I have a light bulb in a scene that is supposed to fall and hit the ground, but the glass should behave like a soft body instead of shattering.
My problem is that I cannot figure out how to make part of the bulb (base metal and coils) a rigid body and make the glass a soft one.

I've tried in vellum constraints to control bend and stretch stiffness via attribute with no luck. The base will not go rigid enough even with high substeps.

I also tried with two solvers, though the bulb parts will not stay connected together.

The project file, along with the bulb alembic, is attached.

kindly advice

It's not true RBD and Vellum, but you can simulate only your softbody group while pinning it to the rigidbody group. Then you can animate the rigidbody group to drag the softbody around. Add a shape match constraint to prevent total collapse. Not sure what your final look is.

With that part working, there's no reason you couldn't simulate the rigidbody group. After the simulation, copy the softbody group to the center point of the RBD simulation result. Use the same pinning technique and merge the RBD mesh animation into the Vellum sim. This case demonstrates using the shape match to keep most of the original bulb shape.

Enivob
With that part working, there's no reason you couldn't simulate the rigid body group. After the simulation, copy the soft body group to the center point of the RBD simulation result. Use the same pinning technique and merge the RBD mesh animation into the Vellum sim. This case demonstrates using the shape match to keep most of the original bulb shape.

Thank you, Enivob. That's a great way of thinking.
So actually, It's two separate solvers pinned with a transform and copy-to-point.
Appreciate your time and effort on this.

Cheers
Happy new year