ASTM D6742/D6742M-02(2007)
(Practice)Standard Practice for Filled-Hole Tension and Compression Testing of Polymer Matrix Composite Laminates
Standard Practice for Filled-Hole Tension and Compression Testing of Polymer Matrix Composite Laminates
SIGNIFICANCE AND USE
This practice provides supplemental instructions that allow Test Methods D 5766/D 5766M (for tension testing) and D 6484/D 6484M (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 and compressive strengths and shall therefore be reported include the following: material, methods of material fabrication, accuracy of lay-up, laminate stacking sequence and overall thickness, specimen geometry (including hole diameter, diameter-to-thickness ratio, and width-to-diameter ratio), specimen preparation (especially of the hole), fastener-hole clearance, fastener type, fastener geometry, 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 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.
SCOPE
1.1 This practice provides instructions for modifying open-hole tension and compression test methods to determine filled-hole tensile and compressive strengths. The composite material forms are limited to continuous-fiber reinforced polymer matrix composites in which the laminate is both symmetric and balanced with respect to the test direction. The range of acceptable test laminates and thicknesses are described in .
1.2 This practice supplements Test Methods D 5766/D 5766M (for tension testing) and D 6484/D 6484M (for compression testing) with provisions for testing specimens that contain a close-tolerance fastener or pin installed in the hole. Several important test specimen parameters (for example, fastener selection, fastener installation method, and fastener hole tolerance) are not mandated 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 regarded separately as standard. Within the text the inch-pound units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation:D6742/D6742M–02(Reapproved2007)
Standard Practice for
Filled-Hole Tension and Compression Testing of Polymer
Matrix Composite Laminates
This standard is issued under the fixed designation D6742/D6742M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D792 TestMethodsforDensityandSpecificGravity(Rela-
tive Density) of Plastics by Displacement
1.1 This practice provides instructions for modifying open-
D883 Terminology Relating to Plastics
hole tension and compression test methods to determine
D3171 TestMethodsforConstituentContentofComposite
filled-hole tensile and compressive strengths. The composite
Materials
material forms are limited to continuous-fiber reinforced poly-
D3878 Terminology for Composite Materials
mermatrixcompositesinwhichthelaminateisbothsymmetric
D5229/D5229M Test Method for Moisture Absorption
and balanced with respect to the test direction. The range of
Properties and Equilibrium Conditioning of Polymer Ma-
acceptable test laminates and thicknesses are described in
trix Composite Materials
8.2.1.
D 5766/D 5766M Test Method for Open Hole Tensile
1.2 This practice supplements Test Methods D 5766/
Strength of Polymer Matrix Composite Laminates
D5766M (for tension testing) and D6484/D6484M (for
D6484/D6484M TestMethodforOpen-HoleCompressive
compressiontesting)withprovisionsfortestingspecimensthat
Strength of Polymer Matrix Composite Laminates
contain a close-tolerance fastener or pin installed in the hole.
D6507 PracticeforFiberReinforcementOrientationCodes
Several important test specimen parameters (for example,
for Composite Materials
fastener selection, fastener installation method, and fastener
E6 Terminology Relating to Methods of Mechanical Test-
hole tolerance) are not mandated by this practice; however,
ing
repeatableresultsrequirethattheseparametersbespecifiedand
E177 Practice for Use of the Terms Precision and Bias in
reported.
ASTM Test Methods
1.3 The values stated in either SI units or inch-pound units
E456 Terminology Relating to Quality and Statistics
are to be regarded separately as standard. Within the text the
E 1309 Guide for Identification of Fiber-Reinforced
inch-pound units are shown in brackets. The values stated in
Polymer-Matrix Composite Materials in Databases
each system are not exact equivalents; therefore, each system
E1434 GuideforRecordingMechanicalTestDataofFiber-
must be used independently of the other. Combining values
Reinforced Composite Materials in Databases
from the two systems may result in nonconformance with the
standard.
3. Terminology
1.4 This standard does not purport to address all of the
3.1 Definitions—TerminologyD3878definestermsrelating
safety concerns, if any, associated with its use. It is the
to high-modulus fibers and their composites. Terminology
responsibility of the user of this standard to establish appro-
D883 defines terms relating to plastics. Terminology E6
priate safety and health practices and determine the applica-
defines terms relating to mechanical testing. Terminology
bility of regulatory limitations prior to use.
E456 and Practice E177 define terms relating to statistics. In
2. Referenced Documents the event of a conflict between terms, Terminology D3878
shall have precedence over the other standards.
2.1 ASTM Standards:
3.2 Definitions of Terms Specific to This Standard:
NOTE 1—If the term represents a physical quantity, its analytical
This practice is under the jurisdiction ofASTM Committee D30 on Composite
dimensionsarestatedimmediatelyfollowingtheterm(orlettersymbol)in
Materials , and is the direct responsibility of Subcommittee D30.05 on Structural
fundamental dimension form, using the following ASTM International
Test Methods.
standard symbology for fundamental dimensions, shown within square
Current edition approved May 1, 2007. Published June 2007. Originally
brackets:[M]formass,[L]forlength,[T]fortime,[u]forthermodynamic
approvedin2001.Lastpreviouseditionapprovedin2002asD6742/D6742M–02.
temperature,and[nd]fornondimensionalquantities.Useofthesesymbols
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM is restricted to analytical dimensions when used with square brackets, as
Standards volume information, refer to the standard’s Document Summary page on
the symbols may have other definitions when used without the brackets.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6742/D6742M–02 (2007)
3.2.1 nominal value, n—a value, existing in name only, overall thickness, specimen geometry, specimen preparation
assigned to a measurable property for the purpose of conve- (especially of the hole), fastener-hole clearance, fastener type,
nient designation. Tolerances may be applied to a nominal fastenergeometry,fastenerinstallationmethod,fastenertorque
value to define an acceptable range for the property. (if appropriate), countersink depth (if appropriate), specimen
3.2.2 countersink flushness, n—depthorprotrusionofcoun- conditioning, environment of testing, specimen alignment and
tersunk fastener head relative to the laminate surface after gripping, speed of testing, void content, and volume percent
installation. A positive value indicates protrusion of the fas- reinforcement. Properties that result include the following:
fhtu
tener head above the laminate surface; a negative value 5.1.1 Filled-hole tensile (FHT) strength, F .
x
fhcu
indicates depth below the surface. 5.1.2 Filled-hole compressive (FHC) strength, F .
x
3.2.3 countersink depth, n—depth of countersinking re-
quired to properly install a countersunk fastener, such that
6. Interferences
countersink flushness is nominally zero. Countersink depth is
6.1 Fastener-Hole Clearance—Compression test results, in
nominally equivalent to the height of the fastener head.
particular, are affected by the clearance arising from the
3.3 Symbols:
difference between hole and fastener diameters. A 25−µm
3.3.1 A = cross-sectional area of a specimen.
[0.001−in.] change in clearance can change the observed
3.3.2 d = fastener diameter.
failure mode and affect strength results by as much as 25%
3.3.3 D = specimen hole diameter. 3
(1). Forthisreason,boththeholeandfastenerdiametersmust
3.3.4 d = countersink depth.
csk
be accurately measured and recorded. A typical aerospace
3.3.5 d = countersink flushness.
fl
tolerance on fastener-hole clearance is +75/−0 µm [+0.003/
3.3.6 f = distance, perpendicular to loading axis, from hole
−0.000 in.] for structural fastener holes. Filled-hole specimen
edge to closest side of specimen.
behaviorisalsoaffectedbyclearanceundertensileloading,but
fhcu
3.3.7 F =ultimatefilled-holecompressivestrengthinthe
x
toalesserdegreethanundercompressiveloads (2-3).Damage
test direction.
caused by insufficient clearance during fastener installation
fhtu
3.3.8 F = ultimate filled-hole tensile strength in the test
x
will affect strength results. Countersink flushness (depth or
direction.
protrusion of the fastener head in a countersunk hole) will
3.3.9 g = distance, parallel to loading axis, from hole edge
affect strength results, and must be accurately measured and
to end of specimen.
recorded.
3.3.10 h = specimen thickness.
6.2 Fastener Torque/Preload—Results are affected by the
max
3.3.11 P = maximum load prior to failure.
installed fastener preload (clamping pressure). Laminates can
3.3.12 w = specimen width.
exhibit significant differences in both failure load and failure
modebecauseofchangesinfastenerpreloadunderbothtensile
4. Summary of Practice
andcompressiveloading.Thecriticalpreloadcondition(either
4.1 Filled-Hole Tensile Strength—In accordance with Test high or low clamping pressure) can vary depending upon the
Method D5766/D5766M, but with a close-tolerance fastener
type of loading, the material system, laminate stacking se-
or pin installed in the hole, perform a uniaxial tension test of a quence, and test environment (3-5). Compared to open-hole
balanced, symmetric laminate with a centrally located hole.
tensile(OHT)strengths,filled-holetensile(FHT)strengthscan
4.2 Filled-Hole Compressive Strength—In accordance with be either higher or lower than corresponding OHT values,
Test Method D6484/D6484M, but with a close-tolerance depending on the material system, stacking sequence, test
fastener or pin installed in the hole, perform a uniaxial environment, and amount of fastener torque (6). Notched
compression test of a balanced, symmetric laminate with a tensilestrengthscanbehightorquecriticalforsomelayupsand
centrally located hole.
low torque (or open hole) critical for others, depending upon
the characteristics of the material system (resin brittleness,
NOTE 2—Forbothtestmethods,ultimatestrengthiscalculatedbasedon
fiber strain to failure, and so forth), the test environment, and
the gross cross-sectional area, disregarding the presence of the filled hole.
the modes of failure that arise. Filled-hole compressive (FHC)
Whilethefilledholecausesastressconcentrationandreducednetsection,
it is common aerospace practice to develop notched design allowable strengths are almost always higher than the corresponding
strengths based on gross section stress to account for various stress
open-hole compressive (OHC) strengths, although high versus
concentrations(fastenerholes,freeedges,flaws,damage,andsoforth)not
low clamp-up criticality can vary depending upon the material
explicitly modeled in the stress analysis.
system, stacking sequence, and test environment (5).
6.3 Fastener Type/Hole Preparation—Results are affected
5. Significance and Use
by the geometry and type of fastener used (for example,
5.1 This practice provides supplemental instructions that
lockbolt, blind bolt) and the fastener installation procedures.
allowTest Methods D5766/D5766M (for tension testing) and
Results are also affected by the hole preparation procedures.
D6484/D6484M(forcompressiontesting)todeterminefilled-
6.4 Environment—Results are affected by the environmen-
hole tensile and compressive strength data for material speci-
tal conditions under which the tests are conducted. Laminates
fications, research and development, material design allow-
ables, and quality assurance. Factors that influence filled-hole
tensile and compressive strengths and shall therefore be
reported include the following: material, methods of material
Boldfacenumbersinparenthesesrefertothelistofreferencesattheendofthis
fabrication,accuracyoflay-up,laminatestackingsequenceand practice.
D6742/D6742M–02 (2007)
tested in various environments can exhibit significant differ- 8.2 Geometry:
ences in both failure load and failure mode. Experience has 8.2.1 Stacking Sequence—The standard tape and fabric
demonstratedthatcoldtemperatureenvironmentsaregenerally laminates shall have multidirectional fiber orientations (fibers
critical for filled-hole tensile strength, while elevated tempera- shallbeorientedinaminimumoftwodirections)andbalanced
ture, humid environments are generally critical for filled-hole and symmetric stacking sequences. For tension specimens,
compressive strength. However, critical environments must be nominal thickness shall be 2.5 mm [0.10 in.], with a permis-
assessed independently for each material system, stacking sible range of 2 to 4 mm [0.080 to 0.160 in.], inclusive. For
sequence, and torque condition tested. compression specimens, nominal thickness shall be 4 mm
6.5 Specimen Geometry—In addition to the geometrical [0.160 in.], with a permissible range of 3 to 5 mm [0.125 to
interferences documented in Test Methods D5766/D5766M 0.200 in.], inclusive. Fabric laminates containing satin-type
and D6484/D6484M, results may be affected by the ratio of weaves shall have symmetric warp surfaces, unless otherwise
countersunk (flush) head depth to thickness; the preferred ratio specified and noted in the report.
is the range of 0.0 to 0.7 unless the experiment is investigating
NOTE 3—Typically, a [45/−45/0/90 ] tape or [45/0] fabric lami-
i i j k ns i j ns
the influence of this ratio. Results may also be affected by the
nate should be selected such that a minimum of 5% of the fibers lay in
ratio of specimen width to fastener diameter, which may vary
each of the four principal orientations. This laminate design has been
from the preferred ratio of 6 depending upon the particular
found to yield the highest likelihood of acceptable failure modes. Consult
Practice D6507 for information on fiber orientation codes.
fastener and hole diameters used. Results may also be affected
if the hole is not centered by length or width.
8.2.2 Specimen Configuration—For tension tests, the test
6.6 Material Orthotropy—The degree of laminate orthot-
specimen configuration shall be in accordance with Test
ropy strongly affects the failure mode and measured FHT and
Method D5766/D5766M. For compression tests, the test
FHC strengths. Valid FHT and FHC strength results should
specimen configuration shall be in accordance with Test
only be reported when appropriate failure modes are observed,
Method D6484/D6484M. The nominal hole diameter may
according to 11.5.
varyfromthatspecifiedinTestMethodsD5766/D5766Mand
6.7 Other—Additional sources of potential data scatter are
D6484/D6484M depending upon the type of fastener used.
documented inTest Method D5766/D5766M for tension tests
8.3 Specimen Preparation—For tension tests, specimens
and in Test Method D6484/D6484 for compression tests.
shall be prepared in accordance with Test Method D5766/
D5766M. For compression tests, specimens shall be prepared
7. Apparatus
in accordance withTest Method D6484/D6484M. Use appro-
7.1 General Apparatus—General apparatus shall be in ac-
priate hole preparation procedures specified by the test re-
cordance with Test Methods D5766/D5766M (for tension
questor.
tests) and D6484/D6484M (for compression tests), although
9. Calibration
with a fastener or pin installed in the specimen hole. The
micrometer or gage used shall be capable of determining the
9.1 The accuracy of all measuring equipment shall have
hole and fastener diameters to 68µm[60.0003 in.].
certified calibrations that are current at the time of use of the
7.2 Fastener—The fastener or pin type shall be specified as
equipment.
an initial test parameter and reported. The nominal fastener
10. Conditioning
diameter shall be 6 mm [0.25 in.], unless a range of diameters
is being investigated. Some fastener types (for example b
...
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