[SOLVED] Rigid body on floor

[nicklj]

I would like to inquire a simple question which troubles me long time……. I’d like to model a rigid object (say a potato) put on a floor, as shown in the following example:

https://www.dropbox.com/s/80bc9rnnf21v16j/potato.tar?dl=0

However, obvious one of the potatos is definitly wrong behavior. I’m so curious why this happes as I cannot see too much differences for these two potatos. Probably I made some mistakes in both potatos.

Besides, may I know why there is some “flashing” black shadows on the potatos? Does that indicate some problems in the geometry?

I tested the case on both release version v19.06 and v19.12.

Could anyone kind to help me on this? Thanks a lot.

[Hugo]

Hi @nicklj

I needed to look twice at your scene, but the problem is rather simple.
The rigid frame of your ProblemPotato (thanks for the nice names 😉 ) is no centered and even outside the potato itself! Take a look:

(see the left handside frame)

So, when collision occurs, then, forces are applied on the collision model. The mapping projects these forces back to the rigid frame. But since this frame is not centered, and outside the ProblemPotato, it creates a momentum.

Best,

Hugo

[nicklj]

Hi, @Hugo,

Thanks a lot. Based on your suggestion, I tried GenerateRigidMass and can move the MechanicalObject to the mass center of imported geometry, and it seems work fine.

[Hugo]

Hi @nicklj

You could also have just translated the collision model of the potato problem.
But it’s equivalent I guess.

I’m glad it helped.
Best wishes,

Hugo

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