1、Designation: F1649 13Standard Test Methods forEvaluating Wet Braking Traction Performance of PassengerCar Tires on Vehicles Equipped with Anti-Lock BrakingSystems1This standard is issued under the fixed designation F1649; the number immediately following the designation indicates the year oforiginal
2、 adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThese test methods cover procedures for measuring the wet braking p
3、erformance 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 are connected to a cont
4、rol 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 control in an emergency bra
5、king 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 “vehicle-ABS-driver”
6、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 evaluated.1.1.1 The sto
7、pping 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 effort on the part of
8、 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 wheelrotation and allow
9、 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 for tirewet traction p
10、erformance.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 test vehicle); the t
11、wo 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 with all traction testin
12、g 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.1These test methods are under the jurisdiction ofASTM Committee F09 on Tiresand is
13、 the direct responsibility of Subcommittee F09.20 on Vehicular Testing.Current edition approved May 1, 2013. Published June 2013. Originallyapproved in 1995. Last previous edition approved in 2003 as F1649 96 (2003)which was withdrawn January 2012 and reinstated in May 2013. DOI: 10.1520/F1649-13.Co
14、pyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Standard precautions are roll-bars, secure mounting of allinternal instrumentation, driver helmet, and secure seat beltharness, etc.1.4 This standard does not purport to address all of the
15、safety 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.2. Referenced Documents2.1 ASTM Standards:2E274 Test Method for Skid Re
16、sistance of Paved SurfacesUsing a Full-Scale TireE303 Test Method for Measuring Surface Frictional Proper-ties Using the British Pendulum TesterE501 Specification for Rib Tire for Pavement Skid-Resistance TestsE524 Specification for Smooth Tire for Pavement Skid-Resistance TestsE965 Test Method for
17、Measuring Pavement MacrotextureDepth Using a Volumetric TechniqueE1136 Specification for P195/75R14 Radial Standard Refer-ence Test TireE1337 Test Method for Determining Longitudinal PeakBraking Coefficient of Paved Surfaces Using StandardReference Test TireF457 Test Method for Speed and Distance Ca
18、libration ofFifth Wheel Equipped With Either Analog or DigitalInstrumentationF538 Terminology Relating to the Characteristics and Per-formance of TiresF1046 Guide for Preparing Artificially Worn Passenger andLight Truck Tires for TestingF1572 Test Methods for Tire Performance Testing on Snowand Ice
19、SurfacesF1650 Practice for Evaluating Tire Traction PerformanceData Under Varying Test ConditionsF1805 Test Method for Single Wheel Driving Traction in aStraight Line on Snow- and Ice-Covered SurfacesF1806 Practice for Tire Testing OperationsBasic Conceptsand Terminology for Reference Tire UseF2493
20、Specification for P225/60R16 97S Radial StandardReference Test Tire3. Terminology3.1 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. F5383.1.2 can
21、didate tire, na test tire that is part of a testprogram. F5383.1.2.1 DiscussionThe term “candidate object” may beused in the same sense as candidate tire.3.1.3 candidate tire set, na set of candidate tires. F5383.1.4 control tire, na reference tire used in a specifiedmanner throughout a test program
22、. F5383.1.4.1 DiscussionAcontrol tire may be of either type andtypical tire use is the reference (control) tire in Practice F1650that provides algorithms for correcting (adjusting) test data forbias trend variations (see Practice F1650 and Annex A1).3.1.5 reference tire, na special tire included in
23、a testprogram; the test results for this tire have significance as a basevalue or internal benchmark. F5383.1.6 spinout, nin tire testing, a type of uncontrollabilitydefined by a loss of steering control due to rapid or substantialyaw, or both. F5383.1.7 standard reference test tire, (SRTT), na tire
24、 that isused as a control tire or surface monitoring tire (for example,Specification E1136 and F2493 tires). E1136, F1572, F1649,F1650, F1805, F1806, F24933.1.7.1 DiscussionThis is a Type 1 reference tire.3.1.8 stopping distance, nthe path distance (rectilinear orcurved) needed to bring a vehicle to
25、 a stop from some selectedinitial brake application speed. F5383.1.9 surface monitoring tire, na reference tire used toevaluate changes in a test surface over a selected time period.F5383.1.10 test (or testing), na procedure performed on anobject (or set of nominally identical objects) using specifi
26、edequipment that produces data unique to the object (or set).F5383.1.10.1 DiscussionTest data are used to evaluate ormodel selected properties or characteristics of the object (or setof objects). The scope of testing depends on the decisions to bemade for any program, and sampling and replication pl
27、ans (seedefinitions below) need to be specified for a complete programdescription.3.1.10.2 split- testa wet traction or stopping distance testconducted on a test course with substantially different wetfriction levels for the left and right tire test lanes. F5383.1.10.3 test runa single pass of a loa
28、ded tire over a giventest surface. F5383.1.10.4 traction testin tire testing, a series of n test runsat a selected operational condition; a traction test is character-ized by an average value for the measured performanceparameter. F5383.1.11 test tire, na tire used in a test. F5383.1.12 test tire se
29、t, none or more test tires as required bythe test equipment or procedure, to perform a test, therebyproducing a single test result. F5383.1.12.1 DiscussionThe four nominally identical tires re-quired for vehicle stopping distance testing constitute a test tireset. In the discussion below where the t
30、est 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 curvilinear path of avehicle during a stopping maneuver; it is defined by the center2For referenced ASTM standards, visit the
31、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.F1649 132of gravity and the transient angular orientation of the vehicle.F5383.1.13.1 intended trajecto
32、rythe intended or ideal path(rectilinear or curvilinear) to bring a vehicle to a stop, that is,under controlled angular orientation. F5383.1.13.2 orthogonal trajectory deviationthe perpendiculardeviation or distance from the center of the vehicle to the TGLat the end of a stopping test. F5383.1.13.3
33、 trajectory guide line (TGL)the centerline markedon the test course pavement that constitutes the intendedtrajectory; it is used by the driver to guide or steer the vehicleon its intended path. F5383.1.14 uncontrollability, nany deviation of the vehiclefrom the intended trajectory (TGL) during or at
34、 the end of atest, or both. F5383.1.14.1 plowingin tire testing, a type of uncontrollabilitydefined by a loss of steering control with no substantial vehicleyaw; the vehicle moves on a trajectory that is dictated byvehicle dynamics as determined by velocity, mass, and theavailable traction at each t
35、ire. F5383.1.15 yaw, nin a vehicle, the angular motion of a vehicleabout its vertical axis through the center of gravity. F5383.1.15.1 yaw velocitythe magnitude of the yaw (rotationor angular displacement); it may be measured by fore and aft,vehicle vs. pavement, velocity sensors. F5384. Summary of
36、Test Method4.1 Methods of MeasurementThese 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 use
37、dto evaluate stopping distance and vehicle 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 yawvelo
38、city. Procedure 3 is the most comprehensive; 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 ARec
39、tilinear Trajectory BrakingThis modeof 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 Trajec
40、tory BrakingThis modeof braking traction 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
41、 abruptlyand with greater frequency with 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
42、 shall be taken to avoid any danger to 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 th
43、at give important information to assist 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 Test
44、ing,4.4.4 Annex A4Measuring Orthogonal 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 thei
45、r relative or comparative perfor-mance 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, th
46、e ability to steer the vehicle on a selected 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 thatpe
47、rmits the ABS to function as intended.5.3 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
48、temperature, water depths, test speeds)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
49、 a brieftesting time period. They may not 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 course).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 ve
