1、Designation: G219 18Standard Guide forDetermination of Static Coefficient of Friction of TestCouples Using an Inclined Plane Testing Device1This standard is issued under the fixed designation G219; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e 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 guide is intended to standardize the use of aninclined plane testing device to measure
3、 the breakaway friction(static) coefficient of mating couples that are of such size andshape that they can be made into a rider (one member of thesliding couple) on a flat surface (the second member of thesliding couple) that can be inclined at an angle to producemotion of the rider. The tangent of
4、the angle at whichbreakaway motion of the rider occurs on the angled plane is thebreakaway or static coefficient of friction for that slidingcouple.1.2 UnitsThe values stated in SI units are to be regardedas the standard. No other units of measurement are included inthis standard.1.3 This standard d
5、oes 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This internati
6、onal 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) Commi
7、ttee.2. Referenced Documents2.1 ASTM Standards:2G40 Terminology Relating to Wear and ErosionG115 Guide for Measuring and Reporting Friction Coeffi-cients3. Terminology3.1 Definitions:3.1.1 friction force, nresisting force tangential to theinterface between two bodies, when under action of an externa
8、lforce, one body moves or tends to move relative to the other.3.1.2 static coeffcient of friction, ncoefficient of frictioncorresponding to the maximum friction force that shall beovercome to initiate macroscopic motion between two bodies.3.1.2.1 DiscussionBreakaway friction coefficient is syn-onymo
9、us with static coefficient of friction.3.2 Definitions of Terms Specific to This Standard:3.2.1 inclined plane device, nmechanism with a flat hori-zontal surface to be made of or covered with a material ofinterest on which a second member made of a material ofinterest can be placed and the mechanism
10、 is then actuated suchthat the horizontal plane is increasingly angled with respect toits original horizontal position until motion is produced on themember placed on the raising plane.3.2.1.1 DiscussionThe device allows for the continuousmeasurement of the angle of inclination and the angle at whic
11、hmotion of the rider commences.3.2.2 rider, nbody to be placed on the inclined plane.4. Summary of Guide4.1 The technique of placing an object on a flat andhorizontal “plane” such as a piece of sheet metal and raisingone end of the sheet until the body placed on the sheet starts toslide has been use
12、d for centuries to compare the ease withwhich different objects or materials slide on each other.Quantitative comparison of various couples can be made bymeasuring the angle at which the body placed on the planestarts to slide. The angle at which motion commences is the testmetric. The test couple i
13、s the plane surface and the surface thatcontacts the plane. For example, if a shoe is placed on aflooring sample on the inclined plane, the test couple is theshoe sole versus the type of flooring. Different shoe bottomscan be compared for their ability to slip on particular flooring.The materials of
14、 construction as well as the nature of thecontacting surfaces determine the breakaway angle. Whenranking, for example, different shoe soles on particularflooring, the shoes are weighted so that they are all the sameweight when compared for ease of sliding on the flooring ofinterest.1This guide is un
15、der the jurisdiction of ASTM Committee G02 on Wear andErosion and is the direct responsibility of Subcommittee G02.50 on Friction.Current edition approved Aug. 1, 2018. Published August 2018. DOI: 10.1520/G0219-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM C
16、ustomer Service at serviceastm.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 de
17、veloped in accordance 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.14.2 The tangent
18、of the breakaway angle becomes the finaltest metric. This converts the breakaway angle to a dimension-less number: the static coefficient of friction.5. Significance and Use5.1 Guide G115 lists a number of ASTM Internationalstandards that use the inclined plane test rig to measure thestatic coeffici
19、ent of specific tribosystems. This guide applies toany couple that can be made into test specimens that can bemade into a rider on a plane that can be angled to producemotion of the body on the plane. Footwear on walkwaysurfaces is an example of a very important application.Flooring surfaces that ar
20、e slippery to various types of footwearcan produce accidents and testing should be done on candidateflooring surfaces and candidate shoe soles and heels to quantifytheir relative slip resistance. This guide shows how an inclinedplane can be used to make such a comparison.5.2 The inclined plane metho
21、d is also very useful inmachine design in which parts of components shall slideunassisted down chutes and the like. An inclined plane test canbe used to determine the chute angle that is needed to allowmotion on all parts that are placed on the chute. The applica-tions are numerous.6. Apparatus6.1 A
22、ppendix X1 shows a typical inclined plane devicebeing used to compare shoe soles on prefinished oak flooring(see Fig. X1.1).6.2 Any apparatus can be used for this test if it canprogressively tilt the plane to produce motion of the rider. Thedevice in Fig. X1.1 is an electronic protractor that automa
23、ti-cally measures the angle of one leg of the protractor.6.3 The simplest mechanism for performing this test is touse a hinge as the pivot for the raising plane and a protractorcan be used to measure that angle that the hinged plane makeswith the horizontal inclined plane surface.6.4 The plane to be
24、 inclined could be elevated with a servomotor and a rotary encoder could monitor the angle with thehorizontal. Whatever the mechanism, the required featuresshall be:6.4.1 A flat plane large enough to hold the rider of interestwith free space all around;6.4.2 A way to put a surface of interest on the
25、 flat plane;6.4.3 A mechanism to raise the plane progressively on anangle of inclination with the horizontal;6.4.4 A way to measure the angle of inclination of the planecontinuously; and6.4.5 A way to apply weights to riders when necessary, forexample, in the shoe study shown in Fig. X1.1, the shoes
26、 weremade by different manufacturers and were of different styles sothey had different weights. When they were friction testedagainst the same counterface, weights were added to the shoesso that they had the same mass. In this way, weight differenceswere eliminated as factors in measuring friction v
27、ersus coun-terface differences.6.5 If a specific environment is part of a study (wet,controlled humidity, with particles, etc.), a means will benecessary to guarantee the same testing environment for eachfriction test.7. Sample Preparation7.1 Test specimens can be any shape that fit the test rigrequ
28、irements, but most inclined plane test rigs consist of a flatrectangle as the plane that will be angled to initiate motion andthe other member is an object/surface of interest: a shoebottom, a plastic part, a package, a part, a donut, a loaf ofbread, and so forth.7.2 The plane should have the surfac
29、e features of interest(coating, topography, surface finish, machine lay, and so forth)of the material of interest. The example test rig in Appendix X1shows a counterface of prefinished oak flooring with a “rider”that is a shoe bottom.7.3 The contacting surface should be free of all films anddirt tha
30、t are not part of the study. The contacting surfacesshould be in the condition that they will be in the tribosystemof interest. In the shoe/flooring example, the shoes haddifferent tread designs and they were cleaned with a dampmicrofiber cloth to remove particulates and allowed to dry. Theflooring
31、counterface was used as-manufactured.8. Procedure8.1 Place the rider on the plane near the edge that will beraised with the desired contact surface on the inclined planecounterface.8.2 Increase the inclination of the plane from the horizontalat a slow steady rate (from 5 to 10/s) until motion of the
32、 ridercommences. If a motor is used to raise the plane, it should notproduce vibrations of the sliding contacts.8.3 Record the incline plane angle at the point of riderbreakaway (61).8.4 Repeat 8.1 8.3 enough times to produce the desireddegree of statistical significance. No less than three replicat
33、esshould be tested. Fresh specimens should be used for each testif they are available or if that represents the system understudy. Otherwise, retests can be done immediately after testingwith the same surfaces as long as they are not handled duringor after testing. If they are contaminated in any wa
34、y, theyshould be recleaned before retesting.8.5 Take the tangent of the breakaway angles. This numberis the metric for each test. It is the static coefficient of frictionfor that tribosystem.9. Report9.1 State the sliding couple, the test conditions, and thestatic coefficient of friction for each te
35、st. Report the averagestatic friction coefficient for the test couple along with thestandard deviation. Test conditions are very important infriction testing and should be described in sufficient detail thatwould allow others to reproduce the test. Test parameters thatare commonly needed to be state
36、d are sample geometry,loading, cleaning procedures, temperature, relative humidity,G219 182surface preparation, surface texture parameters, such as rough-ness and lay. Other parameters may be required in additionswith specific tribosystems.10. Keywords10.1 friction testing; inclined plane test; stat
37、ic friction co-efficientAPPENDIX(Nonmandatory Information)X1. STATIC COEFFICIENT OF FRICTION FOR VARIOUS SHOE SOLES VERSUS NEW PREFINISHED OAK FLOORINGX1.1 The shoes had different sole designs and were made bydifferent manufacturers from different materials but wereweighted so that they all had a ma
38、ss of 2 kg for testing.X1.2 Test ConditionsX1.2.1 EnvironmentRoom air, 21.1C, 50 % RH, testedwith both surfaces dry.X1.2.2 Weight of RiderThe weight of the rider is 2 kg.X1.2.3 CleaningBoth surfaces were wiped with lint-freemicrofiber cloth before and between each test. The shoes usedwere all cleane
39、d with a non-ammonia glass cleaner andallowed to dry 24 h before testing.X1.2.4 ReplicatesTen per test.X1.2.5 ReportingThe average of the ten replicate testswere used in plotting the test results and the standard devia-tions were used to assess the reproducibility for each shoecouple (COV standard d
40、eviation/mean). COVs are not shownin this example, but they were all less than 0.1.G219 183NOTE 1The test data are static coefficients of friction for shoes from various manufacturers (weighted to all be 2 kg for testing) on a counterface ofprefinished oak flooring (Somerset Hardwoods, Somerset, KY,
41、 USA, 2-14 Natural RO, BS 2501A). Test results are the numerical average of 10 tests, takenat 50 % RH, 20C, room air.FIG. X1.1 Electronic Protractor that Automatically Measures the Angle of One Leg of the ProtractorG219 184ASTM International takes no position respecting the validity of any patent ri
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