• The Chassis Group is the core structural components of the car that are not intended to be fractured. This typically includes the axles and suspension components, and it is the geometry that the wheels are constrained to.

• The Ignore Group is anything that you don’t want to be included in the fracture at all. For example, components like antennas can sometimes be excluded from the fracture.

• The Rest Frame is the static frame used for fracturing, which is useful when you have time-dependent animation.

• Wheels need re-alignment when incoming geometry has animations to prevent erratic spinning.

• The Display options let you visualize the output geometry, proxy geometry, constraint geometry, or guides in preview mode. Guides & Preview shows fracture density without full fracturing, making it easier to adjust density interactively.

• The Section parameter lets you choose to see the preview guide geometry for all sections or specific section names.

There are four types of Material to choose from, which all fracture in different ways.

• Section Connector Constraints are crucial for keeping disconnected car pieces together after fracturing. If pieces fall apart when they're not supposed to, you can adjust the Search Radius. For example, if you turn off this checkbox with a model like the truck, it will fall apart without the constraints to hold it together.

  

  

• Unique Names in Sections are important for generating constraint tags and groups, which helps with managing and breaking constraints in the RBD Bullet Solver. You can select what’s in the Groups by preset naming of your geometry, or by selecting it interactively in the viewport.

• Glue constraints are default; however, you can control behavior by turning the Enable Plastic Deformation on or off. Turning it off will allow your material to shatter. Turning it on will switch over to bendable soft constraints upon breaking.

• The parameters in the Constraint Attributes section are the global multipliers for the constraints. It’s recommended to change the Strength settings globally before adjusting each individual section.

• Tweaking constraints is best done after fracturing and collision setup. That way you will already have a rough idea of what your simulation looks like. Once you're happy with this, you can make constraints stronger or weaker.

  Note

  The Bullet solver’s Constraint Breaking tab allows you to select constraint tags for groups, like “windows”, and set breaking thresholds.

• Turning off Constrain to Neighbor Sections will not constrain pieces to neighboring sections. This is useful when you want to create your own constraints, such as hinges for the hood, trunk, or doors.

• There is an optional dive target in this node for advanced users to add custom fracturing or constraints.

• Fracture Density controls the number of pieces, and Thickness adds extrusion to thin geometry for proper Bullet simulation, ensuring piece have non-zero mass and proper collisions. This can still be very thin. For example, a value of 0.005 is enough to make a difference.

• Edge Detail adds noise along the cracks, giving your fracture a more interesting look. This is similar to RBD Material Fracture, and is very useful for simulating metal tearing.

• When fracturing metal, you will use these pieces to deform your high-res geometry using RBD Deform Pieces. It will take the bending you get from the constraints and transfer it onto your high-res geometry, so it looks like the metal is crumbling, bending, and denting.

• If pieces are falling off unexpectedly, you should adjust the Search Radius for the in the Section Connector Constraints section.

• If the car stops during a simulation, particularly when using non-simulated path following, the issue is likely a lack of velocities. You can fix this either by using a Trail SOP to compute the velocities, or set objects to Animated initially on an RBD Configure SOP.

• Use RBD Deform Pieces for metal crumpling and bending.

• Use RBD Car Deform for suspension and tire deformation.