1、Designation: D 3479/D 3479M 96 (Reapproved 2007)Standard Test Method forTension-Tension Fatigue of Polymer Matrix CompositeMaterials1This standard is issued under the fixed designation D 3479/D 3479M; the number immediately following the designation indicates theyear of original adoption or, in the
2、case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This t
3、est method determines the fatigue behavior ofpolymer matrix composite materials subjected to tensile cyclicloading. The composite material forms are limited tocontinuous-fiber or discontinuous-fiber reinforced compositesfor which the elastic properties are specially orthotropic withrespect to the te
4、st direction. This test method is limited tounnotched test specimens subjected to constant amplitudeuniaxial in-plane loading where the loading is defined in termsof a test control parameter.1.2 This test method presents two procedures where eachdefines a different test control parameter.1.2.1 Proce
5、dure AA system in which the test controlparameter is the load (stress) and the machine is controlled sothat the test specimen is subjected to repetitive constantamplitude load cycles. In this procedure, the test controlparameter may be described using either engineering stress orapplied load as a co
6、nstant amplitude fatigue variable.1.2.2 Procedure BA system in which the test controlparameter is the strain in the loading direction and the machineis controlled so that the test specimen is subjected to repetitiveconstant amplitude strain cycles. In this procedure, the testcontrol parameter may be
7、 described using engineering strain inthe loading direction as a constant amplitude fatigue variable.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. Within the text theinch-pound units are shown in brackets. The values stated ineach system are n
8、ot exact equivalents; therefore, each systemmust be used independently of the other. Combining valuesfrom the two systems may result in non-conformance with thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility
9、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:2D 883 Terminology Relating to PlasticsD 3039/D 3039M Test Method for Tensile Properties ofPolymer Matr
10、ix Composite MaterialsD 3878 Terminology for Composite MaterialsD 5229/D 5229M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test
11、-ingE83 Practice for Verification and Classification of Exten-someter SystemsE 122 Practice for Calculating Sample Size to Estimate,With a Specified Tolerable Error, the Average for aCharacteristic of a Lot or ProcessE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 456 Ter
12、minology Relating to Quality and StatisticsE 467 Practice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing SystemE 739 Practice for Statistical Analysis of Linear or Linear-ized Stress-Life ( S-N) and Strain-Life (e-N) Fatigue DataE 1012 Practice for Verification of
13、 Test Frame and Speci-men Alignment Under Tensile and Compressive AxialForce ApplicationE 1823 Terminology Relating to Fatigue and Fracture Test-ing3. Terminology3.1 DefinitionsTerminology D 3878 defines terms relatingto high-modulus fibers and their composites. Terminology1This test method is under
14、 the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.04 onLamina and Laminate Test Methods.Current edition approved May 1, 2007. Published June 2007. Originallyapproved in 1976. Last previous edition approved in 2002 as D 3479/D 3479M 96(
15、2002)e1.2For referenced ASTM standards, visit the ASTM website, www.astm.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.1Copyright ASTM International, 100 Barr Harbor Drive,
16、 PO Box C700, West Conshohocken, PA 19428-2959, United States.E 1823 defines terms relating to fatigue. Terminology D 883defines terms relating to plastics. Terminology E6 definesterms relating to mechanical testing. Terminology E 456 andPractice E 177 define terms relating to statistics. In the eve
17、nt ofa conflict between terms, Terminology D 3878 shall haveprecedence over the other standards.3.2 Definitions of Terms Specific to This Standard: Thefollowing definitions shall have precedence over TerminologyD 3878 and over other standards.3.2.1 constant amplitude loading, nin fatigue, a loadingi
18、n which all of the peak values of the test control parameter areequal and all of the valley values of the test control parameterare equal.3.2.2 fatigue loading transition, nin the beginning offatigue loading, the number of cycles before the test controlparameter reaches the desired peak and valley v
19、alues.3.2.3 frequency, f T1, nin fatigue loading, the numberof load (stress) or strain cycles completed in 1 s (Hz).3.2.4 load (stress) ratio, R nd, nin fatigue loading, theratio of the minimum applied load (stress) to the maximumapplied load (stress).3.2.5 peak, nin fatigue loading, the occurrence
20、where thefirst derivative of the test control parameter versus timechanges from positive to negative sign; the point of maximumload (stress) or strain in constant amplitude loading.3.2.6 replicate (repeat) tests, nnominally identical testson different test specimens conducted at the same nominalvalu
21、e of the independent variable.3.2.7 residual stiffness, FL2, nthe value of modulus ofa specimen under quasi-static loading conditions after thespecimen is subjected to fatigue loading.3.2.8 residual strength, FL2, nthe value of load (stress)required to cause failure of a specimen under quasi-staticl
22、oading conditions after the specimen is subjected to fatigueloading.3.2.9 spectrum loading, nin fatigue, a loading in whichthe peak values of the test control parameter are not equal orthe valley values of the test control parameter are not equal(also known as variable amplitude loading or irregular
23、 load-ing.)3.2.10 strain ratio, Rend, nin fatigue loading, the ratioof the minimum applied strain to the maximum applied strain.3.2.11 test control parameter, nthe variable in constantamplitude loading whose maximum and minimum valuesremain the same during cyclic loading, in other words, load(stress
24、) or strain.3.2.12 valley, nin fatigue loading, the occurrence wherethe first derivative of the test control parameter versus timechanges from negative to positive; the point of minimum load(stress) or strain in constant amplitude loading.3.2.13 wave form, nthe shape of the peak-to-peak varia-tion o
25、f the test control parameter as a function of time.3.3 Symbols:3.3.1 Smax(or emax)the value of stress (or strain) corre-sponding to the peak value of the test control parameter in aconstant amplitude loading.3.3.2 Smin(or emin)the value of stress (or strain) corre-sponding to the valley value of the
26、 test control parameter in aconstant amplitude loading.3.3.3 Smn(or emn)the mean value of stress (or strain) asillustrated in Fig. 1 and given by Smn=(Smax+ Smin)/2 oremn=(emax+ emin)/2.3.3.4 Sa(or ea)the difference between the mean value ofstress (or strain) and the maximum and minimum stress (orst
27、rain) as illustrated in Figure 1 and given by Sa=(SmaxSmin)/2 or ea=(emax emin)/2.3.3.5 Nfthe scalar value of fatigue life or number ofconstant amplitude cycles to failure.3.3.6 aWeibull fatigue life scale parameter.3.3.7 bWeibull fatigue life shape parameter.4. Summary of Test Method4.1 The tensile
28、 specimen described in Test Method D 3039/D 3039M is mounted in the grips of the testing machine and istested as follows:4.1.1 Procedure AThe specimen is cycled between mini-mum and maximum in-plane axial load (stress) at a specifiedfrequency. The number of load cycles at which failure occurs(or at
29、which a predetermined change in specimen stiffness isobserved) can be determined for a specimen subjected to aspecific load (stress) ratio and maximum stress. For somepurposes it is useful to obtain the in-plane stiffness at selectedcycle intervals from static axial stress-strain curves usingmodulus
30、 determination procedures found in Test MethodD 3039/D 3039M.4.1.2 Procedure BThe specimen is cycled between mini-mum and maximum in-plane axial strain at a specified fre-quency. The number of strain cycles at which specimen failureoccurs (or at which a predetermined change in specimenstiffness is o
31、bserved) can be determined at a given strain ratioand maximum strain. For some purposes it is useful to obtainthe in-plane stiffness at selected cycle intervals from staticaxial stress-strain curves using modulus determination proce-dures found in Test Method D 3039/D 3039M or continuouslyfrom dynam
32、ic axial stress-strain data using similar proceduresas found in Test Method D 3039/D 3039M.5. Significance and Use5.1 This test method is designed to yield tensile fatigue datafor material specifications, research and development, qualityassurance, and structural design and analysis. The primary tes
33、tresult is the fatigue life of the test specimen under a specificloading and environmental condition. Replicate tests may beused to obtain a distribution of fatigue life for specific materialtypes, laminate stacking sequences, environments, and loadingconditions. Guidance in statistical analysis of
34、fatigue life data,such as determination of linearized stress life (S-N) or strain-life (e-N) curves, can be found in Practice E 739.5.2 This test method can be utilized in the study of fatiguedamage in a polymer matrix composite such as the occurrenceof microscopic cracks, fiber fractures, or delami
35、nations.3The3Reifsnider, K. L., 1991, “Damage and Damage Mechanics,” CompositeMaterials Series: Fatigue of Composites, Vol 4, pp. 1175.D 3479/D 3479M 96 (2007)2specimens residual strength or stiffness, or both, may changedue to these damage mechanisms. The loss in stiffness may bequantified by disco
36、ntinuing cyclic loading at selected cycleintervals to obtain the quasi-static axial stress-strain curveusing modulus determination procedures found in Test MethodD 3039/D 3039M. The loss in strength associated with fatiguedamage may be determined by discontinuing cyclic loading toobtain the static s
37、trength using Test Method D 3039/D 3039M.NOTE 1This test method may be used as a guide to conducttension-tension variable amplitude loading.This information can be usefulin the understanding of fatigue behavior of composite structures underspectrum loading conditions, but is not covered in this test
38、 method6. Interferences6.1 Material and Specimen PreparationPoor materialfabrication practices, lack of control of fiber alignment, anddamage induced by improper coupon machining are knowncauses of a large degree scatter in composite fatigue data.6.2 System AlignmentExcessive bending will cause pre-
39、mature failure. Every effort should be made to eliminate excessbending from the test system. Bending may occur due tomisaligned grips, or from specimens themselves if improperlyinstalled in the grips, or from out-of-tolerance due to poorspecimen preparation. If there is any doubt as to the alignment
40、inherent in a given test machine then the alignment should bechecked as discussed in 7.2.6.6.3 Tab FailurePremature failure of the specimen in thetab region is common in tension-tension fatigue testing as aresult of stress concentrations in the vicinity of tab region.Asetof preliminary fatigue tests
41、 are recommended to find thecombination of tab material, tab length, and adhesive thatminimizes tab failures. Using an optical microscope to viewthe edge of the specimen, it can be determined if similar statesof damage occur in the tab region and the gage region.6.4 Load HistoryVariations in testing
42、 frequency, andstress (or strain) ratio from test to test will result in variationsin fatigue life data. Every effort should be made to evaluate thefatigue performance of composite laminates using the sametesting frequencies and load (or stress) ratios.7. Apparatus7.1 MicrometersAs described in Test
43、 Method D 3039/D 3039M.7.2 Testing MachineThe testing machine shall be inconformance with Practices E 4 and E 467, and shall satisfy thefollowing requirements:7.2.1 Testing Machine HeadsThe testing machine shallhave both an essentially stationary head and a movable head.7.2.2 Drive Mechanism and Con
44、trollerThe testing ma-chine shall be capable of imparting to the movable head acontrolled velocity with respect to the stationary head. Thevelocity of the movable head shall be capable of beingregulated under cyclic load (stress) or strain conditions. Thedrive mechanism and controller shall be in co
45、mpliance withPractice E 467 and shall be capable of imparting a continuousloading wave form to the specimen. It is important to minimizedrift of the fatigue loading away from the maximum andminimum values. Achieving such accuracy is critical in thedevelopment of reliable fatigue life data since smal
46、l errors inloading may result in significant errors in fatigue life.7.2.3 Load IndicatorAs described in Test MethodD 3039/D 3039M. The load indicator shall be in compliancewith Practice E4. The fatigue rating of the load indicator shallexceed the loads at which testing will take place. Additionallyt
47、his test method recommends compliance with Practice E 467for the development of a system dynamic conversion for theverification of specimen loads to within 1 % of true loads.7.2.4 Strain IndicatorIt is recommended that an exten-someter be used for strain determination for strain control inProcedure
48、B, or to obtain strain data for Procedure A. Forspecimens to be tested per Procedure A and to be checked forinitial stiffness only, a bonded strain gage (or gages) may beused for static strain measurements. This test method followsextensometer requirements as found in Test Method D 3039/D 3039M. Ver
49、ification of data acquisition and extensometeraccuracy shall be completed in accordance with Practice E83.However, a static verification is insufficient for dynamicloading, and it is recommended as a minimum to conduct adynamic verification using Appendix X3 of Practice E83.Practice E83discusses dynamic calibration of the extensom-eter by comparing extensometer strain to those from straingages during cyclic loading. Practice E83 discusses theassessment of the vibrational sensitivity of the extensometerusing a single moving anvil.NO
