Collision Body

Use the Collision Body command to define how elements collide with other elements that also have a collision body. Elements without a collision body pass through other objects.

Selecting a collision shape

Mechatronics Concept Designer calculates collisions using simplified collision shapes to encapsulate the elements. Increasing the geometric accuracy of the collision shapes increases the likelihood of penetration failures and simulation instability. To reduce the risk of instability (objects passing through, vibrating, or sticking) and maximize the runtime performance, we recommend using simpler collision shapes.

Tip: For complex simulations, you can test and optimize the physics solver options and parameters to improve the simulation behavior with the Mechatronics Concept Designer Preferences command.

The following collision shapes are supported (with their geometric accuracy / reliability / simulation performance trade-offs):

Type	Geometric accuracy	Reliability	Simulation performance
Box	Low	High	High
Sphere	Low	High	High
Capsule	Medium	High	High
Cylinder	Medium	Medium	Medium
User Defined Convex — Through Points	Medium	Medium	Medium

You can change the orientation and origin of the Box, Capsule, and Cylinder collision shapes to increase their physical accuracy to reduce unwanted detections.

Set the Collision Shape to Hole to select either an inside or outside cylindrical face to encapsulate a hole in the geometry of a rigid body with a collision body. You can select a cylindrical face, and then apply an offset to determine the size of the collision shape relative to the selected face. For example, you can create a collision body for a hole that is narrower than the geometry to test diameter tolerances.

Defining a collision shape

To more accurately define the shape of a collision body and optimize its simulation behavior, use the User Defined Convex option to define it manually using points, planes, and a convex factor.

Define a collision shape using a mesh or from a point for geometry such as a nonstandard or highly irregular part shape.

Collision categories

Every collision body has a collision category, which defaults to 0. If you set a different collision category, the collision body only interacts with collision bodies that have the same collision category or a collision category of 0.

You can change or create the collision category specifications that define which categories interact with each other using the Collision Category Specification Mechatronics Concept Designer preference. You can also import and export collision category specifications in the .xls, .xlsx, or .csv format.

Sticking collision bodies on contact

Use the Stick when Collision check box to connect the individual collision bodies on contact during simulations. You can set the sticky factor using the Sticky Force Mechatronics Concept Designer preference.

Although the Stick when Collision option may work for basic scenarios, you can also use the Bond Zone command to bond collision bodies in more complex material-handling situations, such as bundling and unbundling parts.

Pausing a simulation upon a collision

You can configure a simulation to pause automatically when a collision is detected (useful for debugging and inspecting a collision event in detail).

Related tasks

• Create a mesh collision body
• Create a collision body for an important hole
• Define a radial collision shape
• Define an isoparametric collision shape
• Define a convex collision shape using planes
• Define a collision shape using a curve
• Define a collision shape using points
• Define a collision shape between points
• Define a collision shape interactively
• Connect collision bodies

Related reference

• Collision Body dialog box

Command

Collision Body