Simple RBD Explosion

[Fakit]

Hello everyone,

A simple issue that I don't understand : RBD Explosion.
You'll see in the setup attached :
- A base geo (head)
- A quick fracture work (mask + fractures)
- RBD Configure (with active bound)
- A bullet solver

Then, I feed an AttributeAdjustVectorFloat for the Velocity (3rd input/proxy).

--> Frame 1 = Velocity Data OK
--> From Frame 2 = v@v = {0,0,0}

If I deactivate "constraint" in the RBD Material Fracture, then, I have Velocity data. 
Normal --> No constraints.

But even If i put 0.0001 for the Glue constraint : Same !
--> Frame 1 = Velocity Data OK
--> From Frame 2 = v@v = {0,0,0}

As usual, this is possibly a very simple and dumb thing.
Let me know if you can enlighten me.

Thank you !

Ps : Here's a simple tutorial about that.

Simple_RBD_Explosion.hipnc

Edited February 26 by Fakit

[Sepu]

is because you have the constraints on in the fracture, if you do not need them just disable them, pure velocity wont break the constraints.

 

[Fakit]

Thank you for your answer @Sepu !

Yeah that's what I saw. It works If I disable the constraints. 
But let's say that I need them. I should be able to break the constraints with velocity with a very low Glue value no? 

Thanks
 

[Sepu]

you can not break as I said above glue constraint with just velocity.  You need to create some kind of impact like things colliding with them, events, falloffs, etc.

Have a look at this and it will give you quick overview of constraints
 

 

[CarlosGuzman]

Hi Fakit, 

you can break glue constraints based on velocity, in order to achive this you will need to transfer the velocity to the constraint network and remove points or prims based on a rule.

please have a look. 

Simple_RBD_Explosion_CG.hipnc

[Fakit]

Thank you for your answers!

@Sepu I'll take a look at this one for further understanding in case I missed something.

@CarlosGuzman Thank you for the explanation and the file. 
Really good method to break constraint with velocity.

So this is a clear statement, as said @Sepu : We can't break constraint with velocity only.
We need to break the constraint as you have done in your file, with the help of a threshold, but not with velocity only.
If we apply any velocity on a pre-fractured mesh, the constraint will not break by itself.

So I can also see a simple method where we can use the "Break Thresholds" in the RBD Bullet Solver, with the At Frame. (See attached file)
At the end, it's just a matter of breaking the constraints at one moment, to allow velocity to work.

Thank you for your help !
Appreciate it 

Simple_RBD_Explosion_FKT.hipnc