Creating Rotational Body Force Loads

Rotational body force loads represent acceleration fields induced by rotational motion applied to parts. You specify a rotation axis and values for the angular velocity and/or angular acceleration magnitudes. The rotational body force load applied to the part is a combination of the centrifugal load and the rotary acceleration load. The magnitude of the centrifugal load is proportional to the angular velocity squared. The magnitude of the rotary acceleration load is directly proportional to the angular acceleration.

The magnitude of a rotational body force load can vary with time during a step according to an amplitude definition (see Amplitudes for more information on defining amplitudes). The value of the rotational body force is determined by multiplying the centrifugal load and the rotary acceleration load by the value of the amplitude. You can also apply knowledgeware techniques to control the value of a rotational body force load (for more information, see Applying Knowledgeware).

Rotational body force loads can be applied only in mechanical steps.

Rotational body force loads can be applied to volume or part supports, to body groups, or to mesh parts.

This task shows you how to create a rotational body force load on geometry.

  1. Click the Rotational Body Force icon .

    The Rotational Body Force dialog box appears, and a Rotational Body Force object appears in the specification tree under the Loads objects set for the current step.

  2. You can change the identifier of the load by editing the Name field.

  3. Select the geometry support (a volume, part, or mesh part). Any selectable geometry is highlighted when you pass the cursor over it. You can select several supports to apply the load to all supports simultaneously. You can also select a body group.

    The Supports field is updated to reflect your selection. A temporary symbol will appear at the supports to indicate zero values until you apply a nonzero load.

  4. Select an existing line or a construction axis to specify the rotation axis. Any selectable geometry is highlighted when you pass the cursor over it.

    The Axis of rotation field is updated to reflect your selection.

  5. Enter a value for the Rotational velocity.

  6. Enter a value for the Rotational acceleration.

  7. Right-click on the velocity or acceleration field to add knowledgeware controls to the selected field (for more information, see Applying Knowledgeware).

  8. Click More to access additional rotational body force load options.

    1. Toggle on Selected amplitude, and select an amplitude from the specification tree to define a nondefault time variation for the rotational body force load.

      If you do not specify an amplitude in a Nonlinear Structural case, Abaqus applies the reference magnitude based on the Default load variation with time option that you selected when you created the step. Abaqus either applies the reference magnitude linearly over the step (Ramp) or applies it immediately at the beginning of the step and subsequently holds it constant (Instantaneous).

      If you do not specify an amplitude in an Explicit Dynamics case, Abaqus applies the reference magnitude immediately at the beginning of the step and subsequently holds it constant (Instantaneous).

      See About Prescribed Conditions in the Abaqus Prescribed Conditions Guide for more information.

  9. Click OK in the Rotational Body Force dialog box.

    Symbols representing the applied force are displayed on the geometry.