ASTM E2789-2010(2015) Standard Guide for Fretting Fatigue Testing《磨蚀疲劳试验的标准指南》.pdf

1、Designation: E2789 10 (Reapproved 2015)Standard Guide forFretting Fatigue Testing1This standard is issued under the fixed designation E2789; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in par

2、entheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide defines terminology and covers generalrequirements for conducting fretting fatigue tests and reportingthe results. It describes the gener

3、al types of fretting fatiguetests and provides some suggestions on developing and con-ducting fretting fatigue test programs.1.2 Fretting fatigue tests are designed to determine theeffects of mechanical and environmental parameters on thefretting fatigue behavior of metallic materials. This guide is

4、 notintended to establish preference of one apparatus or specimendesign over others, but will establish guidelines for adherencein the design, calibration, and use of fretting fatigue apparatusand recommend the means to collect, record, and reporting ofthe data.1.3 The number of cycles to form a fre

5、tting fatigue crack isdependent on both the material of the fatigue specimen andfretting pad, the geometry of contact between the two, and themethod by which the loading and displacement are imposed.Similar to wear behavior of materials, it is important toconsider fretting fatigue as a system respon

6、se, instead of amaterial response. Because of this dependency on the configu-ration of the system, quantifiable comparisons of variousmaterial combinations should be based on tests using similarfretting fatigue configurations and material couples.1.4 This standard does not purport to address all of

7、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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E3 Guide for Preparation

8、of Metallographic SpecimensE4 Practices for Force Verification of Testing MachinesE466 Practice for Conducting Force Controlled ConstantAmplitude Axial Fatigue Tests of Metallic MaterialsE467 Practice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing SystemE468 Pract

9、ice for Presentation of Constant Amplitude Fa-tigue Test Results for Metallic MaterialsE1012 Practice for Verification of Testing Frame and Speci-men Alignment Under Tensile and Compressive AxialForce ApplicationE1823 Terminology Relating to Fatigue and Fracture TestingE1942 Guide for Evaluating Dat

10、a Acquisition Systems Usedin Cyclic Fatigue and Fracture Mechanics TestingG15 Terminology Relating to Corrosion and Corrosion Test-ing (Withdrawn 2010)3G40 Terminology Relating to Wear and ErosionG190 Guide for Developing and Selecting Wear Tests3. Terminology3.1 Definitions and symbols used in this

11、 guide are inaccordance with Terminology E1823. Relevant definitionsfrom Terminology G15 or G40 are provided in 3.2. Additionaldefinitions specific to this guide are provided in 3.3.3.2 Definitions:3.2.1 Terms from Terminologies G15 and G40.3.2.2 coeffcient of friction (COF)The dimensionless ratioof

12、 the tangential force, Q, between two bodies to the normalforce, P, pressing these bodies together when the two bodies areslipping with respect to each other, =Q/P.3.2.2.1 DiscussionUnder partial slip conditions, the ratioof the tangential force to the normal force is less than the COF.In addition,

13、when COF is defined as the ratio of Q to P, themeasured COF is an average along the interface. In reality, theCOF can vary along the interface. Hence, a local definition isoften used, given by (x,y)=q(x,y)/p(x,y) where q(x,y) is theshear traction distribution along the interface and p(x,y) is thenor

14、mal pressure distribution. The COF is often greater in theslip regions of a partial slip interface compared to the stickregions due to the disruptions in the surface caused by fretting.G401This guide is under the jurisdiction of ASTM Committee E08 on Fatigue andFracture and is the direct responsibil

15、ity of Subcommittee E08.05 on CyclicDeformation and Fatigue Crack Formation.Current edition approved May 1, 2015. Published August 2015. Originallyapproved in 2010. Last previous edition approved in 2010 as E278910. DOI:10.1520/E278910R15.2For referenced ASTM standards, visit the ASTM website, www.a

16、stm.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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr

17、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.3 frettingSmall amplitude oscillatory motion, usuallytangential, between two solid surfaces in contact.3.2.3.1 DiscussionThe term fretting refers only to thenature of the motion without reference to the wear, corrosion,f

18、atigue, or other damage that may occur. It is discouraged touse the term fretting to denote fretting corrosion or other formsof fretting wear due to the ambiguity that may arise. As theamplitude of fretting increases, the condition eventually be-comes reciprocating sliding and the interaction should

19、 nolonger be referred to as fretting.3.2.4 fretting corrosionThe deterioration at the interfacebetween contacting surfaces as the result of corrosion andslight oscillatory slip between the two surfaces. G153.2.5 fretting wearWear that occurs as the result offretting action. G403.3 Definitions of Ter

20、ms Specific to This Standard:3.3.1 displacement amplitudeThe peak-to-peak relativedisplacement divided by two or total cycle displacementdivided by four.3.3.1.1 DiscussionThe displacement amplitude is typi-cally based on a remote reference location. Note that thedefinition of displacement amplitude

21、in the context of frettingwear and tribosystems testing sometimes refers to the fullpeak-to-peak relative displacement, rather than the definitiongiven here, which is consistent with the use of the termamplitude in Terminology E1823. Hence, whenever the termdisplacement amplitude is used, it should

22、be clearly defined ora reference made to this guide.3.3.2 fretting damageThe pits, scarring, disruptions andmaterial transfer on the surface due to fretting.3.3.2.1 DiscussionCracks may be associated with thefretting damage, though in many cases they may not be presentor be sufficiently small, such

23、that the fatigue life is notsignificantly degraded. Hence, the disturbed appearance andlevel of roughness of the fretting damage cannot be reliablyused to determine whether the fatigue life is reduced. In somecases the directionality of roughness, also called the surfacetexture, can be determined vi

24、a profilometry methods. Thistexture may be correlated to the directionality of fretting and insome cases the characteristics of the texture can provide auseful screening metric for fretting damage.3.3.3 fretting fatigueThe process of crack formation at afretting damage site, progressive crack growth

25、 possibly cul-minating in complete fracture, occurring in a material sub-jected to concomitantly fretting and fluctuating stresses andstrains.3.3.3.1 DiscussionFretting fatigue is generally character-ized by a sharp decrease in the fatigue life at the same stresslevel of a standard specimen, attrib

26、uted to the shortened time toform a crack and the acceleration of the crack growth under thecoupling of the fretting and bulk cyclic stresses and strains.3.3.4 fretting fatigue knockdown factorThe reduction infatigue strength due to the presence of fretting, defined as thedifference in the fatigue l

27、imit and fretting fatigue limit dividedby the fatigue limit.3.3.4.1 DiscussionThis knockdown factor may also bebased on the fretting fatigue strength defined either as the stresslevel (maximum stress or stress amplitude for a given meanstress or stress ratio) for failure at a certain number of cycle

28、s orthe stress level at which a percentage of the population wouldsurvive a certain number of cycles.3.3.5 fretting fatigue limitThe limiting value of themedian fatigue strength when fretting is present as the fatiguelife becomes very large.3.3.5.1 DiscussionThe fretting fatigue limit strongly de-pe

29、nds on the fretting conditions.3.3.6 fretting fatigue reduction factorThe reduction infatigue strength due to the presence of fretting, defined as theratio of the fretting fatigue limit and fatigue limit.3.3.6.1 DiscussionThis reduction factor may also bebased on the fretting fatigue strength define

30、d either as the stresslevel (maximum stress or stress amplitude for a given meanstress or stress ratio) for failure at a certain number of cycles orthe stress level at which a percentage of the population wouldsurvive a certain number of cycles.3.3.7 fretting fatigue damage thresholdThe combinationo

31、f fretting fatigue loading conditions and number of frettingcycles that can be sustained before degradation of fatigue lifeis observed.3.3.7.1 DiscussionThe fretting fatigue loading conditionsmay include combinations of the normal force, the displace-ment amplitude, the tangential force amplitude, a

32、nd the bulkfatigue loading. The concept of a fretting fatigue damagethreshold is related to the development of an initial crackcharacterized with a maximum and range in stress intensity thatexceeds the threshold value for crack growth. Generally, afterthe fretting fatigue damage threshold has been r

33、eached, remov-ing the source of fretting, while maintaining the fatigueloading, in configurations where they can be separated, hasminimal effect on the remaining life.3.3.8 gross slipThe condition for which all points incontact experience relative slip over a complete cycle, asillustrated in Fig. 1.

34、3.3.9 normal forceForce normal to the contact interface.3.3.9.1 DiscussionDue to the accumulation of debriswithin the contact or wear in the slip regions, this force maynot remain constant but change during the test.3.3.10 normal pressureResultant of the normal force di-vided by the contact area.3.3

35、10.1 DiscussionTo be considered an average only. Thetrue distribution of pressure within the contact area depends onthe exact profile and roughness of the contacting surfaces.Analytical or computational methods may be used to determinethis pressure; for example, see Ref. (1)4. Wear will cause thepr

36、ofiles of the contacting bodies to change during the test. Ifwear occurs, the size of the non-conforming contacts (forexample, flat on cylindrical, cylindrical on cylindrical, sphereon flat, and so on) will typically increase.3.3.11 partial slipThe condition for which only a portionof the interface

37、of the contacting bodies experience relative slipover a complete cycle, as illustrated in Fig. 1.4The boldface numbers in parentheses refer to a list of references at the end ofthis standard.E2789 10 (2015)23.3.12 plain fatigueOften used to describe fatigue withoutpresence of fretting.3.3.13 recipro

38、cating slidingThe condition when the con-tact area at the two extremes of the cycle do not overlap, asillustrated in Fig. 1.3.3.13.1 DiscussionUnder fretting conditions, at least aportion of the contact areas always overlap at the extremes ofthe cycle.3.3.14 relative slipThe amount of tangential dis

39、placementbetween a point on the interface of one body and a point on thesurface of the second body.3.3.14.1 DiscussionThe point on one of the bodies servesas a reference, which is often defined as the location when thetwo bodies first come into contact under application of thenormal pressure at the

40、interface. The relative slip may bedefined as a local or remote reference. Fundamentally, a localmeasure is desired, however, experimentally a remote displace-ment is measured and in many times controlled.3.3.15 slipLocal movement of surfaces in contact.3.3.16 tangential forceForce acting parallel t

41、o the contactinterface.4. Significance and Use4.1 Fretting fatigue tests are used to determine the effects ofseveral fretting parameters on the fatigue lives of metallicmaterials. Some of these parameters include differingmaterials, relative displacement amplitudes, normal force at thefretting conta

42、ct, alternating tangential force, the contactgeometry, surface integrity parameters such as finish, and theenvironment. Comparative tests are used to determine theeffectiveness of palliatives on the fatigue life of specimens withwell-controlled boundary conditions so that the mechanics ofthe frettin

43、g fatigue test can be modeled. Generally, it is usefulto compare the fretting fatigue response to plain fatigue toobtain knockdown or reduction factors from fretting fatigue.The results may be used as a guide in selecting materialcombinations, design stress levels, lubricants, and coatings toallevia

44、te or eliminate fretting fatigue concerns in new orexisting designs. However, due to the synergisms of fatigue,wear, and corrosion on the fretting fatigue parameters, extremecare should be exercised in the judgment to determine if thetest conditions meet the design or system conditions.4.2 For data

45、to be comparable, reproducible, and correlatedamongst laboratories and relevant to mimic fretting in anapplication, all parameters critical to the fretting fatigue life ofthe material in question will need to be replicated. Becausealterations in environment, metallurgical properties, frettingloading

46、 (controlled forces and displacements), compliance ofthe test system, etc. can affect the response, no generalguidelines exist to quantitatively ascertain what the effect willbe on the specimen fretting fatigue life if a single parameter isvaried. To assure test results can be correlated and reprodu

47、ced,all material variables, testing information, physical procedures,and analytical procedures should be reported in a manner thatis consistent with good current test practices.4.3 Because of the wear phenomenon involved in fretting,idealized contact conditions from which the fretting contactarea an

48、d pressure may be calculated exist only at the onset ofthe test. Although it is still possible to calculate an averagefretting pressure using the initial contact area, the pressurewithin the contact area may vary considerably.4.4 Results of the fretting fatigue tests may be suitable forapplication t

49、o design when the test conditions adequatelymimic the design service conditions.5. Background5.1 Interfacial Conditions:When designing a test program to mimic the design serviceconditions, one must first identify whether the interface con-ditions are partial slip or gross slip. This will help determinewhich type of fretting fatigue test may be more relevant. In Fig.2, a running condition fretting map is shown (2). Two primaryvariables in fretting are the normal force and displacementamplitude. The latter is linearly related to the tangential force