Vellum Sand breaking

[FXlover9]

Hi all,I am making a ground breaking effect in which a stone comes out of the ground and making primary debris and all.The condition is I also required to bring soil and ground dirt during eruptions I have managed to use the vellum grains to solve this, along I have used the 

"attach to geometry" constraints to make the vellum grains stick to the broken pieces. But now I also want during the collapse and hit on ground once the pieces fall on ground and make an impact ,some amount of dirt should also left on floor due to the impact.

I can do this while playing with the breaking threshold but its not on per Debri I want to customize it so only some pieces would leave dirt rest not all.

 

If anybody wants a file I can share too.

[FXlover9]

Hi so ,I got some better options using vellum constraint property node.I was just wondering on how to use the vex, using the length(V@v) of velocity to drive the value of stiffness or breaking threshold. Does anyone has any info on how to use the expressions in bottom section of this node."use VEx".

or How I can break this constraint based upon speed or position or impact hit or anything to break the sand from the constraint upon falling.