Help

The Help button in the panel area can be used to quickly access information on AutoTire and the associated parameters. On clicking the Help button, the following window is displayed.



Figure 1.

The following section reproduces some information available in the Help dialog.

Tire Models

Auto Tire supports the following tire models.
CD Tire
Refer, HyperWorks Desktop Applications > MotionView > Vehicle Modeling > Tire Modeling > CD-Tire Modeling: CD-Tire Modeling path in the help section.
Licensing
Refer, HyperWorks Desktop Applications > MotionView > Vehicle Modeling > Tire Modeling > CD-Tire Modeling > Altair CD-Tire Documentation: CD-Tire Licensing path in the help section.
FIALA

Refer, HyperWorks Desktop Applications > MotionView > Vehicle Modeling > Tire Modeling: FIALA Tire Overview path in the help section.

FTire
Refer, HyperWorks Desktop Applications > MotionView > Vehicle Modeling > Tire Modeling: FTire Modeling path in the help section.
Licensing
For FTire license request please visit www.cosin.eu
MF-TIRE/MF-SWIFT

Refer, HyperWorks Desktop Applications > MotionView > Vehicle Modeling > Tire Modeling: MF-SWIFT/MF-Tyre Modeling path in the help section.

User Tire

Refer, HyperWorks Desktop Applications > MotionView > Vehicle Modeling > Tire Modeling: User Written Tire and Road Models path in the help section.

Outputs

Label Description Units
Radius X- Deformed radius of the Tire Length
  Y- Actual Rotational speed of the tire rad/time
  Z- Rotational speed considering Unloaded radius rad/time
LonSlip LatSlip IncAngle (ISO) X- Longitudinal Slip of the tree %
  Y- Lateral Slip of the tree rad
  Z- Inclination angle of the tire rad
Tire CP Forces

(W- Axis system)

 Tire forces and moments with reference to the ISO- Axis system at the tire contact patch. Force

Force*Length
Tire CP Forces

(SAE-Axis System)

 Tire forces and moments with reference to the SAE- Axis system at the tire contact patch. Force

Force*Length
LonSlip LatSlip IncAngle (SAE) X- Longitudinal Slip of the tree %
  Y- Lateral Slip of the tree rad
  Z- Inclination angle of the tire rad
Tire Hub Forces

(C-Axis System)

 Tire forces and moments with reference to the ISO axis system at the wheel center. Force

Force*Length
Contact Patch Location X, Y,Z of the contact patch location Length

VARSUB Switch

By switching “VARSUB Switch” to “On”, you can access internal states of the tire. These states are available as solver variables. To access these internal states use the following syntax:

For AutoTire - Single entity:

<autoTire varname>.sys_varsub.<varname of state variable>

For AutoTire - Pair entity:

<autoTire varname>.sys_tire_<side>.sys_varsub.<varname of state variable>
Note: Use left for the Left side of the pair and right for the Right side of the pair entity.
The description of VARSUB solver variable is given below:
Varname Description
sv_long_slip Longitudinal Slip (%) (ISO System)
sv_slip_angle Lateral Slip (ISO)
sv_camber_angle Camber Angle (ISO)
sv_cp_force_x Contact Patch Force in X (W-Axis System)
sv_cp_force_y Contact Patch Force in Y (W-Axis System)
sv_cp_force_z Contact Patch Force in Z (W-Axis System)
sv_cp_moment_x Contact Patch Moment in X (W-Axis System)
sv_cp_moment_y Contact Patch Moment in Y (W-Axis System)
sv_cp_moment_z Contact Patch Moment in Z (W-Axis System)
sv_rim_ang_vel Rim Angular Velocity
sv_rim_long_vel Rim Longitudinal Velocity
sv_rim_vert_vel Rim Vertical Velocity
sv_roll_rad Rolling Radius
sv_cp_loc_x Contact Patch Location in X (Global Frame)
sv_cp_loc_y Contact Patch Location in Y (Global Frame)
sv_cp_loc_z Contact Patch Location in Z (Global Frame)
Note: The output units will be mdl units.

Co-Ordinate Systems

Tydex-C Axis System
The “C” is for wheel center, and the C axis system has the following properties:
  • The origin of the C-axis system is the wheel center.
  • The X axis lies in the wheel plane and is parallel to the ground plane and points in the forward direction.
  • The Y axis is perpendicular to the wheel plane and points towards the vehicle’s left side so that a positive rotation of the wheel and tire about the Y axis rolls the tire forward.
  • The Z axis lies in the wheel plane, differs from vertical by inclination angle, and is perpendicular to the X and Y axis (Z= X x Y).


Figure 2.
Tydex-W Axis System
The “W” is for wheel. The Tydex W axis system considers the local slope of the road where the tire contacts the road, rather than assuming the road is flat.
  • The origin of the W axis system lies at the ideal contact point between the wheel plane and local road plane, which is the intersection of the Tydex C System Z axis with local road plane.
  • The X axis points forward along the line of intersection between the wheel plane and the local road plane.
  • The Z axis is parallel to the local road normal and hence perpendicular to the local road plane.
  • The Y axis is the projection of the wheel spin axis (Tydex C-Axis System Y) into the local road plane. The Y axis is perpendicular to both the X and Z axis (Y = Z x X).


Figure 3.
SAE Axis System
  • X is forward
  • Y is to the right
  • Z is down

Multi-Threading

Tire-Model Multi-Thread Enabling Multi-Threading
CD Tire YES

The CDTire.ini file controls multi-threading for CDTire. To enable multithreading, set the maximum threads in the parallel block to a number greater than one.

For example:

[Parallel]

MaxThreads=4
F Tire YES Multi-threading is controlled by the environment variable NUSOL_MT_TIRE.

NUSOL_MT_TIRE= 1 (Multi-Threaded execution)

NUSOL_MT_TIRE= 0 (Single Threaded execution)
MF-Tire/MF-SWIFT NO Not Applicable
User Tire NO Not Applicable