- Constraint is a set of two or more joints that are constrained such that their displacements relate. Constraints may be used to model (1) rigid-body behavior, in which joints translate and rotate together in a rigid connection; (2) equal-displacement behavior, in which displacement along certain degrees of freedom (DOF) is equal; and (3) symmetry / anti-symmetry conditions. Constraints enhance computational efficiency by reducing the number of equations necessary for solution. Multiple constraints should not be assigned to a single joint.
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