1、Designation: E3145 18Standard Test Method forUser-Level Calibration of Dynamic Friction Tester (DFTester)1This standard is issued under the fixed designation E3145; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. 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 test method describes the equipment and procedureto ensure that the calibration performed by various dynamicfriction te
3、ster (DF tester) users is uniform and in accordancewith manufacturer specifications. There are three models of theDF tester in use: (1) USB/personal computer, (2) controller,and (3) X-Y plotter. Procedures specific to the different modelsare noted. User-level calibration software is separate from th
4、eoperation software and must be obtained from the manufac-turer for the USB/personal computer model.1.2 This test method is a static calibration of the verticalload, friction () force, and speed of the DF tester. Complianceto this user-level calibration procedure ensures a higher level ofrepeatable
5、and reproducible performance of the DF tester whenused in accordance with Test Method E1911.1.3 The user-level calibration doesnt include the replace-ment of the mu spring or the adjustment of linearity of the DFtester. It is recommended that DF testers be inspected by amanufacturer-approved laborat
6、ory on an annual basis to re-place the mu spring, ensure linearity, and to identify other nonuser-serviceable wear.1.4 The values stated in SI (metric) units are to be regardedas standard. The inch-pound equivalents are rationalized, ratherthan exact mathematical conversions.1.5 This standard does n
7、ot 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international
8、standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.
9、2. Referenced Documents2.1 ASTM Standards:2E867 Terminology Relating to Vehicle-Pavement SystemsE1911 Test Method for Measuring Paved Surface FrictionalProperties Using the Dynamic Friction Tester3. Terminology3.1 Definitions:3.1.1 calibration platforma platform with weighing capa-bility built speci
10、fically to calibrate the DF tester. The designand requirements for the calibration platform are describedherein.3.1.2 calibration weightsweights of known and stablevalue used to apply a load to the flywheel and disk during thecalibration of the friction () force. These weights should besized to appl
11、y an initial load of 1.80 kg (60.01 kg) and a totalof 3.60 kg (60.01 kg). The weights must be verified annuallyusing an accredited, calibrated scale or calibrated by anaccredited facility to ensure accuracy.3.1.3 friction () forcethe force measured by the potenti-ometer and spring between the flywhe
12、el and the disk of the DFtester.3.1.4 standard surfacea paved surface with a consistentand resilient surface friction that is used to verify the output ofthe DF tester before use in lieu of using a verification plate.3.1.5 verification platea plate with a consistent and resil-ient surface friction t
13、hat is used to verify the output of the DFtester before use, including before and after a calibrationprocedure is performed.3.1.6 verification weightsweights of known and stablevalue used to verify the correct operation of the calibrationplatform. These weights should be sized to apply incrementallo
14、ading up to a total of 4.00 kg (60.01 kg). The weights mustbe verified annually using an accredited, calibrated scale orcalibrated by an accredited facility to ensure accuracy.1This test method is under the jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibil
15、ity of Subcommittee E17.21 onField Methods for Measuring Tire Pavement Friction.Current edition approved Jan. 1, 2018. Published January 2018. Originallyapproved in 2018. DOI: 10.1520/E3145-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se
16、rviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance
17、 with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.7 vertical loadthe vertical load
18、applied to the rubberpads that are in contact with the surface of the pavement whenthe DF tester feet are in the same plane as the test surface.3.2 For definitions of additional terms used in this standard,refer to Terminology E867.4. Summary of Test Method4.1 Verification of the functionality and o
19、utput of the DFtester is performed on a verification plate (or standard surface)prior to starting the user-level calibration procedure.4.2 The static vertical load on the rubber sliders is measuredby the integrated scale in the calibration platform.4.3 The friction () force output is adjusted, eithe
20、r electroni-cally or manually depending on the DF tester model, to thevalue of a known weight that is applied to the flywheel/disk.4.4 The rotational speed of the flywheel/disk is checked andadjusted as necessary to meet manufacturers specifications.4.5 Verification of the functionality and output o
21、f the DFtester is performed on a verification plate (or standard surface)after the user-level calibration procedure is completed. Signifi-cant differences between pre- and post-calibration data fromthe verification plate should be noted. Any significant differ-ences should be investigated to determi
22、ne the potential effecton previously acquired data.5. Significance and Use5.1 The user-level calibration process may be used to verifythat the DF tester is functioning properly, that it is withinmanufacturer specifications, and to perform minor adjustmentsto bring the unit back into conformance with
23、 manufacturerspecifications.5.2 The DF tester user-level calibration described hereindoes not eliminate all error sources, nor does it guarantee theproper operation of the device. Several adjustments and repairsare beyond the scope of this standard, and manufacturer-approved calibrations are still r
24、ecommended on an annualbasis.6. Apparatus6.1 A vertical load weighing calibration platform consistingof a flat, 500-mm2aluminum base plate (20 mm thick); a flat,circular aluminum disk measuring 340 mm in diameter and15 mm thick; a digital display; and four pedestals measuring80 mm high and 40 mm in
25、diameter is shown in Fig. 1. Theplatform must have an integrated scale that measures thevertical load exerted on the slider pads when the disk islowered to the level of a plane defined by the bottom of thedevices feet. The scale must be insensitive to off-centerloading and capable of measuring and d
26、isplaying weights of0.00 to 5.00 kg (60.001 kg). The four pedestals are mounted toFIG. 1 Calibration Platform with Load Scale and Digital MeterE3145 182the base plate so that the feet of the DF tester rest on thepedestals and the rotating disk of the DF tester is centered overthe circular aluminum d
27、isk. It is critical that the height of thepedestals exactly match the height of the top of the circularaluminum disk. The digital display may be mounted to the baseplate provided it doesnt interfere with the pedestals or thecircular disk. Calibrated verification weights totaling 4.00 kg in1.00-kg in
28、crements are suggested for verification of verticalload calibration platform prior to use.6.2 Calibrated weight totaling 3.60 kg is required for thefriction () force calibration. The USB-PC model DF testeroffers the option of using two 1.80-kg calibrated weights. Ifthis option is selected, weights m
29、ust have a means by whichthey connect to one another as seen in Fig. 2.6.3 A wire assembly and thumb screw are used in thefriction () force calibration (Fig. 3). The wire is 300 mm inlength by 0.7 mm in diameter and has loops on either end towhich a spring and the calibration weights are affixed dur
30、ingthe user-level calibration process. The thumb screw is M4 by15 mm and is used to fasten the flywheel plate to the bracketon the bottom of the DF tester to lock the disk and preventrotation during calibration.6.4 Avariable DC power supply is required to power the DFtester during the user-level cal
31、ibration. The minimum specifi-cations for the power supply should be 0 to 15 V DC andminimum current output of 45 amps. An example of the powersupply is shown in Fig. 4 with the power cable for the DFtester.6.5 The DF tester to be calibrated, including the controller(where applicable) and associated
32、 cables, is required for thistest method. The cables are shown in Fig. 5 for the differentmodels of DF testers.7. Hazards7.1 To avoid the potential for personal injury, please adhereto the following precautions.7.1.1 The calibration surface must be free of obstructions.7.1.2 Never insert fingers or
33、other objects under DF testerwhile operating.7.1.3 The DF tester should not be moved, tilted, or liftedwhile operating.7.1.4 Each of the four feet must be in solid contact with thesurface while operating.8. Preparation of Apparatus8.1 Allow the calibration platform digital indicator suffi-cient time
34、 to warm up and stabilize before using. Ensure thatcalibration platform is level and placed on a stable surface.9. Environmental Conditions9.1 It is recommended that the user-level calibration beperformed indoors in an area free from drafts or vibrations. Theambient room temperature where the calibr
35、ation is performedshould be between 5 and 38 C (40 and 100 F).10. Procedure10.1 VerificationPlace the DF tester on a verification plate(or standard surface) and perform at least three measurementsin accordance with Test Method E1911. Record this data.10.2 Vertical Load CalibrationThe vertical load c
36、alibra-tion is the same for all three models of the DF tester. Theexception is that the center cover over the drive motor must beremoved from the device of the USB-PC model DF tester toexpose the suspensions springs for adjusting vertical load. Theprocedure is provided in 10.2.1 10.2.7.10.2.1 Instal
37、l new rubber sliders on the fiberglass disk.10.2.2 Level the calibration platform in all directions.10.2.3 Using calibrated weights, confirm the proper opera-tion of the calibration platform scale.10.2.4 Place the DF tester on the calibration platform asshown in Fig. Fig. A1.1.10.2.5 Manually press
38、down on the damper to lift the diskoff the circular table of the calibration platform. While holdingthe disk off the platform, confirm that the digital indicator reads0.00 kg. Quickly release the damper to allow the disk to dropback down onto the circular table on the calibration platform.Verify tha
39、t the disk moves up and down in the horizontal planeFIG. 2 Example of Calibration Weights (Total of 3.6 kg)FIG. 3 Calibration Wire Assembly and ScrewE3145 183and the three rubber pads contact the disk of the calibration plate at the same time. The lift/lower mechanism and damperFIG. 4 DC Power Suppl
40、y and DF Tester Power CableFIG. 5 Cables Associated with the Various DF Tester ModelsE3145 184should move up and down freely and smoothly and shouldallow the weight of the flywheel to be applied to the surface inapproximately 1 s. A damper that moves too quickly will resultin the rubber sliders not
41、maintaining consistent contact with thetest surface. A damper that moves too slowly will result in thevertical load not being fully applied to the test surface. Checkthe value of the vertical load on the calibration plate display.Record the as-arrived vertical load displayed on the calibrationplatfo
42、rms digital display. Repeat this process three times.NOTE 1If damper is scratched, pitted, or not moving freely andsmoothly, or rubber sliders are not contacting the calibration platform atthe same time, the DF tester should be inspected and repaired.10.2.6 The vertical load should be 3.60 kg (60.01
43、 kg). If itis not 3.59 to 3.61 kg, then loosen the nuts on the vertical loadspring adjustment screws and turn the adjustment screws toincrease or decrease spring tension accordingly. The springsmust be adjusted equally. Measure the length of the screwabove the top bar to ensure the springs are adjus
44、ted equally.Tighten the nuts to lock the screws when the required load isachieved. Take care not to twist the springs when tightening thelocknuts. Cautionre-check vertical load after tightening toensure that the normal force is 3.60 kg (60.01 kg).10.2.7 Manually press down on the damper to raise the
45、 diskand then quickly release it. Verify that the three rubber padscontact the disk of the calibration plate. Check the value of thevertical load on the calibration plate display. Record thecalibrated vertical load displayed on the calibration platformsdigital display. Repeat this process three time
46、s to ensure thatthe mechanism is free and smooth and the load is withinspecifications.10.3 Friction () Force CalibrationApart from the firstthree steps, the calibration of the friction () force varies by DFtester model. After completing 10.3.1 10.3.3, please refer tothe specific instructions for the
47、 model of DF tester that is beingcalibrated (USB-PC, controller, or X-Y plotter).10.3.1 Connect the signal cable and main power supplycable as appropriate for the specific model. (For the controllermodel, do not connect the three-prong power supply cable forthe motor.)10.3.2 Place the DF tester on i
48、ts back side on a sturdy, flat,level surface with the damper mechanism at the top. Lift thedamper to lower the disk and install the flywheel locking screwthrough the bracket at the bottom using an M4 screw.10.3.3 Attach the calibration wire to the lug on the fiberglassdisk as shown in Fig. A1.2.10.3
49、.4 USB-PC Model DF Tester:10.3.4.1 Connect the DF tester and the PC using the USBcable (Fig.A1.3) and then turn PC on. Connect the power cableto the DF tester and an appropriate 12-V DC power source.Turn the power switch on.10.3.4.2 Start the DF tester user calibration program. Thecalibration and confirmation program main menu window willappear (Fig. A1.4).10.3.4.3 Click on the “ values” confirmation button and anew window will open. Click on the “Read from DFT” buttonand check the values. If the values are 0 6 0.01 and 1.006 0.01, then no user
