1、Designation: D 6742/D 6742M 07Standard Practice forFilled-Hole Tension and Compression Testing of PolymerMatrix Composite Laminates1This standard is issued under the fixed designation D 6742/D 6742M; 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice provides instructions for modifying open-hole tension and compression test
3、 methods to determinefilled-hole tensile and compressive strengths. The compositematerial forms are limited to continuous-fiber reinforced poly-mer matrix composites in which the laminate is both symmetricand balanced with respect to the test direction. The range ofacceptable test laminates and thic
4、knesses are described in8.2.1.1.2 This practice supplements Test Methods D 5766/D 5766M (for tension testing) and D 6484/D 6484M (forcompression testing) with provisions for testing specimens thatcontain a close-tolerance fastener or pin installed in the hole.Several important test specimen paramete
5、rs (for example,fastener selection, fastener installation method, and fastenerhole tolerance) are not mandated by this practice; however,repeatable results require that these parameters be specified andreported.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately
6、 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 independently of the other. Combining valuesfrom the two systems may result in nonconformance with thestandard.1.4 This standard does
7、 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Stand
8、ards:2D 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 3171 Test Methods for Constituent Content of CompositeMaterialsD 3878 Terminology for Composite MaterialsD 5229/D 5229M Test Method for Moisture Absorption
9、Properties and Equilibrium Conditioning of Polymer Ma-trix Composite MaterialsD 5766/D5766M Test Method for Open-Hole TensileStrength of Polymer Matrix Composite LaminatesD 6484/D 6484M Test Method for Open-Hole CompressiveStrength of Polymer Matrix Composite LaminatesD 6507 Practice for Fiber Reinf
10、orcement Orientation Codesfor 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 1309 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Co
11、mposite Materials in DatabasesE 1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases3. Terminology3.1 DefinitionsTerminology D 3878 defines terms relatingto high-modulus fibers and their composites. TerminologyD 883 defines terms relating to plastics. Te
12、rminology E6defines terms relating to mechanical testing. TerminologyE 456 and Practice E 177 define terms relating to statistics. Inthe 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
13、 term represents a physical quantity, its analyticaldimensions are stated immediately following the term (or letter symbol) infundamental dimension form, using the following ASTM Internationalstandard symbology for fundamental dimensions, shown within squarebrackets: M for mass, L for length, T for
14、time, u for thermodynamictemperature, and nd for nondimensional quantities. Use of these symbolsis restricted to analytical dimensions when used with square brackets, asthe symbols may have other definitions when used without the brackets.1This practice is under the jurisdiction of ASTM Committee D3
15、0 on CompositeMaterials , and is the direct responsibility of Subcommittee D30.05 on StructuralTest Methods.Current edition approved Oct. 15, 2007. Published November 2007. Originallyapproved in 2001. Last previous edition approved in 2007 as D 6742/D 6742M 02(2007).2For referenced ASTM standards, v
16、isit 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 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428
17、-2959, United States.3.2.1 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.3.2.2 countersink flushness, ndepth or protrusion of coun
18、-tersunk fastener head relative to the laminate surface afterinstallation. A positive value indicates protrusion of the fas-tener head above the laminate surface; a negative valueindicates depth below the surface.3.2.3 countersink depth, ndepth of countersinking re-quired to properly install a count
19、ersunk fastener, such thatcountersink flushness is nominally zero. Countersink depth isnominally equivalent to the height of the fastener head.3.3 Symbols:A = cross-sectional area of a specimend = fastener diameterD = specimen hole diameterdcsk= countersink depthdfl= countersink flushnessf = distanc
20、e, perpendicular to loading axis, from hole edge toclosest side of specimenFxfhcu= ultimate filled-hole compressive strength in the testdirectionFxfhtu= ultimate filled-hole tensile strength in the test direc-tiong1= distance, parallel to loading axis, from hole edge to endof specimenh = specimen th
21、icknessPmax= maximum force carried by test specimen prior tofailurew = specimen width4. Summary of Practice4.1 Filled-Hole Tensile StrengthIn accordance with TestMethod D 5766/D 5766M, but with a close-tolerance fasteneror pin installed in the hole, perform a uniaxial tension test of abalanced, symm
22、etric laminate with a centrally located hole.4.2 Filled-Hole Compressive StrengthIn accordance withTest Method D 6484/D 6484M, but with a close-tolerancefastener or pin installed in the hole, perform a uniaxialcompression test of a balanced, symmetric laminate with acentrally located hole.NOTE 2For
23、both test methods, ultimate strength is calculated based onthe gross cross-sectional area, disregarding the presence of the filled hole.While the filled hole causes a stress concentration and reduced net section,it is common aerospace practice to develop notched design allowablestrengths based on gr
24、oss section stress to account for various stressconcentrations (fastener holes, free edges, flaws, damage, and so forth) notexplicitly modeled in the stress analysis.5. Significance and Use5.1 This practice provides supplemental instructions thatallow Test Methods D 5766/D 5766M (for tension testing
25、) andD 6484/D 6484M (for compression testing) to determine filled-hole tensile and compressive strength data for material speci-fications, research and development, material design allow-ables, and quality assurance. Factors that influence filled-holetensile and compressive strengths and shall there
26、fore bereported include the following: material, methods of materialfabrication, accuracy of lay-up, laminate stacking sequence andoverall thickness, specimen geometry (including hole diameter,diameter-to-thickness ratio, and width-to-diameter ratio),specimen preparation (especially of the hole), fa
27、stener-holeclearance, fastener type, fastener geometry, fastener installa-tion method, fastener torque (if appropriate), countersink depth(if appropriate), specimen conditioning, environment of test-ing, specimen alignment and gripping, speed of testing, time attemperature, void content, and volume
28、percent reinforcement.Properties that result include the following:5.1.1 Filled-hole tensile (FHT) strength, Fxfhtu.5.1.2 Filled-hole compressive (FHC) strength, Fxfhcu.6. Interferences6.1 Fastener-Hole ClearanceCompression test results, inparticular, are affected by the clearance arising from thedi
29、fference between hole and fastener diameters. A 25m0.001in. change in clearance can change the observedfailure mode and affect strength results by as much as 25 %(1).3For this reason, both the hole and fastener diameters mustbe accurately measured and recorded. A typical aerospacetolerance on fasten
30、er-hole clearance is +75/0 m +0.003/0.000 in. for structural fastener holes. Filled-hole specimenbehavior is also affected by clearance under tensile loading, butto a lesser degree than under compressive forces (2-3). Damagecaused by insufficient clearance during fastener installationwill affect str
31、ength results. Countersink flushness (depth orprotrusion of the fastener head in a countersunk hole) willaffect strength results, and must be accurately measured andrecorded.6.2 Fastener Torque/PreloadResults are affected by theinstalled fastener preload (clamping pressure). Laminates canexhibit sig
32、nificant differences in both failure force and failuremode because of changes in fastener preload under both tensileand compressive loading. The critical preload condition (eitherhigh or low clamping pressure) can vary depending upon thetype of loading, the material system, laminate stacking se-quen
33、ce, and test environment (3-5). Compared to open-holetensile (OHT) strengths, filled-hole tensile (FHT) strengths canbe either higher or lower than corresponding OHT values,depending on the material system, stacking sequence, testenvironment, and amount of fastener torque (6). Notchedtensile strengt
34、hs can be high torque critical for some layups andlow torque (or open hole) critical for others, depending uponthe characteristics of the material system (resin brittleness,fiber strain to failure, and so forth), the test environment, andthe modes of failure that arise. Filled-hole compressive (FHC)
35、strengths are almost always higher than the correspondingopen-hole compressive (OHC) strengths, although high versuslow clamp-up criticality can vary depending upon the materialsystem, stacking sequence, and test environment (5).6.3 Fastener Type/Hole PreparationResults are affectedby the geometry a
36、nd type of fastener used (for example,lockbolt, blind bolt) and the fastener installation procedures.Results are also affected by the hole preparation procedures.3Boldface numbers in parentheses refer to the list of references at the end of thispractice.D 6742/D 6742M 0726.4 EnvironmentResults are a
37、ffected by the environmen-tal conditions under which the tests are conducted. Laminatestested in various environments can exhibit significant differ-ences in both failure force and failure mode. Experience hasdemonstrated that cold temperature environments are generallycritical for filled-hole tensi
38、le strength, while elevated tempera-ture, humid environments are generally critical for filled-holecompressive strength. However, critical environments must beassessed independently for each material system, stackingsequence, and torque condition tested.6.5 Specimen GeometryIn addition to the geomet
39、ricalinterferences documented in Test Methods D 5766/D 5766Mand D 6484/D 6484M, results may be affected by the ratio ofcountersunk (flush) head depth to thickness; the preferred ratiois the range of 0.0 to 0.7 unless the experiment is investigatingthe influence of this ratio. Results may also be aff
40、ected by theratio of specimen width to fastener diameter, which may varyfrom the preferred ratio of 6 depending upon the particularfastener and hole diameters used. Results may also be affectedif the hole is not centered by length or width.6.6 Material OrthotropyThe degree of laminate orthot-ropy st
41、rongly affects the failure mode and measured FHT andFHC strengths. Valid FHT and FHC strength results shouldonly be reported when appropriate failure modes are observed,according to 11.6.6.7 OtherAdditional sources of potential data scatter aredocumented in Test Method D 5766/D 5766M for tension tes
42、tsand in Test Method D 6484/D 6484 for compression tests.7. Apparatus7.1 General ApparatusGeneral apparatus shall be in ac-cordance with Test Methods D 5766/D 5766M (for tensiontests) and D 6484/D 6484M (for compression tests), althoughwith a fastener or pin installed in the specimen hole. Themicrom
43、eter or gage used shall be capable of determining thehole and fastener diameters to 68m60.0003 in.7.2 FastenerThe fastener or pin type shall be specified asan initial test parameter and reported. The nominal fastenerdiameter shall be 6 mm 0.25 in., unless a range of diametersis being investigated. S
44、ome fastener types (for example blindbolts) may not be available in this diameter; for these, it isrecommended to use a fastener for which the diameter is asclose as possible to 6 mm 0.25 in. The installation torque (ifapplicable) shall be specified as an initial test parameter andreported. This val
45、ue may be a measured torque or a specifica-tion torque for fasteners with lock-setting features. If washersare used, the washer type, number of washers, and washerlocation(s) shall be specified as initial test parameters andreported. Reuse of fasteners is not recommended because ofpotential differen
46、ces in through-thickness clamp-up for a giventorque level, caused by wear of the threads.7.3 Torque WrenchIf using a torqued fastener, the torquewrench used to tighten the fastener shall be capable ofdetermining the applied torque to within 610 % of the desiredvalue.8. Sampling and Test Specimens8.1
47、 SamplingFor tension tests, sampling shall be in ac-cordance with Test Method D 5766/D 5766M. For compres-sion tests, sampling shall be in accordance with Test MethodD 6484/D 6484M.8.2 Geometry:8.2.1 Stacking SequenceThe standard laminates shallhave multidirectional fiber orientations (fibers shall
48、be orientedin a minimum of two directions) and balanced and symmetricstacking sequences. For tension specimens, nominal thicknessshall be 2.5 mm 0.10 in., with a permissible range of 2 to 4mm 0.080 to 0.160 in., inclusive. For compression speci-mens, nominal thickness shall be 4 mm 0.160 in., with a
49、permissible range of 3 to 5 mm 0.125 to 0.200 in., inclusive.Fabric laminates containing satin-type weaves shall havesymmetric warp surfaces, unless otherwise specified and notedin the report.NOTE 3Typically, a 45i/45i/0j/90knstape or 45i/0jnsfabric 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 acceptable failure modes. ConsultPractice D 6507 for information on fiber orientation code
