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3.11.1.3 Force Rigid Constraint
The force rigid constraint applies a load directly to the rigid degree of freedom. For a displacement degree of freedom, this is similar to applying a force in the corresponding direction. For a rotational degree of freedom, this is similar to applying a moment to the corresponding direction.It requires the following parameters.
| parameters | Description |
| rb | The rigid body's material ID. (1) |
| dof | The rigid degree of freedom to prescribe. (2) |
| value | The prescribed force value |
| load_type | Defines the type of load. (3) |
Comments:
- This is the “id” attribute assigned to the corresponding rigid body material as defined in the Material section.
- The values allowed for the dof parameter are: Rx, Ry, Rz, Ru, Rv, Rw. The first three (Rx, Ry, Rz) represent the displacement degrees of freedom. The other three (Ru, Rv, Rw) are the rotational degrees of freedom.
- The load_type allows the following values:
- 0 = a load (force/moment) is applied directly to the degree of freedom.
- 1 = a follower load applied is applied to the rigid body. The load is applied in the rigid body's coordinate system, so it rotates with the rigid body. This only works for Rx, Ry, Rz.
- 2 = target load. The load's value is ramped up from its initial value at the start of the step, and ramped up linearly to the value specified in the value parameter.
The following example applies a force in the x-direction.
<rigid_constraint type="force"> <rb>1</rb> <dof>Rx</dofs> <value lc="1">3.14</value> </rigid_constraint>