1、Designation: D3479/D3479M 96 (Reapproved 2007) D3479/D3479M 12Standard Test Method forTension-Tension Fatigue of Polymer Matrix CompositeMaterials1This standard is issued under the fixed designation D3479/D3479M; the number immediately following the designation indicates theyear of original adoption
2、 or, 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.This standard has been approved for use by agencies of the Department of Defense.1. Scop
3、e1.1 This test method determines the fatigue behavior of polymer matrix composite materials subjected to tensile cyclic loading.The composite material forms are limited to continuous-fiber or discontinuous-fiber reinforced composites for which the elasticproperties are specially orthotropic with res
4、pect to the test direction. This test method is limited to unnotched test specimenssubjected to constant amplitude uniaxial in-plane loading where the loading is defined in terms of a test control parameter.1.2 This test method presents two procedures where each defines a different test control para
5、meter.1.2.1 Procedure AA system in which the test control parameter is the load (stress) and the machine is controlled so that thetest specimen is subjected to repetitive constant amplitude load cycles. In this procedure, the test control parameter may bedescribed using either engineering stress or
6、applied load as a constant amplitude fatigue variable.1.2.2 Procedure BA system in which the test control parameter is the strain in the loading direction and the machine iscontrolled so that the test specimen is subjected to repetitive constant amplitude strain cycles. In this procedure, the test c
7、ontrolparameter may be described using engineering strain in the loading direction as a constant amplitude fatigue variable.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text theinch-pound units are shown in brackets. The values st
8、ated in each system aremay not be exact equivalents; therefore, each systemmustshall be used independently of the other. Combining values from the two systems may result in non-conformance with thisthestandard.1.4 This standard does not purport to address all of the safety concerns, if any, associat
9、ed with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD3039/D3039M Test Method fo
10、r Tensile Properties of Polymer Matrix Composite MaterialsD3878 Terminology for Composite MaterialsD5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix CompositeMaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relati
11、ng to Methods of Mechanical TestingE83 Practice for Verification and Classification of Extensometer SystemsE122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot orProcessE177 Practice for Use of the Terms Precision and Bias in ASTM
12、 Test MethodsE456 Terminology Relating to Quality and StatisticsE467 Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing System1 This test method is under the jurisdiction of ASTM Committee D30 on Composite Materials and is the direct responsibility of Subcommi
13、ttee D30.04 on Lamina andLaminate Test Methods.Current edition approved May 1, 2007Aug. 1, 2012. Published June 2007January 2013. Originally approved in 1976. Last previous edition approved in 20022007 asD3479/D3479M 96 (2002)(2007).1. DOI: 10.1520/D3479_D3479M-96R07.10.1520/D3479_D3479M-12.2 For re
14、ferenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM 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 standard and is intended only to prov
15、ide 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 only the current versionof the
16、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 States1E739 Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (-N) Fatigue Data
17、E1012 Practice for Verification of Testing Frame and Specimen Alignment Under Tensile and Compressive Axial ForceApplicationE1823 Terminology Relating to Fatigue and Fracture Testing3. Terminology3.1 DefinitionsTerminology D3878 defines terms relating to high-modulus fibers and their composites. Ter
18、minology E1823defines terms relating to fatigue. Terminology D883 defines terms relating to plastics. Terminology E6 defines terms relating tomechanical testing. Terminology E456 and Practice E177 define terms relating to statistics. In the event of a conflict between terms,Terminology D3878 shall h
19、ave precedence over the other standards.3.2 Definitions of Terms Specific to This Standard: The following definitions shall have precedence over Terminology D3878and over other standards.3.2.1 constant amplitude loading, nin fatigue, a loading in which all of the peak values of the test control para
20、meter are equaland all of the valley values of the test control parameter are equal.3.2.2 fatigue loading transition, nin the beginning of fatigue loading, the number of cycles before the test control parameterreaches the desired peak and valley values.3.2.3 frequency, f T1,nin fatigue loading, the
21、number of load (stress) or strain cycles completed in 1 s (Hz).3.2.4 load (stress) ratio, R nd, nin fatigue loading, the ratio of the minimum applied load (stress) to the maximum appliedload (stress).3.2.5 peak, nin fatigue loading, the occurrence where the first derivative of the test control param
22、eter versus time changesfrom positive to negative sign; the point of maximum load (stress) or strain in constant amplitude loading.3.2.6 replicate (repeat) tests, nnominally identical tests on different test specimens conducted at the same nominal value ofthe independent variable.3.2.7 residual stif
23、fness, FL2,nthe value of modulus of a specimen under quasi-static loading conditions after the specimenis subjected to fatigue loading.3.2.8 residual strength, FL2,nthe value of load (stress) required to cause failure of a specimen under quasi-static loadingconditions after the specimen is subjected
24、 to fatigue loading.3.2.9 spectrum loading, nin fatigue, a loading in which the peak values of the test control parameter are not equal or the valleyvalues of the test control parameter are not equal (also known as variable amplitude loading or irregular loading.)3.2.10 strain ratio, R nd,nin fatigu
25、e loading, the ratio of the minimum applied strain to the maximum applied strain.3.2.11 test control parameter, nthe variable in constant amplitude loading whose maximum and minimum values remain thesame during cyclic loading, in other words, load (stress) or strain.3.2.12 valley, nin fatigue loadin
26、g, the occurrence where the first derivative of the test control parameter versus time changesfrom 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 variation of the test control parameter as a function o
27、f time.3.3 Symbols:3.3.1 Smax (or max)the value of stress (or strain) corresponding to the peak value of the test control parameter in a constantamplitude loading.3.3.2 Smin (or min)the value of stress (or strain) corresponding to the valley value of the test control parameter in a constantamplitude
28、 loading.3.3.3 Smn (or mn)the mean value of stress (or strain) as illustrated in Fig. 1 and given by Smn = (Smax + Smin)/2 ormn = (max + min)/2.3.3.4 Sa (or a)the difference between the mean value of stress (or strain) and the maximum and minimum stress (or strain)as illustrated in Figure 1 and give
29、n by Sa = (Smax Smin)/2 or a = (max min)/2.3.3.5 Nfthe scalar value of fatigue life or number of constant amplitude cycles to failure.3.3.6 Weibull fatigue life scale parameter.3.3.7 Weibull fatigue life shape parameter.4. Summary of Test Method4.1 The tensile specimen described in Test Method D3039
30、/D3039M is mounted in the grips of the testing machine and is testedas follows:4.1.1 Procedure AThe specimen is cycled between minimum and maximum in-plane axial load (stress) at a specifiedfrequency. The number of load cycles at which failure occurs (or at which a predetermined change in specimen s
31、tiffness isobserved) can be determined for a specimen subjected to a specific load (stress) ratio and maximum stress. For some purposes itD3479/D3479M 122is useful to obtain the in-plane stiffness at selected cycle intervals from static axial stress-strain curves using modulus determinationprocedure
32、s found in Test Method D3039/D3039M.4.1.2 Procedure BThe specimen is cycled between minimum and maximum in-plane axial strain at a specified frequency. Thenumber of strain cycles at which specimen failure occurs (or at which a predetermined change in specimen stiffness is observed)can be determined
33、at a given strain ratio and maximum strain. For some purposes it is useful to obtain the in-plane stiffness atselected cycle intervals from static axial stress-strain curves using modulus determination procedures found in Test MethodD3039/D3039M or continuously from dynamic axial stress-strain data
34、using similar procedures as found in Test MethodD3039/D3039M.5. Significance and Use5.1 This test method is designed to yield tensile fatigue data for material specifications, research and development, qualityassurance, and structural design and analysis. The primary test result is the fatigue life
35、of the test specimen under a specific loadingand environmental condition. Replicate tests may be used to obtain a distribution of fatigue life for specific material types, laminatestacking sequences, environments, and loading conditions. Guidance in statistical analysis of fatigue life data, such as
36、determination of linearized stress life (S-N) or strain-life (-N) curves, can be found in Practice E739.5.2 This test method can be utilized in the study of fatigue damage in a polymer matrix composite such as the occurrence ofmicroscopic cracks, fiber fractures, or delaminations.3 The specimens res
37、idual strength or stiffness, or both, may change due tothese damage mechanisms. The loss in stiffness may be quantified by discontinuing cyclic loading at selected cycle intervals toobtain the quasi-static axial stress-strain curve using modulus determination procedures found in Test Method D3039/D3
38、039M.The loss in strength associated with fatigue damage may be determined by discontinuing cyclic loading to obtain the static strengthusing Test Method D3039/D3039M.NOTE 1This test method may be used as a guide to conduct tension-tension variable amplitude loading. This information can be useful i
39、n theunderstanding of fatigue behavior of composite structures under spectrum loading conditions, but is not covered in this test methodmethod.6. Interferences6.1 Material and Specimen PreparationPoor material fabrication practices, lack of control of fiber alignment, and damageinduced by improper c
40、oupon machining are known causes of a large degree scatter in composite fatigue data.6.2 System AlignmentExcessive bending will cause premature failure. Every effort should be made to eliminate excessbending from the test system. Bending may occur due to misaligned grips, or from specimens themselve
41、s if improperly installedin the grips, or from out-of-tolerance due to poor specimen preparation. If there is any doubt as to the alignment inherent in a giventest machine then the alignment should be checked as discussed in 7.2.6.6.3 Tab FailurePremature failure of the specimen in the tab region is
42、 common in tension-tension fatigue testing as a resultof stress concentrations in the vicinity of tab region. A set of preliminary fatigue tests are recommended to find the combinationof tab material, tab length, and adhesive that minimizes tab failures. Using an optical microscope to view the edge
43、of the specimen,it can be determined if similar states of damage occur in the tab region and the gage region.6.4 Load HistoryVariations in testing frequency, and stress (or strain) ratio from test to test will result in variations in fatiguelife data. Every effort should be made to evaluate the fati
44、gue performance of composite laminates using the same testingfrequencies and load (or stress) ratios.7. Apparatus7.1 MicrometersAs described in Test Method D3039/D3039M.7.2 Testing MachineThe testing machine shall be in conformance with Practices E4 and E467, and shall satisfy the followingrequireme
45、nts:7.2.1 Testing Machine HeadsThe testing machine shall have both an essentially stationary head and a movable head.7.2.2 Drive Mechanism and ControllerThe testing machine shall be capable of imparting to the movable head a controlledvelocity with respect to the stationary head. The velocity of the
46、 movable head shall be capable of being regulated under cyclic load(stress) or strain conditions. The drive mechanism and controller shall be in compliance with Practice E467 and shall be capableof imparting a continuous loading wave form to the specimen. It is important to minimize drift of the fat
47、igue loading away fromthe maximum and minimum values. Achieving such accuracy is critical in the development of reliable fatigue life data since smallerrors in loading may result in significant errors in fatigue life.7.2.3 Load IndicatorAs described in Test Method D3039/D3039M. The load indicator sh
48、all be in compliance with PracticeE4. The fatigue rating of the load indicator shall exceed the loads at which testing will take place. Additionally this test methodrecommends compliance with Practice E467 for the development of a system dynamic conversion for the verification of specimenloads to wi
49、thin 1 % of true loads.3 Reifsnider, K. L., 1991, “Damage and Damage Mechanics,” Composite Materials Series: Fatigue of Composites, Vol 4, pp. 1175.D3479/D3479M 1237.2.4 Strain IndicatorIt is recommended that an extensometer be used for strain determination for strain control in ProcedureB, or to obtain strain data for Procedure A. For specimens to be tested per Procedure A and to be checked for initial stiffness only,a bonded strain gage (or gages) may be used for static strain measurements. This test method
