1、Designation: D 5766/D 5766M 07Standard Test Method forOpen-Hole Tensile Strength of Polymer Matrix CompositeLaminates1This standard is issued under the fixed designation D 5766/D 5766M; the number immediately following the designation indicates theyear of original adoption or, in the case of revisio
2、n, 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.1. Scope1.1 This test method determines the open-hole tensilestrength of multidirectional polymer matrix composite
3、 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 test laminates
4、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. Within the text theinch-pound units are shown in brackets. The values stated ineach system are not exact equivalents; therefore, each systemmust be used inde
5、pendently of the other. Combining valuesfrom the two systems may result in nonconformance with thestandard.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 safety a
6、nd health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 2584 Test Method for Ignit
7、ion Loss of Cured ReinforcedResinsD 2734 Test Methods for Void Content of Reinforced Plas-ticsD 3039/D 3039M Test Method for Tensile Properties ofPolymer Matrix Composite MaterialsD 3171 Test Methods for Constituent Content of CompositeMaterialsD 3878 Terminology for Composite MaterialsD 5229/D 5229
8、M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite MaterialsE6 Terminology Relating to Methods of Mechanical Test-ingE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 456 Terminology Relating to Quality and StatisticsE
9、691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1309 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Composite Materials in DatabasesE 1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases3. Term
10、inology3.1 DefinitionsTerminology D 3878 defines terms relatingto high-modulus fibers and their composites. TerminologyD 883 defines terms relating to plastics. Terminology E6defines terms relating to mechanical testing. TerminologyE 456 and Practice E 177 define terms relating to statistics. Inthe
11、event of a conflict between terms, Terminology D 3878shall have precedence over the other standards.3.2 Definitions of Terms Specific to This Standard:NOTE 1If the term represents a physical quantity, its analyticaldimensions are stated immediately following the term (or letter symbol) infundamental
12、 dimension form, using the following ASTM standard sym-bology for fundamental dimensions, shown within square brackets: Mfor mass, L for length, T for time, u for thermodynamic temperature,1This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct respo
13、nsibility of Subcommittee D30.05 onStructural Test Methods.Current edition approved Oct. 15, 2007. Published November 2007. Originallyapproved in 1995. Last previous edition approved in 2007 as D 5766/D 5766M 02a(2007).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact A
14、STM 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, PO Box C700, West Conshohocken, PA 19428-2959, United States.and nd for non-dimensional
15、quantities. Use of these symbols is restrictedto analytical dimensions when used with square brackets, as the 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
16、.3.2.1.1 DiscussionThe diameter-to-thickness ratio may beeither a nominal value determined from nominal dimensions 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.
17、Tolerances may be applied to a nominalvalue to define an acceptable range for the property.3.2.3 principal material 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, a
18、nd so forth), generally assigns the coordinatesystem axes to the normal directions of planes of symmetry inorder 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. Anisotropicma
19、terials do not have a principal material coordinate systemdue to the total lack of symmetry, while, for isotropic 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 individua
20、lorthotropic lamina. The related term for laminated compositesis “reference coordinate system.”3.2.4 reference 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 th
21、e reference axis, assigned aposition, and the ply principal axis of each ply in the laminateis referenced relative 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 coordinates
22、ystem. In laminated composites, a specially orthotropic lami-nate is a balanced and symmetric laminate of the 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 n
23、d, nin an open-holespecimen, the ratio of the specimen width to the hole diameter.3.2.6.1 DiscussionThe width-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 =
24、 coefficient of variation statistic of a sample populationfor a given property (in percent)D = hole diameterh = specimen thicknessn = number of specimens per sample populationN = number of plies in laminate under testFxOHTu= ultimate open-hole (notched) tensile strength in thetest directionPmax= max
25、imum force carried by test specimen prior tofailuresn-1= standard deviation statistic of a sample population fora given propertyw = specimen widthxi= test result for an individual specimen from the samplepopulation for a given propertyx = mean or average (estimate of mean) of a samplepopulation for
26、a given propertys = normal stress4. Summary of Test Method4.1 A uniaxial tension test of a balanced, symmetric lami-nate is performed in accordance with Test Method D 3039/D 3039M, although with a centrally located hole. Edge-mounted extensometer displacement transducers are optional.Ultimate streng
27、th 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 practice to develop notched design allow-able strengths based on gross section stress to account forvarious stre
28、ss 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 strength is one which passes through the hole in the testspecimen.5. Significance and Use5.1 This test method is
29、designed to produce notched tensilestrength data for structural design allowables, material speci-fications, research and development, and quality assurance.Factors that influence the notched tensile strength and shouldtherefore be reported include the following: material, methodsof material fabrica
30、tion, accuracy of lay-up, laminate stackingsequence and overall thickness, specimen geometry (includinghole diameter, diameter-to-thickness ratio, and width-to-diameter ratio), specimen preparation (especially of the hole),specimen conditioning, environment of testing, specimenalignment and gripping
31、, speed of testing, time at temperature,void content, and volume percent reinforcement. Propertiesthat may be derived from this test method include the follow-ing:5.1.1 Open-hole (notched) tensile strength (OHT).6. Interferences6.1 Hole PreparationDue to the dominating presence ofthe notch, and the
32、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, since the notch dominates the strength,consistent preparation of the hole, without damage to thelaminate, is imp
33、ortant to meaningful results. Damage due tohole preparation will affect strength results. Some types ofdamage, such as delaminations, can blunt the stress concentra-tion due to the hole, increasing the force-carrying capacity ofthe specimen and the calculated strength. Other types ofdamage can reduc
34、e the calculated strength.D 5766/D 5766M 0726.2 Specimen GeometryResults are affected by the ratioof specimen width to hole diameter (w/D); this ratio should bemaintained at 6, unless the experiment is investigating theinfluence of this ratio. Results may also be affected by the ratioof hole diamete
35、r to thickness (D/h); the preferred ratio is therange from 1.5 to 3.0 unless the experiment is investigating theinfluence of this ratio.6.3 Material OrthotropyThe degree of laminate orthot-ropy strongly affects the failure mode and measured OHTstrength. Valid OHT strength results should only be repo
36、rtedwhen appropriate failure modes are observed, in accordancewith 11.5.6.4 Thickness ScalingThick composite structures do notnecessarily fail at the same strengths as thin structures with thesame laminate orientation (that is, strength does not alwaysscale directly with thickness). Thus, data gathe
37、red using thistest method may not translate directly into equivalent thick-structure properties.6.5 OtherAdditional sources of potential data scatter intesting of composite materials are described in Test MethodD 3039/D 3039M.7. Apparatus7.1 Apparatus shall be in accordance with Test MethodD 3039/D
38、3039M. Additionally, a micrometer or gage capableof determining the hole diameter to 60.025 mm 60.001 in.is required.8. Sampling and Test Specimens8.1 SamplingSampling shall be in accordance with TestMethod D 3039/D 3039M.8.2 GeometryThe specimen geometry shall be in accor-dance with Test Method D 3
39、039/D 3039M, as modified by thefollowing, and illustrated by the schematic of Fig. 1. Anyvariation of the stacking sequence, specimen width or length,or hole diameter from that specified shall be clearly noted inthe report.8.2.1 Stacking SequenceThe standard laminate shall havemultidirectional fiber
40、 orientations (fibers shall be oriented in aminimum of two directions), and balanced and symmetricstacking sequences. Nominal thickness shall 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
41、surfaces, unless otherwise noted in thereport.NOTE 2Typically a 45i/-45i/0j/90kmstape or 45i/0jmsfabric lami-nate should be selected such that 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 acceptabl
42、e failure modes.8.2.2 DimensionsThe width of the specimen is 36 6 1mm 1.50 6 0.05 in. and the length range is 200 to 300 mm8.0 to 12.0 in. The notch consists of a centrally located hole,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 within0.0
43、5 mm 0.002 in. While tabs may be used, they are notrequired and generally not needed, since the open hole acts assufficient stress riser to force failure in the notched region.8.3 Specimen PreparationSpecial care shall be taken toensure that creation of the specimen hole does not delaminateor otherw
44、ise damage the material surrounding the hole. Holesshould be drilled undersized and reamed to final dimensions.Record and report the specimen hole preparation methods.Other specimen preparation techniques and requirements arenoted in Test Method D 3039/D 3039M.9. Calibration9.1 Calibration shall be
45、in accordance with Test MethodD 3039/D 3039M.10. Conditioning10.1 The recommended pre-test condition is effective mois-ture equilibrium at a specific relative humidity as establishedby Test Method D 5229/D 5229M; however, if the test re-questor does not explicitly specify a pre-test conditioningenvi
46、ronment, no conditioning is required and the test speci-mens may be tested as prepared.10.2 The pre-test specimen conditioning process, to includespecified environmental exposure levels and resulting moisturecontent, shall be reported with the test data.NOTE 3The term moisture, as used in Test Metho
47、d D 5229/D 5229M,includes not only the vapor of a liquid and its condensate, but the liquiditself in large quantities, as for immersion.10.3 If no explicit conditioning process is performed thespecimen conditioning process shall be reported as “uncondi-tioned” and the moisture content as “unknown.”F
48、IG. 1 Schematic of Open-Hole Tension Test SpecimenD 5766/D 5766M 07311. Procedure11.1 Parameters To Be Specified Prior to Test:11.1.1 The tension specimen sampling method, specimentype and geometry, and conditioning travelers (if required).11.1.2 The tensile properties and data reporting formatdesir
49、ed.NOTE 4Determine specific material property, accuracy, and datareporting requirements prior to test for proper selection of instrumentationand data recording equipment. Estimate the specimen strength to aid intransducer selection, calibration of equipment, and determination ofequipment settings.11.1.3 The environmental conditioning test parameters.11.1.4 If performed, extensometry requirements and relatedcalculations.11.1.5 If performed, the sampling method, specimen geom-etry, and test parameters used to determine den
