FEM ConstraintRigidBody: Difference between revisions

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<languages/>
<translate>
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{{Docnav
{{Docnav
|[[FEM_ConstraintFixed|Constraint fixed]]
|[[FEM_ConstraintFixed|Constraint fixed]]
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{{GuiCommand
{{GuiCommand
|Name=FEM ConstraintRigidBody
|Name=FEM ConstraintRigidBody
|MenuLocation=Model → Mechanical boundary conditions and loads → Constraint rigid body
|MenuLocation=Model → Mechanical boundary conditions and loads → Rigid body constraint
|Workbenches=[[FEM_Workbench|FEM]]
|Workbenches=[[FEM_Workbench|FEM]]
|Version=1.0
|Version=1.0
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}}
}}


==Description==
==Description== <!--T:3-->




<!--T:4-->
Defines the CalculiX's rigid body constraint that constrains the motion of the nodes of a selected geometrical entity to the motion of a reference node whose location is defined by the user. In practice, this can be used to apply a boundary condition or load that will be propagated to the selected face. Since the reference node has rotational degrees of freedom, it's possible to apply a moment load or a rotational boundary condition to any face this way. The location of the reference node can be selected, if it's offset from a face, a remote load (a force acting on a lever) can be applied.
Defines the CalculiX's rigid body constraint that constrains the motion of the nodes of a selected geometrical entity to the motion of a reference node whose location is defined by the user. In practice, this can be used to apply a boundary condition or load that will be propagated to the selected object. Since the reference node has rotational degrees of freedom, it's possible to apply a moment load or a rotational boundary condition to any face this way. The location of the reference node can be selected, if it's offset from a geometrical entity, a remote load (a force acting on a lever) can be applied.


==Usage==
==Usage== <!--T:5-->




<!--T:6-->
# There are several ways to invoke the command:
# There are several ways to invoke the command:
#* Press the {{Button|[[Image:FEM_ConstraintRigidBody.svg|16px]] [[FEM_ConstraintRigidBody|Constraint rigid body]]}} button.
#* Press the {{Button|[[Image:FEM_ConstraintRigidBody.svg|16px]] [[FEM_ConstraintRigidBody|Rigid body constraint]]}} button.
#* Select the {{MenuCommand|Model → Mechanical boundary conditions and loads → [[Image:FEM_ConstraintRigidBody.svg|16px]] Constraint rigid body}} option from the menu.
#* Select the {{MenuCommand|Model → Mechanical boundary conditions and loads → [[Image:FEM_ConstraintRigidBody.svg|16px]] Rigid body constraint}} option from the menu.
# In the [[3D_view|3D view]] select the geometrical entity/entities (vertices, edges or faces but not a mix of them) to which the constraint should be applied.
# In the [[3D_view|3D view]] select the geometrical element(s) (vertices, edges or faces but not a mix of them) to which the constraint should be applied.
# Specify the coordinates of the reference node.
# Specify the coordinates of the reference node. After closing the task panel, a spherical symbol will show this location.
# Choose modes for the 3 translational and 3 rotational degrees of freedom (DOFs):
# Choose modes for the 3 translational and 3 rotational degrees of freedom (DOFs):
#* ''Free'' - default, no boundary condition or load on that DOF
#* ''Free'' - default, no boundary condition or load on that DOF
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#* ''Load'' - force/moment load with a specified value on that DOF
#* ''Load'' - force/moment load with a specified value on that DOF


==Limitations==
==Limitations== <!--T:7-->




<!--T:8-->
* Currently, the moment units can be somewhat confusing. To apply 1 N*m, one needs to set 1 J in the input field (those units are equivalent).
* Currently, the moment units can be somewhat confusing. To apply 1 N*m, one needs to set 1 J in the input field (those units are equivalent).
* The feature can be applied only to vertices, edges and faces for now, support for solids (to make whole volumes/parts rigid) should follow in the future.
* The feature can be applied only to vertices, edges and faces for now, support for solids (to make whole volumes/parts rigid) should follow in the future.
* The selected object is made rigid. To apply loads in a more flexible way, one would need to use CalculiX's distributing coupling constraints which are currently unsupported.
* The selected object is made rigid. To apply loads in a more flexible way, one would need to use CalculiX's distributing coupling constraints which are currently unsupported.


==Notes==
==Notes== <!--T:9-->


<!--T:10-->
* This constraint is the standard way of applying torque to arbitrary parts. The other options are the [[FEM_ConstraintTransform|Local coordinate system]] (only for cylindrical faces) or a pair of forces but the rigid body constraint should be sufficient in pretty much all the cases.
* No other constraints/boundary conditions should be applied to the nodes involved in a rigid body constraint.
* No other constraints/boundary conditions should be applied to the nodes involved in a rigid body constraint.
* When applying this constraint to a vertex or an edge, one should set a proper rotational DOF (in the case of an edge, the one that will prevent the rotation about it) to zero.
* This feature uses the [https://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node236.html *RIGID BODY card in CalculiX].
* This feature uses the [https://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node236.html *RIGID BODY card in CalculiX].






<!--T:11-->
{{Docnav
{{Docnav
|[[FEM_ConstraintFixed|Constraint fixed]]
|[[FEM_ConstraintFixed|Constraint fixed]]

Latest revision as of 07:40, 28 May 2024

Other languages:


FEM ConstraintRigidBody

Menu location
Model → Mechanical boundary conditions and loads → Rigid body constraint
Workbenches
FEM
Default shortcut
None
Introduced in version
1.0
See also
FEM Constraint displacement

Description

Defines the CalculiX's rigid body constraint that constrains the motion of the nodes of a selected geometrical entity to the motion of a reference node whose location is defined by the user. In practice, this can be used to apply a boundary condition or load that will be propagated to the selected object. Since the reference node has rotational degrees of freedom, it's possible to apply a moment load or a rotational boundary condition to any face this way. The location of the reference node can be selected, if it's offset from a geometrical entity, a remote load (a force acting on a lever) can be applied.

Usage

  1. There are several ways to invoke the command:
    • Press the Rigid body constraint button.
    • Select the Model → Mechanical boundary conditions and loads → Rigid body constraint option from the menu.
  2. In the 3D view select the geometrical element(s) (vertices, edges or faces but not a mix of them) to which the constraint should be applied.
  3. Specify the coordinates of the reference node. After closing the task panel, a spherical symbol will show this location.
  4. Choose modes for the 3 translational and 3 rotational degrees of freedom (DOFs):
    • Free - default, no boundary condition or load on that DOF
    • Constraint - displacement/rotation boundary condition with a specified value (default: 0 = fixed) on that DOF - for rotation, one needs to set an axis (X, Y or Z) and specify the Angle
    • Load - force/moment load with a specified value on that DOF

Limitations

  • Currently, the moment units can be somewhat confusing. To apply 1 N*m, one needs to set 1 J in the input field (those units are equivalent).
  • The feature can be applied only to vertices, edges and faces for now, support for solids (to make whole volumes/parts rigid) should follow in the future.
  • The selected object is made rigid. To apply loads in a more flexible way, one would need to use CalculiX's distributing coupling constraints which are currently unsupported.

Notes

  • This constraint is the standard way of applying torque to arbitrary parts. The other options are the Local coordinate system (only for cylindrical faces) or a pair of forces but the rigid body constraint should be sufficient in pretty much all the cases.
  • No other constraints/boundary conditions should be applied to the nodes involved in a rigid body constraint.
  • When applying this constraint to a vertex or an edge, one should set a proper rotational DOF (in the case of an edge, the one that will prevent the rotation about it) to zero.
  • This feature uses the *RIGID BODY card in CalculiX.