Solid's center of gravity?

I was wondering if Kangaroo can find a particular point which will represent the center of the gravity of that structure (for example free formed solid).
The center of gravity should be the self weight of the structure itself.

Is that possible?

Thank you.

Replies to This Discussion

Permalink Reply by Daniel Piker on August 31, 2012 at 3:21pm

Hi Djordje,

Provided your solid is of uniform density*, its volume centroid will be its center of mass.

Grasshopper already contains a component for finding this point (Surface>Analysis>Volume)

In Kangaroo you can then make use of the way you can treat a rigid body as though all its mass is concentrated at this point, and still have the laws of motion and Newtonian mechanics hold true.

For accurate simulation of the rotation of a rigid body though, you will still need to actually have some mass points distributed away from the center of your object, as Kangaroo does not** contain a method for concentrating angular momentum at a point.

*I guess if the structure has parts made of materials of different densities, you can find the centroids of each part and then use an appropriately weighted average to get the overall center of mass.

**yet! - I'm working on this though, as having orientations for each particle could open up many other interesting paths...

Permalink Reply by djordje on August 31, 2012 at 6:18pm

Thank you for the reply Daniel.

I was not aware of this.
Now I see that both "Volume" and "Volume moments" default Grasshopper components have an output which gives us Volume and center of geometry. Which is exactly what I need - I am designing a chair which is a bit asymmetric - it has a large momentums related to the center point of it's center of stand (pedestal).
Thus I want to get a centers of gravity of particular parts and materials from which the chair is consisted. Then I will multiply the unit weight of particular parts in accordance to their material properties, with volumes I got from above components. That will result in forces - vectors, which will be "put" into the gravity centers I also got from above components.
In that way I could calculate the momentums for each part(material) and check my chair is susceptible to overlapping.

The only problem I have is which point should I choose for the momentums point?

I guess it should be the gravity center of my chair's stand (pedestal)?

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