Relative displacement definition

@EDGE_NAME {EdgeName}
@COMMENTS {CommentText}


Figure 1. Topological representation of a prismatic joint
with associated relative displacement element.
  1. A relative displacement joint is a constraint element that allows the definition of the relative displacement, Δ, of a master joint that can be a cylindrical joint, a planar joint, or a prismatic joint. The master joint must define this relative displacement through the optional @RELATIVE_DISPLACEMENT_NAME keyword.
  2. The relative displacement joint is associated with an edge, EdgeName. Vertices Vertex0Name and Vertex1Name are associated with this edge. A positive relative displacement is obtained when the body connected to Vertex1 of the master joint displaces with respect to the body connected to Vertex0 of the master joint along the common axis of the joint. Find more information about: the representation of multibody systems, and the formulation of constraints in multibody systems.
  3. Figure 1 illustrates the connection between the master joint and its relative displacement joint. In this case, the master joint is a prismatic joint with associated edge EdgePrj, whereas the edge associated with the relative displacement element is denoted EdgePru. Note that edges EdgePrj and EdgePru must share their vertex v0, labeled VertexB1. The relative displacement, Δ, is a degree of freedom associated with vertex v1 of the relative displacement joint, labeled VertexB3.
  4. It is possible to prescribe relative displacement Δ to a specific schedule by associating the relative displacement joint with prescribed displacement element PrdName.
  5. Optionally, a rectilinear elastomeric damper, EldModlName, can be added to the joint. An rectilinear elastomeric damper is a force element that generates a force Fed = Fed (Δ, dΔ/dt); it consists of elastic branches, dashpot branches, viscous branches, and plastic branches.
  6. It is possible to attach comments to the definition of the object; these comments have no effect on its definition.


  1. Sensors can be defined to extract information about prescribed displacements. The following SensorType and associated FrameName specifications are allowed for prescribed displacements: RELATIVE_DISPLACEMENTS.
  2. No u value or v value are accepted for prescribed displacements.