1、Designation: D5766/D5766M 11 (Reapproved 2018)Standard Test Method forOpen-Hole Tensile Strength of Polymer Matrix CompositeLaminates1This standard is issued under the fixed designation D5766/D5766M; the number immediately following the designation indicates theyear of original adoption or, in the c
2、ase 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 test method determines the open-hole tensilestrength of multidirectional polymer mat
3、rix composite lami-nates reinforced by high-modulus fibers. The composite mate-rial forms are limited to continuous-fiber or discontinuous-fiber(tape or fabric, or both) reinforced composites in which thelaminate is balanced and symmetric with respect to the testdirection. The range of acceptable te
4、st laminates and thick-nesses are described in 8.2.1.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues fr
5、om the two systems may result in non-conformancewith the standard.1.2.1 Within the text the inch-pound units are shown inbrackets.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 establis
6、h appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for
7、 theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD883
8、Terminology Relating to PlasticsD2584 Test Method for Ignition Loss of Cured ReinforcedResinsD2734 Test Methods for Void Content of Reinforced PlasticsD3039/D3039M Test Method for Tensile Properties of Poly-mer Matrix Composite MaterialsD3171 Test Methods for Constituent Content of CompositeMaterial
9、sD3878 Terminology for Composite MaterialsD5229/D5229M Test Method for MoistureAbsorption Prop-erties and Equilibrium Conditioning of Polymer MatrixComposite MaterialsE6 Terminology Relating to Methods of Mechanical TestingE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456
10、 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1309 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Composite Materials in Databases (With-drawn 2015)3E1434 Guide for Recording Mechanical Test
11、 Data of Fiber-Reinforced Composite Materials in Databases (Withdrawn2015)33. 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.
12、Terminology E456 andPractice E177 define terms relating to statistics. In the event ofa conflict between terms, Terminology D3878 shall haveprecedence over the other standards.3.2 Definitions of Terms Specific to This Standard:NOTE 1If the term represents a physical quantity, its analyticaldimension
13、s are stated immediately following the term (or letter symbol) infundamental dimension form, using the following ASTM standard sym-bology for fundamental dimensions, shown within square brackets: Mfor mass, L for length, T for time, for thermodynamic temperature,1This test method is under the jurisd
14、iction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.05 onStructural Test Methods.Current edition approved June 1, 2018. Published July 2018. Originally approvedin 1995. Last previous edition approved in 2011 as D5766/D5766M 11. DOI:10.1520/D5766_D5
15、766M-11R18.2For 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 version of this historical stan
16、dard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Prin
17、ciples for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1and nd for non-dimensional quantities. Use of these symbols is restrictedto analytical dimensions when used with square brackets, as th
18、e symbolsmay have other definitions when used without the brackets.3.2.1 diameter-to-thickness ratio, D/h nd, nin an open-hole specimen, the ratio of the hole diameter to the specimenthickness.3.2.1.1 DiscussionThe diameter-to-thickness ratio may beeither a nominal value determined from nominal dime
19、nsions oran actual value determined from measured dimensions.3.2.2 nominal value, na value, existing in name only,assigned to a measurable property for the purpose of conve-nient designation. Tolerances may be applied to a nominalvalue to define an acceptable range for the property.3.2.3 principal m
20、aterial coordinate system, na coordinatesystem with axes that are normal to the planes of symmetryinherent to a material.3.2.3.1 DiscussionCommon usage, at least for Cartesianaxes (123, xyz, and so forth), generally assigns the coordinatesystem axes to the normal directions of planes of symmetry ino
21、rder that the highest property value in a normal direction (forelastic properties, the axis of greatest stiffness) would be 1 orx, and the lowest (if applicable) would be 3 or z. Anisotropicmaterials do not have a principal material coordinate systemdue to the total lack of symmetry, while, for isot
22、ropic materials,any coordinate system is a principal material coordinatesystem. In laminated composites, the principal material coor-dinate system has meaning only with respect to an individualorthotropic lamina. The related term for laminated compositesis “reference coordinate system.”3.2.4 referen
23、ce coordinate system, na coordinate systemfor laminated composites used to define ply orientations. Oneof the reference coordinate system axes (normally the Carte-sian x-axis) is designated the reference axis, assigned aposition, and the ply principal axis of each ply in the laminateis referenced re
24、lative to the reference axis to define the plyorientation for that ply.3.2.5 specially orthotropic, adja description of an ortho-tropic material as viewed in its principal material coordinatesystem. In laminated composites, a specially orthotropic lami-nate is a balanced and symmetric laminate of th
25、e 0i/90jnsfamily as viewed from the reference coordinate system, suchthat the membrane-bending coupling terms of the laminateconstitutive relation are zero.3.2.6 width-to-diameter ratio, w/D nd, nin an open-holespecimen, the ratio of the specimen width to the hole diameter.3.2.6.1 DiscussionThe widt
26、h-to-diameter ratio may beeither a nominal value determined from nominal dimensions oran actual value determined from measured dimensions.3.3 Symbols:A = cross-sectional area of a specimenCV = coefficient of variation statistic of a sample populationfor a given property (in percent)D = hole diameter
27、h = specimen thicknessn = number of specimens per sample populationN = number of plies in laminate under testFxOHTu= ultimate open-hole (notched) tensile strength in thetest directionPmax= maximum force carried by test specimen prior tofailuresn-1= standard deviation statistic of a sample population
28、 fora given propertySr= repeatability (within laboratory precision) standarddeviation, calculated in accordance with Practice E691SR= reproducibility (between laboratory precision) standarddeviation, calculated in accordance with Practice E691w = specimen widthxi= test result for an individual speci
29、men from the samplepopulation for a given propertyx5 mean or average (estimate of mean) of a samplepopulation for a given property = normal stress4. Summary of Test Method4.1 A uniaxial tension test of a balanced, symmetric lami-nate is performed in accordance with Test Method D3039/D3039M, although
30、 with a centrally located hole. Edge-mounted extensometer displacement transducers are optional.Ultimate strength is calculated based on the gross cross-sectional area, disregarding the presence of the hole. While thehole causes a stress concentration and reduced net section, it iscommon aerospace p
31、ractice to develop notched design allow-able strengths based on gross section stress to account forvarious stress concentrations (fastener holes, free edges, flaws,damage, and so forth) not explicitly modeled in the stressanalysis.4.2 The only acceptable failure mode for ultimate open-holetensile st
32、rength is one which passes through the hole in the testspecimen.5. Significance and Use5.1 This test method is designed to produce notched tensilestrength data for structural design allowables, materialspecifications, research and development, and quality assur-ance. Factors that influence the notch
33、ed tensile strength andshould therefore be reported include the following: material,methods of material fabrication, accuracy of lay-up, laminatestacking sequence and overall thickness, specimen geometry(including hole diameter, diameter-to-thickness ratio, andwidth-to-diameter ratio), specimen prep
34、aration (especially ofthe hole), specimen conditioning, environment of testing,specimen alignment and gripping, speed of testing, time attemperature, void content, and volume percent reinforcement.Properties that may be derived from this test method includethe following:5.1.1 Open-hole (notched) ten
35、sile strength (OHT).6. Interferences6.1 Hole PreparationDue to the dominating presence ofthe notch, and the lack of need to measure the materialresponse, results from this test method are relatively insensitiveto parameters that would be of concern in an unnotched tensileproperty test. However, sinc
36、e the notch dominates the strength,consistent preparation of the hole, without damage to thelaminate, is important to meaningful results. Damage due tohole preparation will affect strength results. Some types ofD5766/D5766M 11 (2018)2damage, such as delaminations, can blunt the stress concentra-tion
37、 due to the hole, increasing the force-carrying capacity ofthe specimen and the calculated strength. Other types ofdamage can reduce the calculated strength.6.2 Specimen GeometryResults are affected by the ratio ofspecimen width to hole diameter (w/D); this ratio should bemaintained at 6, unless the
38、 experiment is investigating theinfluence of this ratio. Results may also be affected by the ratioof hole diameter to thickness (D/h); the preferred ratio is therange from 1.5 to 3.0 unless the experiment is investigating theinfluence of this ratio. Results may also be affected byspecimen length4; t
39、he preferred specimen length is in the rangefrom 200 to 300 mm 8.0 to 12.0 in. Shorter specimens (150to 200 mm 6.0 to 8.0 in) may be utilized in accordance withthe limitations defined in 8.2.2. The equivalence of test resultsfrom Configurations A and B is contingent upon severalfactors, including fi
40、ber strain-to-failure, resin strength andfracture toughness. Laminates with a propensity to developsub-critical resin splits and cracks could potentially be affectedby a change in specimen length due to closer grip proximity tothe hole (and any longitudinal cracks that may develop).6.3 Material Orth
41、otropyThe degree of laminate orthot-ropy strongly affects the failure mode and measured OHTstrength. Valid OHT strength results should only be reportedwhen appropriate failure modes are observed, in accordancewith 11.5.6.4 Thickness ScalingThick composite structures do notnecessarily fail at the sam
42、e strengths as thin structures with thesame laminate orientation (that is, strength does not alwaysremain constant independent of specimen thickness). Thus,data gathered using this test method may not translate directlyinto equivalent thick-structure properties.6.5 OtherAdditional sources of potenti
43、al data scatter intesting of composite materials are described in Test MethodD3039/D3039M.7. Apparatus7.1 Apparatus shall be in accordance with Test MethodD3039/D3039M. Additionally, a micrometer or gage capableof determining the hole diameter to 60.025 mm 60.001 in.is required.8. Sampling and Test
44、Specimens8.1 SamplingSampling shall be in accordance with TestMethod D3039/D3039M.8.2 GeometryThe specimen geometry shall be in accor-dance with Test Method D3039/D3039M, as modified by thefollowing, and illustrated by the schematic of Fig. 1. Anyvariation of the stacking sequence, specimen width or
45、 length,or hole diameter from that specified shall be clearly noted inthe report.8.2.1 Stacking SequenceThe standard laminate shall havemultidirectional fiber orientations (fibers shall be oriented in aminimum of two directions), and balanced and symmetricstacking sequences. Nominal thickness shall
46、be 2.5 mm 0.10in., with a permissible range of 2 to 4 mm 0.080 to 0.160 in.,inclusive. Fabric laminates containing satin-type weaves shallhave symmetric warp surfaces, unless otherwise noted in thereport.NOTE 2Typically a 45i/-45i/0j/90kmstape or 45i/0jmsfabric lami-nate should be selected such that
47、 a minimum of 5 % of the fibers lay ineach of the four principal orientations. This laminate design has beenfound to yield the highest likelihood of acceptable failure modes.8.2.2 Configuration:8.2.2.1 Configuration AThe width of the specimen is 366 1 mm 1.50 6 0.05 in. and the length range is 200 t
48、o 300mm 8.0 to 12.0 in. The notch consists of a centrally locatedhole, 6 6 0.06 mm 0.250 6 0.003 in. in diameter, centered bylength to within 0.12 mm 0.005 in. and by width to within0.05 mm 0.002 in. While tabs may be used, they are notrequired and generally not needed, since the open hole acts assu
49、fficient stress riser to force failure in the notched region.Configuration A is preferred for the general laminate stackingsequences defined in 8.2.1 because it is long enough to ensurea uniform strain field is achieved in the specimen outside of theinfluence of the hole.8.2.2.2 Configuration BThe width of the specimen is 366 1 mm 1.50 6 0.05 in. and the length range is 150 to 200mm 6.0 to 8.0 in. The notch consists of a centrally locatedhole, 6 6 0.06 mm 0.250 6 0.003 in. in diameter, centered by4Chris, R.
