9.4 Performing a Quasi-Static Steady-State Cornering Analysis

You use an Steady-State Cornering (SSC) analysis to evaluate your full vehicle’s understeer and oversteer characteristics. The SSC analysis holds the turn radius constant and varies the vehicle velocity to produce increasing amounts of lateral acceleration. A control subroutine, CONSUB, controls the analysis and balances all the forces on the body and applies a lateral acceleration to all model parts.

You can now specify the inputs for the full-vehicle analysis and perform a quasi-static maneuver.

To set up the analysis:

1) From the Simulate menu, point to Full-Vehicle Analysis, point to Quasi-Static Maneuvers, and then select Constant Radius Cornering.

2) Run an analysis with the following specifications:

• Output Prefix: ssc1

• Number of Steps: 30

• Final Lateral Accel: .9

• Turn Radius: 50

• Make sure you set the units pull-down menu for the turn radius to m.

3) Select OK.

ADAMS/Car updates the properties of force entities such as dampers, springs, and bushings, with the values specified in their property files and sets up the vehicle assembly for the maneuver.

The number of steps for the output is directly related to the acceleration increment (that is, acceleration increment = final lateral acceleration / number of steps). ADAMS/Car performs a static analysis at each lateral acceleration increment. When the vehicle reaches the specified final lateral acceleration, the maneuver ends automatically.

9.5 Performing a Baseline iso Lane-Change Analysis

You now perform a baseline ISO lane-change analysis on the new assembly and then plot and view the results. You then modify the spring and analyze the assembly again.

In an ISO lane-change analysis, the Driving Machine drives your full vehicle through a lane-change course as described in ISO-3888: Double Lane Change. You specify the gear position and the desired speed at which to perform the lane change. The analysis stops after the vehicle travels 250 meters; therefore, the time to complete the return maneuver depends on the speed that you input.

To set up the analysis:

1) From the Simulate menu, point to Full-Vehicle Analysis, point to Course Events, and then select ISO Lane Change.

2) Set up the analysis with the following characteristics:

• Output Prefix: iso1

• Initial Velocity: 100

• Gear Position: 3

3) Select OK.

9.6 Modifying the Full-Vehicle Assembly

To change the roll angle versus lateral acceleration vehicle characteristic, modify the spring by creating and assigning a new property file.

A fter you create a spring property file, assign the

newly created property file to the front and rear springs.

1. To create a new spring property file:

1) From the Tools menu, select Curve Manager.

2) From the File menu, select New.

3) Verify that Type is set to spring.

4) Select OK.

ADAMS/Car generates a plot of the spring displacement

versus force characteristic in the plot window of the Curve Manager.

5) In the Slope text box, enter 225.

6) Make sure the extension/compressions limits are set to

-100, 100.

7 ) Select Apply.

ADAMS/Car modifies the spring characteristic.

8) In the Free Length text box, enter 300.

9 ) Select Apply.

10) From the File menu, select Save.

11) In the File text box, enter my_spring.

12) Select OK.

13) Close the Curve Manager.

ADAMS/Car returns to the main window.