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Figure 4.20 Analytical and Geometrical Representation of Tire

RDR: Specifies the tire radial damping ratio(ζ). RDR is the ratio of tire damping to critical damping.

U0: Specifies the tire/road coefficient of friction at zero slip and represents the “sticking” or “static” friction coefficient.

U1: Specifies the tire/road coefficient of friction for the full slip case and represents the “sliding” or “kinetic” friction coefficient.

The tire property file (jeep_tire.tpf) appears as shown next.

! ----------------------

! | TIRE_PROPERTY_FILE |

! ----------------------

MODEL=

ANALYTICAL

! ANALYTICAL PARAMETERS BLOCK

R1 (undeflected outside tire radius)

1 375

R2 (idealized toroidal cross section carcass radius)

1 107.5

CN (vertical stiffness at zero deflection)

1 261.3

CSLIP (longitudinal stiffness at zero slip ratio)

1 30000

CALPHA (lateral stiffness due to slip angle at zero slip angle)

0.01745 46000

CGAMMA (lateral stiffness due to inclination angle at zero inclination angle)

0.01745 4000

CRR (rolling resistance moment)

1.00 5.625

RDR (vertical damping ratio)

0.75

U0 (maximum friction coefficient, friction coefficient at zero slip)

0.94

U1 (minimum friction coefficient, friction coefficient at full slip)

0.75

2. Creating Road Data File

The road data file (jeep_road.rdf) appears as shown next.

! ----------------------

! | ROAD DATA FILE |

! ----------------------

! jeep road file - flat

METHOD

GENDATA

!

! Conversion factors

!

X_SCALE

1.0

Y_SCALE

1.0

Z_SCALE

1.0

!

! Road origin is located at the following global coordinates in the data set.

!

ORIGIN

0 0 0

UP

0.0,1.0,0.0

!

! Road coordinate system is oriented with respect to the global origin

! by the following transformation matrix.

!

ORIENTATION

1 0 0

0 1 0

0 0 1

!

!coordinates for the node points on road

!

NODES

4

1 200000.0 0.0 -20000.0

2 -500000.0 0.0 -20000.0

3 200000.0 0.0 400000.0

4 -500000.0 0.0 400000.0

!

! Connectivity of node points defining the triangular element

!

ELEMENTS

2

1 2 3 1.0 1.0

2 3 4 1.0 1.0

3. Creating Tire and Road

1) From the Main Toll menu, point to Force Database, point to Tire. The Create Tire Force dialog box appears.

2) Select Tire Type: UA Tire.

3) In the Attachment Marker text box, enter .JEEP.Left_Knuckle.MARKer_11, it is the marker of Left_Knuckle in the Left_Wheel_center.

4) In the Tire Mass text box, enter 29.2.

5) In the Tire Inertia Moments text box, enter 5.002E+005, 5.002E+005, 6.904E+005.

6) In the Tire Property File text box, enter jeep_tire.tpf and path.

7) In the Road Data File text box, enter jeep_road.rdf and path.

8) In the Tire Width text box, enter 215.

9) Select OK, to create the left tire of front suspension.

10) Repeat above steps, to create the right tire of front suspension and the tires of rear suspension.

Figure 4.21 shows the model of tires. Figure 4.22 shows the full vehicle model.

Figure 4.21 The model of Tire