MotionView User's Guide

AutoCDTire

AutoCDTire

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AutoCDTire

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Introduction

The tire models describe the interface between the wheel and the road.  Tire models apply forces and moments on wheel body so as to simulate a real tire forces and moments that tires apply on the vehicle.

Altair MotionView and MotionSolve support multiple tire models.  One of the models supported on the windows platform is CD-Tire (Fraunhofer LBF).  The CD-Tire is implemented via the Auto Entity: AutoTireCD.

The CD-Tire model is defined by a set of property files that describe the tire model parameters and the road model parameters.  User defined road models are also supported with what is run with the model:

$(ALTAIR_HOME) \hw\mdl\autoentities\properties\Tires   < tire property file with .tir extension>

$(ALTAIR_HOME) \hw\mdl\autoentities\properties\Tires   < road property file with .rdf extension>

In addition to this, physical properties of the tire such as the unloaded radius, aspect ratio, width, mass, and moment of inertia’s need to be explicitly specified.

Connectivity

One Body, one Point, and two Marker connections need to be made to define the tire interface:

Connection

Significance

Body 1

The wheel body on which the tire forces act.

Point 1

The point corresponding to the wheel center.

Marker 1

The wheel reference marker which determines the direction in which the tire forces act.

Marker 2

The road reference marker, is the marker with respect to which the road is positioned and oriented for the simulation.

cdtire_panel_mv

cdtire_example_mv

cdtire_example2_mv

Symmetry

The AutoTireCD Auto Entity can be added to a full vehicle model as a Single entity or as a Pair.  The Pair entity, like other MotionView Pair entities, establishes two symmetric (left and right) Tire models about the X axis.  An additional option determines if the symmetry should be mapped from left to right or right to left.  Symmetry can be disabled for AutoTireCD Pairs.

cdtire_panel_symmetry_mv

Tire models

CD-Tire Version 3.0 is supported in this release.  This release also supports various tire and road models as described below:

Tire Models

•CDTire 20-Rigid ring
•CDTire 30-Flexible Ring
•CDTire 40-3D Tire
•CD2030- Adaptive tire
•CD2040-Adaptive tire

The tire models, their use, and the underlying assumptions behind them are described in the CDTire Users Manual provided by Fraunhofer LBF.

Road Surface

The complete Road Surface library is supported in this release, as described in the CD Tire manual.  This includes the following road surface descriptions:

•Model 1000-Parametric road surface description
•Model 1002-Rolling Drum Model
•Model 1100-User defined
•Model 2000-Parametric and digitized road surface

Geometry-Inertia Tab

Information about the physical tire properties such as mass, inertia, and dimensions need to be provided in the Geometry-Inertias Tab.

cdtire_panel_geo_inertias_mv

Parameter

Description

Units [Model Units]

Unloaded radius

Distance between the WC and the contact point of tire in unloaded conditions.

Length

Aspect ratio

Tire Sidewall profile aspect ratio.  Describes the sidewall height as a percentage of the tire section width.

%

Width

Section width of the tire.

Length

Tire mass

Mass of the tire.

Mass

Ixx,Iyy,Izz

Moment of Inertia of the tire (y-axis out of plane of tire).

Mass * Length2

Property Files Tab

cdtire_panel_property_files_mv

The following files are required to specify the properties of the CD-Tire model:

hmtoggle_plus1Tire Parameter File

This file contains the parameters used by CD-Tire to describe the tire model.  The file format is defined by CD-Tire.  The file name convention is described in the CD-Tire User Manual and is of the form <path> <name> <model> <type>.  The naming convention must be followed strictly.  The naming convention is described in the CD-Tire manual.

Example:

TIRE PARAMETER FOR CDTIRE 40

DIMENSION 195/65 R 15

 

NMP [1]       NSP [1]      NSEN [1]     NFMIN [1]     NFMAX [1]

200           3            5            1             100

 

RFEL [mm]     BFEL [mm]    MGRT [Ns^2/mm]

200.0         140.0        7.62E-3

 

RGRT [mm]     BGRT [mm]

307.0         307.0        307.0        307.0

-70.0         -23.3         23.3         70.0

 

BETF [grad]   RHOF [1/mm]

21.0          0.05

 

EFS [N]       EFC [N]      EIY [Nmm^2]  EIX [Nmm^2]

1.35E6        1.51E6       2.65E6       1.37E9

 

FTX [Hz]     FTY [Hz]     FRY [Hz]

89.5         45.7         65.4

 

DTX [1]      DTY [1]      DRY [1]

0.05         0.05         0.05

 

KSRED [1]    RADIAL_FREE [1]    RADIAL_SPRING [1]

1.1          0.75               10.0

 

PREF [N/mm^2] PIN [N/mm^2]

2.2E-1        2.1E-1

 

EG [N/mm^2]   KM [1]      CREV [1]      BL [N/mm^2]

134.4         0.9         1             44.8

 

HL [mm]

10.0          10.0         10.0         10.0

 

NGLT [1]

3

 

MGLT [1]      VGLT [mm/s]

1.2           1.2          1.0

0.0           1.0E3        10.0E3

 

NRWB [1]

3

 

RWB [1]       OMRW [rad/s]

0.0           0.0193       0.0193

0.0           0.3          1.0E4
hmtoggle_plus1Tire Control File

CD-Tire requires a tire control file, which controls the integration time step and other parameters for the tire model.

Example:

# CONTROL PARAMETER FOR CDTIRE

#

# GRAV [mm/s^2]  DSSCAN [mm]  DPHISCAN [deg]  KAPMAX [1/mm]  TOL [1]

 9.81E3         0.05E3       0.0             0.3E-3         1.0E-3

#

# OBSOLETE       DTM20 [s]    DTM30 [s]       DTM40 [s]

 1.001E-3       4.0E-4       0.501E-3        1.001E-5

#

# TSTART [s]     TSWITCH [s]  TSECURE [s]

 0.2            0.1          0.05

#

# NWARN [1]      MONITOR_FILE [1]

 1000           0
hmtoggle_plus1Road Property File

CD-Tire requires a road definition file, which defines the road surface.  The road type is part of the file naming convention.  A typical file for a road with a cleat on it might be flat_cleat_1000.

Example:

# EXAMPLE ROAD DATA FILE: FLAT

# X0_ROAD   Y0_ROAD   Z0_ROAD   MU_ROAD        

 0.0       0.0       0.0       1.0

# DATA TYPE : DISCRETE OBSTACLE

 1

# TYPE   X_OBST   Y_OBST    LX       LY       H       MU_OBST

 2      -2500.0  -2500.0   20.0     400.0    0.0     1.0

END

Output Requests

The AutoTireCD entity generates some standard output requests into the solver deck.  These requests track the tire kinematics and the tire forces generated by the tire model.

Label

Description

Units

Force- (on wheel_part)

Tire force and moments with reference to the Global- Axis system measure at the hub.

Force &
Force*Length

CDTire Rolling States

X – Deformed radius of the Tire.
Y – Actual Rotational speed of the tire.

length
rad/time

CDTire Kinematic States

X – Longitudinal Slip of the tire.
Y – Lateral Slip of the tire.
Z – Inclination angle of the tire.

In the ISO axis system.

%

rad

rad

CDTire Force

Tire force and moments with reference to the TYDEX-C- Axis system measured at the hub.

Force &
Force*Length

CDTire Force

Tire force and moments with reference to the Global- Axis system at the tire contact patch.

Force &
Force*Length

CDTire Model, CPU Time

X – Tire Model Enumerator.
Y – CPU Time.