Products: ABAQUS/Standard ABAQUS/Explicit ABAQUS/CAE
Connector stops and locks can be:
specified in any connector with available components of relative motion;
used to specify contact-enforced stops in individual components of relative motion; and
used to lock in position an available component of relative motion when a certain criterion is met.
In the physical construction of most connectors the admissible position of one body relative to the other is limited by a certain range. In ABAQUS these limits are modeled as built-in inequality constraints. You specify the available components of relative motion for which the connector stops are to be defined and the lower and upper limit values of the connector's admissible range of positions in the directions of the components of relative motion.
| Input File Usage: | Use the following options to define a connector stop: |
*CONNECTOR BEHAVIOR, NAME=name *CONNECTOR STOP, COMPONENT=component number lower limit, upper limit |
| ABAQUS/CAE Usage: | Interaction module: connector section editor: Add |
Since the shock in Figure 25.2.8–1 has finite length, contact with the ends of the shock determines the upper and lower limit values of the distance that node b can be from node a.
Assume that the maximum length of the shock is 15.0 units and that the minimum length is 7.5 units. Modify the input file presented in “Connectors: overview,” Section 25.1.1, that is associated with the example in Figure 25.2.8–1 to include the following lines:*CONNECTOR BEHAVIOR, NAME=sbehavior ... *CONNECTOR STOP, COMPONENT=1 7.5, 15.0
Connector mechanisms may have devices designed to lock the connector in place once a desired configuration is achieved. For example, a revolute connection might have a falling-pin mechanism that locks the rotational motion after achieving a desired angle. A user-defined connector locking criterion can be defined for connector elements that contain available components of relative motion. You can select the component of relative motion for which the locking criterion is defined.
Connector locks can be used to specify connector behavior for constrained as well as available components of relative motion. Limit values for force or moment can be specified for all components of relative motion involved in the connection. In addition, limit values can be specified for relative position corresponding to the available components of relative motion.
In ABAQUS/Explicit you can also specify the limiting values of velocity in the available components as a criterion for locking. Velocity-dependent locking criteria are useful in modeling seatbelt systems in automobiles (see “Seat belt analysis of a simplified crash dummy,” Section 3.3.1 of the ABAQUS Example Problems Manual). Moreover, the limiting values can be dependent on temperature and field variables. Field variable dependencies can be used to model time-dependent locks.
If the locking criterion specified for the selected component of relative motion is met, either all components lock or a single available component locks in place. By default, all components of relative motion are locked in place upon meeting the locking criterion. In this case the connector element will be completely kinematically locked from that point on. In dynamic analyses this locking may introduce high accelerations. You can specify if only a selected component of relative motion is locked.
| Input File Usage: | Use the following options to define a connector lock: |
*CONNECTOR BEHAVIOR, NAME=name *CONNECTOR LOCK, COMPONENT=component number, LOCK=ALL or component number |
| ABAQUS/CAE Usage: | Interaction module: connector section editor: Add |
In the example in Figure 25.2.8–1 assume that relative rotations about the shock will lock if the force in the local 3-direction exceeds 500.0 units of force.
*CONNECTOR BEHAVIOR, NAME=sbehavior *CONNECTOR LOCK, COMPONENT=3, LOCK=4 , , -500.0, 500.0
The status of connector locks or stops cannot change during a linear perturbation analysis; all connector stop and connector lock definitions remain in the same status as in the base state.
The ABAQUS output variables available for connectors are listed in “ABAQUS/Standard output variable identifiers,” Section 4.2.1, and “ABAQUS/Explicit output variable identifiers,” Section 4.2.2. The following output variables are of particular interest when defining stops and locks in connectors:
CSLST | Flags for connector stops and locks. |
CRF | Connector reaction forces/moments. |
