Sand Bags HIP Files

A Vellum solver study: I wanted to fill a bag with heavy sand so that it tears apart from the weight of the sand pushing down on it.

I started with bags that had quadrilateral connectivity with some grains inside, then I varied the grains stiffness and re-meshed the bags to study the different outcomes of different wireframes (and because it looked cool), then I up-ressed the bags and the grains, added another piece of cloth underneath the bag held by 4 wires so that when the grains fall down we have another layer of cloth tearing.

In every iteration, I explored different break thresholds, different substep counts, different constraint iterations, and different tearing patterns. (I also wanted to have tear patterns that were more organic than the default "edge fracture" pattern we see all the time in Houdini sims.) It was interesting to see how changing one thing affects the look, feel, and weight of the entire sim.

Speaking of weights, I experimented with different masses for every object as well to get that sweet believable relationship and behavior between the sand and cloth.

Houdini 19