An Equal Constraint causes all of its constrained joints to move together with the same displacements for each chosen degree of freedom. The other degrees of freedom are unaffected. The Equal Constraint differs from the rigid-body types of Constraints in that there is no coupling between the rotations and the translations. This Constraint can be used to:
Partially connect different parts of the structural model, such as at expansion joints and hinges.
Model symmetry and anti-symmetry conditions with respect to a plane.
The constraint must apply to at least two joints to have any effect on the model. These joints may have any arbitrary location in space. For connecting meshes, it is better to use the Body Constraint when the constrained joints are not in exactly the same location. Otherwise, rotational restraints may be inadvertently imposed on the model.
Use the following areas on the Equal Constraints form to make the appropriate entries:
Constraint Name. Use the default, or enter a unique name for the constraint being defined.
Coordinate System. Choose the coordinate system in which the constrained degrees of freedom (below) are being defined. If all degrees of freedom are being used, the choice of coordinate system has no effect on the constraint.
Constrained DOFs. Choose the degrees of freedom being constrained.
If the Define menu > Joint Constraints command was used to access the Equal Constraints form, the defined constraint must be assigned to the joints.
See Also
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Access the Equal Constraints form as follows:
Click the Define menu > Joint Constraints command to display the Define Constraints form or select the joints to be constrained and click the Assign menu > Joint > Constraints command to display the Define/Assign Constraints form. Then do one of the following:
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