1、Designation: D6484/D6484M 14Standard Test Method forOpen-Hole Compressive Strength of Polymer MatrixComposite Laminates1This standard is issued under the fixed designation D6484/D6484M; 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method determines the open-hole compressivestrength of multidirectional polymer matrix compos
3、ite 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 laminat
4、es 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 i
5、ndependently 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 safet
6、y and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD883 Terminology Relating to PlasticsD2584 Test Method for Ignit
7、ion 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 CompositeMaterialsD3878 Terminology for Composite MaterialsD5229/D5229M Test
8、 Method for MoistureAbsorption Prop-erties and Equilibrium Conditioning of Polymer MatrixComposite MaterialsD5687/D5687M Guide for Preparation of Flat CompositePanels with Processing Guidelines for Specimen Prepara-tionE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to
9、 Methods of Mechanical TestingE83 Practice for Verification and Classification of Exten-someter SystemsE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or ProcessE177 Practice for Use of the Terms Precision and Bias inASTM Test
10、MethodsE456 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 DatabasesE1434 Guide for Recording Mechanical Test Data of
11、 Fiber-Reinforced Composite Materials in DatabasesE1471 Guide for Identification of Fibers, Fillers, and CoreMaterials in Computerized Material Property Databases3. Terminology3.1 DefinitionsTerminology D3878 defines terms relatingto high-modulus fibers and their composites. TerminologyD883 defines
12、terms relating to plastics. Terminology E6 definesterms relating to mechanical testing. Terminology E456 andPractice E177 define terms relating to statistics. In the event ofa conflict between terms, Terminology D3878 shall haveprecedence over the other terminologies.3.2 Definitions of Terms Specifi
13、c to This Standard:NOTE 1If the term represents a physical quantity, its analyticaldimensions 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
14、 for length, T for time, for thermodynamic temperature,and nd for nondimensional quantities. Use of these symbols is restricted1This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.05 onStructural Test Methods.Cur
15、rent edition approved May 15, 2014. Published May 2014. Originallyapproved in 1999. Last previous edition approved in 2009 as D6484/D6484M 091. DOI: 10.1520/D6484_D6484M-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For A
16、nnual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1to analytical dimensions when used with square brackets, as the symbolsmay
17、 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 dimensions oran
18、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 material coor
19、dinate 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 inorder that th
20、e 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 isotropic materi
21、als,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 reference coordinat
22、e 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 relative to th
23、e 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 the 0i/90jnsfa
24、mily 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 width-to-diamete
25、r ratio may beeither a nominal value determined from nominal dimensions oran actual value determined from measured dimensions.3.3 Symbols:Across-sectional area of a specimenCVcoefficient of variation statistic of a sample populationfor a given property (in percent)Bzedgewise percent bendingDhole dia
26、meterhspecimen thicknessnnumber of specimens per sample populationNnumber of plies in laminate under testFxohcuultimate open hole (notched) compressive strengthin the test directionPmaxmaximum force carried by test specimen beforefailurer95 % repeatability confidence limit, equal to 2.8 timesthe rep
27、eatability standard deviationR95 % reproducibility confidence limit, equal to 2.8 timesthe reproducibility standard deviationSn1standard deviation statistic of a sample population fora given propertySrrepeatability (within laboratory precision) standarddeviation, calculated in accordance with Practi
28、ce E691SRreproducibility (between laboratory precision) standarddeviation, calculated in accordance with Practice E691wspecimen widthx1test result for an individual specimen from the samplepopulation for a given propertyxmean or average (estimate of mean) of a sample popu-lation for a given property
29、normal stress4. Summary of Test Method4.1 A uniaxial compression test of a balanced, symmetriclaminate is performed 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
30、 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 stress concentrations (fastener holes, free edges, flaws,damage, and so forth)
31、 not explicitly modeled in the stressanalysis.4.2 The test specimen is face-supported in a multi-piecebolted support fixture. Two acceptable test procedures areprovided. In Procedure A, the specimen/fixture assembly isclamped in hydraulic wedge grips. The force is transmitted byshear into the suppor
32、t fixture and then is transmitted by shearinto the test specimen. In Procedure B, the specimen/fixtureassembly is placed between flat platens, such that the specimenand fixture are end-loaded. The portion of the force initiallytransferred into the support fixture is transmitted by shear intothe test
33、 specimen.4.3 The only acceptable failure mode for ultimate open-holecompressive strength is one which passes through the hole inthe test specimen.5. Significance and Use5.1 This test method is designed to produce notched com-pressive strength data for structural design allowables, materialspecifica
34、tions, research and development, and quality assur-ance. Factors that influence the notched compressive strengthand shall therefore be reported include the following: material,methods of material fabrication, accuracy of lay-up, laminatestacking sequence and overall thickness, specimen geometry,(inc
35、luding hole diameter, diameter-to-thickness ratio, andwidth-to-diameter ratio), specimen preparation (especially ofthe hole), specimen conditioning, environment of testing,specimen alignment and gripping, loading procedure, speed oftesting, time at temperature, void content, and volume percentD6484/
36、D6484M 142reinforcement. Properties that may be derived from this testmethod include open-hole (notched) compressive strength(OHC).6. Interferences6.1 Hole PreparationBecause of the dominating presenceof the notch, and the lack of need to measure the materialresponse, results from this test method a
37、re relatively insensitiveto parameters that would be of concern in an unnotchedcompressive property test. However, since the notch dominatesthe strength, consistent preparation of the hole, without damageto the laminate, is important to meaningful results. Damagecaused by hole preparation will affec
38、t strength results. Sometypes of damage, such as longitudinal splitting anddelamination, can blunt the stress concentration caused by thehole, increasing the force-carrying capacity of the specimenand the calculated strength. Other types of damage can reducethe calculated strength.6.2 Specimen Geome
39、tryResults are affected by the ratio ofspecimen 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 diameter to thickness (D/h); the preferred ratio is therange from 1.5
40、 to 3.0 unless the experiment is investigating theinfluence of this ratio. Results may also be affected by the ratioof ungripped specimen length to specimen width; this ratioshould be maintained at 2.7, unless the experiment is investi-gating the influence of this ratio.6.3 Support FixtureResults ar
41、e affected by the amount oflateral pressure applied to the test specimen by the supportfixture. Sources of variation in this lateral pressure includefixture bolt torque, hydraulic gripping pressure, and fixtureshimming choices, and should be controlled and reported asrequired in the Procedure and Re
42、port sections. The supportfixture can inhibit the growth of delamination damage byinhibiting out-of-plane deformation beyond the cutout, and byrelieving force from the specimen via friction effects. This mayresult in non-conservative data.6.4 Material OrthotropyThe degree of laminate orthot-ropy str
43、ongly affects the failure mode and measured OHCstrength. Valid OHC strength results should only be reportedwhen appropriate failure modes are observed, in accordancewith 11.9.6.5 Thickness ScalingThick composite structures do notnecessarily fail at the same strengths as thin structures with thesame
44、laminate orientation (that is, strength does not alwaysscale linearly with thickness). Thus, data gathered using thistest method may not translate directly into equivalent thick-structure properties.6.6 Type of LoadingDifferences in force versus crossheaddisplacement and force versus extensometer st
45、rain responsemay be observed when comparing hydraulic grip-loaded speci-mens with end-loaded specimens. Hydraulic grip-loaded datatypically exhibit linear behavior at the onset of loading.At highforce levels, some nonlinear behavior may be observed due togrip slippage. End-loaded data typically disp
46、lay some initialnonlinear behavior at low force levels, due to seating of thespecimen/fixture assembly underneath the load platens, butthen exhibit linear behavior to failure.7. Apparatus7.1 Micrometers and CalipersA micrometer with a 4 to 7mm 0.16 to 0.28 in. nominal diameter ball interface shall b
47、eused to measure the specimen thickness when at least onesurface is irregular (such as the bag-side of a laminate). Amicrometer witha4to7mm0.16 to 0.28 in. nominaldiameter ball interface or with a flat anvil interface shall beused to measure the specimen thickness when both surfaces aresmooth (such
48、as tooled surfaces).Amicrometer or caliper, witha flat anvil interface, shall be used to measure the width of thespecimen. The accuracy of the instruments shall be suitable forreading to within 1% of the sample dimensions. For typicalspecimen geometries, an instrument with an accuracy of60.0025 mm 6
49、0.0001 in. is adequate for the thicknessmeasurement, while an instrument with an accuracy of 60.025mm 60.001 in. is adequate for the width measurement.Additionally, a micrometer or gage capable of determining thehole diameter to 60.025 mm 60.001 in. shall be used.7.2 Support FixtureThe fixture is a face-supported com-pressive test fixture as shown in Fig. 1. The fixture consists oftwo short-grip/long-grip assemblies, two support plates, andsteel shims as required to maintain a nominally zero (0.00- to0.12-mm 0.00
