Constraining the model

For a Stress analysis, constraints are applied to the model nodes to prevent rigid body motion (global translations and rotations) of the model, in response to the applied loads, whilst not interfering with the shrinkages of the part.

Why constrain the part?

When undertaking the structural analysis, any system of constraints can be used, providing it prevents rigid-body motion. Rigid-body motion is any motion in which the relative positions of all points making up the body remain unchanged.

General rigid-body motion in space involves six components (three orthogonal translations and three orthogonal rotations). This means that the minimum number of constrained degrees of freedom that must be set in the model is also six. In practice, you must decide whether the global coordinate system or a local coordinate system best simulates your perception of the physical situation being modeled.

Note: By default, the six degrees of freedom of all nodes in the model are free. To constrain the model, you need to specify which degrees of freedom are to be constrained for one or more nodes.

Model constraint types

The following types of constraints can be set:

Structural constraints

Constrains any required combination of degrees of freedom at node(s). This includes the fixed, pin, and general constraints.

Spring constraints

Applies a spring constraint at node(s).