Locking
Use the Locking subnode to put a lock condition on the relative motion between two components on a joint. Lock conditions are similar to Constraints, but after the displacement in the joint degree of freedom reaches the limiting value, it will be fixed to that value. You can specify the locking value for the relative motion in the form of upper and lower bound. This node can be added more than once if required, and the most restrictive value will then take precedence.
The Locking subnode can be added to the Prismatic Joint, Hinge Joint, Cylindrical Joint, Screw Joint, Planar Joint, Ball Joint, Slot Joint, and Reduced Slot Joint.
If multiple degrees of freedom are present in a joint, a lock condition can be put on each of the degrees of freedom. If all the degrees of freedom are locked, the components attached to the joint move as a single object. The contents of the settings sections will differ between different joint types.
The Theory for Joint Locking section describes the theory for each of the different types of locks: translational, rotational, inclination angle, and axial rotation.
Translational Locking
This section is available for the Prismatic Joint, Cylindrical Joint, Screw Joint, Planar Joint, Slot Joint, and Reduced Slot Joint nodes.
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For the Planar Joint only, enter values or expressions for the Initial locking axis el0.
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Enter the Maximum relative displacement umax.
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Enter the Minimum relative displacement umin.
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Select the Locking parameters — Automatic or User defined. For User defined enter a value or expression for the Penalty factor pu1, which supplies a penalty stiffness used for enforcing the constraint. The default is ((0.01)*(mbd.prj1.lk1.Eequ))*(mbd.diag). Enter a value or expression for the Penalty factor pu2, which supplies damping suppressing vibrations. The default is (mbd.prj1.lk1.p_u1)*(10[ms]). The exact naming of the variables depends on the tags of the nodes in the model tree.
Rotational Locking
This section is available for the Hinge Joint, Cylindrical Joint, Screw Joint, Planar Joint, and Reduced Slot Joint.
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Enter the Maximum relative rotation θmax.
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Enter the Minimum relative rotation θmin.
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Select the Locking parameters — Automatic or User defined. For User defined enter a value or expression for the Penalty factor pθ1.
The default is ((1e-4)*(mbd.hgj1.lk1.Eequ))*((mbd.diag)^(3)). The exact naming of the variables depends on the tags of the nodes in the model tree. Enter a value or expression for the Penalty factor pθ2. The default is (mbd.hgj1.lk1.p_th1)*(10[ms]). The exact naming of the variable depends on the tags of the nodes in the model tree.
Inclination Angle Locking
This section is available for the Ball Joint and Slot Joint.
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Select the Initial reference axis — Initial source axis, Initial destination axis, or User defined. For User defined enter values for eR0.
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Enter a value or expression for the Maximum inclination angle θmax.
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Select the Locking parameters — Automatic or User defined. For User defined enter a value or expression for the Penalty factor pθ1.
The default is ((1e-4)*(mbd.blj1.lk1.Eequ))*((mbd.diag)^(3)). The exact naming of the variables depends on the tags of the nodes in the model tree. Enter a value or expression for the Penalty factor pθ2. The default is (mbd.blj1.lk1.p_th1)*(10[ms]). The exact naming of the variable depends on the tags of the nodes in the model tree.
Axial Rotation Locking
This section is available for the Ball Joint and Slot Joint.
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Enter the Maximum axial rotation ψmax.
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Enter the Minimum axial rotation ψmin.
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Select the Locking parameters — Automatic or User defined. For User defined enter a value or expression for the Penalty factor pψ1.
The default is (1e-4)*(mbd.blj1.lk1.Eequ)*(mbd.diag)^(3). The exact naming of the variables depends on the tags of the nodes in the model tree. Enter a value or expression for the Penalty factor pψ2. The default is (mbd.blj1.lk1.p_psi1)*(10[ms]). The exact naming of the variable depends on the tags of the nodes in the model tree.
Location in User Interface
Context Menus
Multibody Dynamics>Prismatic Joint>Locking
Multibody Dynamics>Hinge Joint>Locking
Multibody Dynamics>Cylindrical Joint>Locking
Multibody Dynamics>Screw Joint>Locking
Multibody Dynamics>Planar Joint>Locking
Multibody Dynamics>Ball Joint>Locking
Multibody Dynamics>Slot Joint>Locking
Multibody Dynamics>Reduced Slot Joint>Locking
Ribbon
Physics tab with Prismatic Joint, Hinge Joint, Cylindrical Joint, Screw Joint, Planar Joint, Ball Joint, Slot Joint, or Reduced Slot Joint selected in the model tree:
Attributes>Locking