1、Designation: E 1859 97 (Reapproved 2006)Standard Test Method forFriction Coefficient Measurements Between Tire andPavement Using a Variable Slip Technique1This standard is issued under the fixed designation E 1859; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of the longi-tudinal friction coe
3、fficient 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 pavem
4、ent surface. 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 p
5、lane is 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 frictio
6、n measuring 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 brakin
7、g friction 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 from
8、vehicle 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
9、, wet, or contaminated pavement. They are alsoinsufficient for determining the speed at which control of avehicle would be lost.1.6 The values stated in SI units are to be regarded as thestandard. The inch-pound values given in parentheses areprovided for information only.1.7 This standard does not
10、purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are gi
11、ven in Section 6 and Note 4.2. Referenced Documents2.1 ASTM Standards:3E 178 Practice for Dealing With Outlying ObservationsE 274 Test Method for Skid Resistance of Paved SurfacesUsing a Full-Scale TireE 501 Specification for Rib Tire for Pavement Skid-Resistance TestsE 524 Specification for Smooth
12、Tire for Pavement Skid-Resistance TestsE 867 Terminology Relating to Vehicle-Pavement SystemsE 1136 Specification for A Radial Standard Reference TestTireE 1551 Specification for Special Purpose, SmoothTreadTire, Operated on Fixed Braking Slip Continuous FrictionMeasuring EquipmentF 377 Practice for
13、 Calibration of Braking/Tractive Measur-ing Devices for Testing Tires3. Terminology3.1 Definitions: The terminology used in this test methodconforms to the terminology included in Terminology E 867.3.2 Definitions of Terms Specific to This Standard:3.2.1 peak slip friction number, nthe maximum value
14、 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.1This test method is under the jurisdiction of ASTM Committee E17 onVehicle-Pavement Systems and is the direct responsibility of Subcommittee E17.21on
15、Field Methods for Measuring Tire Pavement Friction.Current edition approved Aug. 1, 2006. Published August 2006. Originallyapproved in 1997. Last previous edition approved in 2001 as E 1859 97 (2001).2Slush thickness less than 25 mm (1 in.). Loose snow thickness less than 50 mm(2 in.).3For reference
16、d ASTM standards, 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 Con
17、shohocken, PA 19428-2959, United States.3.2.2 slip friction number, nthe quotient of the longitudi-nal friction 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 va
18、lues in time, or sfn(x) for instanta-neous values in location. The notation SFNcharacteristicspecifiescomputed 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 o
19、f the measuring device, and the speed of point on theperimeter of the rotating measuring wheel with undeflectedradius, 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-sk
20、id friction number is de-noted SFNskid(v) where v is the vehicle speed v at whichslip-to-skid occurred.3.2.5 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 f
21、riction number expressed as an angle nearthe zero value of the time or location.4. Summary of Test Method4.1 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
22、brake system and a pavement wettingsystem. The test wheel is equipped with a standard pavementtest tire, a reference 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 con
23、trolled by a programmablecontrol unit. The proper test control program is selected in thecontrol unit for either 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 optiona
24、lly delivered ahead of thetest tire and the braking system is actuated to control the slipratio of the test 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 differe
25、nce, commonly called the slip speed, a longi-tudinal force is generated called the longitudinal braking slipfriction 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 tir
26、e and pavement surface is sampled, filtered,calculated, and recorded by suitable data acquisition routines.The 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 wheel
27、s,both are subjected to the same test run control logic for equalspin velocities and loads in parallel wheel 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 tra
28、veled distance, sfn(x).4.7 The slip friction numbers are typically presented in agraphical form. See Fig. 1 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
29、-to-skid friction number (similar toTest Method E 274 Skid Number, SN),4.7.4 The slope of the tangent at zero 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 a
30、pplied, shall be capable ofmaintaining constant test speeds over the range of speed for theapplication. For example, 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
31、by a hydraulic pump as a braking device.The pump can be installed in a closed hydraulic circuit suchthat the 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. Se
32、e Fig. 2. The brake system shall be capableFIG. 1 Sample Slip Friction Number Trace Versus Slip SpeedE 1859 97 (2006)2of maintaining controlled test wheel rotational velocities inde-pendent of influence by test speed and external forces actingupon the wheel. For example, it shall maintain fixed slip
33、 ratioswithin 62%.5.3 Test Wheel Specifications and LoadingThe load set-tings shall be the following for these nominal tire and rim4combinations:5.3.1 Tire Rim 15 3 6JJ:5.3.1.1 Suitable test tires are given in Specifications E 501and E 524, but note that data from the two tires are notinterchangeabl
34、e.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 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 E 1136. The normal load shall be 4.8 kN 6 65 N(1080 6 14.6 lbf). The inflation pressure
35、 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 E 1551. The 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 Sys
36、temTheinstrumentation and control system shall conform to thefollowing overall requirements at ambient temperatures 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 E
37、 524 with a normal load of 4.8 kN(1079 lbf), applied calibration force of the system output shallbe within 696 N (21 lbf). For the tire given in Specification4In accordance with Tire and Rim Association (TRA), 3200 W. Market St.,Akron, OH 44313, USA.FIG. 2 Sample Brake SystemsFIG. 3 Sample Instrumen
38、tation Scheme for Control andMeasurementsE 1859 97 (2006)3E 1551 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
39、the test wheel and to thenature of the friction process, particularly at high friction values.5.4.1.2 Time stability 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
40、, shock, and vibrations that may beencountered in operations on paved surfaces.5.4.1.4 A programmable logic controller, or other suitabledigital computer, shall be used to monitor and control theoverall instrumentation and collect, buffer, filter, smooth,calculate and put the measurements into stora
41、ge in digital form.Scanning frequency for the data collection shall be 10 Hz orhigher.5.4.2 Programmable Control System: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 minimumo
42、f 12-bits, corresponding to decimal number range 0 to 4095.5.4.2.2 The clocking system shall have a minimum of a 10kHz 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
43、 one fulltest run of conditioned data.5.4.3 Force-Measuring TransducerThe tire force measur-ing transducer shall be of 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 t
44、han 1 % of the applied load,nonlinearity less than 1 % of the applied load up to themaximum expected loading, and sensitivity 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 angul
45、ar rotation withrespect to its measuring plane at the maximum expectedloading.5.4.4 Additional TransducersForce transducers 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-
46、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 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 m
47、easurement shall comply with therecommendations in 5.4.5.5.4.6.2 Output shall be directly viewable for the driver.5.4.7 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 readin
48、g resolution to meet the requirements of5.4.1. Recording equipment shall be digital.5.4.7.2 Raw force data shall be written 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
49、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, separate data collection records for each data samplingand a trailer record for file integrity control.5.5 Pavement Wetting System:5.5.1 The quantity of water shall be applied such as toprovi
