17.2.8 Connector stops and locks

Products: ABAQUS/Standard  ABAQUS/Explicit  ABAQUS/CAE  

References

Overview

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.

Defining connector stops

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 property editor: AddStop: Components: component or components, Lower bound: lower limit, Upper bound: upper limit


Example

Since the shock in Figure 17.2.8–1 has finite length, contact with the ends of the shock determines the upper and lower limit values of the distance that node can be from node .

Figure 17.2.8–1 Simplified connector model of a shock absorber.

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 17.1.1, that is associated with the example in Figure 17.2.8–1 to include the following lines:

*CONNECTOR BEHAVIOR, NAME=sbehavior
...
*CONNECTOR STOP, COMPONENT=1
7.5, 15.0

Defining connector locks

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.

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 property editor: AddLock: Components: component or components, Lock: All or Specify component


Example

In the example in Figure 17.2.8–1 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

Defining connector stops and locks in linear perturbation procedures

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.

Output

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.