So I've been trying to create a road impact for several hours now and I've come very very close to what I want, but ultimately it always ends in frustration.

I'm trying to create a small impact crater in a square that's been stretched out to be very thin. Basically I've been fracturing it and then smashing it in the center with a tube. The square fractures (I either shatter or break it before making it a RBD) but you can't really tell that's its caved in.

What I want is a small shallow area that caves in slightly on impact. I want there to be a lot of small pieces that fracture then cave in but I can never get it right. I have been having problems with break and shatter because I can never get it to split the square up into small enough pieces. So this is either a problem with that, or the impact.

I place the square on top of a caved in static square (done with a metaball) so that when the fractured square is struck it will only cave in the center.

That's what I've been doing but it never comes out right. Please help.

btw: the effect is for something heavy or forceful hitting the ground. thanks