1、Designation: D6873/D6873M 08 (Reapproved 2014)D6873/D6873M 17Standard Practice forBearing Fatigue Response of Polymer Matrix CompositeLaminates1This standard is issued under the fixed designation D6873/D6873M; the number immediately following the designation indicates theyear of original adoption or
2、, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice provides instructions for modifying static bearing test methods t
3、o determine the fatigue behavior of compositematerials subjected to cyclic bearing forces. The composite material forms are limited to continuous-fiber reinforced polymermatrix composites in which the laminate is both symmetric and balanced with respect to the test direction. The range of acceptable
4、test laminates and thicknesses are described in 8.2.1.2 This practice supplements Test Method D5961/D5961M with provisions for testing specimens under cyclic loading. Severalimportant test specimen parameters (for example, fastener selection, fastener installation method, and fatigue force/stress ra
5、tio) arenot mandated by this practice; however, repeatable results require that these parameters be specified and reported.1.3 This practice is limited to test specimens subjected to constant amplitude uniaxial loading, where the machine is controlledso that the test specimen is subjected to repetit
6、ive constant amplitude force (stress) cycles. Either engineering stress or applied forcemay be used as a constant amplitude fatigue variable. The repetitive loadings may be tensile, compressive, or reversed, dependingupon the test specimen and procedure utilized.1.4 The values stated in either SI un
7、its or inch-pound units are to be regarded separately as standard. Within the text theinch-pound units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system mustbe used independently of the other. Combining values from the two systems may result in
8、 nonconformance with the standard.1.4.1 Within the text the inch-pound units are shown in brackets.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and healt
9、h practices and determine the applicability of regulatorylimitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides
10、and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD3878 Terminology for Composite MaterialsD5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium C
11、onditioning of Polymer Matrix CompositeMaterialsD5961/D5961M Test Method for Bearing Response of Polymer Matrix Composite LaminatesE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE122 Practice for Calculating Sample Size to Estimate, Wit
12、h Specified Precision, the Average for a Characteristic of a Lot orProcessE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE456 Terminology Relating to Quality and Statistics1 This practice is under the jurisdiction of ASTM Committee D30 on Composite Materials and is the dir
13、ect responsibility of Subcommittee D30.05 on Structural TestMethods.Current edition approved Aug. 1, 2014April 1, 2017. Published September 2014April 2017. Originally approved in 2003. Last previous edition approved in 20082014 asD6873/D6873M 08.D6873/D6873M 08(2014). DOI: 10.1520/D6873_D6873M-08R14
14、.10.1520/D6873_D6873M-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standar
15、d and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases o
16、nly the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E467 Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fati
17、gue Testing SystemE739 Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (-N) Fatigue DataE1309 Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in Databases (Withdrawn 2015)3E1434 Guide for Recording Mechanical Test Data of Fi
18、ber-Reinforced Composite Materials in Databases (Withdrawn 2015)3E1823 Terminology Relating to Fatigue and Fracture Testing3. Terminology3.1 DefinitionsTerminology D3878 defines terms relating to high-modulus fibers and their composites. Terminology D883defines terms relating to plastics. Terminolog
19、y E6 defines terms relating to mechanical testing. Terminology E1823 defines termsrelating to fatigue. Terminology E456 and Practice E177 define terms relating to statistics. In the event of a conflict between terms,Terminology D3878 shall have precedence over the other standards.NOTE 1If the term r
20、epresents a physical quantity, its analytical dimensions are stated immediately following the term (or letter symbol) infundamental dimension form, using the following ASTM standard symbology for fundamental dimensions, shown within square brackets: M for mass,L for length, T for time, for thermodyn
21、amic temperature, and nd for non-dimensional quantities. Use of these symbols is restricted to analyticaldimensions when used with square brackets, as the symbols may have other definitions when used without the brackets.3.2 Definitions of Terms Specific to This Standard:3.2.1 bearing force, P MLT-2
22、, nthe total force carried by a bearing coupon.3.2.2 constant amplitude loading, nin fatigue, a loading in which all of the peak values of force (stress) are equal and all ofthe valley values of force (stress) are equal.3.2.3 fatigue loading transition, nin the beginning of fatigue loading, the numb
23、er of cycles before the force (stress) reachesthe desired peak and valley values.3.2.4 force (stress) ratio, R nd, nin fatigue loading, the ratio of the minimum applied force (stress) to the maximum appliedforce (stress).3.2.5 frequency, f T-1, nin fatigue loading, the number of force (stress) cycle
24、s completed in 1 s (Hz).3.2.6 hole elongation, D L, nthe permanent change in hole diameter in a bearing coupon caused by damage formation,equal to the difference between the hole diameter in the direction of the bearing force after a prescribed loading and the holediameter prior to loading.3.2.7 nom
25、inal value, na value, existing in name only, assigned to a measurable property for the purpose of convenientdesignation. Tolerances may be applied to a nominal value to define an acceptable range for the property.3.2.8 peak, nin fatigue loading, the occurrence where the first derivative of the force
26、 (stress) versus time changes frompositive to negative sign; the point of maximum force (stress) in constant amplitude loading.3.2.9 residual strength, ML-1T-2, nthe value of force (stress) required to cause failure of a specimen under quasi-staticloading conditions after the specimen is subjected t
27、o fatigue loading.3.2.10 run-out, nin fatigue, an upper limit on the number of force cycles to be applied.3.2.11 spectrum loading, nin fatigue, a loading in which the peak values of force (stress) are not equal or the valley valuesof force (stress) are not equal (also known as variable amplitude loa
28、ding or irregular loading).3.2.12 valley, nin fatigue loading, the occurrence where the first derivative of the force (stress) versus time changes fromnegative to positive sign; the point of minimum force (stress) in constant amplitude loading.3.2.13 wave form, nthe shape of the peak-to-peak variati
29、on of the force (stress) as a function of time.3.3 Symbols:d = fastener or pin diameterD = specimen hole diameterDi = measured hole diameter prior to fatigue loadingDN = measured hole diameter after N fatigue cyclesh = specimen thicknessk = calculation factor used in bearing equations to distinguish
30、 single-fastener tests from double-fastener testsLg = extensometer gage lengthKi = joint stiffness prior to fatigue loadingKN = joint stiffness after N fatigue cyclesN = number of constant amplitude cyclesP = force carried by specimenPmax = greater of the absolute values of the peak and valley value
31、s of forcePmin = lesser of the absolute values of the peak and valley values of force = crosshead or extensometer translationi = fastener translation prior to fatigue loadingD6873/D6873M 172N = fastener translation after N fatigue cyclesNc = crosshead or extensometer displacement at zero force after
32、 quasi-static compressive loadingNt = crosshead or extensometer displacement at zero force after quasi-static tensile loading = hole elongationDN = hole elongation after N fatigue cyclesKN = percent reduction in joint stiffness after N fatigue cyclesP = change in force over joint stiffness range und
33、er quasi-static loading = change in crosshead or extensometer displacement over joint stiffness range under quasi-static loadingalt = alternating bearing stress during fatigue loadingbrm = maximum cyclic bearing stress magnitude, given by the greater of the absolute values of max and minmax = value
34、of stress corresponding to the peak value of force (stress) under constant amplitude loadingmaxq = value of stress corresponding to the peak value of force (stress) under quasi-static loading for measurement of holeelongation, given by the greater of the absolute values of max and 0.5 minmaxq = valu
35、e of stress corresponding to the peak value of force (stress) under quasi-static loading for measurement of holeelongation and joint stiffness, given by the greater of the absolute values of max and 0.5 minmean = mean bearing stress during fatigue loadingmin = value of stress corresponding to the va
36、lley value of force (stress) under constant amplitude loadingminq = value of stress corresponding to the valley value of force (stress) under quasi-static loading for measurement of holeelongation, given by the greater of the absolute values of min and 0.5 maxminq = value of stress corresponding to
37、the valley value of force (stress) under quasi-static loading for measurement of holeelongation and joint stiffness, given by the greater of the absolute values of min and 0.5 max4. Summary of Practice4.1 In accordance with Test Method D5961/D5961M, but under constant amplitude fatigue loading, perf
38、orm a uniaxial test ofa bearing specimen. Cycle the specimen between minimum and maximum axial forces (stresses) at a specified frequency. Atselected cyclic intervals, determine the hole elongation either through direct measurement or from a force (stress) versusdeformation curve obtained by quasi-s
39、tatically loading the specimen through one tension-compression cycle. If hole elongation isdetermined from a force (stress) versus deformation curve, also determine the percent joint stiffness reduction using the forceversus deformation data. Determine the number of force cycles at which failure occ
40、urs, or at which a predetermined holeelongation or percent joint stiffness reduction is achieved, for a specimen subjected to a specific force (stress) ratio and bearingstress magnitude.5. Significance and Use5.1 This practice provides supplemental instructions for using Test Method D5961/D5961M to
41、obtain bearing fatigue data formaterial specifications, research and development, material design allowables, and quality assurance. The primary property thatresults is the fatigue life of the test specimen under a specific loading and environmental condition. Replicate tests may be usedto obtain a
42、distribution of fatigue life for specific material types, laminate stacking sequences, environments, and loadingconditions. Guidance in statistical analysis of fatigue data, such as determination of linearized stress life (S-N) curves, can be foundin Practice E739.5.2 This practice can be utilized i
43、n the study of fatigue damage in a polymer matrix composite bearing specimen. The loss instrength associated with fatigue damage may be determined by discontinuing cyclic loading to obtain the static strength using TestMethod D5961/D5961M.NOTE 2This practice may be used as a guide to conduct spectru
44、m loading. This information can be useful in the understanding of fatigue behaviorof composite structures under spectrum loading conditions, but is not covered in this standard.5.3 Factors that influence bearing fatigue response and shall therefore be reported include the following: material, method
45、s ofmaterial fabrication, accuracy of lay-up, laminate stacking sequence and overall thickness, specimen geometry, specimenpreparation (especially of the hole), fastener-hole clearance, fastener type, fastener geometry, fastener installation method, fastenertorque (if appropriate), countersink depth
46、 (if appropriate), specimen conditioning, environment of testing, time at temperature, typeof mating material, number of fasteners, type of support fixture, specimen alignment and gripping, test frequency, force (stress)ratio, bearing stress magnitude, void content, and volume percent reinforcement.
47、 Properties that result include the following:5.3.1 Hole elongation versus fatigue life curves for selected bearing stress values.5.3.2 Percent joint stiffness reduction versus fatigue life curves for selected bearing stress values.5.3.3 Bearing stress versus hole elongation curves at selected cycli
48、c intervals.5.3.4 Bearing stress versus percent joint stiffness reduction curves at selected cyclic intervals.5.3.5 Bearing stress versus fatigue life curves for selected hole elongation values.5.3.6 Bearing stress versus fatigue life curves for selected percent joint stiffness reduction values.6. I
49、nterferences6.1 Force (Stress) RatioResults are affected by the force (stress) ratio under which the tests are conducted. Specimens loadedunder tension-tension or compression-compression force (stress) ratios develop hole elongation damage on one side of the fastenerD6873/D6873M 173hole, whereas specimens loaded under tension-compression force (stress) ratios can develop damage on both sides of the fastenerhole. Experience has demonstrated that reversed (tension-compression) force ratios are critic
