1、Designation: D6484/D6484M 09Standard 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 Plas-ticsD3039/D3039M Test Method for Tensile Properties ofPolymer Matrix Composite MaterialsD3171 Test Methods for Constituent Content of CompositeMaterialsD3878 Terminology for Composite MaterialsD5229/D5229M Test
8、Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite 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,With Specified Precision, the Average for a Characteristicof a Lot 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 E456E456and Practice E177 define terms relating to statistics. In theevent of a conflict between terms, Terminology D3878 shallhave precedence over the other terminologies.3.2 Definitions of Terms Spe
13、cific 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: M1This t
14、est method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.05 onStructural Test Methods.Current edition approved Dec. 1, 2009. Published January 2010. Originallyapproved in 1999. Last previous edition approved in 2004 as D648
15、4/D6484M 041. DOI: 10.1520/D6484_D6484M-09.2For 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.1Copyright ASTM In
16、ternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.for mass, L for length, T for time, u for thermodynamic temperature,and nd for nondimensional quantities. Use of these symbols is restrictedto analytical dimensions when used with square brackets, as the
17、 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 dimen
18、sions 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 ma
19、terial 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 inor
20、der 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 isotr
21、opic 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 referenc
22、e 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 rel
23、ative 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 the
24、 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 width
25、-to-diameter 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 bendi
26、ngDhole diameterhspecimen 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 t
27、imesthe repeatability 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) standard de-viation, calculated in accordanc
28、e with Practice 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 g
29、iven propertysnormal 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, di
30、sregarding 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 stress concentrations (fastener holes, free edges, flaws,damage,
31、 and so forth) 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 i
32、nto the support 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 shea
33、r intothe test 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, mat
34、erialspecifications, 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
35、 geometry,(including 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 ofD6484/D6484M 092testing, time at temperature, void con
36、tent, and volume percentreinforcement. 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
37、 test method are 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 preparat
38、ion will affect strength results. Sometypes of damage, such as longitudinal splitting and delamina-tion, can blunt the stress concentration caused by the hole,increasing the force-carrying capacity of the specimen and thecalculated strength. Other types of damage can reduce thecalculated strength.6.
39、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 diameter to thickness (D/h); the preferred ratio is t
40、herange from 1.5 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 F
41、ixtureResults are 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
42、Procedure and Report 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
43、 orthot-ropy strongly 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 structur
44、es with thesame 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
45、 extensometer strain 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 dat
46、a typically display 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 MicrometersThe micrometer(s) shall use a 4- to 5-mm0.16- to 0.20-in. nominal diameter ball-in
47、terface on irregularsurfaces such as the bag-side of a laminate, and a flat anvilinterface on machined edges or very smooth-tooled surfaces.The accuracy of the instrument(s) shall be suitable for readingto within 1 % of the sample width and thickness. For typicalspecimen geometries, an instrument wi
48、th an accuracy of 625m 60.001 in. is desirable for thickness measurement, whilean instrument with an accuracy of 676 m 60.003 in. isdesirable for width measurement. Additionally, a micrometeror gage capable of determining the hole diameter to 625 m60.001 in. is required.7.2 Support FixtureThe fixtur
49、e 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 0.000- to 0.005-in. tolerance) gap between supportplates and long grips. If this gap does not meet the minimumrequirement, shim the contact area between the support plateand the short grip with steel shim stock. If the gap is too large,shim between the support plate and the long grip, holding thesh
