ASTM D8069-2017a 6875 Standard Test Method for Determining Flexural Modulus of Full Section Pultruded Fiber Reinforced Polymer (FRP) Composite Members with Doubly Symmetric Cross S.pdf

1、Designation: D8069 17aStandard Test Method forDetermining Flexural Modulus of Full Section PultrudedFiber Reinforced Polymer (FRP) Composite Members withDoubly Symmetric Cross Sections under Bending1This standard is issued under the fixed designation D8069; the number immediately following the desig

2、nation indicates the year oforiginal adoption or, in the case 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. Scope*1.1 This test method covers the de

3、termination of FlexuralModulus of pultruded open and closed fiber reinforced polymer(FRP) composites of doubly symmetrical cross sections (sec-tions having geometric symmetry about both the major andminor axes) about their geometric centroid subjected to flexureand shear. This test method utilizes a

4、 three-point loadingsystem applied to a simply supported beam.1.2 The values stated in SI units are to be regarded as thestandard. The values provided in parentheses are for informa-tion only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It

5、 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.NOTE 1The is no known ISO equivalent to this standard.1.4 This international standard was developed in acco

6、r-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) Committee.2. Referenced Documents2.1 AST

7、M Standards:2D883 Terminology Relating to PlasticsD790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-alsD3878 Terminology for Composite MaterialsD4000 Classification System for Specifying Plastic Materi-alsD4762 Guide for Testing Polymer

8、 Matrix Composite Mate-rialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Tes

9、t MethodE1309 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Composite Materials in Databases (With-drawn 2015)3E1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases (Withdrawn2015)3E2309/E2309M Practices for Verification of DisplacementMeasu

10、ring Systems and Devices Used in Material TestingMachines3. Terminology3.1 DefinitionsTerminology D3878 defines terms relatingto high-modulus fibers and their composites. TerminologyD883 defines terms relating to plastics.Terminology E6 definesterms relating to mechanical testing. In the event of a

11、conflictbetween terms, Terminology D3878 shall have precedenceover the other terminologies.3.2 Definitions of variables used in calculations as shown inSection 11 and 12 are as follows:P20% 20% of estimated ultimate load, N (lbf)I = moment of inertia about the neutral axis, mm4(in.4)L = test span le

12、ngth, mm (in.)h = total height of test specimen, mm (in.)P5% 5% of estimated ultimate load, N (lbf)P = load value used to calculate E, N (lbf) = deflection value used to calculate E, mm (in.)20% deflection at 20% of estimated ultimate load, mm (in.)5% deflection at 5% of estimated ultimate load, mm

13、(in.)1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.18 on Reinforced Thermoset-ting Plastics.Current edition approved Dec. 1, 2017. Published January 2018. Originallyapproved in 2017. Last previous edition approved in

14、2017 as D806917. DOI:10.1520/D8069-17A.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.3The last approved ver

15、sion of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with

16、 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.1E = Flexural modulus, MPa (psi)4. Summary

17、of Test Method4.1 The full-scale specimen rests on two rounded solidmetal cylindrical supports or pivoted end supports and isloaded by means of a loading ram located midway between thesupports, as shown in Fig. 1. The beam span-to-depth ratio(L/h) should be within the range of 20 L/h 32 to determine

18、the flexural modulus.4.2 The maximum load placed on the specimen shall beapproximately equal to 20 percent of the estimated ultimateload determined in accordance with 11.10.4.3 Load and deflection are recorded at mid-span during allstages of the test procedure as outlined in Section 11.4.4 If a span

19、 specified by the user, in the contract for aparticular application, is under the span-to-depth ratio of 20(L/h 32), the flexural modulus shall bereported as apparent flexural modulus.5. Significance and Use5.1 Determination of flexural modulus by this test method isespecially useful for quality con

20、trol and specification purposes.5.2 Experimental values for flexural modulus will vary withspecimen depth, span length, loading rate, ambient testtemperature, and other atmospheric conditions.5.3 Before proceeding with this test method, referenceshould be made to the specification of the material be

21、ing tested,including constituent materials of the specimen. Any testspecimen preparation, environmental or loading conditioning,dimensions, or testing parameters covered in the materialspecification, or both, shall take precedence over those men-tioned in this test method. If there are no materialsp

22、ecifications, then these default conditions apply. Table 1 inClassification D4000 lists the ASTM materials standards thatcurrently exist.6. Apparatus6.1 Testing MachineA properly installed and operatedhydraulic or mechanical load actuator, ideally one which canbe operated at constant rates of load o

23、r deflection, is used incombination with a properly calibrated load cell. Error in theload measuring system shall not exceed 61% of the maximumload expected to be measured. The test setup shall also beequipped with deflection measuring devices. The stiffness ofthe testing apparatus shall be such tha

24、t the total elasticdeformation of the load frame does not exceed 1% of the totaldeflection of the test specimen during testing, or appropriatecorrections shall be made. The accuracy of the testing machineshall be calibrated and verified in accordance with PracticesE4.6.2 Reaction Supports and Loadin

25、g NoseThe beam speci-men shall be placed over two rounded metal cylindricalsupports or over pivoted bearing surfaces which can accom-modate free rotation at the ends of the beam specimen. If themetal cylindrical supports or pivoted bearing surfaces causeany local crushing to the test specimen under

26、loading, the beamspecimen shall be supported by metal bearing plates to preventdamage to the beam at the point of contact between the beamspecimen and reaction support. The plates shall be of sufficientlength, thickness, and width to provide a firm bearing surfaceand ensure a uniform bearing stress

27、across the flange width ofthe beam specimen. The bearing plates shall be supported bydevices that provide unrestricted longitudinal deformation androtation of the beam specimen at the reactions due to loading.6.3 Loading NoseThe transverse loading at the center ofthe test specimen span shall be appl

28、ied through a metal blockwith 4 in. width (along the length of the beam specimen) by12in. thick, with rounded edges or with a radius of curvatureapproximately equal to two times the beam specimen depth,extending across the entire specimen flange width. If the userchooses to test the specimen by plac

29、ing an elastomeric pad inbetween the metal block and the top flange surface of the beamFIG. 1 Test Fixture and SetupD8069 17a2specimen to avoid any local crushing of the sample, a12 in.thick Shore A durometer hardness 40 to 60 shall be used andthe deflection shall be measured at the bottom flange su

30、rface ofthe test specimen using a dial gauge or LVDT.6.4 Measuring Devices for Sectional DimensionsAll mea-suring devices used to measure cross-sectional dimensionsshall be accurate to within 60.0254 mm (60.001 in.). Devicesused to measure span length shall be accurate to within 61.5875 mm (6116 in.

31、).6.5 Deflection Measuring DeviceA properly calibrateddevice to measure the deflection of the beam at mid-span shallbe used. The device shall record the deflection during the testfor certain magnitude of applied load (in accordance with11.10). In the absence of an automated system, a properlycalibra

32、ted deflection dial gauge may be used with at least onereading for every five seconds throughout the duration of thetest. The deflection dial gauge shall be accurate to 60.0254mm (60.001 in).7. Sampling and Test Specimens7.1 SamplingTest at least five specimens per test condi-tion unless valid resul

33、ts within 1 % can be gained through theuse of at least three specimens, as in the case of a designedexperiment.7.2 SpecimensThe test beam specimens shall be moldedshapes manufactured using a pultrusion process. Specimensshall be full-scale samples, tested at the desired span length.The span-to-depth

34、 ratio of specimens shall never be less than20 or greater than 32 unless the sample needs to be tested inaccordance with 13.4 for apparent modulus. Sufficient over-hang (a length of 5 % - 10 % of the test span) shall be providedover each end support to prevent sample from slipping from thesupports.7

35、.3 Specimen PreparationTake precautions when cuttingbeam specimens to the desired span length to avoid notches,rough or uneven surfaces, or delaminations due to inappropri-ate test specimen preparation methods. The use of diamondcoated machining tools are recommended in the preparation oftest specim

36、ens.7.4 LabelingLabel the test specimens (date, batch number,line number) so that they will be distinct from each other andtraceable back to the specimen of origin of manufacturing, andwill neither influence the test nor be affected by it.8. Hazards8.1 Precautions shall be taken to prevent the sampl

37、e fromkicking out of place under increasing transverse load resultingin lateral torsional movement, to avoid any accidents whiletesting under 3-point bending.9. Calibration9.1 The accuracy of all testing and measuring equipmentshall have certified calibrations that are current at the time ofuse of t

38、he equipment.10. Conditioning10.1 If the test requestor does not explicitly specify apre-test conditioning environment, conditioning is not requiredand the test specimens may be tested at normal room tempera-ture (20-25C or 68-77F).10.2 If no explicit conditioning process is performed thespecimen co

39、nditioning process shall be reported as “uncondi-tioned.”11. Test Setup and Procedure11.1 If needed, condition test specimens as required. Storethe test specimens in the conditioned environment until testtime if the test environment is different than the conditioningenvironment.11.2 Before testing,

40、measure and record the cross-sectionalshape and dimensions as necessary. Record the dimensions tothree significant figures.11.3 Measure and record the length of the support andloading spans.11.4 Rate of TestingSet the loading nose displacement tobe continuous and at a rate as calculated by Eq 1:R 5

41、Z 3 L2!6 3 h! (1)where:R = loading nose displacement rate, mm/min (in./min),Z = rate of straining of the outer fiber, mm/mm/min (in./in./min), which shall be rangning from 0.001 to 0.0008,L = test span length, mm (in.), andh = depth of test specimen, mm (in.).11.5 The actual loading nose displacemen

42、t rate range shallbe within 610 % of that calculated by Eq 1.11.6 Fixture InstallationArrange the loading fixture for athree-point bend test, and place specimen in the testingapparatus accordingly.11.7 Specimen Insertion and AlignmentPlace the speci-men into the test fixture.Align the fixture and sp

43、ecimen so thatthe longitudinal axis of the specimen is perpendicular (within1) to the longitudinal axis of the loading nose, and the loadingnose is parallel (within 1) to the plane of the top face of thespecimen.11.8 LoadingApply force at the mid-span of the specimenfor three-point bending (Section

44、6) at the rate calculated in 11.4while recording data. Even though continuous recording isrecommended, discrete recording of load-displacement datashall be permitted.NOTE 2Discrete recording may result in slightly lower bendingmodulus.When using any deflection measuring device, other than one thatco

45、ntinuously records deflection vs. force (stress vs. strain) for modulusdeterminations a compliance correction can be applied as per the appendixof ASTM D790 under “Development of a Flexural Machine ComplianceCorrection.”11.9 If the user chooses to use a LVDTor a dial gauge, placea deflection measuri

46、ng device under the bottom flange of thebeam specimen in the line of loading at the mid-span.11.10 The beam specimens shall be loaded up to 20 % of theestimated failure load using the formula given in Eq 2.For SI Units, (2)P20%5 230 3 S!LD8069 17a3For US Customary Units,P20%5 33600 3 S!Lwhere:P20% 2

47、0 % of estimated ultimate load, N (lbf),S = section modulus of the sample about the plane ofbending, mm3(in.3), andL = test span length, mm (in.).NOTE 3The maximum failure load can be estimated by back calcu-lating the stresses related to an estimated maximum strain of 15000 microstrains and an esti

48、mated bending modulus of 19,300 MPa (2.8 106psi)If the EOR (Engineer of Record) or the user requires taking the sampleto failure in accordance with the contract, proper precautions shall befollowed as given in Section 8 to prevent any accidents. The ultimatefailure load and mode of failure shall be

49、reported. In this case, the bendingmodulus shall be calculated in accordance with 13.2 using the load anddeflections at 20% and 5% of the ultimate failure load.Similarly, the estimated 5% ultimate load can be calculatedas given in Eq 3.For SI Units, (3)P5%5 58 3 S!LFor US Customary Units,P5%5 8400 3 S!Lwhere:P5% 5 % of estimated ultimate load, N (lbf),S = section modulus of the sample about the plane ofbending, mm3(in.3), andL = test span length, mm (in.).11.11 Data RecordingRecord load and vertical mid-spandeflection versus time data co