simulation). So the name center of gravity in mass properties is wrong: it's a center of mass. It's the intern in charge of the translation who screwed up: it's OK in English:
As a result, there is an inconsistency... (And since on the Internet, we are told about the two centers (mass and gravity...) it casts doubt on the information we get with these measurements.)
Ok, that would be a translation error, So normally, we should have the same contact details. Except that I get differences...??
@Marc_JIMENEZ You mean that you still have coordinate differences between the two " Centers " even after complete rebuilds of the assembly components? According to my own experiences the coordinates are identical after rebuilding the assemblies (Ctrl + Shift + Q then Ctrl + Q)... Cases where the two coordinates are different:
One or more components have a hand-forced center of mass.
One or more components is/are an envelope.
One or more components is a 3Dconnect import that is not translated into Solidworks.
One or more components are forced into " light" mode.
One or more components remained in surface with errors.
The mass of a body is proportional at each of the points that constitute it to the local density. Its weight depends on the density weight, which is the product of the density by the gravity at the point considered. If the gravity field can be considered uniform, the center of mass Gm and the center of gravity Gg are confused. At the scale of the objects we manipulate with Solidworks, I think we can consider that Gm and Gg are one and the same point.
There is a third point which is the volume center Gv, which depends only on the geometry of the body. If the material is homogeneous, it is confused with the center of mass. It is in fact this point Gv that is determined by SW, as well as the volume V of the body, and its " moments of volume inertia Iv ".
Knowing the density of the material, which he assumes to be uniform, it is sufficient for SW to multiply volume V and inertia Iv by the density to propose the mass properties of the body. The term " Center of Gravity " in this page is a misnomer. Distinguishing these different points only makes sense at the scale of a planet in the field of attraction of a neighboring planet. And again...
As for explaining the discrepancy found by @Marc_JIMENEZ, I didn't see anything on the assemblies I tested. It's best to look in SW: the " Include hidden pieces" box is not checked. Could there be hidden parts in the assembly?
