1、Designation:D6742/D6742M07 Designation: D6742/D6742M 12Standard 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 origina
2、l adoption or, 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 tensio
3、n and compression 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
4、testlaminates 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 importantte
5、st specimen 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 t
6、o be regarded separately as standard. Within the text theinch-pound units are shown in brackets. The values stated in each system aremay not be exact equivalents; therefore, each systemmustshall be used independently of the other. Combining values from the two systems may result in non-conformance w
7、ith thestandard.1.3.1 Within the text the inch-pound units are shown in brackets.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 health practices and de
8、termine the applicability of regulatorylimitations prior to use.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 Mat
9、erialsD3878 Terminology for Composite 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-H
10、ole Compressive Strength of Polymer 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
11、 Quality and StatisticsE1309 Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in DatabasesE1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases3. Terminology3.1 DefinitionsTerminology D3878 defines terms relating to high-mo
12、dulus fibers and their composites. Terminology D883defines terms relating to plastics. Terminology E6 defines terms relating to mechanical testing. Terminology E456 and Practice1This practice is under the jurisdiction of ASTM Committee D30 on Composite Materials , and is the direct responsibility of
13、 Subcommittee D30.05 on Structural TestMethods.Current edition approved Oct. 15, 2007.April 1, 2012. Published November 2007.May 2012. Originally approved in 2001. Last previous edition approved in 2007 asD6742/D6742M02(2007).D6742/D6742M 07. DOI: 10.1520/D6742_D6742M-0712.2For referencedASTM standa
14、rds, 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.1This document is not an ASTM standard and is intended only to provide the user of an AS
15、TM 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 appropriate. In all cases only the current versionof the standard as published
16、 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 States.E177 define terms relating to statistics. In the event of a conflict between terms, Terminology D3878 shall have precedence overthe oth
17、er 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 standard symbology for fundame
18、ntal dimensions, shown within square brackets:M 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 symbols may have other definitions when used wi
19、thout 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 or protrusion of counte
20、rsunk 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 properly install a countersun
21、k 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 flushnessf = distance, p
22、erpendicular 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 of specimenh = specimen thic
23、knessPmax= 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 tension test of a balanced, symme
24、tric laminate with a centrally located hole.4.2 Filled-Hole Compressive StrengthIn accordance with Test Method D6484/D6484M, but with a close-tolerance fasteneror pin installed in the hole, perform a uniaxial compression test of a balanced, symmetric laminate with a centrally located hole.NOTE 2For
25、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 allowable strengthsbased on
26、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 D5766/D5766M (for tension testi
27、ng) 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 strengths and shall therefor
28、e 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 (especially of the hole), fa
29、stener-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 temperature, void content, and volume p
30、ercentreinforcement. 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 clearance arising from the d
31、ifferencebetween hole and fastener diameters. A25m 0.001in. change in clearance can change the observed failure mode and affectstrength results by as much as 25 % (1).3For this reason, both the hole and fastener diameters must be accurately measured and3Boldface numbers in parentheses refer to the l
32、ist of references at the end of this practice.D6742/D6742M 122recorded. A typical aerospace tolerance on fastener-hole clearance is +75/0 m +0.003/0.000 in. for structural fastener holes.Filled-hole specimen behavior is also affected by clearance under tensile loading, but to a lesser degree than un
33、der compressiveforces (2-3). Damage caused by insufficient 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 be accurately measured andrecorded.6.2 Fastener
34、 Torque/PreloadResults are affected by the installed fastener 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
35、 or low clamping pressure) can vary depending upon the type 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
36、 on thematerial system, stacking sequence, test environment, 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 s
37、train to failure, and so forth), the test environment, and 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
38、system, stacking sequence, and test environment (5).6.3 Fastener 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 Environme
39、ntResults are affected by the environmental conditions under 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 fil
40、led-hole tensile strength, while elevated temperature, humidenvironments 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
41、 to the geometrical interferences documented in Test Methods 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 ma
42、y also be affected by the ratio of specimenwidth to fastener 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
43、 orthotropy strongly affects the failure mode and measured 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 f
44、or tension tests andin Test Method D6484/D6484M for compression 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.
45、The micrometer or gageused shall be capable of determining the hole and fastener diameters to 68m60.0003 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 inve
46、stigated. Some fastener types (for example blind bolts) 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 repo
47、rted. This value may be ameasured torque or a specification 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 pote
48、ntial differences in through-thickness clamp-up for a given 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
49、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:8.2.1 Stacking SequenceThe standard laminates shall have multidirectional fiber orientations (fibers shall be oriented in aminimum of two directions) and balanced and symmetric stacking sequences. For tension specimens, nominal thickness shall be2.5 mm 0.10 in., with a permissible range of 2 to 4 mm 0.080 to 0.160 in., inclusiv
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