Strange RBD problem

[Skip]

Hi everyone,

I posted this over at the Houdini Forums but was hoping y'all could help me shed some light on the issue too.

I'm working on some RBD effects for a final year Uni course and have run into some problems that I was hoping you all could help with?

Basically I am trying to create a wall panel with a spherical cut out that will have a magnet force applied to it in order to make it look as if the panel is exploding outwards. I have the magnet force working in my scenes but the problems lie with the behavior of the object once it becomes active.

Basically, when using the bullet solver, the spherical cut out wants to "pop" out of the wall on its activation frame before it begins to shatter. Sometimes it only pops out by a unit or two that isn't noticeable when played at real-time. But other times it does a full on 45 degree rotation which is very noticeable. It seems that this problem doesn't exist with the RBD solver, just with bullet. But I'm fairly certain problem exists between keyboard and chair, not Houdini .

Ive uploaded a quick scene with it doing its usual thing, I have noticed in other scenes, if I were to copy my SOP Geo and translate it either in geometry level, scene level or with a null, the degree in which it all goes horribly horribly wrong changes. (The exact same wall panel translated +10 in the x will behave differently?) This boggles my mind.

Any help would be much appreciated,

Thanks in advance

S

fracture_problem.hip