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2D Road TypesThe available road types are:•DRUM - Tire test drum (requires a zero-speed-capable tire model). •FLAT - Flat road.•PLANK - Single plank perpendicular, or in oblique direction relative to x-axis, with or without bevel edges. • POLY_LINE - Piece-wise linear description of the road profile. The profiles for the left and right track are independent. •POT_HOLE - Single pothole of rectangular shape. •RAMP - Single ramp, either rising or falling. •ROOF - Single roof-shaped, triangular obstacle. •SINE - Sine waves with constant wave length. •SINE_SWEEP - Sine waves with decreasing wave lengths.•STOCHASTIC_UNEVEN - Synthetically generated irregular road profiles that match measured stochastic properties of typical roads. The profiles for left and right track are independent, or may have a certain correlation. Examples of 2D RoadsSample files for all the road types for Adams/Car are in the standard Adams/Car database:install_dir /shared_car_database.cdb/roads.tbl/Sample files for all the road types for Adams/Tire are in: install_dir /solver/atire/Sample files for all the road types for Adams/Chassis are in: install_dir /achassis/examples/rdf/Note that you must select a specific contact method, such as point-follower or equivalent plane, to define how the roads will interact with the tires. Not allcombinations of road, tire, and contact methods are permitted. Allowable combinations are explained in Tire Models help under the description of the specific tire model.2D Road Model ParametersThe [PARAMETERS] block must contain the following data, some of which are independent of the type of road. Learn about parameters:•Independent of Road Type •Drum •Flat •Plank •Polyline•Pothole•Ramp•Roof•Sine•Sweep•Stochastic UnevenParameters Independent of Road TypeThe following parameters are required regardless of the road type.If ROAD_TYPE = drum, then define the following parameters:If ROAD_TYPE = flat, then no further parameters are required.Parameters for Road Type of PlankIf ROAD_TYPE = plank, then define the following parameters:If ROAD_TYPE = poly_line, then the [PARAMETERS] block must have a (XZ_DATA) subblock. The subblock consists of three columns of numerical data:•Column one is a set of x-values in ascending order.•Columns two and three are sets of respective z-values for left and right track.The following is an example of the full [PARAMETERS] Body for a road type of polyline: $---------------------------PARAMETERS[PARAMETERS]OFFSET = 0ROTATION_ANGLE_XY_PLANE = 180$(XZ_DATA)0 0 01000 100 502000 -1000 1003000 -100 1003001 50 04000 -100 100The XZ_DATA subblock can be extremely large. In this case, only the portion that is needed at the moment is loaded. To facilitate efficient reloading while simulation is running, do not use any comment lines in a subblock that contains more than 2000 lines. Parameters for Road Type of PotholeIf ROAD_TYPE = pot_hole, then the parameters are:If ROAD_TYPE = ramp, then the parameters are:If ROAD_TYPE = roof, then the parameters are:If ROAD_TYPE = sine, then the parameters are:amplitude Amplitude of sine wave (a).wave_lengthWave length of sine wave ().start Start of sine waves (traveldistance) (s s).The road height, z, is given by:Parameters for Road Type of Stochastic UnevenA stochastic uneven road profile both for left and right wheels is generated, with properties very close to measured road profiles.In a first step, discrete white noise signals are formed on the basis of nearly uniformly distributed random numbers. Two of these numbers are assigned to every 10 mm of travel path. The distribution of these random numbers is approximated by summing several equally distributed random numbers, taking advantage of the ‘law of large numbers’ of mathematical statistics.Next, these values are integrated with respect to travel distance, using a simplefirst order time-discrete integration filter. The independent variable of that filter is not time, but travel path. That is why the filter cutoff frequency is controlled by a path constant instead of a time constant. The filter process results in two approximate realizations of white velocity noise; that is, two signals, thederivatives of which are close to white noise. Signals with that property are known as road profiles with waviness 2. Several investigations in the past showed that the waviness derived from measured road spectral densities ranges from about 1.8 to 2.2. The last step is to linearly combine the two realizations of the aboveprocess:,, resulting in the left and right profile,. This is done such that the two signals are completely independent if , and identical if:If ROAD_TYPE = stochastic_uneven, then the parameters are:The parameter: Indicates:intensity Variable to control intensity of white velocity noise, whichapproximates measured spectra of road profiles fairly well.path_constant Variable to control high-pass integration filter.correlation_rl Variable to control correlation between left and right track:•If 0, no correlation.•If 1, complete correlation (that is, left track = right track). Can be any value between 0 and 1.startStart of unevenness (travel distance).Parameters for Road Type of SweepIf ROAD_TYPE = sine_sweep, then the parameters are:[PARAMETERS] Data for Road Type of Sine Sweep The parameter: Indicates:start Start of swept sine wave (travel distance) (). endEnd of swept sine wave (travel distance) ().amplitude_at_sta rtAmplitude of swept sine wave at start travel distance (). amplitude_at_end Amplitude of swept sine wave at end travel distance ().wave_length_at_s tartWave length of swept sine wave a start travel distance ().wave_length_at_e ndWave length of swept sine wave at end travel distance. Must be less than or equal to wave_length_at_start ().sweep_type•sweep_type = 0: frequency increases linearly with respect to travel distance. •sweep_type = 1: wave length decreases by a constant factor per cycle. Depending on the value of sweep_type, the road height is given by the following functions, where:• Linear sweep: (sweep_type = 0) The frequency increases linearly with respect to travel distance. The road height value z (s) as function of travel distance s is alculated as follows:Note the factor 2 in the denominator is not an error. The actual frequency (= derivative of the sine function argument with respect to travel path, divided by ; this is not equal to that factor that is multiplied by in the sine function) is given by thefollowing:•Logarithmic sweep: (sweep_type = 1) with every cycle, the wave length decreases by a constant factor. The road height value is calculated as follows:where:is the travel path where theoretically an infinitely high frequency was reached, measured relative to sweep start . Theactual frequency is given by:Using the UA-Tire ModelLearn about using the University of Arizona (UA) tire model:•Background Information •Tire Model Parameters •Force Evaluation •Operating Mode: USE_MODE •Tire Carcass Shape •Property File Format ExampleBackground Information for UA-TireThe University of Arizona tire model was originally developed by Drs. P.E. Nikravesh and G. Gim. Reference documentation: G. Gim, Vehicle Dynamic Simulation with aComprehensive Model for Pneumatic Tires, PhD Thesis, University of Arizona, 1988. The UA-Tire model also includes relaxation effects, both in the longitudinal and lateral direction.The UA-Tire model calculates the forces at the ground contact point as a function of the tire kinematic states, see Inputs and Output of the UA-Tire Model. A description of the inputs longitudinal slip k, side slip a and camber angle can be found in About Tire Kinematic and Force Outputs. The tire deflection and deflection velocity are determined using either a point follower or durability contact model. For more information, see Road Models in Adams/Tire . A description of outputs, longitudinal force Fx, lateral force Fy, normal force Fz, rolling resistance moment My and self aligningmoment Mz is given in About Tire Kinematic and Force Outputs. The required tire model parameters are described in Tire Model Parameters.Inputs and Output of the UA-Tire ModelDefinition of Tire Slip QuantitiesSlip Quantities at Combined Cornering and Braking/TractionThe longitudinal slip velocity Vsx in the SAE-axis system is defined using thelongitudinal speed Vx, the wheel rotational velocity , and the effective rolling radius Re: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:When the UA Tire is used for the force calculation the slip quantities during positive Vsx (driving) are defined as:The rolling speed Vr is determined using the effective rolling radius Re:Note that for realistic tire forces the slip angle is limited to 45 degrees and thelongitudinal slip Ss (= ) 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 forthe longitudinal slip as the side slip angle, . Considering the tire belt as a stretched string, which is supported to the rim with lateral spring, 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 BehaviorWhen 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. When the UA Tire is used for the force calculations, at positive Vsx (traction) the Vx should be replaced by Vr in these differential equations.A similar approach yields the following for the deflection of the string in longitudinal direction: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. kVlow_x and kVlow_y are the damping rates at low speed applied below the LOW_SPEED_THRESHOLD speed. For the LOW_SPEED_DAMPING parameter in the tire property file yields:kVlow_x= 100 · kVlow_y= LOW_SPEED_DAMPINGNote: If the tire property file's REL_LEN_LON or REL_LEN_LAT = 0, then steady-state tire behavior is calculated as tire response on change of the slip and .Tire Model ParametersSymbol: Name in tire propertyfile: Units*: Description:r1 UNLOADED_RADIUS L Tire unloaded radiuskz VERTICAL_STIFFNESS F/L Vertical stiffnesscz VERTICAL_DAMPING FT/L Vertical dampingCr ROLLING_RESISTANCE L Rolling resistance parameter Cs CSLIP F Longitudinal slip stiffness,C CALPHA F/A Cornering stiffness,C CGAMMA F/ACamber stiffness,UMIN UMIN - Minimum friction coefficient(Sg=1)UMAX UMAX - Maximum friction coefficient(Ssg=0)x REL_LEN_LON L Relaxation length inlongitudinal directiony REL_LEN_LAT L Relaxation length in lateraldirection* L=length, F=force, A=angle, T=timeForce Evaluation in UA-Tire•Normal Force•Slip Ratios•Friction CoefficientNormal ForceThe normal force F z is calculated assuming a linear spring (stiffness: k z ) and damper (damping constant c z ), so the next equation holds:If the tire loses contact with the road, the tire deflection and deflection velocity become zero so the resulting normal force F z will also be zero. For very small positive tire deflections the value of the damping constant is reduced and care is taken to ensure that the normal force Fz will not become negative.In stead of the linear vertical tire stiffness cz , also an arbitrary tire deflection - load curve can be defined in the tire property file in the section[DEFLECTION_LOAD_CURVE], see also the Property File Format Example. 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. Note that you must specify VERTICAL_STIFFNESS in the tire property file but it does not play any role.Slip RatiosFor the calculation of the slip forces and moments a number of slip ratios will be introduced:Longitudinal Slip Ratio: SsThe absolute value of longitudinal slip ratio, Ss, is defined as:Where k is limited to be within the range -1 to 1.Lateral Slip Ratios: Sa , Sg , SagThe lateral slip ratio due to slip angle, S, is defined as:The lateral slip ratio due to inclination angle, S, is defined as:A combined lateral slip ratio due to slip and inclination angles, S, is defined as:where is the length of the contact patch.Comprehensive Slip Ratio: SsagA comprehensive slip ratio due to longitudinal slip, slip angle, and inclination angle may be defined as:Friction CoefficientThe resultant friction coefficient between the tire tread base and the terrain surfaceis determined as a function of the resultant slip ratio (Ss) and friction parameters (UMAX and UMIN ). The friction parameters are experimentally obtained data representing the kinematic property between the surfaces of tire tread and the terrain.A linear relationship between Ss and , the corresponding road-tire friction coefficient, is assumed. The figure below depicts this relationship.Linear Tire-Terrain Friction ModelThis can be analytically described as:m = UMAX - (UMAX - UMIN) * SsagThe friction circle concept allows for different values of longitudinal and lateralfriction coefficients (x and y) but limits the maximum value for both coefficientsto . See the figure below.Friction Circle ConceptThe relationship that defines the friction circle follows:or andwhere:Slip Forces and MomentsTo compute longitudinal force, lateral force, and self-aligning torque in the SAE coordinate system, you must perform a test to determine the precise operating conditions. The conditions of interest are:•Case 1: 0•Case 2: 0 and C S C S•Case 3: 0 and C S C S•Forces and moments at the contact pointThe lateral force Fh can be decomposed into two components: Fha and Fhg. The twocomponents are in the same direction if a· g < 0 and in opposite direction if 0. Case 1. ag < 0Before computing the longitudinal force, the lateral force, and the self-aligning torque, some slip parameters and a modified lateral friction coefficient should bedetermined. If a slip ratio due to the critical inclination angle is denoted by S c, then it can be evaluated as:If Ssc represents a slip ratio due to the critical (longitudinal) slip ratio, then it can be evaluated as:If a slip ratio due to the critical slip angle is denoted by S c, then it can be determined as:when Ss Ssc.The term critical stands for the maximum value which allows an elastic deformation of a tire during pure slip due to pure slip ratio, slip angle, or inclination angle. Whenever any slip ratio becomes greater than its corresponding critical value, an elastic deformation no longer exists, but instead complete sliding state representsthe contact condition between the tire tread base and the terrain surface.A nondimensional slip ratio Sn is determined as:where:A nondimensional contact patch length is determined as:A modified lateral friction coefficient is evaluated as:where is the available friction as determined by the friction circle.To determine the longitudinal force, the lateral force, and the self-aligning torque, consider two subcases separately. The first case is for the elastic deformation state, while the other is for the complete sliding state without any elastic deformation of a tire. These two subcases are distinguished by slip ratios caused by the critical values of the slip ratio, the slip angle, and the inclination angle. Specifically, if all of slip ratios are smaller than those of their corresponding critical values, then there exists an elastic deformation state, otherwise there exists only completesliding state between the tire tread base and the terrain surface.(i) Elastic Deformation State: S S c, Ss Ssc, and S S cIn the elastic deformation state, the longitudinal force F, the lateral force F, and three components of the self-aligning torque are written as functions of the elastic stiffness and the slip ratio as well as the normal force and the friction coefficients, such as:where:•is the offset between the wheel plane center and the tire treadbase.•is set to zero if it is negative.•the length of the contact patch.Mz is the portion of the self-aligning torque generated by the slip angle . Mzsand Mzs are other components of the self-aligning torque produced by thelongitudinal force, which has an offset between the wheel center plane and the tire tread base, due to the slip angle and the inclination angle , respectively. The self-aligning torque Mz is determined as combinations of Mz, Mzs and Mzs.(ii) Complete Sliding State: S S c, Ss Ssc, and S S cIn the complete sliding state, the longitudinal force, the lateral force, and three components of the self-aligning torque are determined as functions of the normal force and the friction coefficients without any elastic stiffness and slip ratio as:Case 2:0 and C S C SAs in Case 1, a slip ratio due to the critical value of the slip ratio can be obtained as:A slip ratio due to the critical value of the slip angle can be found as:when Ss Ssc.The nondimensional slip ratio Sn, is determined as:where:The nondimensional contact patch length ln is found from the equation ln = 1 - Sn, and the modified lateral friction coefficient is expressed as:For the longitudinal force, the lateral force and the self-aligning torque two subcases should also be considered separately. A slip ratio due to the critical value of the inclination angle is not needed here since the required condition for Case 2,C S C S, replaces the critical condition of the inclination angle.(i) Elastic Deformation State: Ss Ssc and S SacIn the elastic deformation state:(ii) Complete Sliding State: Ss Ssc and S SacCase 3:0 and C S C SSimilar to Cases 1 and 2, slip ratios due to the critical values of the inclination angle and the slip ratio are obtained as:The nondimensional slip ratio Sn, is expressed as:where:For the longitudinal force, the lateral force, and the self-aligning torque, two subcases should also be considered similar to Cases 1 and 2. A slip ratio due to the critical value of the slip angle is not needed here since the required condition forCase 3, C S C S, replaces the critical condition of the slip angle. (i) Elastic Deformation State: S S c and Ss SscIn the elastic deformation state, F and Mz can be written:(ii) Complete Sliding State: S S c and Ss SscIn the complete sliding state, F, F, Mz, Mzs, and Mzs can be determined by using:respectively. The longitudinal force F , the lateral force F, and three componentsof the self-aligning torques, Mz , Mzs , and Mzs , always have positive values, but they can be transformed to have positive or negative values depending on the slip ratio s, the slip angle , and the inclination angle in the SAE coordinate system. Tire Forces and Moments in the SAE Coordinate SystemFor the general formulations of the longitudinal force Fx, lateral force Fy, and self-aligning torque Mz, in the SAE coordinate system, the three possible combinations of the slip ratio, the slip angle, and the inclination angle are also considered. Longitudinal Force:Fx = sin(k) F , for all cases Lateral Force: F y = -sin() F, for cases 1 and 2F y = sin() F , for case 3 Self-aligning Torque:M z = sin() M z - sin() [-sin() M zs + sin()M zs ]Rolling Resistance Moment:My = -Cr Fz, for a forward rolling tire. My = Cr Fz , for a backward rolling tire.Operating Mode: USE_MODEYou can change the behavior of the tire model through the switch USE_MODE in the [MODEL] section of the tire property file.•USE_MODE = 0: Steady-state forces and moments • The tire forces and moments react instantaneously to changes in the tire kinematic states. •USE_MODE = 1: Transient tire behavior • The tire will have a lagged response because of the so-called relaxation length in both longitudinal and lateral direction. See Lagged Longitudinal and Lateral Slip Quantities (transient tire behavior).•The effect of the relaxation lengths will be most pronounced at low forward velocityand/or high excitation frequencies. •USE_MODE = 2: Smoothing of forces and moments on startup of the simulation •When 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 0.1seconds of 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 FLon = S*FLon Lateral Force FLat = S*FLat Aligning Torque Mz = S*MzTire Carcass ShapeYou can optionally supply a tire carcass cross-sectional shape in the tire property file in the [SHAPE] block. The 3D-durability, tire-to-road contact algorithm uses this information when calculating the tire-to-road volume of interference. If you omit the [SHAPE] block from a tire property file, the tire carcass cross-section defaults to the rectangle that the tire radius and width define.You specify the tire carcass shape by entering points in fractions of the tire radius and width. Because Adams/Tire assumes that the tire cross-section is symmetrical about the wheel plane, you only specify points for half the width of the tire. The following apply:•For width, a value of zero (0) lies in the wheel center plane. •For width, a value of one (1) lies in the plane of the side wall. •For radius, a value of one (1) lies on the tread. For example, suppose your tire has a radius of 300 mm and a width of 185 mm and that the tread is joined to the side wall with a fillet of 12.5 mm radius. The tread then begins to curve to meet the side wall at >+/- 80 mm from the wheel center plane. If you define the shape table using six points with four points along the fillet, the resulting table might look like the shape block that is at the end of the property format example (see SHAPE ).Property File Format Example$--------------------------------------------------------MDI_HEADER [MDI_HEADER]FILE_TYPE = 'tir' FILE_VERSION = 2.0 FILE_FORMAT = 'ASCII'(COMMENTS) {comment_string} 'Tire - XXXXXX''Pressure - XXXXXX' 'TestDate - XXXXXX' 'Test tire''New File Format v2.1'$-------------------------------------------------------------units [UNITS] LENGTH= 'meter' FORCE= 'newton'ANGLE= 'rad'MASS= 'kg'TIME= 'sec'$-------------------------------------------------------------model [MODEL]! use mode123! ------------------------------------------! relaxation lengthsX! smoothingX !PROPERTY_FILE_FORMAT= 'UATIRE'USE_MODE= 2$---------------------------------------------------------dimension [DIMENSION]UNLOADED_RADIUS= 0.295WIDTH= 0.195ASPECT_RATIO= 0.55$---------------------------------------------------------parameter [PARAMETER]VERTICAL_STIFFNESS= 190000VERTICAL_DAMPING= 50ROLLING_RESISTANCE= 0.003CSLIP= 80000CALPHA= 60000CGAMMA= 3000UMIN= 0.8UMAX= 1.1REL_LEN_LON= 0.6REL_LEN_LAT= 0.5$-------------------------------------------------------------shape[SHAPE]{radial width}1.0 0.01.0 0.21.0 0.41.0 0.61.0 0.80.9 1.0$---------------------------------------------------------------------load_curve $ For a non-linear tire vertical stiffness (optional)$ Maximum of 100 points[DEFLECTION_LOAD_CURVE]{penfz}0.0000.00.001212.00.002428.00.003648.00.0051100.00.0102300.00.0205000.00.0308100.0。
ADAMS/CAR不同轮胎模型的整车平顺性分析实例在相同条件下，对使用不同轮胎模型的整车模型进行平顺性仿真。
仿真结束后，在后处理模块获得汽车底盘质心处x 、y 、z 三个轴向的加速度曲线。
为了确定路面引起汽车振动所在的频率范围，还需获取相应的加速度功率谱密度。
最后，求加速度加权均方根值，评价振动对人体的影响。
目录第一章、参考资料 (1)第二章、建模说明 (5)一、生成5.2.1前轮胎模型 (5)二、生成5.2.1后轮胎模型 (9)三、生成其他三个轮胎模型 (10)四、生成整车模型 (12)第三章、仿真分析 (16)一、平顺性仿真概述 (16)二、随机路面生成 (16)三、平顺性仿真条件设置 (16)四、仿真过程 (17)第四章、结果分析 (19)一、概述 (19)二、操作说明 (20)三、同等条件下，不同轮胎模型的汽车平顺性比较 (27)四、同等条件下，不同车速的汽车平顺性比较 (34)五、同等条件下，不同路面的汽车平顺性比较 (37)第一章、参考资料在ADAMS虚拟样机仿真软件中按照实际使用情况可将轮胎模型分为操作性分析轮胎模型、耐久性分析即3D接触分析轮胎模型以及摩托车用轮胎模型三大类。
由于本文中主要研究的是轮胎与路面间垂直力所引起的冲击振动情况，故应选用操纵性分析轮胎模型，其使用的是point follower的方式来计算轮胎由于路面不平激励所引起的垂直力。
在操纵性分析轮胎模型组中提供了MF-tyre、Pacejka ’89、Pacejka ’94、PAC2002、Fiala、5.2.1以及UA等轮胎模型，用户可以根据实际需要对模型数据进行修改。
通过修改软件自带的轮胎模型文件来生成轮胎模型能够保证车辆仿真要求的一致性，从而保证仿真结果的可靠性。
第二章、建模说明一、生成5.2.1前轮胎模型为建立轮胎模型，需先将acar共享文件中需要的轮胎数据复制到个人文件夹，本文进行汽车平顺性分析，适用于平顺性分析的轮胎模型有MF-tyre、Pacejka ’89、Pacejka ’94、PAC2002、Fiala、5.2.1以及UA等轮胎模型，本文选取4种类型：521_equation、mdi_fiala01、mdi_pac94、uat。
使用魔术公式的轮胎模型使用魔术公式的轮胎模型主要有Pacejka ' 89Pacejka 94、MF-Tyre、MF-Swift四种。
Pacejka ' 8和 ' 9轮胎模型Pacejka '和9 轮胎模型是以魔术公式主要提出者H. B. Pacejka教授命名的，根据其发布的年限命名。
目前有两种直接被ADAMS弓I用。
魔术公式是用三角函数的组合公式拟合轮胎试验数据，用一套形式相同的公式就可以完整地表达轮胎的纵向力F x、侧向力F y、回正力矩M z、翻转力矩M x、阻力矩M y以及纵向力、侧向力的联合作用工况，故称为“魔术公式”。
魔术公式的一般表达式为：Y x = Ds in C arctan Bx - E Bx - arcta n Bx i v 1式中Y(x)可以是侧向力，也可以是回正力矩或者纵向力，自变量x可以在不同的情况下分别表示轮胎的侧偏角或纵向滑移率，式中的系数B、C、D依次由轮胎的垂直载荷和外倾角来确定。
Pacejka '轮胎模型认为轮胎在垂直、侧向方向上是线性的、阻尼为常量，这在侧向加速度常见范围W 0.4g，侧偏角W 5°的情景下对常规轮胎具有很高的拟合精度。
此外，由于魔术公式基于试验数据，除在试验范围的高精度外，甚至在极限值以外一定程度仍可使用，可以对有限工况进行外推且具有较好的置信度。
魔术公式正在成为工业标准，即轮胎制造商向整车厂提供魔术公式系数表示的轮胎数据，而不再是表格或图形。
基于魔术公式的轮胎模型还有较好的健壮性，如果没有某一轮胎的试验数据，而使用同类轮胎数据替代仍可取得很好的效果。
图基于魔术公式的轮胎模型的输入和输出变量Pacejka 89轮胎力与力矩的计算轮胎纵向力计算公式为：F x 二Dsin Carctan BX1 - E BX1 -arctanBX1川〕厂S V其中X1为纵向力组合自变量：X1=( K +S h) , K为纵向滑移率(负值出现在制动态，-100表示车轮抱死)C――曲线形状因子，纵向力计算时取B0值：C = B0D ――巅因子，表示曲线的最大值： D =B1F；B2F ZBCD ——纵向力零点处的纵向刚度：BCD fE F z2B4F Z e"^B -刚度因子：B=BCD/(C X D) S h ――曲线的水平方向漂移：S h 二B 9F Z - B 10Sv ——曲线的垂直方向漂移： Sv=0轮胎侧向力计算公式为：F Y = Dsin CarctanBX j -E BX 1 -arctan BX j ]]]]]亠 S V此时的X 1为侧向力计算组合自变量： X 1=( a +S h ), a 为侧偏角 C ――曲线形状因子，侧向力计算时取 A o 值：C = A oD ――巅因子，表示曲线的最大值：D = AF ； A 2F ZBCD ――侧向力零点处的侧向刚度：BCD = A 3sin 2arctan^ 汉(1 —A ^])<A4丿B -刚度因子：B=BCD/(C X D) S h ――曲线的水平方向漂移：S ^A 9F Z A ^0 A 8E ――曲线曲率因子，表示曲线最大值附近的形状:图轮胎属性文件中的纵向力计算系数数据块longitudina[L ONG I TUD IN AL_C OEFFICI ENTS]=2.372^72hl = ^9.46000laZ =1^90.00 153 = 130.00□ b4 = 375- 000 b5 =0.08S6Dh6 =0.00402b7 = -0.06150 bS = 1.20000- 0.02990bLO ■ -0.17600曲线形状因子图Pacejka '轮胎纵向力示例纵向力----------------------------------------SOOD3000 100D - arc t an (BCD)£)-10-^OODJ-30M1 --------------------------------------B 8Longitudinal Slip (%}s」亡S v――曲线的垂直方向漂移：S/ = A^F z A2F Z A13E――曲线曲率因子，表示曲线最大值附近的形状： E = A e F z A7图轮胎属性文件中的侧向力计算系数数据块$--------------- ----------------------------------------------------------------------------------------------------------- LATERAL_COEFFIC IEKTS [LATERAL_COEFFI ENTS] -----------------------------aO - 1,65000 ---------------------------------------------------------------------------- 曲线形状因子al = -3^.0 —屏=1Z50 ・口口一= GO36.OO —訥=12,30a5 = 0,00501 —aS = -0.02103 —a7 = 0.77394 —aB = 0.0022830&9 =0.013442alO = 0.003709all - 19.1656 —al2 - 1*21356- 6.26206 —图Pacejka '轮胎纵向力示例侧向力轮胎回正力矩计算公式为：亠王aM z 二Dsin Carctan BX“ -E BX“ -arctanBX“ ]]]『&此时的X1为回正力矩计算组合自变量：X1=( a +S h), a为侧偏角C――曲线形状因子，回正力矩计算时取C o值：C = C oD――巅因子，表示曲线的最大值：D二GF； C2F ZBCD ――回正力矩零点处的扭转刚度：BCD =：C3F；• C4F Z 1-C6 e"5B -刚度因子：B=BCD/(C X D)S h――曲线的水平方向漂移：S^C11C12F Z C13S v ――曲线的垂直方向漂移：Sz "J C g F ； C 15F Z C i6F z - C i7E ――曲线曲率因子，表示曲线最大值附近的形状：E =(C 7F ； +C g F z +C 9 )<(1 —GoY )-□.□001151 □ .1000 -1.33329 cio = □.ozssniCll = -0.O23S7 C12 = 0.03027 CL3 = -0.DC47 C14 = 0,0211329 015 = 0,89469 C16 - 099443 C17 - -3.336941侧偏刚度(Lateral Stiffness )侧偏刚度在Pacejka ' 和9' 9轮胎模型中假定是一个常量，在轮胎属性文件的参数 PARAMETER 数据段中通过LATERAL_STIFFNESS 语句设定。
ADAMS在汽车动⼒学仿真中的应⽤研究ADAMS在汽车动⼒学仿真中的应⽤研究newmaker⼀、引⾔数字化虚拟样机技术是缩短车辆研发周期、降低开发成本、提⾼产品设计和制造质量的重要途径。
随着虚拟产品开发、虚拟制造技术的逐渐成熟，计算机仿真技术得到⼤量应⽤。
系统动⼒学仿真是数字化虚拟样机的核⼼、关键技术。
对汽车⽽⾔，车辆动⼒学性能尤为重要。
为了降低产品开发风险，在样车制造出之前，利⽤数字化样机对车辆的动⼒学性能进⾏计算机仿真，并优化其参数就显得⼗分必要了。
对操纵稳定性的研究常采⽤仿真分析⽅法和试验⽅法来进⾏。
仿真分析是在计算机上建⽴简化到⼀定程度的模型，输⼊驾驶员对汽车的各种操纵信号，解算出系统的时域响应和频域响应，以此来表征汽车的操纵稳定性能。
因为仿真分析花费时间短，可在计算机上重复进⾏，对各种设计⽅案进⾏快速优化对⽐，并且可实现试验条件下不能进⾏的严酷⼯况分析，因此该⽅法⽇益被⼈们采⽤。
建⽴整车仿真模型常有多种⽅法，笔者应⽤机械系统运动学、动⼒学仿真分析软件ADAMS，来建⽴仿真模型，并对不同⽅向盘转⾓下的操纵稳定性进⾏了动⼒学仿真。
⼆、数字化分析模型的准备（⼀）仿真分析模型所需要的参数类型建⽴多体系统动⼒学分析模型，参数需要量⼤，精度要求⾼，参数准备⼯作量⼤。
所需的参数主要可划分为四类：尺⼨（⼏何定位）参数、质量特性参数（质量、质⼼与转动惯量等）、⼒学特性参数（刚度、阻尼等特性）与外界参数（道路谱等）。
其中的尺⼨参数和⼤部分的质量特性参数可以通过建⽴三维数字模型得到，其他参数尚需要别的参数获得⼿段来获取。
总的来说，参数的获得⽅法主要有以下⼏种：图纸查阅法、试验法、计算法、CAD建模法等。
可根据具体实际情况采⽤。
（⼆）数字模型间的数据传递基于CAD/CAM软件建⽴三维数字模型是建⽴数字化分析模型的基础。
使⽤CAD/CAM软件建⽴系统的三维实体数字模型，并以各个运动部件的形式先将零部件合并，装配好；将模型存为ADAMS软件可调⽤的特定格式的数据⽂件；然后利⽤CAD/CAM软件与ADAMS 软件之间的数据接⼝⽂件将三维模型传递到ADAMS软件中去；之后输⼊各运动部件的密度等必要参数，就可以直接得到各运动部件的质量、质⼼与转动惯量等质量参数。
详细介绍轮胎模型，主要是自己做课题时，用到的整理汇总出来的，轮胎这部分的资料比较少的，记录下来帮助大家一起学习一起进步；主要分以下两部分介绍一、轮胎模型简介轮胎是汽车重要的部件，它的结构参数和力学特性决定着汽车的主要行驶性能。
轮胎所受的垂直力、纵向力、侧向力和回正力矩对汽车的平顺性、操纵稳定性和安全性起重要作用。
轮胎模型对车辆动力学仿真技术的发展及仿真计算结果有很大影响，轮胎模型的精度必须与车辆模型精度相匹配。
因此，选用轮胎模型是至关重要的。
由于轮胎具有结构的复杂性和力学性能的非线性，选择符合实际又便于使用的轮胎模型是建立虚拟样车模型的关键。
一、轮胎模型简介轮胎建模的方法分为三种：1）经验—半经验模型针对具体轮胎的某一具体特性。
目前广泛应用的有Magic Formula公式和吉林大学郭孔辉院士利用指数函数建立的描述轮胎六分力特性的统一轮胎半经验模型UniTire，其主要用于车辆的操纵动力学的研究。
2）物理模型根据轮胎的力学特性，用物理结构去代替轮胎结构，用物理结构变形看作是轮胎的变形。
比较复杂的物理模型有梁、弦模型。
特点是具有解析表达式，能探讨轮胎特性的形成机理。
缺点是精确度较经验—半经验模型差，且梁、弦模型的计算较繁复。
3）有限元模型基于对轮胎结构的详细描述 ,包括几何和材料特性，精确的建模能较准确的计算出轮胎的稳态和动态响应。
但是其与地面的接触模型很复杂，占用计算机资源太大，在现阶段应用于不平路面的车辆动力学仿真还不现实，处于研究阶段。
主要用于轮胎的设计与制造二、ADAMS/TIRE轮胎不是刚体也不是柔体，而是一组数学函数。
由于轮胎结构材料和力学性能的复杂性和非线性以及适用工况的多样性，目前还没有一个轮胎模型可适用于所有工况的仿真，每个轮胎模型都有优缺点和适用的范围。
必须根据需要选择合适的轮胎模型。
ADAMS/TIRE分为两大类：一）.用于操稳分析的轮胎模型魔术公式是用三角函数的组合公式拟合轮胎试验数据，用一套形式相同的公式完整地表达轮胎的纵向力、侧向力、回正力矩、翻转力矩、阻力矩以及纵向力、侧向力的联合作用工况，主要包括以下的前四种模型。
我的car，发动机，制动器，驱动半轴,车身,横向稳定杆,轮胎等参数总结用car能有大半年了。
前几日发表了几个帖子说过要与苦闷专研的兄弟共享学习经验的。
我就创建一个自己的帖子吧，把自己随时随刻的经验或是困惑拿出来与大家共享或讨论。
可能有些唠叨可我还是要感谢一下我应当感谢的：首先是领我入门的师兄；二是“逼”我上梁山可上海科曼公司；三是有这么好的一个simwe；四是武汉的我那帮从未叫过师兄的师兄们，五就是我的网上的难兄难弟们；六~~~~~~~~~~~一：发动机参数的修改：发动机模块本人认为是最难的模块，其难处有二，一是模型的建立主要就是与整车的communicators 这个我以前的帖子有说过，下面我会剪过来，这里就不重复了。
二就是建完发动机后对其参数的修改。
其中发动机参数修改有两大块 1：build—parameter variable_table这个里面的参数应当好理解一些各位参考一下help应当不难2：build_general Data elements _spline_modify 然后在name对话框里选择gss_engine_torque，那里面你就可以看到采用的发动机文件。
（当然也可以直接到安装目录下找到）关键是对这个文件的理解，只有理解了才好修改。
(Z_DATA) {throttle}0.01.00(XY_DATA){engine_speed <no_units> torque <Nmm>}0 0 0500 -20000 800001000 -42000 1350001500 -44000 2000002000 -46000 2450002500 -48000 2630003000 -50000 3100003500 -50000 3580004000 -50000 4040004500 -50000 4550005000 -50000 4750005500 -50000 4850006000 -50000 4680006250 -50000 4620006500 -52000 4550006750 -56000 4270007000 -60000 3700007500 -64000 259000最关键的就是这三列数据，很不容易搞懂。
标准路面激励下的车轮动态负载分析李能; 刘春光; 燕玉林【期刊名称】《《机械设计与制造》》【年(卷),期】2019(000)008【总页数】4页(P41-44)【关键词】ADAMS; 动力学; 随机路面; 动态负载【作者】李能; 刘春光; 燕玉林【作者单位】装甲兵工程学院控制工程系北京 100072【正文语种】中文【中图分类】TH16; TJ8111 引言车辆匀速驶过平直路面会产生恒定轮胎力，由于实际道路表面形状不规则，导致轮胎受力波动，产生连续变化负载[1]。
动态负载易造成轮轴疲劳损伤，同时影响轮毂电机寿命。
因此，研究确定车轮动态负载对电机选择和车辆结构优化有重要意义。
当前有关动态负载研究，大多针对车辆部件疲劳损伤的载荷谱[2-3]。
载荷谱属于统计数据，不能实时反映车辆位置与车轮负载的关系。
道路重构技术大多采用MATLAB软件编程，过程繁琐，程序复杂。
基于ADAMS软件搭建整车动力学模型[4]，构建等级路面，研究直驶工况下不同路面与车速对车轮动态负载的影响。
2 车—路系统动力学模型2.1 整车模型搭建研究对象是包含多个精细结构的复杂系统，为简化模型只对车轮负载产生主要影响的部件建模，主要包括车身、悬架、双桥转向系统、轮胎模型。
车辆的主要技术参数，如表1所示。
车辆坐标系定义，如图1（a）所示。
X轴—车辆前进的方向，向后为正；Y轴—车身的侧向方向，指向车身右侧为正；Z轴—垂直于地面的方向，向上为正，Z轴的负方向—重力加速度的方向。
表1 整车基本性能参数Tab.1 Basic Performance Parameters项目数值车长（mm） 7 873车宽（mm） 2 936车高（至顶甲板/炮塔顶端）（mm） 2125/2 688一桥轮距（mm） 2 600二桥轮距（mm） 2 600三桥轮距（mm） 2 600四桥轮距（mm） 2 600轮胎半径（mm） 615整车质量（kg） 23 000图1 车-路系统动力学模型Fig.1 Dynamics Model of Vehicle-Road System车身是根据实车质量和转动惯量构建3D刚体模型。
详细介绍轮胎模型，主要是自己做课题时，用到的整理汇总出来的，轮胎这部分的资料比较少的，记录下来帮助大家一起学习一起进步；主要分以下两部分介绍一、轮胎模型简介轮胎是汽车重要的部件，它的结构参数和力学特性决定着汽车的主要行驶性能。
轮胎所受的垂直力、纵向力、侧向力和回正力矩对汽车的平顺性、操纵稳定性和安全性起重要作用。
轮胎模型对车辆动力学仿真技术的发展及仿真计算结果有很大影响，轮胎模型的精度必须与车辆模型精度相匹配。
因此，选用轮胎模型是至关重要的。
由于轮胎具有结构的复杂性和力学性能的非线性，选择符合实际又便于使用的轮胎模型是建立虚拟样车模型的关键。
一、轮胎模型简介轮胎建模的方法分为三种：1）经验—半经验模型针对具体轮胎的某一具体特性。
目前广泛应用的有 Magic Formula公式和吉林大学郭孔辉院士利用指数函数建立的描述轮胎六分力特性的统一轮胎半经验模型UniTire ，其主要用于车辆的操纵动力学的研究。
2）物理模型根据轮胎的力学特性，用物理结构去代替轮胎结构，用物理结构变形看作是轮胎的变形。
比较复杂的物理模型有梁、弦模型。
特点是具有解析表达式，能探讨轮胎特性的形成机理。
缺点是精确度较经验—半经验模型差，且梁、弦模型的计算较繁复。
3）有限元模型基于对轮胎结构的详细描述 , 包括几何和材料特性，精确的建模能较准确的计算出轮胎的稳态和动态响应。
但是其与地面的接触模型很复杂，占用计算机资源太大，在现阶段应用于不平路面的车辆动力学仿真还不现实，处于研究阶段。
主要用于轮胎的设计与制造二、 ADAMS/TIRE轮胎不是刚体也不是柔体，而是一组数学函数。
由于轮胎结构材料和力学性能的复杂性和非线性以及适用工况的多样性，目前还没有一个轮胎模型可适用于所有工况的仿真，每个轮胎模型都有优缺点和适用的范围。
必须根据需要选择合适的轮胎模型。
ADAMS/TIRE分为两大类：一） .用于操稳分析的轮胎模型魔术公式是用三角函数的组合公式拟合轮胎试验数据，用一套形式相同的公式完整地表达轮胎的纵向力、侧向力、回正力矩、翻转力矩、阻力矩以及纵向力、侧向力的联合作用工况，主要包括以下的前四种模型。
不同路面附着条件下轮胎模型参数值
不同路面附着条件下，轮胎模型参数的数值可能会产生变化。
以下是一些可能会受到影响的轮胎模型参数：
1. 刚度参数（Stiffness Parameters）：包括侧向刚度、径向刚度和分界径向刚度等。
在不同的路面附着条件下，轮胎的刚度参数可能会有所不同。
2. 摩擦参数（Friction Parameters）：包括侧向摩擦系数和径向摩擦系数等。
在不同的路面附着条件下，轮胎与地面之间的摩擦特性可能会有很大差异。
3. 轮胎动力学参数（Tire Dynamics Parameters）：包括侧向刹车刚度、侧向加速度反应和纵向力反应等。
不同的路面附着条件会导致轮胎在这些动力学参数上的响应不同。
4. 弯曲刚度参数（Bending Stiffness Parameters）：轮胎的弯曲刚度与路面附着条件之间有一定的关系。
不同的路面附着条件可能会影响轮胎的弯曲特性。
需要注意的是，轮胎模型参数是由轮胎制造商提供的，并且根据标准化测试条件进行确定。
在实际应用中，随着路面附着条件的变化，轮胎模型参数的数值可能需要根据实际测试数据进行调整。
Adams/car的悬架分析（Suspension Analyses），共提供悬架38种性能。
对所有悬架均提供：• Aligning Torque - Steer and Camber Compliance //单位回正力矩的转角或外倾角• Camber Angle //外倾角• Caster Angle //后倾角• Dive Braking/Lift Braking //制动点头/制动抬头• Fore-Aft Wheel Center Stiffness //悬架纵向刚度• Front-View Swing Arm Length and Angle //前视图（虚拟）摆臂长度和角度• Kingpin Inclination Angle //主销内倾角• Lateral Force - Deflection, Steer, and Camber Compliance //• Lift/Squat Acceleration //抬头（一般指启动时前悬架抬升，后悬架压缩）• Percent Anti-Dive Braking/Percent Anti-Lift Braking //（前悬架）防点头/（后悬架）防抬升• Percent Anti-Lift Acceleration/Percent Anti-Squat Acceleration //• Ride Rate //悬架动刚度• Ride Steer //悬架转向性能• Roll Camber Coefficient //侧倾轮倾系数（车身侧倾时车轮侧倾角与车身侧倾角的比值）• Roll Caster Coefficient //• Roll Center Location //侧倾中心位置• Roll Steer //Ride steer is the slope of the steer angle versus the vertical wheel travel curve. Ride steer is the change in steer angle per unit of wheel center vertical deflection due to equal vertical forces at the wheel centers. Positive ride steer implies that the wheels steer to the right, as the wheel centers move upward.引导滚/ /骑牛引导的坡角与垂直轮旅行曲线。
ADAMSCAR车辆操稳性国标试验仿真设定参数为了确保汽车的行驶安全性和操控稳定性，各国都制定了相应的国际标准试验来评估车辆的操稳性。
ADAMSCAR是一种常用的车辆动力学仿真软件，可以用于模拟车辆在各种情况下的行驶状况。
下面将介绍ADAMSCAR仿真设定参数的一些关键参数。
1.悬挂系统参数：悬挂系统的刚度和阻尼是影响车辆操控稳定性的重要参数。
在ADAMSCAR中，可以设置前后悬挂系统的刚度和阻尼系数，以模拟车辆在行驶过程中悬挂系统的响应。
2.轮胎参数：轮胎是车辆与地面接触的唯一部件，其性能对车辆的操控稳定性有很大影响。
在ADAMSCAR中，可以设置轮胎的摩擦系数、刚度和阻尼等参数，以模拟轮胎在不同路面和行驶状况下的转向性能和抓地力。
3.动力系统参数：动力系统的性能也会对车辆的操控稳定性产生影响。
在ADAMSCAR中，可以设置发动机的输出扭矩和转速曲线，以及传动系统的传动比和换挡速度等参数，以模拟车辆在加速、减速和换挡等情况下的动力响应。
4.车辆结构参数：车辆的结构刚度和质量分布也会对车辆的操控稳定性产生影响。
在ADAMSCAR中，可以设置车辆的结构刚度、质量分布和悬挂系统的几何尺寸等参数，以模拟车辆在转弯、制动和通过障碍物等情况下的动力学响应。
除了上述参数外，还可以根据需要设置其他一些参数，如车辆的空气动力学特性、制动系统的性能和车辆的转向系统等。
这些参数的设定需要根据具体的国际标准试验要求和车辆的实际情况进行调整和优化。
需要注意的是，ADAMSCAR仿真只是一个辅助工具，实际的车辆操控稳定性还需要通过道路试验和真实行驶来验证。
因此，在进行ADAMSCAR 仿真时，需要理解并合理设置各种参数，以尽可能准确地模拟车辆的行为和响应。
同时，还需要结合其他方法和工具，如实车试验和数据分析等，来综合评估车辆的操控稳定性。
详细介绍轮胎模型，主要是自己做课题时，用到的整理汇总出来的，轮胎这部分的资料比较少的，记录下来帮助大家一起学习一起进步；主要分以下两部分介绍一、轮胎模型简介轮胎是汽车重要的部件，它的结构参数和力学特性决定着汽车的主要行驶性能。
轮胎所受的垂直力、纵向力、侧向力和回正力矩对汽车的平顺性、操纵稳定性和安全性起重要作用。
轮胎模型对车辆动力学仿真技术的发展及仿真计算结果有很大影响，轮胎模型的精度必须与车辆模型精度相匹配。
因此，选用轮胎模型是至关重要的。
由于轮胎具有结构的复杂性和力学性能的非线性，选择符合实际又便于使用的轮胎模型是建立虚拟样车模型的关键。
一、轮胎模型简介轮胎建模的方法分为三种：1）经验—半经验模型针对具体轮胎的某一具体特性。
目前广泛应用的有Magic Formula公式和吉林大学郭孔辉院士利用指数函数建立的描述轮胎六分力特性的统一轮胎半经验模型UniTire，其主要用于车辆的操纵动力学的研究。
2）物理模型根据轮胎的力学特性，用物理结构去代替轮胎结构，用物理结构变形看作是轮胎的变形。
比较复杂的物理模型有梁、弦模型。
特点是具有解析表达式，能探讨轮胎特性的形成机理。
缺点是精确度较经验—半经验模型差，且梁、弦模型的计算较繁复。
3）有限元模型基于对轮胎结构的详细描述,包括几何和材料特性，精确的建模能较准确的计算出轮胎的稳态和动态响应。
但是其与地面的接触模型很复杂，占用计算机资源太大，在现阶段应用于不平路面的车辆动力学仿真还不现实，处于研究阶段。
主要用于轮胎的设计与制造二、ADAMS/TIRE轮胎不是刚体也不是柔体，而是一组数学函数。
由于轮胎结构材料和力学性能的复杂性和非线性以及适用工况的多样性，目前还没有一个轮胎模型可适用于所有工况的仿真，每个轮胎模型都有优缺点和适用的范围。
必须根据需要选择合适的轮胎模型。
ADAMS/TIRE分为两大类：一）.用于操稳分析的轮胎模型魔术公式是用三角函数的组合公式拟合轮胎试验数据，用一套形式相同的公式完整地表达轮胎的纵向力、侧向力、回正力矩、翻转力矩、阻力矩以及纵向力、侧向力的联合作用工况，主要包括以下的前四种模型。
时域道路模型在MSC.ADAMS中道路时域道路模型是通过属性文件来表达的，而属性文件的创建是使用独立插件Road Builder来完成，通过Road Builder还可以创建IPG和ARM格式包括路肩的3D 道路。
它支持以下种类的路面几何轨迹✧常规仿真车道（开环或闭环）✧赛车道（Chicane）✧椭圆环车道（Oval）✧路标筒车道通过Road Builder可以生成下列种类的文件：✧.rdf✧.drd✧.dcd✧.shl✧.dig （仅用于IPG）✧.road （仅用于IPG）注：使用Road Builder需要单独的许可证文件（license file），但在ADAMS 2005R2版里已经作为标准插件。
在ADAMS里路面模型是通过后缀名为.rdf的路面文件引入到仿真环境中，路面文件的结构仍然是TeimOrbit格式的ASCII文本文件。
例如在操纵性仿真中常用的平整路面文件有：在路面文件中的标题数据块、单位数据块的定义方式与DCF、DCD文件一样，[MODEL]数据块定义路面的类型，[GRAPHICS]数据块定义路面几何图形，注意，在2D道路中只有平整路面Flat才有路面图形；其他类型的路面可以通过专用软件包FTire-tools提供的road visualization功能观察路面形状（另一种方法是用函数构造器下的create_shell_from_rdf函数将路面文件转化为shell文件，再将shell壳文件加入到模型中）；[PARAMETERS]数据块定义路面的如摩擦系数、几何形态等参数。
道路类型：道路的类型在TeimOrbit格式的道路属性文件中通过[MODEL]数据块中的METHOD、ROAD_TYPE语句定义，[MODEL]数据块定义的常用道路类型如下：SINE 正弦波路面SINE_SWEEP 正弦变波纹路面STOCHASTIC_UNEVEN 随机不平路面‘3D’‘ARC904’ /none 3D等效容积道路‘3D_SPLINE’'ARC903'/none 3D样条路面'5.2.1' 'ARC913' FLAT或INPUT 521轮胎模型专用路面‘USER’‘ARC501’自定义[FUNCTION_NAME]函数名称变量指路面与轮胎接触函数ID号2D道路文件MTTHOD＝2D时二维路面的参数[PARAMETERS]子数据块：参数子数据块[PARAMETERS]的结构根据路面类型的不同而不同，基本上可以划分为3隔部分：通用参数段、路型参数段和数据组，用符号$分开。
汽车制动时湿滑路面对运行状态的影响分析吕江毅;宋建桐;刘敏杰【摘要】Slippery road has a significant effect on automobile moving states especially in braking. To gain insight into the mechanism of traffic accident in wet weather, studying automobile moving state in braking on different slippery roads is needed. The automobile-road model was built to simulate automobile motion on five types of slippery roads using system dynamics software, and the kinematical and dynamic responses of an automobile were derived. The results showed that automobile moving parameters such as braking distance, lateral displacement and yaw rate rely on the slippery degree of roads. Specifically, slippery discrepancy in two sides of a road contacted with tires shortens the braking distance, but the lateral displacement and yaw rate increase, which raises the side crash risk.%路面湿滑状态影响行车安全性.研究汽车在不同湿滑路面上制动时的运行规律及轮胎受力情况,有助于探索雨天交通事故发生机理.将轮胎接地面的湿滑程度分为五类,采用机械系统动力学仿真软件,构建了整车模型、轮胎模型及路面模型,分别模拟了汽车在各种路面上制动时的纵向位移、横摆角、横向位移变化情况.并通过分析胎—路作用力,解释了汽车运行参数变化的原因.研究结果表明,汽车制动时的运行参数与路面湿滑状态密切相关,轮胎接地两侧路面的湿滑程度及其差异性越高,则汽车运行安全性越低；两侧路面湿滑程度不均衡虽然有可能使得制动距离缩短,但是汽车横向位移变化率却极大,容易发生因横摆角过大出现急转的危险.【期刊名称】《科学技术与工程》【年(卷),期】2013(013)002【总页数】7页(P372-378)【关键词】交通安全;仿真;汽车运行;路面状态;制动【作者】吕江毅;宋建桐;刘敏杰【作者单位】北京电子科技职业学院,北京100026;北京电子科技职业学院,北京100026;北京电子科技职业学院,北京100026【正文语种】中文【中图分类】U491.25;U461.3路面湿滑导致汽车制动效能下降，极易出现跑偏、侧滑等现象。
ADAMS/CAR不同轮胎模型的整车平顺性分析实例在相同条件下，对使用不同轮胎模型的整车模型进行平顺性仿真。
仿真结束后，在后处理模块获得汽车底盘质心处x 、y 、z 三个轴向的加速度曲线。
为了确定路面引起汽车振动所在的频率范围，还需获取相应的加速度功率谱密度。
最后，求加速度加权均方根值，评价振动对人体的影响。
目录第一章、参考资料 (1)第二章、建模说明 (5)一、生成5.2.1前轮胎模型 (5)二、生成5.2.1后轮胎模型 (9)三、生成其他三个轮胎模型 (10)四、生成整车模型 (12)第三章、仿真分析 (16)一、平顺性仿真概述 (16)二、随机路面生成 (16)三、平顺性仿真条件设置 (16)四、仿真过程 (17)第四章、结果分析 (19)一、概述 (19)二、操作说明 (20)三、同等条件下，不同轮胎模型的汽车平顺性比较 (27)四、同等条件下，不同车速的汽车平顺性比较 (35)五、同等条件下，不同路面的汽车平顺性比较 (38)第一章、参考资料在ADAMS虚拟样机仿真软件中按照实际使用情况可将轮胎模型分为操作性分析轮胎模型、耐久性分析即3D接触分析轮胎模型以及摩托车用轮胎模型三大类。
由于本文中主要研究的是轮胎与路面间垂直力所引起的冲击振动情况，故应选用操纵性分析轮胎模型，其使用的是point follower的方式来计算轮胎由于路面不平激励所引起的垂直力。
在操纵性分析轮胎模型组中提供了MF-tyre、Pacejka ’89、Pacejka ’94、PAC2002、Fiala、5.2.1以及UA等轮胎模型，用户可以根据实际需要对模型数据进行修改。
通过修改软件自带的轮胎模型文件来生成轮胎模型能够保证车辆仿真要求的一致性，从而保证仿真结果的可靠性。
第二章、建模说明一、生成5.2.1前轮胎模型为建立轮胎模型，需先将acar共享文件中需要的轮胎数据复制到个人文件夹，本文进行汽车平顺性分析，适用于平顺性分析的轮胎模型有MF-tyre、Pacejka ’89、Pacejka ’94、PAC2002、Fiala、5.2.1以及UA等轮胎模型，本文选取4种类型：521_equation、mdi_fiala01、mdi_pac94、uat。
2D Road TypesThe available road types are:•DRUM - Tire test drum (requires a zero-speed-capable tire model). •FLAT - Flat road.•PLANK - Single plank perpendicular, or in oblique direction relative to x-axis, with or without bevel edges. • POLY_LINE - Piece-wise linear description of the road profile. The profiles for the left and right track are independent. •POT_HOLE - Single pothole of rectangular shape. •RAMP - Single ramp, either rising or falling. •ROOF - Single roof-shaped, triangular obstacle. •SINE - Sine waves with constant wave length. •SINE_SWEEP - Sine waves with decreasing wave lengths.•STOCHASTIC_UNEVEN - Synthetically generated irregular road profiles that match measured stochastic properties of typical roads. The profiles for left and right track are independent, or may have a certain correlation. Examples of 2D RoadsSample files for all the road types for Adams/Car are in the standard Adams/Car database:install_dir /shared_car_database.cdb/roads.tbl/Sample files for all the road types for Adams/Tire are in: install_dir /solver/atire/Sample files for all the road types for Adams/Chassis are in: install_dir /achassis/examples/rdf/Note that you must select a specific contact method, such as point-follower or equivalent plane, to define how the roads will interact with the tires. Not allcombinations of road, tire, and contact methods are permitted. Allowable combinations are explained in Tire Models help under the description of the specific tire model.2D Road Model ParametersThe [PARAMETERS] block must contain the following data, some of which are independent of the type of road. Learn about parameters:•Independent of Road Type •Drum •Flat •Plank •Polyline•Pothole•Ramp•Roof•Sine•Sweep•Stochastic UnevenParameters Independent of Road TypeThe following parameters are required regardless of the road type.If ROAD_TYPE = drum, then define the following parameters:If ROAD_TYPE = flat, then no further parameters are required.Parameters for Road Type of PlankIf ROAD_TYPE = plank, then define the following parameters:If ROAD_TYPE = poly_line, then the [PARAMETERS] block must have a (XZ_DATA) subblock. The subblock consists of three columns of numerical data:•Column one is a set of x-values in ascending order.•Columns two and three are sets of respective z-values for left and right track.The following is an example of the full [PARAMETERS] Body for a road type of polyline: $---------------------------PARAMETERS[PARAMETERS]OFFSET = 0ROTATION_ANGLE_XY_PLANE = 180$(XZ_DATA)0 0 01000 100 502000 -1000 1003000 -100 1003001 50 04000 -100 100The XZ_DATA subblock can be extremely large. In this case, only the portion that is needed at the moment is loaded. To facilitate efficient reloading while simulation is running, do not use any comment lines in a subblock that contains more than 2000 lines. Parameters for Road Type of PotholeIf ROAD_TYPE = pot_hole, then the parameters are:If ROAD_TYPE = ramp, then the parameters are:If ROAD_TYPE = roof, then the parameters are:If ROAD_TYPE = sine, then the parameters are:amplitude Amplitude of sine wave (a).wave_lengthWave length of sine wave ().start Start of sine waves (traveldistance) (s s).The road height, z, is given by:Parameters for Road Type of Stochastic UnevenA stochastic uneven road profile both for left and right wheels is generated, with properties very close to measured road profiles.In a first step, discrete white noise signals are formed on the basis of nearly uniformly distributed random numbers. Two of these numbers are assigned to every 10 mm of travel path. The distribution of these random numbers is approximated by summing several equally distributed random numbers, taking advantage of the ‘law of large numbers’ of mathematical statistics.Next, these values are integrated with respect to travel distance, using a simplefirst order time-discrete integration filter. The independent variable of that filter is not time, but travel path. That is why the filter cutoff frequency is controlled by a path constant instead of a time constant. The filter process results in two approximate realizations of white velocity noise; that is, two signals, thederivatives of which are close to white noise. Signals with that property are known as road profiles with waviness 2. Several investigations in the past showed that the waviness derived from measured road spectral densities ranges from about 1.8 to 2.2. The last step is to linearly combine the two realizations of the aboveprocess:,, resulting in the left and right profile,. This is done such that the two signals are completely independent if , and identical if:If ROAD_TYPE = stochastic_uneven, then the parameters are:The parameter: Indicates:intensity Variable to control intensity of white velocity noise, whichapproximates measured spectra of road profiles fairly well.path_constant Variable to control high-pass integration filter.correlation_rl Variable to control correlation between left and right track:•If 0, no correlation.•If 1, complete correlation (that is, left track = right track). Can be any value between 0 and 1.startStart of unevenness (travel distance).Parameters for Road Type of SweepIf ROAD_TYPE = sine_sweep, then the parameters are:[PARAMETERS] Data for Road Type of Sine Sweep The parameter: Indicates:start Start of swept sine wave (travel distance) (). endEnd of swept sine wave (travel distance) ().amplitude_at_sta rtAmplitude of swept sine wave at start travel distance (). amplitude_at_end Amplitude of swept sine wave at end travel distance ().wave_length_at_s tartWave length of swept sine wave a start travel distance ().wave_length_at_e ndWave length of swept sine wave at end travel distance. Must be less than or equal to wave_length_at_start ().sweep_type•sweep_type = 0: frequency increases linearly with respect to travel distance. •sweep_type = 1: wave length decreases by a constant factor per cycle. Depending on the value of sweep_type, the road height is given by the following functions, where:• Linear sweep: (sweep_type = 0) The frequency increases linearly with respect to travel distance. The road height value z (s) as function of travel distance s is alculated as follows:Note the factor 2 in the denominator is not an error. The actual frequency (= derivative of the sine function argument with respect to travel path, divided by ; this is not equal to that factor that is multiplied by in the sine function) is given by thefollowing:•Logarithmic sweep: (sweep_type = 1) with every cycle, the wave length decreases by a constant factor. The road height value is calculated as follows:where:is the travel path where theoretically an infinitely high frequency was reached, measured relative to sweep start . Theactual frequency is given by:Using the UA-Tire ModelLearn about using the University of Arizona (UA) tire model:•Background Information •Tire Model Parameters •Force Evaluation •Operating Mode: USE_MODE •Tire Carcass Shape •Property File Format ExampleBackground Information for UA-TireThe University of Arizona tire model was originally developed by Drs. P.E. Nikravesh and G. Gim. Reference documentation: G. Gim, Vehicle Dynamic Simulation with aComprehensive Model for Pneumatic Tires, PhD Thesis, University of Arizona, 1988. The UA-Tire model also includes relaxation effects, both in the longitudinal and lateral direction.The UA-Tire model calculates the forces at the ground contact point as a function of the tire kinematic states, see Inputs and Output of the UA-Tire Model. A description of the inputs longitudinal slip k, side slip a and camber angle can be found in About Tire Kinematic and Force Outputs. The tire deflection and deflection velocity are determined using either a point follower or durability contact model. For more information, see Road Models in Adams/Tire . A description of outputs, longitudinal force Fx, lateral force Fy, normal force Fz, rolling resistance moment My and self aligningmoment Mz is given in About Tire Kinematic and Force Outputs. The required tire model parameters are described in Tire Model Parameters.Inputs and Output of the UA-Tire ModelDefinition of Tire Slip QuantitiesSlip Quantities at Combined Cornering and Braking/TractionThe longitudinal slip velocity Vsx in the SAE-axis system is defined using thelongitudinal speed Vx, the wheel rotational velocity , and the effective rolling radius Re: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:When the UA Tire is used for the force calculation the slip quantities during positive Vsx (driving) are defined as:The rolling speed Vr is determined using the effective rolling radius Re:Note that for realistic tire forces the slip angle is limited to 45 degrees and thelongitudinal slip Ss (= ) 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 forthe longitudinal slip as the side slip angle, . Considering the tire belt as a stretched string, which is supported to the rim with lateral spring, 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 BehaviorWhen 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. When the UA Tire is used for the force calculations, at positive Vsx (traction) the Vx should be replaced by Vr in these differential equations.A similar approach yields the following for the deflection of the string in longitudinal direction: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. kVlow_x and kVlow_y are the damping rates at low speed applied below the LOW_SPEED_THRESHOLD speed. For the LOW_SPEED_DAMPING parameter in the tire property file yields:kVlow_x= 100 · kVlow_y= LOW_SPEED_DAMPINGNote: If the tire property file's REL_LEN_LON or REL_LEN_LAT = 0, then steady-state tire behavior is calculated as tire response on change of the slip and .Tire Model ParametersSymbol: Name in tire propertyfile: Units*: Description:r1 UNLOADED_RADIUS L Tire unloaded radiuskz VERTICAL_STIFFNESS F/L Vertical stiffnesscz VERTICAL_DAMPING FT/L Vertical dampingCr ROLLING_RESISTANCE L Rolling resistance parameter Cs CSLIP F Longitudinal slip stiffness,C CALPHA F/A Cornering stiffness,C CGAMMA F/ACamber stiffness,UMIN UMIN - Minimum friction coefficient(Sg=1)UMAX UMAX - Maximum friction coefficient(Ssg=0)x REL_LEN_LON L Relaxation length inlongitudinal directiony REL_LEN_LAT L Relaxation length in lateraldirection* L=length, F=force, A=angle, T=timeForce Evaluation in UA-Tire•Normal Force•Slip Ratios•Friction CoefficientNormal ForceThe normal force F z is calculated assuming a linear spring (stiffness: k z ) and damper (damping constant c z ), so the next equation holds:If the tire loses contact with the road, the tire deflection and deflection velocity become zero so the resulting normal force F z will also be zero. For very small positive tire deflections the value of the damping constant is reduced and care is taken to ensure that the normal force Fz will not become negative.In stead of the linear vertical tire stiffness cz , also an arbitrary tire deflection - load curve can be defined in the tire property file in the section[DEFLECTION_LOAD_CURVE], see also the Property File Format Example. 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. Note that you must specify VERTICAL_STIFFNESS in the tire property file but it does not play any role.Slip RatiosFor the calculation of the slip forces and moments a number of slip ratios will be introduced:Longitudinal Slip Ratio: SsThe absolute value of longitudinal slip ratio, Ss, is defined as:Where k is limited to be within the range -1 to 1.Lateral Slip Ratios: Sa , Sg , SagThe lateral slip ratio due to slip angle, S, is defined as:The lateral slip ratio due to inclination angle, S, is defined as:A combined lateral slip ratio due to slip and inclination angles, S, is defined as:where is the length of the contact patch.Comprehensive Slip Ratio: SsagA comprehensive slip ratio due to longitudinal slip, slip angle, and inclination angle may be defined as:Friction CoefficientThe resultant friction coefficient between the tire tread base and the terrain surfaceis determined as a function of the resultant slip ratio (Ss) and friction parameters (UMAX and UMIN ). The friction parameters are experimentally obtained data representing the kinematic property between the surfaces of tire tread and the terrain.A linear relationship between Ss and , the corresponding road-tire friction coefficient, is assumed. The figure below depicts this relationship.Linear Tire-Terrain Friction ModelThis can be analytically described as:m = UMAX - (UMAX - UMIN) * SsagThe friction circle concept allows for different values of longitudinal and lateralfriction coefficients (x and y) but limits the maximum value for both coefficientsto . See the figure below.Friction Circle ConceptThe relationship that defines the friction circle follows:or andwhere:Slip Forces and MomentsTo compute longitudinal force, lateral force, and self-aligning torque in the SAE coordinate system, you must perform a test to determine the precise operating conditions. The conditions of interest are:•Case 1: 0•Case 2: 0 and C S C S•Case 3: 0 and C S C S•Forces and moments at the contact pointThe lateral force Fh can be decomposed into two components: Fha and Fhg. The twocomponents are in the same direction if a· g < 0 and in opposite direction if 0. Case 1. ag < 0Before computing the longitudinal force, the lateral force, and the self-aligning torque, some slip parameters and a modified lateral friction coefficient should bedetermined. If a slip ratio due to the critical inclination angle is denoted by S c, then it can be evaluated as:If Ssc represents a slip ratio due to the critical (longitudinal) slip ratio, then it can be evaluated as:If a slip ratio due to the critical slip angle is denoted by S c, then it can be determined as:when Ss Ssc.The term critical stands for the maximum value which allows an elastic deformation of a tire during pure slip due to pure slip ratio, slip angle, or inclination angle. Whenever any slip ratio becomes greater than its corresponding critical value, an elastic deformation no longer exists, but instead complete sliding state representsthe contact condition between the tire tread base and the terrain surface.A nondimensional slip ratio Sn is determined as:where:A nondimensional contact patch length is determined as:A modified lateral friction coefficient is evaluated as:where is the available friction as determined by the friction circle.To determine the longitudinal force, the lateral force, and the self-aligning torque, consider two subcases separately. The first case is for the elastic deformation state, while the other is for the complete sliding state without any elastic deformation of a tire. These two subcases are distinguished by slip ratios caused by the critical values of the slip ratio, the slip angle, and the inclination angle. Specifically, if all of slip ratios are smaller than those of their corresponding critical values, then there exists an elastic deformation state, otherwise there exists only completesliding state between the tire tread base and the terrain surface.(i) Elastic Deformation State: S S c, Ss Ssc, and S S cIn the elastic deformation state, the longitudinal force F, the lateral force F, and three components of the self-aligning torque are written as functions of the elastic stiffness and the slip ratio as well as the normal force and the friction coefficients, such as:where:•is the offset between the wheel plane center and the tire treadbase.•is set to zero if it is negative.•the length of the contact patch.Mz is the portion of the self-aligning torque generated by the slip angle . Mzsand Mzs are other components of the self-aligning torque produced by thelongitudinal force, which has an offset between the wheel center plane and the tire tread base, due to the slip angle and the inclination angle , respectively. The self-aligning torque Mz is determined as combinations of Mz, Mzs and Mzs.(ii) Complete Sliding State: S S c, Ss Ssc, and S S cIn the complete sliding state, the longitudinal force, the lateral force, and three components of the self-aligning torque are determined as functions of the normal force and the friction coefficients without any elastic stiffness and slip ratio as:Case 2:0 and C S C SAs in Case 1, a slip ratio due to the critical value of the slip ratio can be obtained as:A slip ratio due to the critical value of the slip angle can be found as:when Ss Ssc.The nondimensional slip ratio Sn, is determined as:where:The nondimensional contact patch length ln is found from the equation ln = 1 - Sn, and the modified lateral friction coefficient is expressed as:For the longitudinal force, the lateral force and the self-aligning torque two subcases should also be considered separately. A slip ratio due to the critical value of the inclination angle is not needed here since the required condition for Case 2,C S C S, replaces the critical condition of the inclination angle.(i) Elastic Deformation State: Ss Ssc and S SacIn the elastic deformation state:(ii) Complete Sliding State: Ss Ssc and S SacCase 3:0 and C S C SSimilar to Cases 1 and 2, slip ratios due to the critical values of the inclination angle and the slip ratio are obtained as:The nondimensional slip ratio Sn, is expressed as:where:For the longitudinal force, the lateral force, and the self-aligning torque, two subcases should also be considered similar to Cases 1 and 2. A slip ratio due to the critical value of the slip angle is not needed here since the required condition forCase 3, C S C S, replaces the critical condition of the slip angle. (i) Elastic Deformation State: S S c and Ss SscIn the elastic deformation state, F and Mz can be written:(ii) Complete Sliding State: S S c and Ss SscIn the complete sliding state, F, F, Mz, Mzs, and Mzs can be determined by using:respectively. The longitudinal force F , the lateral force F, and three componentsof the self-aligning torques, Mz , Mzs , and Mzs , always have positive values, but they can be transformed to have positive or negative values depending on the slip ratio s, the slip angle , and the inclination angle in the SAE coordinate system. Tire Forces and Moments in the SAE Coordinate SystemFor the general formulations of the longitudinal force Fx, lateral force Fy, and self-aligning torque Mz, in the SAE coordinate system, the three possible combinations of the slip ratio, the slip angle, and the inclination angle are also considered. Longitudinal Force:Fx = sin(k) F , for all cases Lateral Force: F y = -sin() F, for cases 1 and 2F y = sin() F , for case 3 Self-aligning Torque:M z = sin() M z - sin() [-sin() M zs + sin()M zs ]Rolling Resistance Moment:My = -Cr Fz, for a forward rolling tire. My = Cr Fz , for a backward rolling tire.Operating Mode: USE_MODEYou can change the behavior of the tire model through the switch USE_MODE in the [MODEL] section of the tire property file.•USE_MODE = 0: Steady-state forces and moments • The tire forces and moments react instantaneously to changes in the tire kinematic states. •USE_MODE = 1: Transient tire behavior • The tire will have a lagged response because of the so-called relaxation length in both longitudinal and lateral direction. See Lagged Longitudinal and Lateral Slip Quantities (transient tire behavior).•The effect of the relaxation lengths will be most pronounced at low forward velocityand/or high excitation frequencies. •USE_MODE = 2: Smoothing of forces and moments on startup of the simulation •When 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 0.1seconds of 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 FLon = S*FLon Lateral Force FLat = S*FLat Aligning Torque Mz = S*MzTire Carcass ShapeYou can optionally supply a tire carcass cross-sectional shape in the tire property file in the [SHAPE] block. The 3D-durability, tire-to-road contact algorithm uses this information when calculating the tire-to-road volume of interference. If you omit the [SHAPE] block from a tire property file, the tire carcass cross-section defaults to the rectangle that the tire radius and width define.You specify the tire carcass shape by entering points in fractions of the tire radius and width. Because Adams/Tire assumes that the tire cross-section is symmetrical about the wheel plane, you only specify points for half the width of the tire. The following apply:•For width, a value of zero (0) lies in the wheel center plane. •For width, a value of one (1) lies in the plane of the side wall. •For radius, a value of one (1) lies on the tread. For example, suppose your tire has a radius of 300 mm and a width of 185 mm and that the tread is joined to the side wall with a fillet of 12.5 mm radius. The tread then begins to curve to meet the side wall at >+/- 80 mm from the wheel center plane. If you define the shape table using six points with four points along the fillet, the resulting table might look like the shape block that is at the end of the property format example (see SHAPE ).Property File Format Example$--------------------------------------------------------MDI_HEADER [MDI_HEADER]FILE_TYPE = 'tir' FILE_VERSION = 2.0 FILE_FORMAT = 'ASCII'(COMMENTS) {comment_string} 'Tire - XXXXXX''Pressure - XXXXXX' 'TestDate - XXXXXX' 'Test tire''New File Format v2.1'$-------------------------------------------------------------units [UNITS] LENGTH= 'meter' FORCE= 'newton'ANGLE= 'rad'MASS= 'kg'TIME= 'sec'$-------------------------------------------------------------model [MODEL]! use mode123! ------------------------------------------! relaxation lengthsX! smoothingX !PROPERTY_FILE_FORMAT= 'UATIRE'USE_MODE= 2$---------------------------------------------------------dimension [DIMENSION]UNLOADED_RADIUS= 0.295WIDTH= 0.195ASPECT_RATIO= 0.55$---------------------------------------------------------parameter [PARAMETER]VERTICAL_STIFFNESS= 190000VERTICAL_DAMPING= 50ROLLING_RESISTANCE= 0.003CSLIP= 80000CALPHA= 60000CGAMMA= 3000UMIN= 0.8UMAX= 1.1REL_LEN_LON= 0.6REL_LEN_LAT= 0.5$-------------------------------------------------------------shape[SHAPE]{radial width}1.0 0.01.0 0.21.0 0.41.0 0.61.0 0.80.9 1.0$---------------------------------------------------------------------load_curve $ For a non-linear tire vertical stiffness (optional)$ Maximum of 100 points[DEFLECTION_LOAD_CURVE]{penfz}0.0000.00.001212.00.002428.00.003648.00.0051100.00.0102300.00.0205000.00.0308100.0。
