1、Designation: F 1649 96 (Reapproved 2003)Standard Test Methods forEvaluating Wet Braking Traction Performance of PassengerCar Tires on Vehicles Equipped with Anti-Lock BrakingSystems1This standard is issued under the fixed designation F 1649; the number immediately following the designation indicates
2、 the year oforiginal adoption 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.INTRODUCTIONThese test methods cover procedures for measur
3、ing the wet braking performance of passenger cartires when tested on vehicles equipped with an anti-lock braking system (ABS). ABS operation isaccomplished by the use of wheel rotation rate sensors that detect impending wheel lockup andcontrollable brake pressure regulators; both of these systems ar
4、e connected to a control microproces-sor. When potential lockup is detected for any wheel or pair of wheels, brake pressure is lowered toforestall the lockup and maintain wheel rotation. This process is repeated until the vehicle comes toa stop. The necessary lateral force to maintain vehicle contro
5、l in an emergency braking situation isonly possible when wheel rotation is maintained. Although there may be differences in the brakingperformance among the commercially available “vehicle-ABS” combinations, tires may be evaluatedfor their relative or comparative wet braking performance with any one
6、 “vehicle-ABS-driver”combination, by the methods as outlined in these test methods.1. Scope1.1 These test methods cover the measurement of two typesof ABS vehicle behavior that reflect differences in tire wettraction performance when the vehicle is fitted with a series ofdifferent tire sets to be ev
7、aluated.1.1.1 The stopping distance from some selected speed atwhich the brakes are applied.1.1.2 The lack of control of the vehicle during the brakingmaneuver. Uncontrollability occurs when the vehicle does notfollow the intended trajectory during the period of brakeapplication despite a conscious
8、effort on the part of a skilleddriver to maintain trajectory control. Uncontrollability is mea-sured by a series of parameters related to this deviation fromthe intended trajectory and the motions that the vehicle makesduring the stopping maneuver.1.1.3 Although anti-lock braking systems maintain wh
9、eelrotation and allow for a high degree of trajectory control,different sets of tires with variations in construction, treadpattern, and tread compound may influence the degree oftrajectory control in addition to stopping distance. Thus vehicleuncontrollability is an important evaluation parameter f
10、or tirewet traction performance.1.2 These test methods specify that the wet braking tractiontests be conducted on two specially prepared test courses: (1)a straight-line (rectilinear) “split-” ( = friction coefficient)test course, with two test lanes deployed along the test course(as traveled by the
11、 test vehicle); the two lanes have substan-tially different friction levels such that the left pair of wheelstravels on one surface while the right pair of wheels travels onthe other surface; and (2) a curved trajectory constant pathradius course with uniform pavement for both wheel lanes.1.3 As wit
12、h all traction testing where vehicle uncontrolla-bility is a likely outcome, sufficient precautions shall be takento protect the driver, the vehicle, and the test site facilities fromdamage due to vehicle traction breakaway during testing.Standard precautions are roll-bars, secure mounting of allint
13、ernal instrumentation, driver helmet, and secure seat beltharness, etc.1.4 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 establish appro-priate safety and health practices and determine th
14、e applica-bility of regulatory limitations prior to use.1These test methods are under the jurisdiction of ASTM Committee F09 on Tiresand are the direct responsibility of Subcommittee F09.20 on Vehicular Testing.Current edition approved May 10, 2003. Published May 2003. Originallyapproved in 1995. La
15、st previous edition approved in 1996 as F 1649 96e1.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2. Referenced Documents2.1 ASTM Standards:E 274 Test Method for Skid Resistance of Paved SurfacesUsing a Full-Scale Tire2E 303 Test M
16、ethod for Measuring Surface Frictional Prop-erties Using the British Pendulum Tester2E 501 Specification for Standard Rib Tire for PavementSkid-Resistance Tests2E 524 Specification for Standard Smooth Tire for PavementSkid-Resistance Tests2E 965 Test Method for Measuring Pavement MacrotextureDepth U
17、sing a Volumetric Technique2E 1136 Specification for a Radial Standard Reference TestTire2E 1337 Test Method for Determining Longitudinal PeakBraking Coefficient of Paved Surfaces Using a StandardReference Test Tire2F 457 Test Method for Speed and Distance Calibration of aFifth Wheel Equipped with E
18、ither Analog or DigitalInstrumentation3F 538 Terminology Relating to the Characteristics and Per-formance of Tires3F 1046 Guide for Preparing Artificially Worn Passenger andLight Truck Tires for Testing3F 1650 Practice for Evaluating Tire Traction PerformanceData Under Varying Test Conditions33. Ter
19、minology3.1 Definitions of Terms Specific to This Standard:3.1.1 anti-lock braking system (ABS), na collection ofsensing and control hardware installed on a vehicle to preventwheel lockup during brake application.3.1.2 candidate tire, na test tire that is part of a testprogram.3.1.2.1 DiscussionThe
20、term “candidate object” may beused in the same sense as candidate tire.3.1.3 candidate tire seta set of candidate tires.3.1.4 control tire, na reference tire used in a specifiedmanner throughout a test program.3.1.4.1 DiscussionA control tire may be of either type andtypical tire use is the referenc
21、e (control) tire in Practice F 1650that provides algorithms for correcting (adjusting) test data forbias trend variations (see Practice F 1650 and Annex A1).3.1.5 reference tire, na special tire included in a testprogram; the test results for this tire have significance as a basevalue or internal be
22、nchmark.3.1.6 spinout, nin tire testing, a type of uncontrollabilitydefined by a loss of steering control due to rapid or substantialyaw, or both.3.1.7 standard reference test tire (SRTT), na tire thatmeets the requirements of Specification E 1136, commonlyused as a control tire or a surface monitor
23、ing tire.3.1.7.1 DiscussionThis is a Type 1 reference tire.3.1.8 stopping distance, nthe path distance (rectilinear orcurved) needed to bring a vehicle to a stop from some selectedinitial brake application speed.3.1.9 surface monitoring tire, na reference tire used toevaluate changes in a test surfa
24、ce over a selected time period.3.1.10 test (or testing), na procedure performed on anobject (or set of nominally identical objects) using specifiedequipment that produces data unique to the object (or set).3.1.10.1 DiscussionTest data are used to evaluate ormodel selected properties or characteristi
25、cs of the object (or setof objects). The scope of testing depends on the decisions to bemade for any program, and sampling and replication plans (seedefinitions below) need to be specified for a complete programdescription.3.1.10.2 split- test, na wet traction or stopping distancetest conducted on a
26、 test course with substantially different wetfriction levels for the left and right tire test lanes.3.1.10.3 test run, na single pass of a loaded tire over agiven test surface.3.1.10.4 traction test, nin tire testing, a series of n testruns at a selected operational condition; a traction test ischar
27、acterized by an average value for the measured perfor-mance parameter.3.1.11 test tire, na tire used in a test.3.1.12 test tire set, none or more test tires as required bythe test equipment or procedure, to perform a test, therebyproducing a single test result.3.1.12.1 DiscussionThe four nominally i
28、dentical tires re-quired for vehicle stopping distance testing constitute a test tireset. In the discussion below where the test tire is mentioned, itis assumed that test tire set may be substituted for test tire, if atest tire set is required for the testing.3.1.13 trajectory, nthe rectilinear or c
29、urvilinear path of avehicle during a stopping maneuver; it is defined by the centerof gravity and the transient angular orientation of the vehicle.3.1.13.1 intended trajectory, nthe intended or ideal path(rectilinear or curvilinear) to bring a vehicle to a stop, that is,under controlled angular orie
30、ntation.3.1.13.2 orthogonal trajectory deviation, nthe perpen-dicular deviation or distance from the center of the vehicle tothe TGL at the end of a stopping test.3.1.13.3 trajectory guide line (TGL), nthe centerlinemarked on the test course pavement that constitutes theintended trajectory; it is us
31、ed by the driver to guide or steer thevehicle on its intended path.3.1.14 uncontrollability, nany deviation of the vehiclefrom the intended trajectory (TGL) during or at the end of atest, or both.3.1.14.1 plowing, nin tire testing, a type of uncontrolla-bility defined by a loss of steering control w
32、ith no substantialvehicle yaw; the vehicle moves on a trajectory that is dictatedby vehicle dynamics as determined by velocity, mass, and theavailable traction at each tire.3.1.15 yaw, nin a vehicle, the angular motion of a vehicleabout its vertical axis through the center of gravity.3.1.15.1 yaw ve
33、locity, nthe magnitude of the yaw (rota-tion or angular displacement); it may be measured by fore andaft, vehicle vs. pavement, velocity sensors.2Annual Book of ASTM Standards, Vol 04.03.3Annual Book of ASTM Standards, Vol 09.02.F 1649 96 (2003)24. Summary of Test Methods4.1 Methods of MeasurementTh
34、ese test methods are di-vided into two methods:4.1.1 Method ARectilinear Trajectory Braking, and4.1.2 Method BCurvilinear Trajectory Braking.4.1.3 With each method, one of three procedures (Procedure1, 2, or 3) that vary in measurement sophistication may be usedto evaluate stopping distance and vehi
35、cle uncontrollability.4.1.4 Procedure 1 is the simplest, with manually recordedstopping distance and trajectory deviation measurements. Pro-cedure 2 uses computer data acquisition and non-pavement-contact sensors to measure speed, stopping distance, and yawvelocity. Procedure 3 is the most comprehen
36、sive; it includes allthe measurement capabilities of Procedure 2 in addition to therecording of steering wheel angle throughout the stoppingmaneuver. The measurement procedures for the performanceparameters are more fully described in Section 11.4.2 Method ARectilinear Trajectory BrakingThis modeof
37、braking traction testing is conducted by bringing the vehicleto a stop in an intended rectilinear trajectory or straight linemotion, on a split- test course. The test may be conducted ata series of initial brake application speeds.4.3 Method BCurvilinear Trajectory BrakingThis modeof braking tractio
38、n testing is conducted by bringing the vehicleto a stop on a curvilinear trajectory (curved path) on a uniformtest surface pavement. The test may be conducted at a series ofinitial brake application speeds.NOTE 1Vehicle uncontrollability may be experienced more abruptlyand with greater frequency wit
39、h Method B procedures. Therefore, whenusing Method B, precautions should be exercised to avoid any possibledanger during testing. Testing shall begin with the lowest test velocitiesselected for any program and as higher velocities are approached,sufficient care shall be taken to avoid any danger to
40、the driver, the vehicle,and any on-site facilities during traction breakaway conditions.NOTE 2Test speeds lower than 10 km/h are not recommended due toinstrumentation insensitivity at this low speed.4.4 These test methods contain four annexes and oneappendix that give important information to assist
41、 in themeaningful evaluation of tire wet traction performance.4.4.1 Annex A1Interpretation of Results and Tire DesignFeature Evaluation,4.4.2 Annex A2Techniques for Water Application andControl,4.4.3 Annex A3Selecting Path Radius and Test Speed forMethod B Testing,4.4.4 Annex A4Measuring Orthogonal
42、Trajectory Devia-tion (Procedure 1), and4.4.5 Appendix X1List of Instrumentation Suppliers.5. Significance and Use5.1 Braking traction is an important factor in vehicle controlespecially on wet pavements. These test methods permit anevaluation of tires for their relative or comparative perfor-mance
43、on an ABS-equipped vehicle. See Annex A1 forbackground information for interpretation of results and mean-ingful evaluation of tire design features for their influence onwet traction performance.5.2 Although stopping distance is important for vehiclecontrol, the ability to steer the vehicle on a sel
44、ected trajectoryis equally or, in some instances, more important. The wettraction capability of tires influences both of these measuredparameters since the tires are the link between the ABS and thepavement and provide the traction or tire adhesion level thatpermits the ABS to function as intended.5
45、.3 The absolute values of the parameters obtained withthese test methods are highly dependent upon the characteris-tics of the vehicle, the design features of the ABS, the selectedtest pavement(s), and the environmental and test conditions(for example, ambient temperature, water depths, test speeds)
46、at the test course. A change in any of these factors may changethe absolute parameter values and may also change the relativerating of tires so tested.5.4 These test methods are suitable for research and devel-opment purposes where tire sets are compared during a brieftesting time period. They may n
47、ot be suitable for regulatory orspecification acceptance purposes because the values obtainedmay not necessarily agree or correlate, either in rank order orabsolute value, with those obtained under other conditions (forexample, different locations or different seasonal time periodson the same test c
48、ourse).6. Test Vehicle6.1 Test VehicleAny commercially available passengervehicle equipped with an ABS may be used for the testing.However, it is important that the same vehicle (same modelyear, same version of ABS) be used for all tests in any testingprogram. Different vehicles may give different t
49、ire wet tractionperformance because of their varying handling, suspension,and ABS design parameters.6.1.1 During testing with any selected vehicle, the vehicletest mass (driver, fuel, and instrumentation load) shall bemaintained to a tolerance of 62%.6.1.2 All tests in any program of tire comparisons shall beconducted with the same driver and in the shortest time periodpossible for any selected test program.6.2 Precautions in ABS Vehicle UseAs with any complextest system, certain precautions shall be exercised in anytesting program. ABS o
