1、Designation: E1859/E1859M 11Standard Test Method forFriction Coefficient Measurements Between Tire andPavement Using a Variable Slip Technique1This standard is issued under the fixed designation E1859/E1859M; the number immediately following the designation indicates the yearof original adoption or,
2、 in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of the longi-tudinal friction coefficien
3、t with a measurement device thatimposes braking-slip between a tire and a surface for the fullrange of braking-slip speed values.1.2 This test method utilizes a series of incremental singlemeasurements of friction force on a braked test wheel as it ispulled over a wetted or contaminated pavement sur
4、face. Therotational velocity of the braked wheel is feedback controlledin order to give a predetermined variable slip ratio gradient inaccordance with set program parameters. The test wheel is keptunder a constant static normal load and at a constant longitu-dinal speed of travel. Its major plane is
5、 perpendicular to theroad plane and parallel to its direction of motion.1.3 The values measured represent the friction propertiesobtained with the equipment and procedures stated in this testmethod and do not necessarily agree or correlate directly withthose obtained by other pavement friction measu
6、ring methods.1.4 The values are intended for use in:1.4.1 Evaluating the braking friction forces on a pavementrelative to that of other pavements.1.4.2 Evaluating changes in the braking friction forces of aparticular pavement with the passage of time.1.4.3 Evaluating the changes in the braking frict
7、ion force ofa pavement when subjected to polishing wear and loss ofmacrotexture caused by traffic with passage of time.1.4.4 Evaluating changes in the braking friction forces of apavement contaminated with ice, moderate amounts2of slushand snow, pollen, vehicle oil spills and condensates fromvehicle
8、 engine exhaust, and deposits from other pollutionsources.1.4.5 Evaluating the braking friction forces of a specimentire on a clean or contaminated pavement.1.5 The friction values reported by this test method areinsufficient to determine the distance required to stop a vehicleon either a dry, wet,
9、or contaminated pavement. They are alsoinsufficient for determining the speed at which control of avehicle would be lost.1.6 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eac
10、hsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to esta
11、blish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 6 and Note 4.2. Referenced Documents2.1 ASTM Standards:3E178 Practice for Dealing With Outlying ObservationsE274 Test Method
12、 for Skid Resistance of Paved SurfacesUsing a Full-Scale TireE501 Specification for Rib Tire for Pavement Skid-Resistance TestsE524 Specification for Smooth Tire for Pavement Skid-Resistance TestsE867 Terminology Relating to Vehicle-Pavement SystemsE1136 Specification for P195/75R14 Radial Standard
13、Ref-erence Test TireE1551 Specification for Special Purpose, SmoothTreadTire, Operated on Fixed Braking Slip Continuous FrictionMeasuring EquipmentF377 Practice for Calibration of Braking/Tractive Measur-ing Devices for Testing Tires3. Terminology3.1 Definitions: The terminology used in this test me
14、thodconforms to the terminology included in Terminology E867.3.2 Definitions of Terms Specific to This Standard:1This test method is under the jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibility of Subcommittee E17.21 onField Methods for Measuring Tire Pa
15、vement Friction.Current edition approved Jan. 1, 2011. Published March 2011. Originallyapproved in 1997. Last previous edition approved in 2006 as E1859 97 (2006).DOI: 10.1520/E1859_E1859M-11.2Slush thickness less than 25 mm (1 in.). Loose snow thickness less than 50 mm(2 in.).3For referenced ASTM s
16、tandards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocke
17、n, PA 19428-2959, United States.3.2.1 peak slip friction number, nthe maximum value ofthe slip friction number.3.2.1.1 DiscussionThe peak slip friction number is writ-ten as SFNpeak(s) where s is the slip speed at which it occurred.3.2.2 slip friction number, nthe quotient of the longitudi-nal frict
18、ion force in the road plane over the normal load forceat any instant in time and location, multiplied by 100.3.2.2.1 DiscussionThe slip friction number is denoted assfn(t) for instantaneous values in time, or sfn(x) for instanta-neous values in location. The notation SFNcharacteristicspecifiescomput
19、ed values or the slip friction number at a specifiedcharacteristic.3.2.3 slip speed, nthe difference between the speed of theaxis of the measuring wheel, which is equal to the travelingspeed of the measuring device, and the speed of point on theperimeter of the rotating measuring wheel with undeflec
20、tedradius, r.3.2.4 slip-to-skid friction number, nthe value of the slipfriction number at which the test wheel reaches zero rotationalspeed during a brake test.3.2.4.1 DiscussionThe slip-to-skid friction number is de-noted SFNskid(v) where v is the vehicle speed v at whichslip-to-skid occurred.3.2.5
21、 slope indicatorthe rate of change of the slip frictionnumber expressed as an angle near the peak slip frictionnumber.3.2.6 tire longitudinal stiffness indicatorthe rate ofchange of the slip friction number expressed as an angle nearthe zero value of the time or location.4. Summary of Test Method4.1
22、 The test apparatus consists of an automotive vehiclewith one or two independently functioning test wheel systemsincorporated into it. Each test wheel system contains a con-tinuously variable brake system and a pavement wettingsystem. The test wheel is equipped with a standard pavementtest tire, a r
23、eference tire, or a specimen tire as required forperforming pavement surface measurements or tire compari-sons, respectively. See 5.3 for standard tire references.4.2 The overall system is controlled by a programmablecontrol unit. The proper test control program is selected in thecontrol unit for ei
24、ther pavement braking friction or tirecomparison between a reference tire and a specimen tire.4.3 The test apparatus is brought to the desired test speed.Acontrolled amount of water is optionally delivered ahead of thetest tire and the braking system is actuated to control the slipratio of the test
25、wheel.As the brake is applied to the test wheel,the actual rotational velocity of the tire becomes less than thelongitudinal component of the tire velocity. As a result of thisvelocity difference, commonly called the slip speed, a longi-tudinal force is generated called the longitudinal braking slip
26、friction force.NOTE 1Water delivery is not used when testing during winter on iceor snow or at subzero temperatures.4.4 The resulting resistive force from friction acting be-tween the test tire and pavement surface is sampled, filtered,calculated, and recorded by suitable data acquisition routines.T
27、he distance of travel of the test vehicle is added up over timeand recorded with the aid of suitable digital fifth wheelinstrumentation.4.5 For tire comparison testing two identical test wheels,both are subjected to the same test run control logic for equalspin velocities and loads in parallel wheel
28、 paths on the sametest track.4.6 The braking slip friction coefficient of the paved roadsurface is calculated and reported as slip friction numbers,sfn(t), at selected instances in time or traveled distance, sfn(x).4.7 The slip friction numbers are typically presented in agraphical form. See Fig. 1
29、for Cartesian plots of slip frictionnumbers versus slip speed or slip ratio with identification of:4.7.1 Peak friction value,4.7.2 Its corresponding critical slip ratio,4.7.3 An estimated slip-to-skid friction number (similar toTest Method E274 Skid Number, SN),4.7.4 The slope of the tangent at zero
30、 slip speed of thecurve, and4.7.5 The slope of the logarithm curve of friction at high slipratios.5. Apparatus5.1 VehicleThe host vehicle of the measuring system,with variable braking force applied, shall be capable ofmaintaining constant test speeds over the range of speed for theapplication. For e
31、xample, speeds range up to 130 km/h atairports runways.5.2 Braking SystemThe speed of the test wheel shall becontrolled by a suitably rated brake system. For example, thismay be accomplished by a hydraulic pump as a braking device.The pump can be installed in a closed hydraulic circuit suchthat the
32、energy delivered by the test wheel is dissipated eitherby a hydraulic motor that augments the tow vehicle drivesystem or by a suitable pressure reduction valve and a thermalheat exchanger. See Fig. 2. The brake system shall be capableof maintaining controlled test wheel rotational velocities inde-pe
33、ndent of influence by test speed and external forces actingupon the wheel. For example, it shall maintain fixed slip ratioswithin 62%.FIG. 1 Sample Slip Friction Number Trace Versus Slip SpeedE1859/E1859M 1125.3 Test Wheel Specifications and LoadingThe load set-tings shall be the following for these
34、 nominal tire and rim4combinations:5.3.1 Tire Rim 15 3 6JJ:5.3.1.1 Suitable test tires are given in Specifications E501and E524, but note that data from the two tires are notinterchangeable.5.3.1.2 For these tires the normal load shall be 4.8 kN 6 65N (1080 6 14.6 lbf). The inflation pressure shall
35、be 165 6 3kPa (24 6 0.5 psi).5.3.2 Tire Rim 14 3 5.5 JJA suitable test tire is given inSpecification E1136. The normal load shall be 4.8 kN 6 65 N(1080 6 14.6 lbf). The inflation pressure shall be 165 6 3 kPa(24 6 0.5 psi).5.3.3 Tire Rim 8 3 4A suitable test tire is given inSpecification E1551. The
36、normal load shall be 1.423 kN 6 14N (320 6 3 lbf). The inflation pressure shall be 207 6 3 kPa(30 6 0.5 psi).5.4 Instrumentation (See Fig. 3):5.4.1 General Requirements for Measuring SystemTheinstrumentation and control system shall conform to thefollowing overall requirements at ambient temperature
37、s be-tween 20 and 40C (0 and 100F):5.4.1.1 The overall static system accuracy shall be 62.0 %of the normal load for the particular test tire mounted. For thetire given in Specification E524 with a normal load of 4.8 kN(1079 lbf), applied calibration force of the system output shallbe within 696 N (2
38、1 lbf). For the tire given in SpecificationE1551 with a normal load of 1.423 kN (320 lbf), appliedcalibration force of the system output shall be within 628.5 N(6.4 lbf).NOTE 2Dynamic system accuracy may be significantly poorer due tosubstantial inertial and gravitational effects on the test wheel a
39、nd to the4In accordance with Tire and Rim Association (TRA), 3200 W. Market St.,Akron, OH 44313, USA.FIG. 2 Sample Brake SystemsFIG. 3 Sample Instrumentation Scheme for Control andMeasurementsE1859/E1859M 113nature of the friction process, particularly at high friction values.5.4.1.2 Time stability
40、of calibration shall be one year,minimum.5.4.1.3 The exposed portions of the system shall tolerate100 % relative humidity (rain or spray) and all other adverseconditions, such as dust, shock, and vibrations that may beencountered in operations on paved surfaces.5.4.1.4 A programmable logic controlle
41、r, or other suitabledigital computer, shall be used to monitor and control theoverall instrumentation and collect, buffer, filter, smooth,calculate and put the measurements into storage in digital form.Scanning frequency for the data collection shall be 10 Hz orhigher.5.4.2 Programmable Control Syst
42、em:5.4.2.1 Input module shall be capable of sampling analogsignal with a throughput of 50 Hz or higher. The resolution oftransformation from analog to digital form shall be a minimumof 12-bits, corresponding to decimal number range 0 to 4095.5.4.2.2 The clocking system shall have a minimum of a 10kH
43、z resolution.5.4.2.3 The buffer shall have sufficient storage to containminimum three consecutive unfiltered values of each force.5.4.2.4 The storage area shall be sufficient to store one fulltest run of conditioned data.5.4.3 Force-Measuring TransducerThe tire force measur-ing transducer shall be o
44、f such design as to measure the tireroad interface force with no inertial effects. Transducers arerecommended to provide an output directly proportional toforce with hysteresis less than 1 % of the applied load,nonlinearity less than 1 % of the applied load up to themaximum expected loading, and sen
45、sitivity to any expectedcross-axis loading or torque loading less than 1 % of theapplied load. The force transducer shall be mounted in such amanner as to experience less than 1 angular rotation withrespect to its measuring plane at the maximum expectedloading.5.4.4 Additional TransducersForce trans
46、ducers for mea-suring vertical load shall meet the recommendations stated in5.4.3.5.4.5 Test Wheel Rotational Speed-MeasuringTransducersPulse encoders shall provide a distance resolu-tion of 1.0 mm (0.04 in.) per 1 m, measured in the road plane.Speed shall be calculated at 10 Hz or higher and as the
47、 sum ofdistance pulses divided by the elapsed interval time.5.4.6 Vehicle Speed-Measuring Transducers:5.4.6.1 Transducers in a separately mounted free-rollingwheel for vehicle speed measurement shall comply with therecommendations in 5.4.5.5.4.6.2 Output shall be directly viewable for the driver.5.4
48、.7 Signal Conditioning and Recorder System:5.4.7.1 All signals shall be referenced to a common timebase. All signal conditioning shall provide linear output andshall allow data reading resolution to meet the requirements of5.4.1. Recording equipment shall be digital.5.4.7.2 Raw force data shall be w
49、ritten to the buffer in amanner to enable first-in-first-out reading. Force data notpassing the qualification routine of the program logic shall notbe used in the running calculation of sfn(t). Qualified force datashall be filtered to remove high frequency noise. Thesefilter-smoothed data shall be separately buffered in tables foruse by the calculation routine of sfn(t).5.4.7.3 The measurements archive shall be organized in afile of records having specified formats. For each uniquelynumbered test run there shall be a header record with generaldata, separat
