521 Tire Model

Using the 521-Tire Model

About 521-TireThe 521-Tire model is a simple model that requires a small set of parameters or experimental data to simulate the behavior of tires. The 521-Tire is the first tire model incorporated in Adams. The name 521 (actually 5.2.1) refers to the version number of Adams/Tire when it was first released.

The slip forces and moments can be calculated in two ways:

Using the Equation method Using the Interpolation method

Two dedicated contact methods exist for the 521-Tire:

Point Follower, used for Handling analysis models Equivalent Plane Method, used for 3D Contact analysis models

Any combination of force and contact method is allowed.

The road data files used for the 521-Tire are unique and cannot be used in combination with any other Handling tire model. The 521 road file format is described in Road Data File 521_pnt_follow.rdf.

Note that the capability and generality of the 521-Tire have been superseded by other, newer tire models, described throughout this guide. Weve retained the 521-Tire model primarily for backward compatibility. We recommend that you use other tire models for new work.

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Tire Slip Quantities and Transient Tire Behaviour

Definition of Tire Slip QuantitiesSlip Quantities at Combined Cornering and Braking/Traction

The longitudinal slip velocity Vsx in the SAE-axis system is defined using the longitudinal speed Vx, the wheel rotational velocity and the loaded rolling radius Rl:

The lateral slip velocity is equal to the lateral speed in the contact point with respect to the road plane:

The practical slip quantities (longitudinal slip) and (slip angle) are calculated with these slip velocities in the contact point:

Note that for realistic tire forces the slip angle is limited to 90 degrees and the longitudinal slip in between -1 (locked wheel) and 1.

Lagged longitudinal and lateral slip quantities (transient tire behavior)In general, the tire rotational speed and lateral slip will change continuously because of the changing interaction forces in between the tire and the road. Often the tire dynamic response will have an important role on the overall vehicle response. For modeling this so-called transient tire behavior, a first-order system is used both for the longitudinal slip as the side slip angle, . Considering the tire belt as a

Vsx Vz R1=

Vsy Vy=

VsxVx------- and tan VsyVx

--------= =

3


stretched string, which is supported to the rim with lateral springs, the lateral deflection of the belt can be estimated (see also reference [1]). The figure below shows a top-view of the string model.

Stretched String Model for Transient Tire Behavior

When rolling, the first point having contact with the road adheres to the road (no sliding assumed). Therefore, a lateral deflection of the string will arise that depends on the slip angle size and the history of the lateral deflection of previous points having contact with the road.

For calculating the lateral deflection v1 of the string in the first point of contact with the road, the following differential equation is valid during braking slip:

with the relaxation length in the lateral direction. The turnslip can be neglected at radii larger than 10 m. This differential equation cannot be used at zero speed, but when multiplying with Vx, the equation can be transformed to:

When the tire is rolling, the lateral deflection depends on the lateral slip speed; at standstill, the deflection depends on the relaxation length, which is a measure for the lateral stiffness of the tire. Therefore, with this approach, the tire is responding to a slip speed when rolling and behaving like a spring at standstill.

1Vx-----

dv1dt

--------v1------+ tan a+=

dv1dt

-------- Vx v1+ Vsx=A similar approach yields the following for the deflection of the string in longitudinal direction:

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Now the practical slip quantities, and are defined based on the tire deformation:

These practical slip quantities and are used instead of the usual and definitions for steady-state tire behavior.

The longitudinal and lateral relaxation length are read from the tire property file, see Tire Property File 521_equation.tir and 521_interpol.tir

Force CalculationsYou can use the 521-Tire model for handling and durability analyses.

Directional Vectors for the Application of Tire Forces and Torques at the Center of the Tire-Road Surface Contact Patch

du1dt

-------- Vx u1+ Vsx=

' u1------ Vx sin=

' v1------ atan=

5


The forces act along the directional vectors. From the tire spin vector and various information you supply in the tire property and the road profile data files, Adams/Tire determines the positions and orientations of the tire vertical, lateral, and longitudinal directional vectors. Figure 3 shows these directional vectors.

The tire vertical force acts along the vertical directional vector, the tire aligning torque acts about the same vector, the tire lateral force acts along the lateral directional vector, and the tire longitudinal force acts along the longitudinal directional vector. At this point, Adams/Tire determines the force directions as if it were going to apply the tire aligning torque and all of the tire forces at the center of the tire-road surface contact patch.

The tire-road surface contact patch may deflect laterally. Adams/Tire calculates the lateral deflection in the direction (and with the sign) of the lateral force. The magnitude of the deflection is equal to the lateral force divided by the tire lateral stiffness you provide in the tire property data file.

The tire vertical, lateral, and longitudinal forces are forces in the tire vertical, lateral, and longitudinal directions (as determined at the tire-road surface contact patch). The tire aligning torque is a torque about the tire vertical vector. The vehicle durability force has components in both the tire vertical and the tire longitudinal directions.

Normal ForceThe tire normal force Fz is calculated based on the tire deflection and radial velocity. A progressive spring and linear damping constant are employed:

where Fstiff is tire stiffness force and Fdamp is tire damping force. The vertical stiffness force is calculated from:

where Kz is the tire vertical stiffness, is tire deflection, and is the stiffness exponent. The tire damping force is calculated from:

where Cz is the tire damping constant.

The damping constant is reduced for small tire deflections, which are below 5% of the unloaded tire radius.

The tire vertical stiffness can also be described using a spline function (force versus deflection) in the Adams dataset. The user array is used to switch between tire property file stiffness and spline stiffness. If the first value in the user array is equal to '5215', the spline vertical stiffness is used. The second value of the user array refers to the ID of the spline. The message, 'Using spline data for the vertical spring', is shown in the message file. If the first value in the user array is not equal to '5215', the tire property file

Fz Fstiff Fdamp=

Fstiff Kz=

Fdamp Cz RadialVelocity=stiffness is used.

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The following is an example of using the spline vertical stiffness:

! adams_view_name='spline_vertical_stiffness'SPLINE/10, X = -1,0,10,30, Y = 0,0,2000,6000!! adams_view_name='wheel_user_array'ARRAY/102, NUM=5215,10Another option for having a non-linear tire stiffness is to introduce a deflection-load table in the tire property file in a section called [DEFLECTION_LOAD_CURVE]. See 521-Tire Tire and Road Property Files on page 20. If a section called [DEFLECTION_LOAD_CURVE] exists, the load deflection datapoints with a cubic spline for inter- and extrapolation are used for the calculation of the vertical force of the tire.

Longitudinal ForceThe tire longitudinal force Fx can have up to three contributions:

Traction/braking force Rolling resistance force Durability force (in case of durability contact)

Traction/Braking ForceTraction force is developed if the vehicle is starting to move and a braking force if the vehicle is beginning to stop. In either case, the absolute magnitude of the force is calculated from:

where the friction coefficient is a function of the longitudinal slip velocity Vsx in the contact patch. Note that this is somewhat unusual, since all the other Handling tire models in Adams/Tire assume that the longitudinal force Fx is a function of the slip ratio.

Fx Fz=

7


Schematic of Friction Coefficient Versus Local Slip Velocity

The curve as a function of longitudinal slip velocity is created using standard Adams STEP functions (see body 4 on page 10). You have to specify two points on the curve to define this characteristic:

The coordinates of the curve at static: (velocity static, static) The coordinates of the curve at dynamic: (velocity dynamic, dynamic)

The friction values may be available to you as function of slip ratio instead of slip velocity. Converting Slip Ratio Data to Velocity Data on page 16 explains how the slip ratios can be converted to slip velocities.

Rolling Resistance ForceRolling resistance Moment My is calculated from:

where coefrr is the rolling resistance coefficient that should be supplied in the tire property data file.

Durability ForceDurability force, sometimes known as radial planar force, is a special kind of tire vertical force. It is the durability force that resists the action of road bumps. This force acts along the instantaneous vertical directional vector calculated by Adams/Tire. The Adams/Tire durability tire forces are limited to two-

My coefrr Fz=dimensional forces that lie in the plane of the tire and are directed toward the wheel-center marker.

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Adams/Tire superimposes these forces upon any traction or lateral forces developed in the tire-road surface interaction.

You must select the Equivalent Plane Method for generating these durability forces.

Lateral Force and Aligning TorqueTwo methods exist for calculating the lateral force Fy and self-aligning moment Mz:

Interpolation Method Equation Method

Interpolation MethodThe AKIMA spline is employed to calculate Fy and Mz as a function of the slip angle , camber angle , and vertical load Fz. You should provide the data in the SAE axis system.

Note that the slip angle and vertical load Fz input for the force and moment calculation of Fx, Fy, Mx, My, and Mz are limited to minimum and maximum values in the input to avoid unrealistic extrapolated values.

Equation MethodThe Equation Method uses the following equation to generate the lateral force Fy:

where K denotes the tire cornering stiffness coefficient.

The aligning moment Mz is calculated using the pneumatic trail t according to:

while the pneumatic trails are calculated with half the contact length a:

with R0 and Rl are, respectively, the unloaded and loaded tire radius.

Overturning MomentIn both methods, the overturning moment Mx calculation is based on the lateral tire force Fy, the lateral

Fy statFz 1 e K sign =

Mz t Fy=

t 13--- a e

K =

a R02 R1

2=tire stiffness Ky, and the vertical load:

9


Tire Lateral Force as a Function of Slip Angle

The contribution of the camber is disregarded in the Equation Method.

The cornering stiffness equals .

Combined Slip of 5.2.1The combined slip calculation of the 5.2.1. is using the friction ellipse and is similar to the combined slip calculation of the Pacejka '89 and '94 tire models.

Inputs:

Dimensionless longitudinal slip (range -1 to 1) and side slip angle in radians

Longitudinal force Fx and lateral force Fy calculated using the equations of 521-Tire

The vertical shift of Fy,a=0 is Fy calculated at zero slip angle

Output:

Adjusted longitudinal force Fx and lateral force Fy incorporates the reduction due to combined slip:

MxFyKy------= Fz

statFzKa

kk2 2sin+

-----------------------------

acos=Friction coefficients:

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Forces corrected for combined slip conditions:

Due to the lateral deflection of the tire patch, the aligning moment under combined slip conditions increases by the effect of the longitudinal force Fx and the lateral tire stiffness Ky:

and the overturning moment uses the lateral force for combined slip:

SmoothingWhen you indicate smoothing by setting the value of USE_MODE in the tire property file, Adams/Tire smooths initial transients in the tire force over the first 0.1 seconds of the simulation. The longitudinal force, lateral force, and aligning torque are multiplied by a cubic step function of time. (See STEP in the Adams/Solver online help.)

Longitudinal Force Fx = SFx Lateral Force Fy = SFy Overturning moment torque Mx = SMz Aligning torque Mz = SMz

Changing the Operating Mode: USE_MODEYou can change the behavior of the tire model by changing the value of USE_MODE in the [MODEL] section of the tire property file. If USE_MODE equals zero, or when it is absent, the smoothing time

x actFxFz-----= y act

Fy Fy 0=Fz

------------------------------=

x 11x act-------------

2 tanstat-----------

2+

----------------------------------------------------= y tan1stat----------

2 tany act-------------

2+

---------------------------------------------------=

Fx combx

x act-------------Fx= Fy comb

yy act------------- Fy Fy 0=+ =

Mz comb Mz pure Fx comb+=Fy comb

Ky------------------

Mx combFy comb

Ky------------------Fz=

11


equals 0.001 seconds and the 521-Tire model is compatible with the previous Adams/Solver implementation.

By selecting a value of USE_MODE between 1 and 4, smoothing and combined slip correction can be switched on and off, as shown in Table 1. The smoothing time equals 0.1 seconds for these values of USE-MODE.

Converting Slip Ratio Data to Velocity DataAdams/Tire requires that you enter the velocities that correspond to static and dynamic. You will often obtain this information as the coefficient of friction versus slip ratio. You can calculate the velocities required by Adams/Tire from the coefficient of friction versus slip ratio curve in the following way:

where

= Slip ratio

= Free rolling rotational velocity (no slip)

= Actual rotational velocity

Kinematic relationships between translational and rotational velocities and the effective rolling radius give:

where

= Contact patch velocity reletive to road surface

USE_MODE: Smoothing: Combined slip correction:1 off off2 off on3 on off4 on on

a ff------------------=

fa

aVx Vsx

Re-------------------=

fVxRe-----=

Vsx

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= Actual longitudinal velocity

= Effective rolling radius

Substituting these relationships into the original slip ratio equation with some cancelling of variables gives:

Therefore:

During testing for the coefficient of friction as a function of slip ratio, the longitudinal velocity Vx is held constant. Therefore, you can obtain Vsx, the relative velocity of the contact patch with respect to the road surface, from the test data curves for the static and dynamic values of friction.

Contact MethodsFor handling analyses (which use a flat road surface profile), the 521-Tire model uses the point-follower contact method. For durability analyses (which use uneven road surface profiles), the Equivalent Plane Method yields the instantaneous tire radius directly, while finding the new road surface orientation vector.

About the Point-Follower MethodThe point-follower contact method assumes a single contact point between the tire and road. The contact point is the point nearest to the wheel center that lies on the line formed by the intersection of the tire (wheel) plane with the local road plane.

The contact force computed by the point-follower contact method is normal to the road plane. Therefore, in a simulation of a tire hitting a pothole, the point-follower contact method does not generate the expected longitudinal force.

About the Equivalent Plane Method 521-Tire uses the Equivalent Plane method to reorient the vertical road surface vector, which gives the direction of the vertical force, and to calculate the new tire radius. To do this, a new smooth road surface is generated at an angle calculated such that only the shape of the tire is different (see body 6 on page 18).

Equivalent Plane Method

Vx

Re

VsxVx-------=

Vsx Vx=

13


Both the deflected tire area and its centroid remain unchanged. The vector between the deflected area centroid and the wheel-center marker then determines the orientation of the. vertical vector perpendicular to the road surface.

The Equivalent Plane method is best suited for relatively large obstacles because it assumes the tire encompasses the obstacle uniformly. In reality, the pneumatics and the bending stiffness of the tire carcass prevent this. The result is an uneven pressure distribution and possibly gaps between the tire and the road. If the obstacle is larger than the tire contact patch (such as a pothole or curb), the uniform assumption is good. If the obstacle is much smaller than the tire patch, however (such as a tar strip or expansion joint), the assumption is poor, and the Equivalent Plane method may greatly underestimate the durability force.

Definition of Equivalent Plane Parameters

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When using the Equivalent Plane method the following parameters need to be specified in the tire property file:

Equivalent_plane_angleSpecifies the subtended angle (in degrees) bisected by the z-axis of the wheel-center marker, as shown in Figure 7. This angle determines the extent of the road the tire can envelop. The value of the equivalent_plane_angle must be between 0 and 180 degrees.

Equivalent_plane_incrementsSpecifies the number of increments into which the shadow of the tire subtended section is divided, as shown in Figure 7.

521-Tire Tire and Road Property FilesThis section contains four example input data files. For reference, the files are called:

521_equation.tir 521_interpol.tir 521_pnt_follow.rdf 521_equiv_plane.rdf

The first two files are tire property files, and the last two are road files. The file 521_equation.tir illustrates the required format and parameters when you use the Equation method. The file 521_interpol.tir illustrates the Interpolation method. The two *.rdf files show how road data files must be specified when either of the contact methods is used.

Tire Property File 521_equation.tir and 521_interpol.tirYou can select the method for calculating the normal force by setting the VERTICAL_FORCE_METHOD parameter to either POINT_FOLLOWER (for the Point Follower method) or EQUIVALENT_PLANE (for the Equivalent Plane method). See Contact Methods on page 17 for details on these methods.

You can select the method for calculating the lateral force by setting the LATERAL_FORCE_METHOD parameter to either INTERPOLATION or symbol. See Lateral Force and Aligning Torque on page 11 for details on these calculation methods.

The following table specifies how some of the parameter names used in the tire property file correspond to parameters introduced in the equations that were presented in the previous sections.

Parameter in file: Used in equation: As parameter:vertical_stiffness [10] Kzvertical_damping [11] Cz

lateral_stiffness [18] Ky

15


521-equation.tirThe 521-equation.tir example tire property file starts here.

$----------------------------------------------------------MDI_HEADER[MDI_HEADER] FILE_TYPE = 'tir' FILE_VERSION = 3.0 FILE_FORMAT = 'ASCII'(COMMENTS){comment_string}'Tire - XXXXXX''Pressure - XXXXXX''Test Date - XXXXXX''Test tire'$---------------------------------------------------------------units[UNITS] LENGTH = 'mm' FORCE = 'newton' ANGLE = 'rad' MASS = 'kg' TIME = 'second'$---------------------------------------------------------------model[MODEL]! use mode 1 2 3 4 11 12 13 14! ------------------------------------------------------------------! smoothing X X X X! combined X X X X! transient X X X X! PROPERTY_FILE_FORMAT = '5.2.1' USE_MODE = 1$-----------------------------------------------------------dimension[DIMENSION]

cornering_stiffness_coefficient [6] KMu_Static Figure 4 staticMu_Dynamic Figure 4 dynamicMu_Static_velocity Figure 4 velocity staticMu_Dynamic_Velocity Figure 4 velocity dynamicrolling_resistance_coefficient [13] coeffrrvertical_stiffness_exponent [141] Note: If you do not specify

vertical_stiffness_exponent in the tire property file, 521-Tire uses the default value of 1.1.

Parameter in file: Used in equation: As parameter: UNLOADED_RADIUS = 310.0

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WIDTH = 195.0 ASPECT_RATIO = 0.70 RIM_RADIUS = 195,0 RIM_WIDTH = 139.7$----------------------------------------------------------parameters! VERTICAL_FORCE_METHOD = EQUIVALENT_PLANE LATERAL_FORCE_METHOD = EQUATION! vertical_stiffness = 206.0 vertical_stiffness_exponent = 1.1 vertical_damping = 2.06! lateral_stiffness = 50 cornering_stiffness_coefficient = 50! Mu_Static = 0.95 Mu_Dynamic = 0.75 Mu_Static_Velocity = 3000 Mu_Dynamic_Velocity = 6000! rolling_resistance_coefficient = 0.01! EQUIVALENT_PLANE_ANGLE= 100 EQUIVALENT_PLANE_INCREMENTS= 50!

521_interpol.tirThe 521-interpol.tir example tire property file starts here. In addition to the file for 521_equation.tir, it contains data that is used for calculating the lateral force and aligning moment, instead of using formula 6 to 9. Note that the [DEFLECTION_LOAD_CURVE] can also be used in the tire property file for the Equation method.

$----------------------------------------------------------MDI_HEADER[MDI_HEADER] FILE_TYPE = 'tir' FILE_VERSION = 3.0 FILE_FORMAT = 'ASCII'(COMMENTS){comment_string}'Tire - XXXXXX''Pressure - XXXXXX''Test Date - XXXXXX''Test tire'$---------------------------------------------------------------units[UNITS] LENGTH = 'mm' FORCE = 'newton' ANGLE = 'rad' MASS = 'kg'

TIME = 'second'$---------------------------------------------------------------model

17


[MODEL]! use mode 1 2 3 4 11 12 13 14! ----------------------------------------------------------------! smoothing X X X X! combined X X X X! transient X X X X! PROPERTY_FILE_FORMAT = '5.2.1' USE_MODE = 1$-----------------------------------------------------------dimension[DIMENSION] UNLOADED_RADIUS = 310.0 WIDTH = 195.0 ASPECT_RATIO = 0.70 RIM_RADIUS = 195,0 RIM_WIDTH = 139.7$----------------------------------------------------------parameters! VERTICAL_FORCE_METHOD = POINT_FOLLOWER ! or EQUIVALENT_PLANE LATERAL_FORCE_METHOD = INTERPOLATION ! or EQUATION! vertical_stiffness = 206.0 vertical_stiffness_exponent = 1.1 vertical_damping = 2.06 lateral_stiffness = 50 cornering_stiffness_coefficient = 50! Mu_Static = 0.95 Mu_Dynamic = 0.75 Mu_Static_Velocity = 3000 Mu_Dynamic_Velocity = 6000! rolling_resistance_coefficient = 0.01! EQUIVALENT_PLANE_ANGLE= 100 EQUIVALENT_PLANE_INCREMENTS= 50!!------------------CAMBER ANGLE VALUES-------------------------------! Conversion! No. of pnts factor(D to R) pnt1 pnt2 pnt3 pnt4 pnt5! CAMBER_ANGLE_DATA_LIST 5 0.017453292 -3.0 0.0 3.0 6.0 10.0!!------------------SLIP ANGLE VALUES---------------------------------! Conversion! No. of pnts factor(D to R) pnt1 ...... pnt9! SLIP_ANGLE_DATA_LIST 9 0.017453292 -15.0 -10.0 -5.0 -2.5 0.0 2.5 5.0 10.0 15.0!

!-----------------VERTICAL FORCE VALUES------------------------------

Adams/Tire18


! Conversion ! No. of pnts factor! pnt1 pnt2 pnt3 pnt4 pnt5 ! VERTICAL_FORCE_DATA_LIST 5 4.448 200.0 600.0 1100.0 1500.0 1900.0!!-----------------ALLIGNING TORQUE VALUES---------------------------! No. of pnts Conversion! factor!! pnt1 .... pnt225! ALIGNING_TORQUE_DATA_LIST 225 -1355.7504 5.31 6.52 22.88 26.41 30.58 0.11 2.84 5.49 -3.92 -14.04 0.47 -12.44 -37.99 -67.22 -116.07 0.04 -21.38 -69.04 -111.44 -168.11 0.80 -3.70 -27.94 -44.25 -53.74 1.75 17.43 52.20 81.97 145.78 2.54 11.08 40.53 73.54 95.55 -1.28 0.02 14.82 2.93 10.35 1.59 -3.77 -17.17 6.60 -11.91 0.06 14.23 22.93 11.45 15.74 5.95 5.54 13.72 -1.65 -15.64 -1.29 -9.45 -26.98 -57.25 -107.71 -5.05 -17.73 -62.62 -109.03 -161.88 0.46 -2.48 -19.48 -33.54 -49.52 4.71 26.10 60.80 90.85 119.51 4.26 16.60 52.46 93.32 141.34 2.41 4.28 2.21 9.11 30.44 -0.92 0.22 12.61 2.51 -18.77 0.43 -4.62 15.36 7.16 11.70 6.70 15.92 0.14 -4.20 -11.81 -2.20 -5.53 -13.28 -47.48 -92.88 -1.39 -17.28 -52.17 -102.80 -161.71 2.87 -0.38 -14.27 -29.03 -42.42 6.99 24.54 66.06 93.27 126.38 7.10 18.78 58.20 104.51 156.39 1.63 2.91 8.33 20.32 42.09 -0.78 10.13 -9.94 -13.02 -11.95 5.62 4.36 23.16 38.03 8.73 2.31 6.41 14.10 6.03 -11.66 7.87 1.33 -16.31 -40.24 -82.58 1.40 -10.04 -50.94 -93.06 -157.50 2.10 0.56 -16.15 -27.15 -40.13 5.60 26.48 62.92 90.16 122.03

3.56 20.63 60.74 108.26 162.97

19


-0.08 1.81 14.39 34.98 59.72 1.38 -2.13 -2.42 -4.08 -2.72 3.69 1.71 29.06 10.05 11.38 3.09 7.15 -7.92 13.53 -5.78 6.08 0.38 -2.69 -32.10 -62.17 0.76 -7.65 -37.28 -89.05 -145.09 0.70 4.37 -7.59 -23.71 -28.49 5.92 34.39 72.55 92.88 129.34 4.36 29.81 76.70 118.91 180.59 -2.03 5.94 26.18 53.59 89.76 0.39 -5.52 -6.06 10.16 7.81 !-----------------LATERAL FORCE VALUES------------------------------ ! No. of pnt Conversion ! factor ! pnt1 .... pnt225 ! LATERAL_FORCE_DATA_LIST 225 4.448 234.08 585.56 1000.29 1307.77 1603.78 269.79 628.82 1040.78 1331.72 1624.83 213.70 565.29 974.49 1198.82 1387.74 150.79 452.18 752.21 885.23 960.13 11.52 50.58 199.87 199.50 208.75 -116.75 -367.42 -618.68 -683.16 -857.81 -224.15 -588.24 -1001.01 -1235.88 -1488.88 -242.08 -612.70 -1059.55 -1344.53 -1658.66 -213.99 -597.29 -988.14 -1343.86 -1689.35 234.40 572.75 981.30 1352.37 1698.90 239.27 647.77 1007.37 1357.22 1666.30 252.34 603.75 1033.50 1288.76 1483.64 167.55 481.45 826.41 962.64 1028.74 32.23 78.77 231.31 250.14 254.32 -122.59 -423.13 -552.58 -613.52 -607.61 -208.93 -576.28 -948.45 -1149.44 -1314.69 -261.05 -634.90 -1064.15 -1338.52 -1581.84 -241.50 -607.16 -1021.87 -1322.30 -1598.25 210.20 578.56 968.72 1344.05 1730.40 237.91 600.60 1025.67 1377.57 1733.03 226.60 629.48 1084.97 1354.12 1575.22 154.74 496.21 878.72 1028.03 1095.59 34.37 74.19 240.00 284.42 283.85 -130.29 -339.00 -509.04 -543.75 -555.05 -226.48 -557.52 -884.91 -1083.18 -1175.12 -270.70 -595.22 -1059.76 -1314.74 -1564.43 -254.64 -602.76 -1032.71 -1313.22 -1609.96 238.28 531.25 945.70 1305.28 1786.96 227.13 594.51 1038.87 1365.33 1733.29 221.76 633.49 1135.31 1375.28 1619.82

195.50 505.90 899.88 1059.92 1135.28

Adams/Tire20


28.51 68.59 241.99 311.15 331.84 -145.10 -319.56 -464.11 -499.27 -500.83 -230.33 -548.99 -815.88 -991.78 -1108.36 -230.62 -597.10 -1009.76 -1261.43 -1504.09 -218.36 -570.13 -1049.72 -1344.94 -1589.60 228.49 564.69 954.06 1332.84 1687.50 221.19 595.52 1019.74 1378.35 1749.40 224.63 590.58 1108.01 1408.87 1707.09 178.96 474.70 918.87 1125.97 1242.75 42.58 65.26 230.69 306.58 428.45 -144.43 -290.91 -368.02 -398.98 -394.66 -224.99 -494.65 -761.78 -886.03 -941.20 -246.51 -563.13 -980.33 -1249.57 -1462.88 -239.34 -567.10 -1050.56 -1348.66 -1611.11

521-Tire Road Data FilesThe road data files used with the 521-Tire are unique and cannot be used with any other tire model. The data files are fully described by the following two examples.

Road Data File 521_pnt_follow.rdfThis example file shows that, if you use the Point Follower method and indicate it in the associated tire property file, the road_profile_type parameter must be set to FLAT.

$--------------------------------------------------------MDI_HEADER[MDI_HEADER]FILE_TYPE = 'rdf'FILE_VERSION = 5.00FILE_FORMAT = 'ASCII'(COMMENTS){comment_string}'flat 2d contact road for testing purposes'$-------------------------------------------------------------UNITS[UNITS] LENGTH = 'mm' FORCE = 'newton' ANGLE = 'radians' MASS = 'kg' TIME = 'sec'$-------------------------------------------------------------MODEL[MODEL] METHOD = '5.2.1' FUNCTION_NAME = 'ARC913'$--------------------------------------------------------PARAMETERSROAD_PROFILE_TYPE = FLATINITIAL_HEIGHT = 0.000

21


Road Data File 521_equiv_plane.rdfThe following example shows which data the road data file must contain if the Equivalent Plane method is used and specified in the associated tire property file. The main difference with the road data file used in association with the Point Follower method is that here the ROAD_PROFILE_TYPE parameter is set to INPUT and a ROAD_INPUT_DATA_LIST is specified.

$---------------------------------------------------------MDI_HEADER[MDI_HEADER]FILE_TYPE = 'rdf'FILE_VERSION = 5.00FILE_FORMAT = 'ASCII'(COMMENTS){comment_string}'5.2.1 input road for testing purposes'$--------------------------------------------------------------UNITS[UNITS] LENGTH = 'mm' FORCE = 'newton' ANGLE = 'radians' MASS = 'kg' TIME = 'sec'$--------------------------------------------------------------MODEL[MODEL] METHOD = '5.2.1' FUNCTION_NAME = 'ARC913'$---------------------------------------------------------PARAMETERSROAD_PROFILE_TYPE = INPUTINITIAL_HEIGHT = 0.000ROAD_INPUT_DATA_LIST 23, 1 -10000.00, 00.00 1740.00, 00.00 1740.94, 1.92 1743.73, 3.55 1748.31, 4.59 1754.55, 4.79 1762.32, 3.88 1771.41, 1.65 1781.61, 7.89 1792.65, 2.47 1804.28, 5.26 1816.20, 6.20 1828.12, 5.26 1839.75, 2.47 1850.79, 7.89 1860.99, 1.65 1870.08, 3.88 1877.85, 4.79 1884.09, 4.59 1888.67, 3.55 1891.46, 1.92 1892.40, 00.00

40000.00, 00.00

Adams/Tire22


Using the 521-Tire ModelAbout 521-TireTire Slip Quantities and Transient Tire BehaviourForce CalculationsCombined Slip of 5.2.1SmoothingChanging the Operating Mode: USE_MODEConverting Slip Ratio Data to Velocity DataContact Methods521-Tire Tire and Road Property Files

Documents

521 Tire Model