ASTM D6742/D6742M-01
(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
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 8.2.1.
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.
1.4 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)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: D 6742/D 6742M – 01
Standard Practice for
Filled-Hole Tension and Compression Testing of Polymer
Matrix Composite Laminates
This standard is issued under the fixed designation D 6742/D 6742M; 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 D 3171 Test Method for Constituent Content of Composite
Materials
1.1 This practice provides instructions for modifying open-
D 3878 Terminology for Composite Materials
hole tension and compression test methods to determine
D 5229/D 5229M Test Method for Moisture Absorption
filled-hole tensile and compressive strengths. The composite
Properties and Equilibrium Conditioning of Polymer Ma-
material forms are limited to continuous-fiber reinforced poly-
trix Composite Materials
mer matrix composites in which the laminate is both symmetric
D 5766/D 5766M Test Method for Open-Hole Tensile
and balanced with respect to the test direction. The range of
Strength of Polymer Matrix Composite Laminates
acceptable test laminates and thicknesses are described in
D 6484/D 6484M Test Method for Open-Hole Compressive
8.2.1.
Strength of Polymer Matrix Composite Laminates
1.2 This practice supplements Test Methods D 5766/
D 6507 Practice for the Fiber Reinforcement Orientation
D 5766M (for tension testing) and D 6484/D 6484M (for
Codes for Composite Materials
compression testing) with provisions for testing specimens that
E 6 Terminology Relating to Methods of Mechanical Test-
contain a close-tolerance fastener or pin installed in the hole.
ing
Several important test specimen parameters (for example,
E 177 Practice for Use of the Terms Precision and Bias in
fastener selection, fastener installation method, and fastener
ASTM Test Methods
hole tolerance) are not mandated by this practice; however,
E 456 Terminology Relating to Quality and Statistics
repeatable results require that these parameters be specified and
E 1309 Guide for Identification of Fiber-Reinforced
reported.
Polymer-Matrix Composite Materials in Databases
1.3 The values stated in either SI units or inch-pound units
E 1434 Guide for Recording Mechanical Test Data of Fiber-
are to be regarded separately as standard. Within the text the
Reinforced Composite Materials in Databases
inch-pound units are shown in brackets. The values stated in
each system are not exact equivalents; therefore, each system
3. Terminology
must be used independently of the other. Combining values
3.1 Definitions—Terminology D 3878 defines terms relating
from the two systems may result in nonconformance with the
to high-modulus fibers and their composites. Terminology
standard.
D 883 defines terms relating to plastics. Terminology E 6
1.4 This standard does not purport to address all of the
defines terms relating to mechanical testing. Terminology
safety concerns, if any, associated with its use. It is the
E 456 and Practice E 177 define terms relating to statistics. In
responsibility of the user of this standard to establish appro-
the event of a conflict between terms, Terminology D 3878
priate safety and health practices and determine the applica-
shall have precedence over the other standards.
bility of regulatory limitations prior to use.
3.2 Definitions of Terms Specific to This Standard:
2. Referenced Documents
NOTE 1—If the term represents a physical quantity, its analytical
2.1 ASTM Standards:
dimensions are stated immediately following the term (or letter symbol) in
fundamental dimension form, using the following ASTM International
D 792 Test Methods for Specific Gravity (Relative Density)
standard symbology for fundamental dimensions, shown within square
and Density of Plastics by Displacement
2 brackets: [M] for mass, [L] for length, [T] for time, [u] for thermodynamic
D 883 Terminology Relating to Plastics
temperature, and [nd] for nondimensional quantities. Use of these symbols
is restricted to analytical dimensions when used with square brackets, as
the symbols may have other definitions when used without the brackets.
3.2.1 nominal value, n—a value, existing in name only,
This practice is under the jurisdiction of ASTM Committee D30 on Composite
Materials, and is the direct responsibility of Subcommittee D30.05 on Structural
Test Methods.
Annual Book of ASTM Standards, Vol 15.03.
Current edition approved Nov. 10, 2001. Published March 2002.
2 Annual Book of ASTM Standards, Vol 03.01.
Annual Book of ASTM Standards, Vol 08.01.
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 6742/D 6742M
assigned to a measurable property for the purpose of conve- fastener geometry, fastener installation method, fastener torque
nient designation. Tolerances may be applied to a nominal (if appropriate), countersink depth (if appropriate), specimen
value to define an acceptable range for the property. conditioning, environment of testing, specimen alignment and
3.2.2 countersink flushness, n—depth or protrusion of coun- gripping, speed of testing, void content, and volume percent
tersunk fastener head relative to the laminate surface after reinforcement. Properties that result include the following:
fhtu
installation. A positive value indicates protrusion of the fas- 5.1.1 Filled-hole tensile (FHT) strength, F .
x
fhcu
tener head above the laminate surface; a negative value 5.1.2 Filled-hole compressive (FHC) strength, F .
x
indicates depth below the surface.
6. Interferences
3.2.3 countersink depth, n—depth of countersinking re-
quired to properly install a countersunk fastener, such that
6.1 Fastener-Hole Clearance—Compression test results, in
countersink flushness is nominally zero. Countersink depth is particular, are affected by the clearance arising from the
nominally equivalent to the height of the fastener head.
difference between hole and fastener diameters. A 25−μm
3.3 Symbols: [0.001−in.] change in clearance can change the observed
3.3.1 A = cross-sectional area of a specimen.
failure mode and affect strength results by as much as 25 %
3.3.2 d = fastener diameter. (1). For this reason, both the hole and fastener diameters must
3.3.3 D = specimen hole diameter.
be accurately measured and recorded. A typical aerospace
3.3.4 d = countersink depth. tolerance on fastener-hole clearance is +75/−0 μm [+0.003/
csk
3.3.5 d = countersink flushness.
−0.000 in.] for structural fastener holes. Filled-hole specimen
fl
3.3.6 f = distance, perpendicular to loading axis, from hole behavior is also affected by clearance under tensile loading, but
edge to closest side of specimen.
to a lesser degree than under compressive loads (2-3). Damage
fhcu
3.3.7 F = ultimate filled-hole compressive strength in the
caused by insufficient clearance during fastener installation
x
test direction.
will affect strength results. Countersink flushness (depth or
fhtu
3.3.8 F = ultimate filled-hole tensile strength in the test
protrusion of the fastener head in a countersunk hole) will
x
direction. affect strength results, and must be accurately measured and
3.3.9 g = distance, parallel to loading axis, from hole edge
recorded.
to end of specimen. 6.2 Fastener Torque/Preload—Results are affected by the
3.3.10 h = specimen thickness.
installed fastener preload (clamping pressure). Laminates can
max
3.3.11 P = maximum load prior to failure. exhibit significant differences in both failure load and failure
3.3.12 w = specimen width.
mode because of changes in fastener preload under both tensile
and compressive loading. The critical preload condition (either
4. Summary of Practice
high or low clamping pressure) can vary depending upon the
4.1 Filled-Hole Tensile Strength—In accordance with Test
type of loading, the material system, laminate stacking se-
Method D 5766/D 5766M, but with a close-tolerance fastener
quence, and test environment (3-5). Compared to open-hole
or pin installed in the hole, perform a uniaxial tension test of a
tensile (OHT) strengths, filled-hole tensile (FHT) strengths can
balanced, symmetric laminate with a centrally located hole.
be either higher or lower than corresponding OHT values,
4.2 Filled-Hole Compressive Strength—In accordance with
depending on the material system, stacking sequence, test
Test Method D 6484/D 6484M, but with a close-tolerance
environment, and amount of fastener torque (6). Notched
fastener or pin installed in the hole, perform a uniaxial
tensile strengths can be high torque critical for some layups and
compression test of a balanced, symmetric laminate with a
low torque (or open hole) critical for others, depending upon
centrally located hole.
the characteristics of the material system (resin brittleness,
NOTE 2—For both test methods, ultimate strength is calculated based on
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)
While the filled hole causes a stress concentration and reduced net section,
strengths are almost always higher than the corresponding
it is common aerospace practice to develop notched design allowable
open-hole compressive (OHC) strengths, although high versus
strengths based on gross section stress to account for various stress
low clamp-up criticality can vary depending upon the material
concentrations (fastener holes, free edges, flaws, damage, and so forth) not
system, stacking sequence, and test environment (5).
explicitly modeled in the stress analysis.
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.
allow Test Methods D 5766/D 5766M (for tension testing) and
Results are also affected by the hole preparation procedures.
D 6484/D 6484M (for compression testing) to determine filled-
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-
tested in various environments can exhibit significant differ-
ables, and quality assurance. Factors that influence filled-hole
ences in both failure load and failure mode. Experience has
tensile and compressive strengths and shall therefore be
demonstrated that cold temperature environments are generally
reported include the following: material, methods of material
fabrication, accuracy of lay-up, laminate stacking sequence and
overall thickness, specimen geometry, specimen preparation 6
Boldface numbers in parentheses refer to the list of references at the end of this
(especially of the hole), fastener-hole clearance, fastener type, practice.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 6742/D 6742M
critical for filled-hole tensile strength, while evaluated tem- shall be oriented in a minimum of two directions) and balanced
perature, humid environments are generally critical for filled- and symmetric stacking sequences. For tension specimens,
hole compressive strength. However, critical environments nominal thickness shall be 2.5 mm [0.10 in.], with a permis-
must be assessed independently for each material system, sible range of 2 to 4 mm [0.080 to 0.160 in.], inclusive. For
stacking 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 D 5766/D 5766M 0.200 in.], inclusive. Fabric laminates containing satin-type
and D 6484/D 6484M, 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 D 6507 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-
coupon configuration shall be in accordance with Test Method
ropy strongly affects the failure mode and measured FHT and
D 5766/D 5766M. For compression tests, the test coupon
FHC strengths. Valid FHT and FHC strength results should
configuration shall be in accordance with Test Method D 6484/
only be reported when appropriate failure modes are observed,
D 6484M. The nominal hole diameter may vary from that
according to 11.5.
specified in Test Methods D 5766/D 5766M and D 6484/
6.7 Other—Additional sources of potential data scatter are
D 6484M depending upon the type of fastener used.
documented in Test Method D 5766/D 5766M for tension tests
8.3 Specimen Preparation—For tension tests, specimens
and in Test Method D 6484/D 6484 for compression tests.
shall be prepared in accordance with Test Method D 5766/
D 5766M. For compression tests, specimens shall be prepared
7. Apparatus
in accordance with Test Method D 6484/D 6484M. 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 D 5766/D 5766M (for tension
questor.
tests) and D 6484/D 6484M (for compression tests), although
9. Calibration
with a fastener or pin installed in the coupon hole. The
micrometer or gage used shall be capable of determining the
9.1 The accuracy of all measuring equipment shall have
hole and fas
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