The multi-body system must be sufficiently constrained.

Typical types of constraints like joints, couplers, and high-pair joints can be defined. Higher-pair joints include point-to-curve, point-to-surface, and curve-to-curve constraints. They can connect rigid bodies, flexible bodies, or a rigid and flexbody.

Before running the solver, any redundant constraints in the model are removed. Since the constraint forces associated with redundant constraints are set to zero, it is important to review all of the constraints in the model to make sure they are physically meaningful and that there are no unintended redundant constraints.

Joints connect two grid points that belong to a body. They constrain the motion between the bodies. They are defined using the JOINT or JOINTM bulk data entries. SPC type constraints in Multi-body Dynamics analysis are allowed only for MBD-ESL optimization of a flexible body if displacements are used as constraints.

Couplers are constraints between the translational and/or the rotational motion of two or three joints. They are defined using the COUPLER bulk data entries.

Higher-pair joints are connecting points, curves and surfaces. They can be rigid or deformable.

These entries refer to the parametric curve definition (MBPCRV), deformable curve definition (MBPTDCV), and deformable surface definition (MBDSRF).

See Also:

Multi-body Dynamics Simulation