9.11. Driving J-Turn Tutorial (Tire)
![../../../_images/image1157.png](../../../_images/image1157.png)
9.11.1. Overview
9.11.1.1. Task Objectives
The contact force between the tire and the ground is very important when analyzing the behavior of a running vehicle. It is difficult to express the tire contact force as general contact because friction, slip, and others arising from various dynamic loads must be considered. RecurDyn offers UIs and several types of Tire Solvers to easily define the contact force between the tires and the ground.
In this tutorial, you will learn how to create a UA-Tire-type tire using the GTire Toolkit. The GTire Toolkit allows you to easily create and define the geometries of tires and wheels, and you can easily change several types of Tire Solvers.
The model used in this tutorial is a front wheel drive model with the Macpherson Strut Suspension structure, which is configured to check the dynamic characteristics of the vehicle when the J-Turn is performed by changing the steering angle during driving.
Vehicle modeling by importing CAD and subsystem files
Create GTire of GRoad- and UA-Tire-type
Analysis of driving by P control and Steering control
Tire Property modification and result analysis
9.11.1.2. Prerequisites
This tutorial is for users familiar with Basic Tutorial provided by RecurDyn. Therefore, in order to use this tutorial, it is necessary to understand the above mentioned textbook first to improve the understanding of this tutorial.
9.11.1.3. Procedures
This tutorial consists of the following steps, and the time required is shown in the following table.
Procedures |
Time (minutes) |
Setting up the simulation environment |
5 |
Vehicle modeling |
15 |
Analysis of driving |
20 |
Modification and analysis of Tire Property |
10 |
Change and analysis of GRoad |
10 |
Total |
60 |
9.11.1.4. Estimated Time to Complete this Task
75 minutes
9.11.2. Setting up the simulation environment
9.11.2.1. Task Objectives
Set Unit, Gravity, and Icon Size to run the simulation.
9.11.2.2. Estimated Time to complete this task
5 minutes
9.11.2.3. Start RecurDyn
9.11.2.3.1. Creating a new model
Double-click the RecurDyn icon on the Desktop. RecurDyn runs and the Start RecurDyn dialog box appears.
In the Name field, enter the name of the model as Driving_Test.
Set the Unit to MMKS.
Set Gravity to –Z.
Click OK.
9.11.2.4. Resizing icons and markers
Adjust the size of icons and markers to make the model more visible.
9.11.2.4.1. Changing the size of icons and markers
On Render Toolbar, click the Icon Control tool.
Icon Control dialog box appears.
Set Icon Size and Marker Size to 20.
Close Icon Control dialog box.
9.11.3. Vehicle modeling
9.11.3.1. Task Objectives
Vehicle’s CAD files and subsystem files are imported to define the chassis and suspension, and GRoad and GTire are created to complete the vehicle modeling.
Try the following modeling.
Import CAD files to create Chassis Body
Import subsystem files to create Suspension
Create GRoad by using Box Geometry
Creating GTire of UA-Tire type
9.11.3.2. Estimated Time to complete this task
15 minutes
9.11.3.3. Creation of Chassis Body
9.11.3.3.1. Creating Chassis Geometry
To enter the Body Edit Mode, click the General funciton in the Marker and Body group on the Professional tab.
Body1@Driving_Test is displayed in the upper left corner of the Working Window as shown on the below.
In the File menu, click the Import function.
Set Files of type to ParaSolid File (*.x_t,*.x_b …).
- Select the Chassis.x_t file in the GTire tutorial folder.(The file path: <InstallDir>\Help\Tutorial\Toolkit\Tire\DrivingJTurn\Chassis.x_t)
Click Open. The CAD Import Options window appears. Clear the Assembly Hierarchy checkbox and click Import.
The message window displays a message that the import has been successfully completed, and the Chassis is shown as follows.
Click the Exit function on the Geometry tab to exit the Body Edit Mode.
9.11.3.3.2. Changing the property of Body1
Open the Properties dialog box for Body1.
Click the General page and make the following changes.
Name: Chassis
Layer: 2
Click the Graphic Property page.
Check Apply Transparency for All Graphics belong to Body and change the Transparency Level as shown on the below.
Click the Body page.
The material input data of Chassis is very important in vehicle analysis. Therefore, it is necessary to apply it to the body property based on the experimental measurement value or the reliable data.
Change the Material Input Type to User Input and change the information as shown below.
Mass: 1500
Ixx: 300000000
Iyy: 2400000000
Izz: 2550000000
Ixy: 0
Iyz: 0
Izx: 10000000
Click Apply to apply the User Input status. If you do not apply the User Input status, Center Marker cannot be modified.
Click CM to open the Properties dialog box of Center Marker.
In the Properties dialog box of the CM, change Origin to -900, 0, 300 and click OK.
Click OK of the Properties dialog box of body to apply changes. Chassis is shown as below.
9.11.3.4. Creation of Suspension Subsystem
9.11.3.4.1. Loading Suspension Subsystem
In the File menu, click the Import function.
Set Files of type to RecurDyn Subsystem File (*.rdsb).
- Select the Suspension.rdsb file in the GTire tutorial folder.(The file path: <InstallDir>\Help\Tutorial\Toolkit\Tire\DrivingJTurn)
Click Open to open the Import a Subsystem dialog box.
Click OK.
A subsystem called Suspension is created in the database and Suspension appears inside the chassis as shown below.
When entering the Suspension Subsystem from the database, it is divided into four subsystems in front, back, left and right.
Again, if you enter one of the four Suspension subsystems in the Database, you will see that the MBD modeling of each element is finally done.
Once the subsystem analysis is complete, click the Exit function on the Professional tab to go to the top level.
9.11.3.4.2. Changing Subsystem Mother Body
Open the Properties dialog box for Suspension Subsystem.
On the Subsystem page, change Mother Body to Chassis.
Click OK.
Entities shown in the figure below are modeled with Mother Body in Subsystem. In the above, the mother body is changed to the chassis, and the connection between the entities and Chassis is defined. In other words, you can see that Suspension is modeled with Chassis.
![../../../_images/image1739.png](../../../_images/image1739.png)
9.11.3.5. Create Translate Joint for Steering
There is no modeling of the steering in the Suspension Subsystem. Create a Translate Joint between Chassis and RackBar to configure the Steering System.
9.11.3.5.1. Creating Translate Joint
Since you need to click the RackBar hidden in the chassis, open the Layer Settings dialog box in advance.
On the Professional tab, click the Translate Joint function in the Joint group.
Set the Creation Method to Body, Body, Point, Direction.
In the Working Window, click Chassis as the first Body.
In order to click the RackBar hidden in the Chassis, uncheck On of Layer 2 in the Layer Settings dialog box.
To click the RackBar in the Subsystem as the second Body, hold down the Shift key and click Steering_RackBar@Suspension as shown on the below.
When two bodies are selected, enter the remaining two values as shown below.
Point: -216, 0, 176
Direction: 0, 1, 0
Once TraJoint1 is created, place a check mark in On of Layer2 again in the Layer Settings dialog box and click Close to close the dialog box.
Open the Properties dialog box for TraJoint1 and change the Name to Tra_Steering.
9.11.3.5.2. Entering Motion in the Translate Joint
There must be no movement in the steering system to drive the vehicle straight ahead. Define the Expression so that there is no motion and enter it into the Motion of the Translate Joint.
Open the Properties dialog box for Tra_Steering.
On the Joint page, click Include Motion.
Click Motion to open the Motion dialog box.
Set the Type to Displacement(Time) and click EL.
When the Expression List dialog box appears, click Create to open the dialog box.
When the Expression dialog box appears, enter as follows:
Name: Ex_Steering_RackBar_mm
Content: 0
In the Expression dialog box, click OK.
When the Expression List dialog box appears again, activate Ex_Steering_RackBar_mm in the list and click OK.
Make sure that Expression is entered in the Motion dialog box as shown in the figure on the below and click OK.
Click OK in the Tra_Steering’s Property dialog box.
As shown in the figure on the below, Motion is displayed on the Translate Joint.
9.11.3.6. Creation of Rotational Axial Force for Power
Create a Rotational Axial Force on both WheelHubs of the front Suspension to represent the power of the front wheel drive vehicle. Create a rotational axial force by using Revolute Joint located between Knuckle and WheelHub already defined in Suspension Subsystem.
9.11.3.6.1. Creation of Rotational Axial Force
On the Professional tab, click the Rotational Axial Force function in the Force group.
Set the Creation Method to Joint.
To create the right front wheel power, hold down the Shift key and click Rev_Knuckle__WheelHub@Suspension_FR@Suspension at the center of WheelHub in the right subsystem.
On the Professional tab, click the Rotational Axial Force function in the Force group.
Set the Creation Method to Joint.
To create the left front wheel power, hold down the Shift key and click Rev_Knuckle__WheelHub@Suspension_FL@Suspension at the center of WheelHub in the left subsystem.
Open the Properties dialog box for RotationalAxial1 and change the Name to Rot_Torque_FR.
Open the Properties dialog box for RotationalAxial2 and change the Name to Rot_Torque_FL.
9.11.3.6.2. To save the model
Basic vehicle modeling has been completed. On the File menu, click the Save function to save the model.
9.11.3.7. Creation of GRoad
GTire’s Contact requires the definition of GRoad unlike the general Contact entities.
9.11.3.7.1. Creating Box Geometry for creation of GRoad
To enter the Edit mode of the Ground, click the Ground function in the Marker and Body group on the Professional tab.
When you enter Ground Edit Mode, it will appear as Ground@Driving_Test in the upper left corner of the Working Window.
Click Box in the Marker and Geometry group on the Ground tab.
Set the Creation Method to Point, Point and enter as follows:
Point: -5000, 5000, -170
Point: 80000, -50000, -1000
Box1 will be created as shown below.
9.11.3.7.2. Creating GRoad
Click the Face GRoad function in the Road Data group on the Ground tab, and type as below.
Face: Box1.Face1
Direction: 0, 0, 1 (Normal Vector)
Direction: 1, 0, 0 (Heading Vector)
When the Save As dialog box appears, save the GRoad.rdf file in the path where the model is saved.
GRoad1 will be created as shown below.
Click the Exit function on the Ground tab to exit the Ground Edit Mode.
9.11.3.8. Creation of GTire
Solver types supported by GTire include UA-Tire, MF-Tire, F-Tire, etc. This tutorial uses the UA-Tire type, which is intuitive and easy to use.
9.11.3.8.1. Copying UA-Tire type Tire file
- Copy the UATire_MMKS.tir file from the GTire tutorial folder and paste it into where the model is saved.(The file path: <InstallDir>\Help\Tutorial\Toolkit\Tire\DrivingJTurn)
The example files used in this tutorial are defined for the UA-Tire Solver specification. The UA-Tire file configuration is as follows.
![../../../_images/image2928.png](../../../_images/image2928.png)
9.11.3.8.2. Creating GTire
Click the GTire function in the Toolkit group on the Toolkit tab.
Set Creation Method to Point, WithDialog, and enter 0, -800, 150 for Point.
When the GTireGroup dialog box appears, click ….
When the Open dialog box appears, link the UATire_MMKS.tir file copied above.
When connected, geometry information such as Tire Radius and Tire Width is automatically updated.
Click R to select Road.
Select Ground.GRoad1 created above.
Change the Force display to Action.
Click OK.
GTireGroup1 is created in the database.
Open the Properties dialog box for GTireGroup1 and change the Name to GTire_FR.
Repeat steps 2-10 by using the information below.
Point: 0, 800, 150
Name: GTire_FL
Point: -2746.8298265481, -800, 150
Name: GTire_RR
Point: -2746.8298265481, 800, 150
Name: GTire_RL
You must constrain the four GTires created above to each WheelHub with a Fixed Joint.
9.11.3.8.3. Creating a Fixed Joint between GTire and WheelHub
In Working Plane Toolbar, select the Change to XY tool.
In order to zoom in only vehicle, multi-select every GTire entities in Database and click the Fit tool in View Control Toolbar.
In order to click WheelHub hidden in the Chassis, uncheck On of Layer 2 in the Layer Settings dialog box.
When it looks like the picture below.
On the Professional tab, click the Fixed Joint function in the Joint group.
Set the Creation Method to Body, Body, Point.
To click the WheelHub in the Subsystem as the first Body, hold down the Shift key and click WheelHub@Suspension_FR@Suspension as shown below.
Select GTire_FRBody as the second Body.
Enter 0, -800, 150 as the Point.
Open the Properties dialog box for the created Fixed1 and change the Name to Fix_GTire_FR.
Repeat steps 3-8 by using the information below.
Body: WheelHub@Suspension_FL@Suspension
Body: GTire_FLBody
Point: 0, 800, 150
Name: Fix_GTire_FL
Body: WheelHub@Suspension_RR@Suspension
Body: GTire_RRBody
Point: -2746.8298265481, -800, 150
Name: Fix_GTire_RR
Body: WheelHub@Suspension_RL@Suspension
Body: GTire_RLBody
Point: -2746.8298265481, 800, 150
Name: Fix_GTire_RL
Once four Fixed Joints are created, place a check mark in On of Layer2 again in the Layer Settings dialog box and click Close to close the dialog box.
9.11.3.8.4. To save the model
From Road to Tire, all the modeling required for the analysis is complete. On the File menu, click the Save function to save the model.
9.11.4. Analysis of driving
9.11.4.1. Task Objectives
Use the completed vehicle model to perform the following analysis of driving.
Implement the analysis of vehicle landing
Perform analysis on straight driving
Analyze J-Turn driving
9.11.4.2. Estimated Time to complete this task
20 minutes
9.11.4.3. Preparation for the analysis of driving
Define the Torque for generating a driving speed of the vehicle as a spline curve and implement it as Expression. Then use the Expression created to apply it to the two Rotational Axial Forces created in Chapter 3.
9.11.4.3.1. Define the Torque of running speed as Spline
On the SubEntity tab, click the Spline function in the Expression group.
When the Spline List dialog box appears, click Create.
When the Spline dialog box appears, click Add Row and enter the values below.
Name: Sp_Torque_kmph_Nmm
Data:
No
X
Y1
1
0
1260000
2
25
840000
3
50
630000
4
75
525000
5
100
462000
6
125
420000
7
150
378000
8
175
357000
9
200
336000
10
225
325500
The above information is the torque (N*mm) that each wheel receives relative to the vehicle speed (km/h).
Click OK.
Click OK in the Spline List dialog box.
The target speed (km/h) is defined as PV for easy speed control.
9.11.4.3.2. Defining PV
On the SubEntity tab, click the Parametric Value function in the Parameter group.
When the Parametric Value List dialog box appears, click Add to define the values below.
InputV_kmph: 0
Click OK.
9.11.4.3.3. Creating Reference Marker to measure vehicle speed
In Working Plane Toolbar, select the Change to XY tool.
In order to zoom in only vehicle, multi-select every GTire entities in Database Window and click the Fit tool in View Control Toolbar.
On the Professional tab, click the Marker function in the Marker and Body group.
Set the Creation Method to Body, Point, and enter as follows:
Body: Ground
Point: -1400, 0, 540
Repeat steps 3 by using the information below.
Body: Chassis
Point: -1400, 0, 540
Two markers are created in the center of the chassis as shown below.
In the Database Window, select the Marker last created from the Markers under Ground and open the Properties dialog box.
Go to the Origin & Orientation page and make sure the same information as below is entered.
Origin: -1400, 0, 540
Orientation: 0, 0 ,0
Since it is a marker which will be used as a reference marker, please note that the analysis result may vary greatly depending on the origin and orientation.
After confirming that the Properties values are OK, change the Name to VM in the General page.
Click OK.
Repeat steps 6-8 for the markers of Chassis.
9.11.4.3.4. Defining Torque Expression
On the SubEntity tab, click the Expression function in the Expression group.
When the Expression List dialog box appears, click Create to open the dialog box.
When the Expression dialog box appears, enter as follows:
Name: Ex_Torque_Nmm
Content:
AKISPL(ABS((VX(1, 2, 1)/1000*3.6)), 0, 3, 0)*MIN(1.0,(InputV_kmph-VX(1, 2, 1)/1000*3.6)*1.4)
Argument :
ID1: Chassis.VM
ID2: Ground.VM
ID3: Sp_Torque_kmph_Nmm
The detailed look at the configuration of Expression defined above is as follows.
The AKISPL function returns the torque value using the spline information defined above.
Use spline’s X value for the VX function to input the vehicle’s traveling direction speed.
The vehicle speed is converted to km/h and an absolute value is taken by the ABS function.
Multiply the gap between the input velocity and the current speed by the Gain value (1.4) to implement a simple P control. (The gain value can be changed depending on situations.)
Use the MIN function so that the P control syntax does not exceed 1.
Click OK in the Expression dialog box.
Click OK in the Expression List dialog box.
Enter the Expression you created above in the two Rotational Axial Forces.
9.11.4.3.5. Entering Torque Expression
Open the Properties dialog box of Rot_Torque_FR in the database.
Click EL.
When the Expression List dialog box appears, activate Ex_Torque_Nmm in the list and click OK.
Make sure that Expression is entered on the Properties dialog box of Rot_Torque_FR and click OK.
Open the Properties dialog box of Rot_Torque_FL in the database and repeat steps 1-4.
9.11.4.4. Implement the analysis of vehicle’s settling on the road
Run Dynamic/Kinematic to see if the created vehicle is duly settled the road.
9.11.4.4.1. Implement the analysis of vehicle landing
In the Simulation Type group on the Analysis tab, click the Dynamic / Kinematic Analysis function to open the Dynamic/Kinematic Analysis dialog box.
On the General page, values are defined as follows.
End Time: 5
Step: 100
On the Parameter page, change the Maximum Time Step to 1.e-3.
Click Simulate to proceed with the analysis.
In the Animation Control group on the Analysis tab, click the Force Display Setting function.
Change the Scale of Force and Torque to 0.1 and close the dialog box.
Play back the animation to see if the vehicle duly reaches the road as shown below.
9.11.4.5. Perform analysis on straight driving
To create torque for the vehicle, change the target velocity defined by PV.
9.11.4.5.1. Changing velocity PV
On the SubEntity tab, click the Parametric Value function in the Parameter group.
In the Parametric Value List dialog box, change InputV_kmph to 40.
Click OK.
9.11.4.5.2. Perform analysis on straight driving
In the Simulation Type group on the Analysis tab, click the Dynamic / Kinematic Analysis function to open the Dynamic/Kinematic Analysis dialog box.
On the General page, values are defined as follows.
End Time: 8
Step: 160
Click Simulate to proceed with the analysis.
Play back the animation to see if the vehicle drives straight as shown below.
Since the steering motion is fixed, the vehicle will travel straight at 40km/h.
9.11.4.6. Analyze J-Turn driving
During driving, control the steering to analyze the J-Turn driving.
9.11.4.6.1. Modifying the Expression of Steering
On the SubEntity tab, click the Expression function in the Expression group.
When the Expression List dialog box appears, click E in the list to modify Ex_Steering_RackBar_mm.
When the Expression dialog box appears, modify the Content as shown below.
Content:
Step(Time-5,0,0,0.5,50) - Step(Time-7.5,0,0,0.5,50)
The Expression defined above is a formula to move the RackBar by 50mm between 5 and 8 seconds and undo the moving. When the RackBar moves 50mm, the Tire will turn about 12 degrees.
Click OK in the Expression dialog box.
Click OK in the Expression List dialog box.
9.11.4.6.2. Analyze J-Turn driving
In the Simulation Type group on the Analysis tab, click the Dynamic / Kinematic Analysis function to open the Dynamic/Kinematic Analysis dialog box.
On the General page, values are defined as follows.
End Time: 10
Step: 200
Click Simulate to proceed with the analysis.
Play back the animation to see if the vehicle performs J-Turn driving as shown below.
The result of animation analysis can be played back inside the subsystem as well. When played back inside the subsystem, it is played based on the Mother Body.
9.11.4.6.3. Watching an animation by using the subsystem
In the Database Window, right-click Suspension Subsystem and click Edit in the pop-up menu.
In the Database Window, again, right-click Suspension_FR Subsystem and click Edit in the pop-up menu.
Play back the animation to observe the behavior of the suspension.
The animation is played back based on the movement of Chassis, which is the mother body of the subsystem. Therefore, the Suspension connected to the Chassis is seen as a fixed state.
9.11.4.7. Drawing a plot
Draw a plot to see the dynamic behavior of a vehicle driving J-Turn.
![../../../_images/image5214.png](../../../_images/image5214.png)
9.11.4.7.1. Drawing a plot for J-Turn analysis
In the Plot group on the Analysis tab, click the Plot Result function.
Enter the Plot Window.
In the Windows group on the Home tab, click the Show All Windows function.
Use the information below to draw a plot.
Top left Window: Bodies -> Chassis -> Vel_TM
Top right Window: Bodies -> Chassis -> Pos_ROLL
Bottom left Window: Tire -> GTire_FLForce -> FyW_Lateral
Bottom right Window:
AxisX: Bodies -> Chassis -> Pos_TX
AxisY: Bodies -> Chassis -> Pos_TY
The result of plot analysis shows that the vehicle travels at a constant speed after 3.4 seconds. You can also see that when you start J-Turn after 5 seconds, the roll angle of the vehicle and the lateral force of tires occur. Finally, you can see the turning behavior of the vehicle numerically by X-Y position information.
Create and apply a plot template to repeat the same plot easily.
9.11.4.7.2. Exporting plot template
With four curves drawn, click the Template function in the Export group on the Home tab.
When the Export Plot Template Setting dialog box appears, click Export to save the template file.
9.11.4.7.3. Connecting the plot template file
Return to the modeling Window.
In the Plot group on the Analysis tab, click the Export Plot Template function.
When the Template dialog box appears, turn on the Use the Default Template File(*.template) option.
Select Use the Specified File and connect the Plot Template file created above.
Click OK to close the dialog box.
When the Plot Template is connected, the Template icon becomes active as shown on the below.
9.11.5. Modification and analysis of Tire Property
9.11.5.1. Task Objectives
After modifying the contact property of UA-Tire, perform the analysis of driving. Try to understand the impact of parameter change through the plot analysis of analysis results.
9.11.5.2. Estimated Time to complete this task
10 minutes
9.11.5.3. Modification and analysis of UA-Tire Property
There are several parameters in the Tire file that affect behaviors. Especially, during the J-Turn driving, the behaviors are greatly affected by the lateral force applied to the side of the Tire. Modify the parameters that affect the lateral force and try the same analysis.
9.11.5.3.1. Implement the analysis after modifying the UA-Tire Property
Open the Properties dialog box of GTire_FR in the database.
Click Edit to open the UATire_MMKS.tir file.
The file of UA Tire opens as a text format in Notepad as shown below.
Edit LATERAL_STIFFNESS as 30000.
In the File menu of Notepad, click the Save function to close Notepad.
Again, click OK in the Properties dialog box of GTire_FR.
Since the four GTire properties share the same Tire file, your action affects all the others.
Tip
Editing Tire Property directly with a text editorYou can also edit the Tire file directly by opening it in a text editor on the Windows Explorer without having to open it in the GTire Properties dialog box. The Property value thus edited is applied and then analysis is performed.In the Simulation Type group on the Analysis tab, click the Dynamic / Kinematic Analysis function to open the Dynamic/Kinematic Analysis dialog box.
Click Simulate to proceed with the analysis.
Once the analysis is completed, click the Plot Add function in the Plot group on the Analysis tab.
Since the Plot Template has been defined in Chapter 4, curves of newly analyzed results are drawn in the same form over the previously drawn Plot.
If you analyze the plot results, the Lateral Force becomes smaller after lowering LATERAL_STIFFNESS to 30000. So, the vehicle is pushed outward in the direction of turn. You can also see that the roll angle of the chassis becomes smaller during the turn between 5 seconds and 8 seconds.
Repeat steps 1-8 by using the information below.
LATERAL_STIFFNESS: 100000
Curves of newly analyzed results are drawn additionally over the previous plot.
If you analyze the plot result again, raising LATERAL_STIFFNESS to 100000 increases the lateral force as opposed to the previous result. So, the vehicle is pulled inward in the direction of turn. You can also see that the roll angle of the chassis becomes larger during the turn between 5 seconds and 8 seconds. Because of this change, the amplitude of the roll becomes very large immediately after the turn, that is, after 8 seconds.
9.11.6. Change and analysis of GRoad
9.11.6.1. Task Objectives
After changing GRoad, perform the analysis of driving.
9.11.6.2. Estimated Time to complete this task
10 minutes
9.11.6.3. Change and analysis of GRoad
Analyze the behavior of vehicle during a straight driving while changing the ground.
9.11.6.3.1. Changing velocity PV
On the SubEntity tab, click the Parametric Value function in the Parameter group.
In the Parametric Value List dialog box, change InputV_kmph to 30.
Click OK.
9.11.6.3.2. Modifying the Steering Expression for straight driving
On the SubEntity tab, click the Expression function in the Expression group.
When the Expression List dialog box appears, click E in the list to modify Ex_Steering_RackBar_mm.
When the Expression dialog box appears, modify the Content to 0.
Click OK in the Expression dialog box.
Click OK in the Expression List dialog box.
9.11.6.3.3. Modifying the UA-Tire Property
Open the Properties dialog box of GTire_FR in the database.
Click Edit to open the UATire_MMKS.tir file.
Edit LATERAL_STIFFNESS as 50000.
Create GRoad by loading the ground information file provided in this tutorial.
9.11.6.3.4. Copying GRoad files
Copy the GRoad_Rough.rdf file and the GRoad_Hill.rdf file from the GTire tutorial folder and paste it into where the model is saved. (File path: <InstallDir>\Help\Tutorial\Toolkit\Tire\DrivingJTurn)
9.11.6.3.5. Analyzing after changing to rough GRoad
To enter the Ground Edit Mode, click the Ground function in the Marker and Body group on the Professional tab.
When you enter Ground Edit Mode, it will appear as Ground@Driving_Test in the upper left corner of the Working Window.
Delete Box1 and GRoad1 from the Database Window.
In the Road Data group on the Ground tab, click the Import General Road File function to import GRoad_Rough.rdf copied above.
GRoad1 is recreated in the Database Window, and the rough surface is shown as below.
Click the Exit function on the Ground tab to exit the Ground Edit Mode.
In the Properties dialog box for four GTires, enter Road name as Ground.GRoad1.
In the Simulation Type group on the Analysis tab, click the Dynamic / Kinematic Analysis function to open the Dynamic/Kinematic Analysis dialog box.
On the General page, values are defined as follows.
End Time: 10
Step: 1000
Click Simulate to proceed with the analysis.
Play back the animation to check the behavior of the vehicle. You can see the vehicle sway back and forth due to the rough ground.
9.11.6.3.6. Unlink the Plot Template File
In the Plot group on the Analysis tab, click the Plot Template Setting function.
When the Template dialog box appears, turn off the Use the Default Template File(*.template) option.
Click OK to close the dialog box.
9.11.6.3.7. Drawing a Plot for rough surface analysis
In the Plot group on the Analysis tab, click the Plot Result function.
Enter the Plot Window.
Use the information below to draw the vehicle’s Pitch information.
Bodies -> Chassis -> Pos_PITCH
As you saw in the animation, you can also see on the plot numerically that the pitch angle increases due to the irregular ground surface.
9.11.6.3.8. Analyzing after changing to GRoad with hills
In the same way as before, delete the existing GRoad in the Edit mode of Ground and then open GRoad_Hill.rdf and try the same analysis.
![../../../_images/image663.png](../../../_images/image663.png)
![../../../_images/image672.png](../../../_images/image672.png)
9.11.6.4. Various analyses of driving (reference)
You can think about additional driving analyses by considering several factors as follows:
Modify other properties than LATERAL_STIFFNESS and then drive
Using various geometries to change the GRoad and then drive
Change Input Velocity and Steering and then drive
Change spring property of Suspension and then drive