Prescribed displacement definition

@PRESCRIBED_DISPLACEMENT_DEFINITION {
@PRESCRIBED_DISPLACEMENT_NAME {PrdName} {
@EDGE_NAME {EdgeName}
@FUNCTION_1D_NAME {Fun1DName}
@COMMENTS {CommentText}
}
}

Introduction

The prescribed displacement element is used to prescribe

  1. A time dependent relative rotation for a relative rotation joint, or
  2. A time dependent relative displacement for a relative displacement joint.

The prescribed displacement element is associated with an edge, EdgeName. Vertices Vertex0Name and Vertex1Name are associated with this edge. Find more information about: the representation of multibody systems and the formulation of constraints in multibody systems.

NOTES

  1. To prescribe the relative displacement between two bodies, the relative displacement element is first used to define the relative displacement, then, the prescribed displacement element is used to prescribe this relative displacement. Figure 1 illustrates the combination of elements: a prismatic joint associated with edge EdgePrj, the corresponding relative displacement joint with associated edge EdgePru, and finally the prescribed displacement element with associated edge EdgePrd. The labels v0 and v1 indicate the Vertex0 and Vertex1, respectively, of each edge.
  2. Figure 1. Prescribing relative displacements and rotations.
  3. To prescribe the relative rotation between two bodies, the relative rotation element is first used to define the relative rotation, then, the prescribed displacement element is used to prescribe this relative rotation. Figure 1 illustrates the combination of elements: a revolute joint associated with edge EdgeRvj, the corresponding relative rotation joint with associated edge EdgeRvr, and finally the prescribed displacement element with associated edge EdgePrd. The labels v0 and v1 indicate the Vertex0 and Vertex1, respectively, of each edge.
  4. The time history of the degree of freedom will be prescribed by a 1D function, Fun1DName, of type TIME_FUNCTION.
  5. It is possible to attach comments to the definition of the object; these comments have no effect on its definition.

Sensors

  1. Sensors can be defined to extract information about prescribed displacements. The following SensorType are allowed for prescribed displacements.
    • DRIVING_FORCE is the default option when the prescribed displacement element is used to prescribe a relative displacement.
    • DRIVING_MOMENT is the default option when the prescribed displacement element is used to prescribe a relative rotation.
  2. No FrameName is allowed.
  3. No u value or v value are accepted for prescribed displacements.