1、Designation: D6742/D6742M 12D6742/D6742M 17Standard Practice forFilled-Hole Tension and Compression Testing of PolymerMatrix Composite Laminates1This standard is issued under the fixed designation D6742/D6742M; the number immediately following the designation indicates theyear of original adoption o
2、r, in the case 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 practice provides instructions for modifying open-hole tension and compre
3、ssion test methods to determine filled-holetensile and compressive strengths. The composite material forms are limited to continuous-fiber reinforced polymer matrixcomposites in which the laminate is both symmetric and balanced with respect to the test direction. The range of acceptable testlaminate
4、s and thicknesses are described in 8.2.1.1.2 This practice supplements Test Methods D5766/D5766M (for tension testing) and D6484/D6484M (for compressiontesting) with provisions for testing specimens that contain a close-tolerance fastener or pin installed in the hole. Several importanttest specimen
5、parameters (for example, fastener selection, fastener installation method, and fastener hole tolerance) are notmandated by this practice; however, repeatable results require that these parameters be specified and reported.1.3 The values stated in either SI units or inch-pound units are to be regarde
6、d separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.3.1 Within the text the inch-pound units are shown in bracke
7、ts.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and healthsafety, health, environmental practices and determine theapplicability of regulatory limitation
8、s prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical
9、 Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by DisplacementD883 Terminology Relating to PlasticsD3171 Test Methods for Constituent Content of Composite MaterialsD3878 Terminology for C
10、omposite MaterialsD5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix CompositeMaterialsD5766/D5766M Test Method for Open-Hole Tensile Strength of Polymer Matrix Composite LaminatesD6484/D6484M Test Method for Open-Hole Compressive Strength of P
11、olymer Matrix Composite LaminatesD6507 Practice for Fiber Reinforcement Orientation Codes for Composite MaterialsE6 Terminology Relating to Methods of Mechanical TestingE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE1309
12、Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in Databases (Withdrawn 2015)3E1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases (Withdrawn 2015)31 This practice is under the jurisdiction of ASTM Committee D30 on Compos
13、ite Materials, and is the direct responsibility of Subcommittee D30.05 on Structural TestMethods.Current edition approved April 1, 2012Oct. 15, 2017. Published May 2012October 2017. Originally approved in 2001. Last previous edition approved in 20072012 asD6742/D6742M 07.D6742/D6742M 12. DOI: 10.152
14、0/D6742_D6742M-12.10.1520/D6742_D6742M-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is no
15、t an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriat
16、e. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 DefinitionsTerminology D3878 defines terms relati
17、ng to high-modulus fibers and their composites. Terminology D883defines terms relating to plastics. Terminology E6 defines terms relating to mechanical testing. Terminology E456 and PracticeE177 define terms relating to statistics. In the event of a conflict between terms, Terminology D3878 shall ha
18、ve precedence overthe other standards.3.2 Definitions of Terms Specific to This Standard:NOTE 1If the term represents a physical quantity, its analytical dimensions are stated immediately following the term (or letter symbol) infundamental dimension form, using the following ASTM International stand
19、ard symbology for fundamental dimensions, shown within square brackets:M for mass, L for length, T for time, for thermodynamic temperature, and nd for nondimensional quantities. Use of these symbols is restrictedto analytical dimensions when used with square brackets, as the symbols may have other d
20、efinitions when used without the brackets.3.2.1 nominal value, na value, existing in name only, assigned to a measurable property for the purpose of convenientdesignation. Tolerances may be applied to a nominal value to define an acceptable range for the property.3.2.2 countersink flushness, ndepth
21、or protrusion of countersunk fastener head relative to the laminate surface afterinstallation. A positive value indicates protrusion of the fastener head above the laminate surface; a negative value indicates depthbelow the surface.3.2.3 countersink depth, ndepth of countersinking required to proper
22、ly install a countersunk fastener, such that countersinkflushness is nominally zero. Countersink depth is nominally 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
23、 flushnessf = distance, perpendicular to loading axis, from hole edge to closest side of specimenFxfhcu = ultimate filled-hole compressive strength in the test directionFxfhtu = ultimate filled-hole tensile strength in the test directiong1 = distance, parallel to loading axis, from hole edge to end
24、of specimenh = specimen thicknessPmax = maximum force carried by test specimen prior to failurew = specimen width4. Summary of Practice4.1 Filled-Hole Tensile StrengthIn accordance with Test Method D5766/D5766M, but with a close-tolerance fastener or pininstalled in the hole, perform a uniaxial tens
25、ion test of a balanced, symmetric laminate with a centrally located hole.4.2 Filled-Hole Compressive StrengthIn accordance with Test Method D6484/D6484M, but with a close-tolerance fastener orpin installed in the hole, perform a uniaxial compression test of a balanced, symmetric laminate with a cent
26、rally located hole.NOTE 2For both test methods, ultimate strength is calculated based on the 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
27、 allowable strengthsbased on gross section stress to account for various stress concentrations (fastener holes, free edges, flaws, damage, and so forth) not explicitly modeledin the stress analysis.5. Significance and Use5.1 This practice provides supplemental instructions that allow Test Methods D5
28、766/D5766M (for tension testing) andD6484/D6484M (for compression testing) to determine filled-hole tensile and compressive strength data for material specifications,research and development, material design allowables, and quality assurance. Factors that influence filled-hole tensile andcompressive
29、 strengths and shall therefore be reported include the following: material, methods of material fabrication, accuracyof lay-up, laminate stacking sequence and overall thickness, specimen geometry (including hole diameter, diameter-to-thicknessratio, and width-to-diameter ratio), specimen preparation
30、 (especially of the hole), fastener-hole clearance, fastener type, fastenergeometry, fastener installation method, fastener torque (if appropriate), countersink depth (if appropriate), specimen conditioning,environment of testing, specimen alignment and gripping, speed of testing, time at temperatur
31、e, void content, and volume percentreinforcement. 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, in particular, are affected by the
32、 clearance arising from the differencebetween hole and fastener diameters. A25m A 25m 0.001in. change in clearance can change the observed failure modeD6742/D6742M 172and affect strength results by as much as 25 % (1).3 For this reason, both the hole and fastener diameters must be accuratelymeasured
33、 and recorded. A typical aerospace tolerance on fastener-hole clearance is +75/0 m +0.003/0.000 in. for structuralfastener holes. Filled-hole specimen behavior is also affected by clearance under tensile loading, but to a lesser degree than undercompressive forces(2-3). Damage caused by insufficient
34、 clearance during fastener installation will affect strength results.Countersink flushness (depth or protrusion of the fastener head in a countersunk hole) will affect strength results, and must beaccurately measured and recorded.6.2 Fastener Torque/PreloadResults are affected by the installed faste
35、ner preload (clamping pressure). Laminates can exhibitsignificant differences in both failure force and failure mode because of changes in fastener preload under both tensile andcompressive loading. The critical preload condition (either high or low clamping pressure) can vary depending upon the typ
36、e ofloading, the material system, laminate stacking sequence, and test environment (3-5). Compared to open-hole tensile (OHT)strengths, filled-hole tensile (FHT) strengths can be either higher or lower than corresponding OHT values, depending on thematerial system, stacking sequence, test environmen
37、t, and amount of fastener torque (6). Notched tensile strengths can be hightorque critical for some layups and low torque (or open hole) critical for others, depending upon the characteristics of the materialsystem (resin brittleness, fiber strain to failure, and so forth), the test environment, and
38、 the modes of failure that arise. Filled-holecompressive (FHC) strengths are almost always higher than the corresponding open-hole compressive (OHC) strengths, althoughhigh versus low clamp-up criticality can vary depending upon the material system, stacking sequence, and test environment (5).6.3 Fa
39、stener Type/Hole PreparationResults are affected by the geometry and type of fastener used (for example, lockbolt,blind bolt) and the fastener installation procedures. Results are also affected by the hole preparation procedures.6.4 EnvironmentResults are affected by the environmental conditions und
40、er which the tests are conducted. Laminates testedin various environments can exhibit significant differences in both failure force and failure mode. Experience has demonstrated thatcold temperature environments are generally critical for filled-hole tensile strength, while elevated temperature, hum
41、idenvironments are generally critical for filled-hole compressive strength. However, critical environments must be assessedindependently for each material system, stacking sequence, and torque condition tested.6.5 Specimen GeometryIn addition to the geometrical interferences documented in Test Metho
42、ds D5766/D5766M andD6484/D6484M, results may be affected by the ratio of countersunk (flush) head depth to thickness; the preferred ratio is the rangeof 0.0 to 0.7 unless the experiment is investigating the influence of this ratio. Results may also be affected by the ratio of specimenwidth to fasten
43、er diameter, which may vary from the preferred ratio of 6 depending upon the particular fastener and hole diametersused. Results may also be affected if the hole is not centered by length or width.6.6 Material OrthotropyThe degree of laminate orthotropy strongly affects the failure mode and measured
44、 FHT and FHCstrengths. Valid FHT and FHC strength results should only be reported when appropriate failure modes are observed, accordingto 11.6.6.7 OtherAdditional sources of potential data scatter are documented in Test Method D5766/D5766M for tension tests andin Test Method D6484/D6484M for compre
45、ssion tests.7. Apparatus7.1 General ApparatusGeneral apparatus shall be in accordance with Test Methods D5766/D5766M (for tension tests) andD6484/D6484M (for compression tests), although with a fastener or pin installed in the specimen hole. The micrometer or gageused shall be capable of determining
46、 the hole and fastener diameters to 68 m 60.0003 in.7.2 FastenerThe fastener or pin type shall be specified as an initial test parameter and reported. The nominal fastener diametershall be 6 mm 0.25 in., unless a range of diameters is being investigated. Some fastener types (for example blind bolts)
47、 may notbe available in this diameter; for these, it is recommended to use a fastener for which the diameter is as close as possible to 6 mm0.25 in. The installation torque (if applicable) shall be specified as an initial test parameter and reported. This value may be ameasured torque or a specifica
48、tion torque for fasteners with lock-setting features. If washers are used, the washer type, number ofwashers, and washer location(s) shall be specified as initial test parameters and reported. Reuse of fasteners is not recommendedbecause of potential differences in through-thickness clamp-up for a g
49、iven torque level, caused by wear of the threads.7.3 Torque WrenchIf using a torqued fastener, the torque wrench used to tighten the fastener shall be capable of determiningthe applied torque to within 610 % of the desired value.8. Sampling and Test Specimens8.1 SamplingFor tension tests, sampling shall be in accordance with Test Method D5766/D5766M. For compression tests,sampling shall be in accordance with Test Method D6484/D6484M.8.2 Geometry:3 Boldface numbers in parentheses refer to the list of references at the end of thi
