Flexible joint definition

@FLEXIBLE_JOINT_DEFINITION {
@FLEXIBLE_JOINT_NAME {FlxName} {
@EDGE_NAME {EdgeName}
@FLEXIBLE_JOINT_PROPERTY_NAME {FlxPropName}
@RELATIVE_ROTATION_NAME {RvrName}
@GRAPHICAL_PARAMETERS_NAME {GrfParamName}
@COMMENTS {CommentText}
}
}

NOTES

  1. A flexible joint consists of a set of concentrated springs and dampers that is associated with an edge, EdgeName, used for the representation of multibody systems.
  2. The geometry of the flexible joint is inherited from edge, EdgeName, which must have an associated triad, TriadName.
  3. The stiffness matrix, D* of the joint is defined in the flexible joint properties, FlxPropName. The 6 × 6 stiffness matrix is fully populated, allowing the modeling of the various rectilinear and torsional stiffnesses, as well as potential elastic couplings. These physical properties are defined with respect to the local triad, TriadName.
  4. The damping matrix, Q*, of the joint is defined in the flexible joint properties, FlxPropName. The 6 × 6 damping matrix is fully populated, allowing the modeling of the various rectilinear and torsional damping constants, as well as potential coupling terms. These physical properties are defined with respect to the local triad, TriadName.
  5. If the components of the flexible joint stiffness tensor D* are chosen appropriately, it is possible to simulate a revolute joint by means of a flexible joint. First, the rectilinear springs that define the relative motion between bodies Body0Name and Body1Name should be quite stiff to constrain the relative motion. Similarly, the use of two stiff torsional springs will approximately satisfy the orthogonality constraints that define a revolute joint. Then, a relative rotation, Φ, can be defined by means of a relative rotation element RvrName.
  6. It is possible to attach comments to the definition of the object; these comments have no effect on its definition.

Graphical parameters

The appearance of the flexible joint during the visualization phase of the analysis can be controlled by associating graphical parameters, GrfParamName to the element. The following representations are valid for flexible joint elements: RprType = SYMBOL or TRIAD. The TRIAD representation depicts the flexible joint with a triad. The SYMBOL representation depicts the flexible joint as a box symbol. Default value: TRIAD. No vector fields are valid for flexible joint elements.

Sensors

  1. Sensors can be defined to extract information about flexible joints. The following SensorType and associated FrameName specifications are allowed for flexible joints: ACCELERATIONS_0, ACCELERATIONS_1, DISPLACEMENTS_0, DISPLACEMENTS_1, POSITIONS_0, POSITIONS_1, VELOCITIES_0, and VELOCITIES_1. (Default value: DISPLACEMENTS).
  2. No u value or v value are accepted for flexible joints.