General multi-point constraints

Multi-point constraints (MPCs):

  • allow constraints to be imposed between different degrees of freedom of the model; and

  • can be quite general (nonlinear and nonhomogeneous).

The most commonly required constraints are available directly by choosing an MPC type and giving the associated data. The available MPC types are described below; MPCs that are available only in Abaqus/Standard are designated with an (S).

In Abaqus/Standard the constraints can also be given by user subroutine MPC.

Linear constraints can be given directly by defining a linear constraint equation (see Linear constraint equations).

In Abaqus/Explicit some multi-point constraints can be modeled more effectively using rigid bodies (see Rigid body definition).

Several MPC types are also available with connector elements (Connector elements). Although the connector elements impose the same kinematic constraint, connectors do not eliminate degrees of freedom.

MPC constraint forces are not available as output quantities. Therefore, to output the forces required to enforce the constraint specified in an MPC, you should use an equivalent connector element. Connector element force, moment, and kinematic output is readily available and is defined in Connector element library.

The following topics are discussed:

Related Topics
About Kinematic Constraints
In Other Guides
Defining MPC constraints