If the Physics Asset is mostly "collapsed" but still shaking and twitching on the ground, but not violently bouncing around, there are a few values you can tweak to get it to stop
Before doing anything, try simulating with No Gravity, this will show you if any of your Physics Constraints are miss aligned and trying to correct before the Physics Asset has
even hit the ground.
Often times, a small amount of Linear and Angular Damping on all the Physics Asset's Physics Bodies is more than enough to stop the asset from shaking. However, using large
values in Linear Damping will cause a Physics Body slow its movement through the world, even due to gravity. Damping, as it is implemented here, is not "drag" per se. It is
more like moving through a viscous substance.
If jitter is still an issue, perhaps you have a number of really small Physics Bodies, check the Substepping documentation for information on having the
physics simulation calculate in-between solutions.
See the Physics Asset Properties Reference and Physics Constraint Reference for more details on the properties for Physics Constraints.