1、Designation: D8069 17Standard 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 design
2、ation 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. Scope1.1 This test method covers the dete
3、rmination of FlexuralModulus of pultruded open and closed fiber reinforced polymer(FRP) composites of doubly symmetrical cross sections abouttheir geometric centroid subjected to flexure and shear. Thistest method utilizes a three-point loading system applied to asimply supported beam.1.2 The values
4、 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 is theresponsibility of the user of this standard to establish appro-priate
5、 safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-alsD3
6、878 Terminology for Composite MaterialsD4000 Classification System for Specifying Plastic Materi-alsD4762 Guide for Testing Polymer Matrix Composite Mate-rialsD7290 Practice for Evaluating Material Property Character-istic Values for Polymeric Composites for Civil Engineer-ing Structural Application
7、sE4 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 Test MethodE1309 Guide for Ide
8、ntification 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 DisplacementMeasuring Systems and Devices Us
9、ed 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 conflictbetween terms, Term
10、inology 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 length, mm (in.)h = total hei
11、ght 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 (in.)E = Flexural modulus,
12、MPa (psi)4. Summary 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 the1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct re
13、sponsibility of Subcommittee D20.18 on Reinforced Thermoset-ting Plastics.Current edition approved Jan. 1, 2017. Published January 2017. DOI: 10.1520/D8069-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
14、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 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis
15、international standard was developed in accordance with 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
16、) Committee.1supports. The beam span-to-depth ratio (L/h) should be withinthe range of 20 L/h 32 to determine 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 defl
17、ection are recorded at mid-span during allstages of the test procedure as outlined in Section 11.4.4 If a span 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. Sig
18、nificance and Use5.1 Determination of flexural modulus by this test method isespecially useful for quality control and specification purposes.5.2 Experimental values for flexural modulus will vary withspecimen depth, span length, loading rate, ambient testtemperature, and other atmospheric condition
19、s.5.3 Before proceeding with this test method, referenceshould be made to the specification of the material being tested,including constituent materials of the specimen. Any testspecimen preparation, environmental or loading conditioning,dimensions, or testing parameters covered in the materialspeci
20、fication, or both, shall take precedence over those men-tioned in this test method. If there are no materialspecifications, then these default conditions apply. Table 1 inClassification D4000 lists the ASTM materials standards thatcurrently exist.6. Apparatus6.1 Testing MachineA properly installed a
21、nd operatedhydraulic or mechanical load actuator, ideally one which canbe operated at constant rates of load or 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 sh
22、all also beequipped with deflection measuring devices. The stiffness ofthe testing apparatus shall be such that 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 t
23、esting machineshall be calibrated and verified in accordance with PracticesE4.6.2 Reaction Supports and Loading 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
24、 themetal cylindrical supports or pivoted bearing surfaces causeany local crushing to the test specimen under 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 o
25、f sufficientlength, thickness, and width to provide a firm bearing surfaceand ensure a uniform bearing stress 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 reacti
26、ons due to loading.6.3 Loading NoseThe transverse loading at the center ofthe test specimen span shall be applied 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 spe
27、cimen depth,extending across the entire specimen flange width. If the userchooses to test the specimen by placing an elastomeric pad inbetween the metal block and the top flange surface of the beamspecimen to avoid any local crushing of the sample, a12 in.thick Shore A durometer hardness 40 to 60 sh
28、all be used andthe deflection shall be measured at the bottom flange surface 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
29、to measure span length shall be accurate to within 61.5875 mm (6116 in.).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 accordan
30、ce with11.10). In the absence of an automated system, a properlycalibrated 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 Samp
31、lingTest at least five specimens per test condi-tion unless valid results 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
32、full-scale samples, tested at the desired span length.The span-to-depth 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 providedo
33、ver each end support to prevent sample from slipping from thesupports.7.3 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 diamond
34、coated machining tools are recommended in the preparation oftest specimens.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 affec
35、ted by it.8. Hazards8.1 Precautions shall be taken to prevent the sample fromkicking out of place under increasing transverse load resultingin lateral torsional movement, to avoid any accidents whiletesting under 3-point bending.D8069 1729. Calibration9.1 The accuracy of all testing and measuring eq
36、uipmentshall have certified calibrations that are current at the time ofuse of the 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
37、 or 68-77F).10.2 If no explicit conditioning process is performed thespecimen conditioning 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
38、 environment is different than the conditioningenvironment.11.2 Before testing, 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 lo
39、ading nose displacement tobe continuous and at a rate as calculated by Eq 1:R 5 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.),
40、andh = depth of test specimen, mm (in.).11.5 The actual loading nose displacement 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
41、 and AlignmentPlace the speci-men into the test fixture.Align the fixture and specimen 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 Loa
42、dingApply force at the mid-span of the specimenfor three-point bending (Section 6) at the rate calculated in 11.4while recording data. Even though continuous recording isrecommended, discrete recording of load-displacement datashall be permitted.NOTE 1Discrete recording may result in slightly lower
43、bendingmodulus. When using any deflection measuring device, other than one thatcontinuously records deflection vs. force (stress vs. strain) for modulusdeterminations a compliance correction must be applied as per theappendix of ASTM D790 under “Development of a Flexural MachineCompliance Correction
44、.”11.9 If the user chooses to use a LVDTor a dial gauge, placea deflection measuring 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
45、, (2)P20%5 230 3 S!LFor US Customary Units,P20%5 33600 3 S!Lwhere:P20% 20 % 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 2The maximum failure load can be estimated by back calcu-lating the stresses
46、related to an estimated maximum strain of 15000 microstrains and an estimated bending modulus of 19,300 MPa (2.8 106psi)NOTE 3If the EOR (Engineer of Record) or the user requires takingthe sample to failure in accordance with the contract, proper precautionsshall be followed as given in Section 8 to
47、 prevent any accidents. Theultimate failure load and mode of failure shall be reported. In this case, thebending modulus shall be calculated in accordance with 13.2 using theload and deflections at 20% and 5% of the ultimate failure load.Similarly, the estimated 5% ultimate load can be calculatedas
48、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-spandeflectio
49、n versus time data continuously, or at least fiverecordings per second in case of automatic data acquisitionsystem usage and at least one recording per five seconds in caseof manual recording use a mechanical dial gauge. Record themaximum applied load and corresponding deflection at thatload.12. Validation12.1 Values for Flexural Modulus shall not be calculated forany sample which becomes damaged prior to or during testing.Do not exceed applied theoretical equivalent to 20 % of theassumed ultimate stress in accordance with 11.10.12.2 If mor
