About Bodies

Definition

In the tree, the list of bodies appears under the Bodies node. Each body appears under a Body node.

There are 2 types of bodies: rigid bodies and rigid massless bodies. Rigid massless bodies are rigid bodies with no specified mass or inertia.

Tip: You can use rigid massless bodies to perform kinematic simulations, during which inertia is not taken into account.

Bodies contain markers and include at least one body reference marker, always created with a body at its origin.

Note: To modify the list of bodies enforced in a mechanism, you need to edit the mechanism.

Weight Definition

To perform a dynamics simulation, the following weight information must be defined for each body:

Mass

At the creation of a mechanism or of a body, the app computes the weight of the body based on the computed weight of the associated product. If the weight of the associated product is not declared or computed, the app computes the weight automatically based on the product geometry.

By default, during the creation of a body, the center of mass and inertia matrix are defined according to the reference marker of the body. In the panel, the center of mass and inertia matrix of the body are defined according to the global coordinate system of the root product.

In the product structure, the app updates the weight of a product automatically after the modification of its geometry. Update the weight definition of the associated body under the active mechanism for it to correspond to the weight information of the product computed and displayed in the B.I. Essentials.

Material

The app takes the following materials into account when computing the weight definition:

Core materials, based on their density
Covering materials with a specified thickness and applied on the entire product.

Position

Bodies are positioned according to the origin of the 3D shape containing the mechanism.

Note: The initial position of a body corresponds to the position of its associated product when:

A mechanism is created from a product assembly.
A new body is associated with a product using the Geometry parameter.

Modifying the position of a body in the model or in a simulation does not impact the position of the associated product. The position of the product remains the same.

The position of a product associated with a body is specific to the current mechanism. Every product not associated with a body is positioned according to its PLM instance position.