Constraints
The Constraints subnode is used to impose a restriction on the relative motion between two components. You can specify an upper and lower bound of relative motion. This node can be added more than once if required, and the most restrictive value will then take precedence.
The Constraints subnode can be added to the Prismatic Joint, Hinge Joint, Cylindrical Joint, Screw Joint, Planar Joint, Ball Joint, Slot Joint, and Reduced Slot Joint. The contents of the settings sections will differ between different joint types. Multiple sections can be present in a single joint, depending on the number of degrees of freedom it has.
The Theory for Joint Constraints section describes the theory for each of the different types of constraints: translational, rotational, inclination angle, and axial rotation.
Translational Constraints
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, select Constraint type — Axial or Radial. For Axial, enter values or expressions for the Initial constraint axis ec0. For radial, select Constraint center from the list — Center of joint, Center of source, or Center of destination. Enter a value for the Constraint radius.
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For all applicable joints except Planar Joint with Radial type constraints, enter the Maximum relative displacement umax.
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For all applicable joints except Planar Joint with Radial type constraints, enter the Minimum relative displacement umin.
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Select Constraint parameters — Automatic or User defined. For User defined, enter a value or expression for the Penalty factor pu. The default is ((1[1/ms])^(2))*(mbd.prj1.ct1.me). The exact naming of the variable depends on the tags of the nodes in the model tree.
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Enter a value or expression for the Maximum allowable time step Δtmax.
The default is ((pi)/(30))*(sqrt((mbd.prj1.ct1.me)/(mbd.prj1.ct1.p_u))). The exact naming of the variables depends on the tags of the nodes in the model tree.
Rotational Constraints
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 Constraint parameters — Automatic or User defined. For User defined enter a value or expression for the Penalty factor pθ. The default is ((1[1/ms])^(2))*(mbd.hgj1.ct1.Ie). The exact naming of the variable depends on the tags of the nodes in the model tree.
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Enter a value or expression for the Maximum allowable time step Δtmax.
The default is ((pi)/(30))*(sqrt((mbd.hgj1.ct1.Ie)/(mbd.hgj1.ct1.p_th))). The exact naming of the variables depends on the tags of the nodes in the model tree.
Inclination Angle Constraint
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 Constraint parameters — Automatic or User defined. For User defined enter a value or expression for the Penalty factor pθ. The default is ((1[1/ms])^(2))*(mbd.blj1.ct1.Ie_th). The exact naming of the variable depends on the tags of the nodes in the model tree.
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Enter a value or expression for the Maximum allowable time step Δtmax.
The default is ((pi)/(30))*(sqrt((mbd.blj1.ct1.Ie_th)/(mbd.blj1.ct1.p_th))). The exact naming of the variables depends on the tags of the nodes in the model tree.
Axial Rotation Constraints
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 Constraint parameters — Automatic or User defined. For User defined enter a value or expression for the Penalty factor pψ The default is ((1[1/ms])^(2))*(mbd.blj1.ct1.Ie_psi). The exact naming of the variable depends on the tags of the nodes in the model tree.
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Enter a value or expression for the Maximum allowable time step Δtmax.
The default is ((pi)/(30))*(sqrt((mbd.blj1.ct1.Ie_psi)/(mbd.blj1.ct1.p_psi))). The exact naming of the variables depends on the tags of the nodes in the model tree.
Location in User Interface
Context Menus
Multibody Dynamics>Prismatic Joint>Constraints
Multibody Dynamics>Hinge Joint>Constraints
Multibody Dynamics>Cylindrical Joint>Constraints
Multibody Dynamics>Screw Joint>Constraints
Multibody Dynamics>Planar Joint>Constraints
Multibody Dynamics>Ball Joint>Constraints
Multibody Dynamics>Slot Joint>Constraints
Multibody Dynamics>Reduced Slot Joint>Constraints
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>Constraints