Activity 5: Constrain and load the roller

In this activity you specify zero displacement structural constraints to the 3 translational degrees of freedom of the roller, so it can only spin about the axis of rotation. You then prescribe to the roller a constant rotational velocity that lasts for the duration of the event, so that it rotates and flattens the steel slab that passes under it.

Since the roller is already rolling, and to prevent the shock of instantly accelerating to the prescribed rotational velocity, you also set an initial angular velocity to match the prescribed rotational velocity boundary condition.

To constrain the roller you:

Apply a fixed structural constraint to the 3 translational degrees of freedom
Apply a prescribed rotational velocity of 314.159 rad/s to the roller, about the Z axis
Define the multiplier curve that controls the prescribed rotational velocity, to ensure a constant rotational velocity
Apply an initial angular velocity to match the prescribed rotational velocity.

Prerequisites

Activity 4 is complete.

Steps

Set Structural Constraints to fix the three translational degrees of freedom of the roller.
1. Click (Simulation workspace > Setup tab > Constraints panel > Structural Constraints), to open the Structural Constraints dialog.
2. Confirm the constraint Type is set to Fixed.
3. Click the roller in the canvas to select it as the Target.
  
  Note: Since it is a rigid body, the entire body is selected and three rotational degrees of freedom (DOF) appear in the Structural Constraints dialog in addition to the usual translational DOF.
4. Click Rx, Ry, and Rz Axis to deselect them, so that only the three translational degrees of freedom are fixed.
5. Click OK to set the constraints and close the dialog.
From the introductory information, the roller is rotating at 314.159 rad/s. Prescribe a Rotational Velocity of 314.159 rad/s to the roller, about the Z-axis.
1. Click (Simulation workspace > Setup tab > Constraints panel > Prescribed Rotation) to open the Prescribed Rotation dialog.
2. Click the roller in the canvas to identify it as the Body.
  
  Note: You can only select Rigid Bodies.
3. Change the Constraint Type to Rotational Velocity.
4. Select the Omega z Component to define the direction.
5. If necessary, click Change Units and switch the units to rad/s.
6. Set the Magnitude OmegaZ to 314.159 rad/s.
Define the motion of the roller, such that it moves at a constant rotational velocity of 314.159 rad/s for the duration of the event.
1. In the Prescribed Rotation dialog, click Multiplier curve to open the Multiplier Curve dialog.
2. On the right side of the dialog, type 1 as the Multiplier at Time 0 so that the roller moves at 314.159 rad/s at the start.
3. On row 2, confirm that the Time is set to 0.002, which is the event duration you defined in the settings, then set the Multiplier to 1 again so that the roller continues to move at 314.159 rad/s for the entire duration.
4. Press Enter on your keyboard to accept the values.
5. Click OK to accept the curve and close the Multiplier Curve dialog.
6. Click OK to apply the prescribed rotational velocity and close the dialog.
Note: A green arrow appears to indicate the direction of the prescribed rotation.
Apply an Initial Angular Velocity to the roller of 314.159 rad/s. Use an edge of the roller as a Location Reference and the front face of the steel slab as the Direction Reference.
1. Click (Simulation workspace > Setup tab > Loads panel > Initial Angular Velocity), to open the Initial Angular Velocity dialog.
2. Select the roller in the canvas to select it as the Body.
3. Confirm that Direction Type is set to Normal.
4. If necessary, click Change Units and switch the units to rad/s.
5. In the Initial Angular Velocity dialog, click Select associated with Location Reference to activate it, then click a circular edge of the roller.
  
  Note: This defines the center of the circle as the location of the axis of rotation
6. In the Initial Angular Velocity dialog, click Select associated with Direction Reference to activate it, then click the front face of the steel slab.
  
  Note: This identifies the Normal direction that defines the axis of rotation.
7. In the Initial Angular Velocity dialog, click Flip Direction so that the direction of the orange arrow matches the direction of the green arrow.
8. Set the Magnitude to 314.159 rad/s.
9. Click OK to apply the load and close the dialog.

Activity 5 summary

In this activity, you

Applied a fixed structural constraint to the 3 translational degrees of freedom
Applied a prescribed rotational velocity of 314.159 rad/s to the roller, about the Z axis
Defined the multiplier curve to ensure a constant rotational velocity
Applied an initial angular velocity to match the prescribed rotational velocity.