| On this page |
There are several MPM Configure examples available through the tab menu. These are similar to shelf tools that put down networks of nodes for learning purposes. The MPM Configure Metal Tearing example illustrates the use of the Metal material type. It puts down a simple network of nodes to simulate a sphere collider ripping through a metal sheet.
Important nodes ¶
metal_sheet
This is the 
MPM Source that uses the Metal material preset. However, the Type is set to Surface instead of the default Volume. This scatters points on the surface of the input geometry. It also has Relax Iterations of 250 to make sure there is a uniform distribution across the surface that fills as many holes as possible to create a good representation of the surface.
frame, distance_to_frame, and pin_frame
These nodes highlight the frame of the metal sheet, use a Ray SOP to detect the distance between the frame and sheet, and based on that distance, pin to animation all of the points that are near the edge.
sphere_collider
This is the 
MPM Collider, which uses the Animated (Rigid) collider type. It allows for very precise collisions as, for each substep, it interpolates the transforms of a single VDB which is both lighter in memory and more accurate than Animated (Deforming) colliders.
mpmcontainer
This setup uses a default 
MPM Container, which defines the resolution of the simulation using the Particle Separation parameter.
mpmsolver
This setup uses a default 
MPM Solver, which does the work of solving the scene. The Material Condition is decreased slightly to increase the number of substeps based on the stiffness of the material which fixes some instability in this case.
fractured_metal_sheet
This 
MPM Post-Fracture fractures the metal sheet according to its final state at the end of the MPM simulation, which is defined by the End Frame parameter. The Global Scale parameter has been set to 0.1, which affects all scale dependent parameters in a single step. In the Fracture Points tab, the filler points parameters have been adjusted to allow proper bending of the metal sheet near tearing areas by adding additional points. Align Fractures to Stretch Points is turned on to center the fractures where points have been identified as fracturing instead of using them as fracture centroids. In the Cutter Geometry tab, the Add Interior Details checkbox has been turned on to get more interesting fractures.
deformed_metal_sheet
This 
MPM Deform Pieces takes the pieces defined by the upstream MPM Post-Fracture feeding into its first input and deforms them using the MPM particles in the second input according to the Point + Piece Retargeting Type. Close Gaps is turned on to remove cracks by favoring the output from the Point (Deform) when the per-point difference between the Piece (transform) and Point (Deform) Retargeting Type is small. This is especially useful for metal tearing simulations.
Learning from this example ¶
| To... | Do this |
|---|---|
|
Fix instability in the behavior of the material |
In some cases, there could be some instability in the simulation where the material requires more substeps than what you're providing, which could result in points that merge or collapse onto each other. The quickest way to solve this is to slightly decrease the Material Condition on the |