1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243TO PLACE A DOCUMENT
3、 ORDER; (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1998 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICESubmitted for recognition as an American National Sta
4、ndardJ1987ISSUEDJAN1998Issued 1998-01Force and Moment Test Method1. Scope1.1 This SAE Recommended Practice describes the determination of passenger car and light truck tire force andmoment properties on a belt-type flat surface test machine. It is suitable for accurately determining five tireforces
5、and moments in steady-state under free-rolling conditions as a function of slip angle and normal forcewhich are incrementally changed in a given sequence.1.2 Heavy-duty tires are not considered in this document, because the measuring system would have force andmoment ranges too large to meet sensiti
6、vity requirements for passenger and light truck tire force and momentmeasurements. A standard for heavy-duty truck tires would have many of the same features as thisdocument, but the measuring system, would have to be extensively altered.1.3 Inclination angle combined with slip angle, pull forces, a
7、nd any combination with spindle torque are notconsidered in this document. Standards needed for these topics will be considered separately. 1.4 The test method described in this document is suitable for comparative evaluations of tires for research anddevelopment purposes. The method is also suitabl
8、e for use in manufacturing quality control and vehicledynamics modeling.1.5 The values of tire forces and moments obtained on the test machine defined in the procedure outlined can becorrelated with similar test machines using the procedure defined in this document.2. References2.1 Applicable Public
9、ationsThe following publications form a part of the specification to the extent specifiedherein. Unless otherwise indicated the latest revision of SAE publications shall apply.2.1.1 SAE PUBLICATIONSAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001SAE J670Vehicle Dynamic Terminolo
10、gySAE 760029“Effects of Test Speed and Curvature on Cornering Properties of Tires“, M.G. Pottinger,K.D. Marshall, E.A. ArnoldSAE 770870“The Effect of Tire Break-In on Force and Moment Properties“, K.D. Marshall, R.L. Phelps,M.G. Pottinger, W. PelzSAE 810006“The Effect of Tire Aging on the Force and
11、Moment Properties of Radial Tires“, M.G.Pottinger, K.D. MarshallSAE J1987 Issued JAN1998-2-2.1.2 TIRE AND RIM ASSOCIATION PUBLICATIONSAvailable from Tire and Rim Association, Coply, OH 44321-2793.Tire and Rim Association Yearbook2.1.3 Other PublicationsM.G. Pottinger, Tire/Vehicle Pull; “Ply Steer E
12、ffects“, Clemson University Tire meeting, October 1988.3. DefinitionsThese terms follow the definitions given in SAE J670 and in the TRA Yearbook.3.1 Aligning StiffnessFirst derivative of aligning moment of a free-rolling tire with respect to slip angle,evaluated at zero slip angle. For practical pu
13、rposes, aligning stiffness may be approximated by subtractingthe1 degree slip angle value of the aligning moment from the +1 degree slip angle of aligning moment anddividing by 2.3.2 Aligning Stiffness CoefficientRatio of aligning stiffness to the absolute value of normal force.3.3 Aligning MomentMo
14、ment about the Z axis acting on the tire by the road. The aligning moment is shown inFigure 1. The aligning moment shown in Figure 1 is positive.FIGURE 1TIRE AXIS SYSTEM3.4 Aligning Moment OffsetAverage aligning moment of a free straight-rolling tire. The aligning moment offsetis dependent on the di
15、rection of tire rotation. It is different, generally speaking, in left and right tire rotation.see 2.1.3.3.5 Center-of-Tire-ContactIntersection of the wheel plane and the normal projection of the spin axis onto theroad plane. The center-of-tire contact is the origin of the tire axis system shown in
16、Figure 1.SAE J1987 Issued JAN1998-3-3.6 Cornering StiffnessAbsolute value for the first derivative of the lateral force of the free-rolling tire withrespect to slip angle, evaluated at zero slip angle. For practical purposes, cornering stiffness may beapproximated by taking the absolute value of the
17、 quantity yielded by subtracting the +1 degree slip angle valueof the lateral force from the 1 degree slip angle value of the lateral force and dividing by 2.3.7 Cornering Stiffness CoefficientRatio of cornering stiffness to the absolute value of normal force.3.8 Free-Rolling TireLoaded rolling tire
18、 operating without application of driving or braking torque.3.9 Inclination AngleAngle between the XZ plane and the wheel plane. Figure 2 shows a positive inclinationangle. The X axis is into the paper.FIGURE 2INCLINATION ANGLE3.10 Lateral ForceComponent of the tire force vector in the Y direction a
19、cting on the tire by the road. Lateralforce is shown in Figure 1. The lateral force shown in Figure 1 is positive.3.11 Lateral Force OffsetAverage lateral force of a free straight-rolling tire. The lateral force offset is dependenton the direction of tire rotation. The direction of tire rotation may
20、 be taken as either left or right. 2.1.33.12 Left RotationOperation of the tire on the left side of the vehicle moving forward, with the tire face to the left.3.13 Loaded RadiusDistance from the wheel center to the center-of-tire contact measured in the wheel plane.3.14 Longitudinal ForceComponent o
21、f the force vector in the X direction acting on the tire by the road. Positivelongitudinal force is shown in Figure 1.SAE J1987 Issued JAN1998-4-3.15 Normal ForceNormal component of force between the tire and the road acting on the tire by the road anddirected into the road plane. The positive direc
22、tion of normal force is shown in Figure 1. It is common practiceto normalize the force and moment properties of tires with respect to normal force. When this is done, the100% level of normal force is the absolute value of the tire design load with the tire design load expressed inforce, not mass ter
23、ms.3.16 Overturning MomentMoment about the X axis acting on the tire by the road. Positive overturning momentis shown in Figure 1.3.17 Right RotationOperation of the tire on the right side of the vehicle moving forward, with the tire face to theright.3.18 Rolling MomentMoment about Y axis acting on
24、the tire by the road. Positive rolling moment is shown inFigure 1.3.19 Slip AngleAngle between the X axis and the direction of travel of the center-of-tire contact. Figure 3 showsslip angle. The slip angle shown in Figure 3 is positive.FIGURE 3SLIP ANGLE3.20 Spin AxisAxis of rotation of the wheel.3.
25、21 Target Normal LoadA normal force chosen to represent 100%. The normal force test range is 20% to160% of the target normal load.3.22 Tire Design LoadTire design load is the base or reference load assigned to a tire at a specific inflationpressure and service condition. Other load/pressure relation
26、ships applicable to the tire are based upon thatbase or reference load. TRA YearbookSAE J1987 Issued JAN1998-5-3.23 Tire FaceOutward side of a tire mounted on a vehicle according to the vehicle manufacturers specificationor general practice. Currently in the United States, the tire face is usually t
27、he side without the serial number.Other examples commonly used to define the tire face are the side of the tire with the white sidewall or otherdecoration (e.g., large raised letters), or the side with the curb strip. In doubtful cases, the tire face selectedshould be marked and recorded as such.3.2
28、4 Tire Axis SystemRight-hand orthogonal system fixed in the road plane with the origin in the center-of-tirecontact. The X and Y axes are located in the road plane and the Z axis is perpendicular to the road plane,with its positive direction into the road plane. The X axis is the line of intersectio
29、n of the wheel plane with theroad plane with its positive direction forward. The Y axis is perpendicular to the line of intersection of thewheel plane and the road plane, with its positive direction to the right when viewed in the positive X direction.(See Figure 1.)3.25 Wheel CenterThe point at whi
30、ch the spin axis of the wheel intersects the wheel plane.3.26 Wheel PlaneCentral plane of the tire normal to the spin axis. 4. Apparatus4.1 The laboratory tire test machine shall consist of three basic components: a belt-type flat surface simulatedroadway with a drive mechanism, a loading and positi
31、oning system, and a measuring system.4.2 Simulated RoadwayThe simulated roadway shall be a continuous flat surface and coated with a stablenonpolishing material like “Safety Walk, or 3-Mite.“1 The roadway surface shall be maintained free from loosematerial or deposit. 4.2.1 The roadway support area
32、shall be wide enough to support the entire tire footprint.4.2.2 The supporting structure shall be sufficiently rigid to ensure that the specifications for angular accuracy in4.3.3 are met.4.2.3 The surface shall be periodically checked for friction characteristics and flatness. Until a valid check c
33、an bedevised, we must rely on a visual check. If the surface is cracked, torn, dimpled, contaminated, or has someother defect that changes the friction and/or flatness, then the simulated roadway surface should bechanged. 4.2.4 The bearing supporting the simulated roadway shall be maintained flat to
34、 less than 0.5 mm (0.020 in) ofwear.24.2.5 The hydrostatic water bearing supporting the simulated roadway shall be maintained at 24 C 2.5 C (75 F 5 F). The expected deviation induced by the temperature variation allowed in this specification is 1.0%.SAE 7708704.2.6 The drive system shall be capable
35、of operating the simulated roadway at the speed specified within anaccuracy of 1 km/h. At 3.5 km/h, the recommended test speed in this procedure and a 1degree slip angle,reference SAE 760029 shows that there is an expected speed induced deviation in lateral force and aligningmoment of 1.3% and 0.5%
36、respectively. Reference SAE 760029 demonstrates that the speed effectsbecome statistically uncertain as slip angle is changed above 4 degrees.1. A t present, there is no valid way of checking the surface. Most testers look at the appearance of the surface and replace it if it is torn, obviously cont
37、aminated, or subjectively judged to be worn smooth as compared to a recently broken-in new surface2. At present there is no data showing the effect of bearing flatness on force and moment measurements. It is known that more than 0.5 mm of wear in a hydrostatic bearing can lead to rapid bearing failu
38、reSAE J1987 Issued JAN1998-6-4.3 Loading and Positioning SystemA fixture is provided for positioning the tire with respect to the tracksurface and loading it against the simulated roadway at specified normal forces. It shall accommodate all sizesof tires to be tested.4.3.1 The machine shall accommod
39、ate rims with diameters and widths required by the user.4.3.2 The loading mechanism shall have provision for changing the normal force on the test tire from zero to 160%of the target normal load.4.3.2.1 The loading mechanism shall have a setting accuracy of 1% of the maximum normal force as defined
40、in4.4.1.4.3.3 The structure supporting the loading and positioning mechanism shall be sufficiently rigid to ensure thatangular accuracies of at least 0.05 degree can be maintained.4.3.3.1 The accuracy of slip angle setting shall be 0.05 degree.4.3.3.2 The accuracy of inclination angle setting shall
41、be 0.05 degree.4.4 Measuring SystemThe measuring system shall be capable of measuring these data for a free-rolling tire:Aligning moment, lateral force, longitudinal force, normal force, overturning moment, slip angle, inclinationangle, and loaded radius. Individual load cell values shall be correct
42、ed for tare and interactions shall becorrected by a matrix method. Quoted ranges are advisory minimums.4.4.1 LOAD CELL ACCURACYThe accuracy of any single measurement after the tare and interaction effects havebeen removed shall be 1% of full-scale range or better. This accuracy is a system accuracy
43、and includes allsystem errors, such as alignments, computer data acquisition, and signal conditioning. Table 1 lists thetypical measurement accuracy.4.4.2 LOAD CELL MEASUREMENT RANGESFor the best precision, it is important to choose the lowest full-scalerange that exceeds the largest measured datum
44、value for each measurement channel. Listed in Table 1 arethe typical full-scale ranges for force and moment measurement.4.4.3 The slip angle measuring system shall meet the following requirements:4.4.3.1 Full-Scale Range 15 degrees.4.4.3.2 Accuracy 0.05 degree. 4.4.4 The loaded radius measuring syst
45、em shall meet the following requirements:4.4.4.1 Full-Scale Range200 to 450 mm (8.0 to 18 in).4.4.4.2 Accuracy 1.0 mm (0.04 in)TABLE 1LOAD CELL RANGES AND ACCURACYMeasurement Full Scale Range AccuracyLongitudinal Force 0 to 1 kN (0 to 225 lb) 10 N ( 2.3 lb)Lateral Force 0 to 15 kN (0 to 3370 lb) 150
46、 N ( 33.7 lb)Normal Force 0 to 24 kN (0 to 5395 lb) 240 N ( 54 lb)Overturning Moment 0 to 10 kNm (0 to 7375 ft-lb) 100 Nm ( 73.5 ft-lb)Rolling Moment not measuredAligning Torque 0 to 1 kNm (0 to 737.5 ft-lb) 10 Nm ( 7.4 ft-lb)SAE J1987 Issued JAN1998-7-5. Calibration5.1 Calibrate all transducers usi
47、ng the appropriate calibration fixtures along with standard reference load cells,dead weights, and fundamental angle references traceable to the National Institute of Standards andTechnology. 5.1.1 The reference load cells used for calibration of the transducers specified in Table 1 shall be calibra
48、tedaccording to a dead weight procedure using Class F weights, the calibration of which is traceable to theNational Institute of Standards and Technology.5.1.2 Calibrate the transducers for measuring slip and inclination angles using measuring devices such thatcalibration angular resolution is 0.01
49、degree or better.5.1.3 Calibrate the slip angle and inclination angle transducers by incremental changes of angles by clockwise andcounterclockwise rotation of the wheel spindle respectively about the Z and X axes, recording the values ofthe angles and recording outputs of the transducer.5.1.4 Calibrate the load cells using the standard reference load cell and/or optional dead weights. Individually loadeach load cell and record each load cells value. The lo
