1、Designation: F2779 10Standard Practice forCommercial Radial Truck-Bus Tires to Establish EquivalentTest Severity Between a 1.707-m (67.23-in.) DiameterRoadwheel and a Flat Surface1This standard is issued under the fixed designation F2779; the number immediately following the designation indicates th
2、e 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice describes the procedure to identify
3、equiva-lent test severity conditions between a 1.707-m diameterlaboratory roadwheel surface and a flat or highway surface forcommercial radial truck-bus tires.1.1.1 Tire operational severity, as defined as the running oroperational temperature for certain specified internal tire loca-tions, is not t
4、he same for these two test conditions. It istypically higher for the laboratory roadwheel at equal load,speed and inflation pressure conditions due to the curvatureeffect.1.1.2 The practice applies to specific operating conditions ofload range F through L for such commercial radial truck-bustires.1.
5、1.3 The specific operating conditions under which theprocedures of the practice are valid and useful are completelyoutlined in Section 6 (Limitations) of this standard.1.1.4 It is important to note that this standard is composed oftwo distinct formats:1.1.4.1 The usual text format as published in th
6、is volume ofthe Book of Standards (Vol 09.02).1.1.4.2 A special interactive electronic format that uses aspecial software tool, designated as prediction profilers orprofilers. This special profiler may be used to determinelaboratory test conditions that provide equivalent tire internaltemperatures f
7、or the tread centerline, belt edge, or ply endingregion for the two operational conditions, that is, the curvedlaboratory roadwheel and flat highway test surfaces.1.2 The prediction profilers are based on empirically devel-oped linear regression models obtained from the analysis of alarge database t
8、hat was obtained from a comprehensive experi-mental test program for roadwheel and flat surface testing oftypical commercial truck and bus tires. See Section 7 andReferences (1, 2)2,3for more details.1.2.1 For users viewing the standard on CD-ROM or PDF,with an active and working internet connection
9、, the profilerscan be accessed on the ASTM website by clicking on the linksin 7.5 and 7.6.1.2.2 For users viewing the standard in a printed format, theprofilers can be accessed by entering the links to the ASTMwebsite in 7.5 and 7.6 into their internet browsers.1.3 For this standard, SI units shall
10、be used, except whereindicated.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 the applica-bility of regulatory limitatio
11、ns prior to use.2. Referenced Documents2.1 ASTM Standards:4ASTM SI10 - 02 IEEE/ASTM SI 10 American NationalStandard for Use of the International System of Units (SI):The Modern Metric SystemF538 Terminology Relating to the Characteristics and Per-formance of TiresF551 Practice for Using a 67.23-in.
12、(1.707-m) DiameterLaboratory Test Roadwheel in Testing Tires3. Terminology3.1 Definitions:3.1.1 belt edge (BE) temperature, nin the cross section ofa radial tire, the temperature at the edge of the stabilizer(working, widest) plies or belts, for example, in the rubberregion of the belt edges.3.1.2 c
13、ontained air temperature, nthe temperature of theair contained within the tire cavity when the tire is mountedand inflated on the proper rim.3.1.3 curved equivalent test severity, nin tire testing, thetest conditions (load, rotational speed, tire inflation pressure)1This practice is under the jurisd
14、iction of ASTM Committee F09 on Tires and isthe direct responsibility of Subcommittee F09.30 on Laboratory (Non-Vehicular)Testing.Current edition approved April 1, 2010. Published May 2010. DOI: 10.1520/F2779-10.2The boldface numbers in parentheses refer to the list of references at the end ofthis s
15、tandard.3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:F09-1002.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume i
16、nformation, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.on the flat or highway surface that will provide equivalentinternal tire temperatures, for example, at the be
17、lt edge, to aknown set of curved 1.707-m roadwheel surface test condi-tions.3.1.4 endurance, nof a tire, the ability of a tire to performas designed in its intended usage conditions such as load,inflation pressure, speed, time, and environmental conditions.3.1.5 high speed performance, nof a tire, t
18、he rotationalspeed capability of a tire to perform as designed in its intendedusage conditions such as load, inflation pressure, speed, time,and environmental conditions.3.1.6 highway equivalent test severity, nin tire testing, thetest conditions (load, rotational speed, tire inflation pressure)on t
19、he 1.707-m roadwheel that will provide equivalent internaltire temperatures, for example, at the belt edge, to a known setof flat or highway surface test conditions.3.1.7 load range, nof a truck-bus tire, a letter designation(F, G, H, J, L, M) used to identify a given size tire with its loadand infl
20、ation limits when used in a specific type of service.3.1.8 maximum rated load, nthe load corresponding to themaximum tire load capacity at the rated inflation pressure inaccordance with the publications of tire and rim standardscurrent at the time of manufacture.3.1.9 measured inflation pressure, ng
21、age pressure of a tiremeasured at a given time under ambient temperature andbarometric pressure. F5383.1.10 ply ending (PE) temperature, nin the cross sectionof a radial tire, the temperature at the higher turn-up end of thebody ply, for example, in the apex component region of theending.3.1.11 rate
22、d inflation pressure, nthe minimum cold infla-tion pressure specified at the maximum rated load of a tire inaccordance with the publications of tire and rim standardscurrent at the time of manufacture.3.1.12 rim, nspecially shaped circular periphery to whicha tire may be mounted with appropriate bea
23、d fitment. F5383.1.13 test inflation pressure, nspecified gage pressure ofa tire mounted on a rim, measured at a given time underambient temperature and barometric pressure for evaluationpurposes.3.1.14 test load, nthe force applied to a tire through therim; it is normal to the metal loading plate o
24、nto which the tireis loaded. F5383.1.15 test speed, nthe tangential speed at the point ofcontact with the road or curved surface of a rotating tire forevaluation purposes.3.1.16 tire, pneumatic, na hollow tire that becomes load-bearing upon inflation with air, or other gas, to a pressureabove atmosp
25、heric. F5383.1.17 tire, radial, na pneumatic tire in which the plycords that extend to the beads are laid substantially at 90 to thecenter line of the tread, the tire being stabilized by a belt.F5383.1.18 tire speed rating, nthe maximum speed for whichthe use of the tire is rated under certain condi
26、tions asdesignated by the speed symbol marked on the tire sidewall ormaximum speed rating as determined by the manufacturer.3.1.19 tread centerline (CL) temperature, nin the crosssection of a radial tire, the temperature under the center of thetread region, for example, at the bottom region of the t
27、readrubber component.3.1.20 truck-bus tire, na tire that is intended for service oncommercial truck-bus vehicles.4. Summary of Practice4.1 This practice provides a procedure to determine1.707-m diameter roadwheel tire test conditions (speed, load,and inflation pressure) for equivalent test severity
28、with flatsurface test conditions. It also enables the user to determine the1.707-m diameter roadwheel test conditions for a specificincrease or decrease in severity with respect to flat surface testseverity. The converse is also true for the determination of theflat surface tire test conditions for
29、equivalent test severity witha specific set of 1.707-m diameter roadwheel test conditions.4.2 This practice provides a prediction profiler procedure(see Section 7 and Annex A1) to establish equivalent testseverity between a 1.707-m diameter rotating wheel (PracticeF551) and a flat surface, by adjust
30、ing test speed, load andinflation pressure. The prediction profiler provides the abilityto identify numerous test conditions and resultant belt edgetemperature differentials within the confines of this practice asdescribed in section 7.1.4.3 Equivalent test severity is defined as the set of testcond
31、itions (load, speed, and tire inflation pressure) that pro-vides equivalent steady state tire belt edge (BE), tread center-line (CL), or ply ending (PE) temperatures for: (1) a conversionfrom flat surface conditions to 1.707-m diameter roadwheelconditions, or (2) a conversion from 1.707-m diameter r
32、oad-wheel conditions to flat surface conditions.35. Significance and Use5.1 Historically, tires have been tested for endurance by avariety of test methods. Some typical testing protocols havebeen: (1) proving grounds or highway testing over a range ofspeeds, loads, and inflations, (2) testing on fle
33、ets of vehicles forextended periods of time, and (3) indoor (laboratory) testing oftires loaded on a rotating 1.707-m diameter roadwheel; how-ever, the curved surface of a 1.707-m diameter roadwheelresults in a significantly different tire behavior from thatobserved on a flat or highway surface.5.1.
34、1 This practice addresses the need for providing equiva-lent test severity over a range of typical tire operating condi-tions between a 1.707-m diameter roadwheel surface (PracticeF551) and a flat surface. There are different deformations of thetire footprint on curved versus flat surfaces resulting
35、 indifferent footprint mechanics, stress/strain cycles, and signifi-cantly different internal operating temperatures for the twotypes of contact surface. Since tire internal temperatures arekey parameters influencing tire endurance or operating char-acteristics under typical use conditions, it is im
36、portant to beable to calculate internal temperature differentials betweencurved and flat surfaces for a range of loads, inflation pressuresand rotational velocities (speeds).5.2 Data from lab and road tire temperature measurementtrials were combined, statistically analyzed, and tire tempera-ture pre
37、diction models derived.3F2779 1025.2.1 The fit of the models to the data is shown as thecoefficient of determination, R2, for the two critical crown areatemperatures, i.e. tread centerline and belt edge, as well as theply ending area:R2= 0.89, 0.90, and 0.89 respectively5.2.2 These prediction models
38、 were used to develop theprediction profilers described in Section 7 and Annex A1.6. Limitations6.1 The procedures within this standard are valid for com-mercial radial pneumatic truck-bus tires of load range Fthrough load range Land for the following ranges of test speed,tire inflation pressure and
39、 tire load, for flat test surfaces and1.707-m diameter roadwheels:6.1.1 Tire test speed in the range of 77 to 132 km/h (flatsurface) and 40 to 132 km/h (curved surface).6.1.2 Tire test inflation pressure in the range of 58 to 107 %of sidewall-stamped inflation pressure.6.1.3 Tire test load in the ra
40、nge of 49 to 128 % of sidewall-stamped maximum load.6.1.4 Ambient temperature = 38C.6.2 The procedures described in Section 7 identify equiva-lent operating conditions for a flat surface and a 1.707-mdiameter roadwheel by using empirical models to match tireinternal component temperatures. These emp
41、irical modelswere derived from a wide variety of tires tested within theabove ranges and can be used to interpolate at any conditionswithin the constraints listed above. It is not recommended thatthe procedures be used for extrapolation beyond the constraintslisted above.7. Procedure7.1 Equivalent T
42、est Severity Prediction Profilers:7.1.1 The flat-to-curved (FTC) prediction profilers are SASJMPtinteractive displays based on algorithms developed fromlaboratory and highway tire temperature measurements. Theyprovide 1.707-m diameter roadwheel tire test (rotational)speed, tire test load, and tire t
43、est inflation pressure conditionsfor equivalent test severity (as well as for lesser or more severetest severity) based upon the belt edge, tread centerline, or plyending region temperatures. Before using the profilers, the userwill have targeted a roadwheel “delta temperature” amount indegrees C (o
44、r % degrees C) for one (or more) of these regionswith respect to the temperatures in these regions for the tirerunning on a flat surface, that is, the targeted operatingdifference in temperature between the roadwheel and highwaycondition. By first identifying the desired “delta tempera-ture(s),” the
45、 user will be able to identify (via the profilers)roadwheel test conditions to achieve the temperature “del-ta(s).” The equivalency determination is based upon a “delta”in rotational speed, load, and/or inflation from the knownhighway operating conditions within the limitations specifiedin 6.1.7.1.2
46、 The converse also applies for equivalent highway testconditions that can be identified from specified roadwheel testconditions by use of the curved-to-flat (CTF) predictionprofilers.7.2 When using either the FTC (or CTF) Delta DegC orthe FTC (or CTF) Delta % DegC prediction profilers, fourvariables
47、 are available for interactive modification:“RW1.7mDelta km/h” The change in tire rotational speed forthe roadwheel relative to the highwayspeed.“RW1.7m% of Flat Inf” The percent change in roadwheel tireinflation relative to the highway tire infla-tion.“RW1.7m% of Flat Load” The percent change in ro
48、adwheel tireload relative to the highway tire load.“Speed Ratingkm/h” The manufacturers recommended high-way speed rating for a specific tire.7.2.1 These variables appear along the x-axis of the predic-tion profiler and can be changed by clicking and dragging.Effects of changing these variables can
49、be viewed as tempera-ture changes in ply ending, tread centerline, and belt edgeregions identified on the y-axis, depending whether the “DeltaDeg C” or the “Delta % Deg C” prediction profiler is used:“FTC Pred PE Delta DegC” (or “FTC Pred PE Delta % DegC”)“FTC Pred CL Delta DegC” (or “FTC Pred CL Delta % DegC”)“FTC Pred BE Delta DegC” (or “FTC Pred BE Delta % DegC”)7.3 The curved-to-flat (CTF) prediction profilers maintainthe same labels for the y-axis while the x-axis are labeled fromthe perspective of identifying the required changes fromroadwheel conditio
