Create and Test NLFE Stabars

A stabar, also known as anti-roll bar, is a member that is used in automobile suspensions to increase roll stiffness. This helps reduce the body roll of a vehicle during cornering or when the vehicle traverses on road undulations.

An NLFE Stabar system is a MotionView system definition that can be used to represent a stabar as a non-linear finite element body assembled with accessories like drop links and attachment joints. A Stabar needs the following entities to be present in the model:
  • A vehicle body on which the stabar is mounted.
  • Suspension components like control arms/knuckles, etc. to which the stabar end drop-links are attached.
  • Optionally, a pair of points for the drop-link attachments to the suspension components mentioned above.
  1. From the Subsystems toolbar, click the NLFE Stabar Subsystem toolbar icon .
    The Add an NLFEStabar Subsystem dialog is displayed.
  2. Click the System collector and decide which system the stabar needs to be created in.
  3. Specify a variable name and label for the stabar.
    By default, variable names of entities in MotionView follow a certain convention. For example, all NLFE stabar entities have a variable name starting with nlfesb_. This is the recommended convention to follow when building models in MotionView since it has many advantages in model editing and model manipulation.
  4. Double-click the MaterialProperty collector and select a material to define the stabar, or accept Steel as the default.
  5. Click the Body collector and select the vehicle body on which the stabar is mounted from the modeling window, or double-click the collector to display the Model Tree (from which the desired body can be selected).
  6. In the same manner, select the attaching points and bodies on either side for the drop link.
    Note: Select Point 1 and Point 2 if available in the model. If not, activate the Use global point coordinates check box and enter in the coordinates where points for the attachments are to be created.
  7. Enter Outer and Inner diameter values for the stabar tube.
  8. Click on the Profile Points tab to define the profile of the stabar.
  9. Manually enter values for the profile points in the table of coordinates or import values with a .csv file.
    Tip: To change the number of points in the table, enter a value in the Total number of points text box.
  10. Click the Marker collector and select a reference marker in which the profile points are defined.
    The default is the global frame.
  11. Among the profile points defined, select two points as locations to attach the stabar to the mount body (frame) using the check box in the column at the right.
  12. Click OK.
    The stabar system that is created has the following architecture:
    Entity Description
    Body An NLFE body entity for the stabar is created using the profile points.
    DataSet A dataset where editable values are populated. After the creation of the stabar, you can change the outer diameter and inner diameter from this dataset.
    Points The points that define the stabar profile are created.
    Graphics Graphics are created for the joints for visualization.
    Joints Compliant joints are created to define connections between Stabar – Frame – Drop link – Suspension components.
    Outputs Output requests are created to measure stabar and drop link forces.
  • Activate Show additional parameters to specify variable names and labels for the points that are to be created.
  • If at any point you want to return to default settings, simply click Reset to Defaults.

Test a Stabar

A test rig can be used to exercise a stabar and plot its characteristics.

A testrig for stabar is provided in the install at <installation_directory>\utility\mbd\nlfe.

  1. Load the test rig model MDL file testrig_stabar.mdl in MotionView.
  2. Build the NLFE stabar as explained above.
  3. Solve the model using the Solve tool.
  4. From Analysis menu, click Reports.
  5. A stabar test report should be available as an entry. Select it and click OK.
    A couple of pages are loaded with animation and plots. The second page of this report has the plot of stabar moment versus roll angle measured at stabar ends. The slop of this plot gives the stabar roll stiffness.
  6. To view the slope, select the second window and click Coordinate Info.
  7. Click on any point on the curve to view the slope in the panel area.
    This value indicates the stabar roll stiffness.