ASTM D6742/D6742M-23

Standard Practice for Filled-Hole Tension and Compression Testing of Polymer Matrix Composite Laminates

SIGNIFICANCE AND USE
5.1 Refer to Guide D8509.
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 D5766/D5766M (for tension testing) and D6484/D6484M (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. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.  
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 responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Aug-2023
• ICS: 83.120 - Reinforced plastics
• Technical Committee: D30 - Composite Materials
• Drafting Committee: D30.05 - Structural Test Methods

Relations

• Replaces: ASTM D6742/D6742M-17 - Standard Practice for Filled-Hole Tension and Compression Testing of Polymer Matrix Composite Laminates
• Effective Date: 01-Sep-2023
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D883-22 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2022
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM E456-13a(2022) - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D6484/D6484M-20 - Standard Test Method for Open-Hole Compressive Strength of Polymer Matrix Composite Laminates
• Effective Date: 01-Oct-2020
• Referred By: ASTM D6484/D6484M-23 - Standard Test Method for Open-Hole Compressive Strength of Polymer Matrix Composite Laminates
• Effective Date: 01-Sep-2023
• Referred By: ASTM D8387/D8387M-23 - Standard Test Method for High Bypass – Low Bearing Interaction Response of Polymer Matrix Composite Laminates
• Effective Date: 01-Sep-2023
• Referred By: ASTM D8509/D8509M-23 - Standard Guide for Test Method Selection and Test Specimen Design for Bolted Joint Related Properties
• Effective Date: 01-Sep-2023
• Referred By: ASTM D4762-23 - Standard Guide for Testing Polymer Matrix Composite Materials
• Effective Date: 01-Sep-2023
• Referred By: ASTM D7248/D7248M-23 - Standard Test Method for High Bearing - Low Bypass Interaction Response of Polymer Matrix Composite Laminates Using 2-Fastener Specimens
• Effective Date: 01-Sep-2023

Overview

ASTM D6742/D6742M-23: Standard Practice for Filled-Hole Tension and Compression Testing of Polymer Matrix Composite Laminates provides a framework for assessing the tensile and compressive strength of continuous-fiber reinforced polymer matrix composites containing a filled hole. This practice specifically addresses how to modify standard open-hole test methods to include a close-tolerance fastener or pin installed in the specimen, thereby enabling evaluation of filled-hole performance. The standard applies to composite laminates that are symmetric and balanced in the test direction and is crucial for generating reliable data for material characterization, design allowables, research, and quality control in industries where fastener-bearing composite structures are used.

Key Topics

• Filled-Hole Strength Testing: This standard supplements existing tensile (ASTM D5766/D5766M) and compressive (ASTM D6484/D6484M) test methods for evaluating composite laminates with a fastener or pin in the hole.
• Material Scope: Applicable to continuous-fiber reinforced polymer matrix composites with symmetric, balanced laminates as per thickness and configuration guidelines.
• Specimen Parameters: Fastener selection, installation method, hole and fastener tolerances, countersink parameters, and specimen dimensions significantly impact results and must be carefully specified and reported for reproducibility.
• Data Consistency: To maintain accuracy and repeatability, environmental conditions, fastener preload, specimen conditioning, and precise measurement of all physical dimensions are required.
• Reporting and Validation: Results must include critical specimen and testing details, as well as observed failure modes, which are essential for valid data and comparative benchmarking.

Applications

ASTM D6742/D6742M-23 delivers significant practical value for organizations involved in composite material design, engineering, and manufacturing, particularly where bolted or pinned joints are present. Key applications include:

• Aerospace: Used to establish material allowables and performance data for composite structures under realistic loading conditions, such as wing panels and fuselage joints with fasteners.
• Automotive and Transportation: Validates the integrity of composite components subjected to loads with embedded fasteners, supporting lightweight structure initiatives.
• Quality Assurance: Enables repeatable strength assessment for manufacturing control and part certification by specifying detailed procedures for tension and compression testing of filled-hole composite samples.
• Material Development & Research: Essential for understanding the influence of fastener type, installation procedures, and environmental factors on the structural performance of advanced composites.

Related Standards

For comprehensive evaluation and best-practice implementation, ASTM D6742/D6742M-23 should be used in conjunction with related standards, including:

• ASTM D5766/D5766M - Test Method for Open-Hole Tensile Strength of Polymer Matrix Composite Laminates
• ASTM D6484/D6484M - Test Method for Open-Hole Compressive Strength of Polymer Matrix Composite Laminates
• ASTM D792 - Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
• ASTM D3171 - Test Methods for Constituent Content of Composite Materials
• ASTM D8509 - Guide for Test Method Selection and Test Specimen Design for Bolted Joint Related Properties
• ASTM D5229/D5229M - Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials

These standards together facilitate the thorough evaluation of composite laminate behavior in both open-hole and filled-hole conditions, aiding in the design and certification of safe and reliable composite structures.

Keywords: composite materials, filled-hole tension test, filled-hole compression test, bolted joints, polymer matrix composites, laminate testing, ASTM D6742/D6742M-23

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6742/D6742M − 23
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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This practice provides instructions for modifying open-
hole tension and compression test methods to determine
2. Referenced Documents
filled-hole tensile and compressive strengths. The composite
2.1 ASTM Standards:
material forms are limited to continuous-fiber reinforced poly-
D792 Test Methods for Density and Specific Gravity (Rela-
mer matrix composites in which the laminate is both symmetric
tive Density) of Plastics by Displacement
and balanced with respect to the test direction. The range of
D883 Terminology Relating to Plastics
acceptable test laminates and thicknesses are described in
D3171 Test Methods for Constituent Content of Composite
8.2.1.
Materials
1.2 This practice supplements Test Methods D5766/
D3878 Terminology for Composite Materials
D5766M (for tension testing) and D6484/D6484M (for com-
D5229/D5229M Test Method for Moisture Absorption Prop-
pression testing) with provisions for testing specimens that
erties and Equilibrium Conditioning of Polymer Matrix
contain a close-tolerance fastener or pin installed in the hole.
Composite Materials
Several important test specimen parameters (for example,
D5766/D5766M Test Method for Open-Hole Tensile
fastener selection, fastener installation method, and fastener
Strength of Polymer Matrix Composite Laminates
hole tolerance) are not mandated by this practice; however,
D6484/D6484M Test Method for Open-Hole Compressive
repeatable results require that these parameters be specified and
Strength of Polymer Matrix Composite Laminates
reported.
D6507 Practice for Fiber Reinforcement Orientation Codes
1.3 The values stated in either SI units or inch-pound units
for Composite Materials
are to be regarded separately as standard. The values stated in
D8509 Guide for Test Method Selection and Test Specimen
each system may not be exact equivalents; therefore, each
Design for Bolted Joint Related Properties
system shall be used independently of the other. Combining
E6 Terminology Relating to Methods of Mechanical Testing
values from the two systems may result in non-conformance
E177 Practice for Use of the Terms Precision and Bias in
with the standard.
ASTM Test Methods
1.3.1 Within the text the inch-pound units are shown in
E456 Terminology Relating to Quality and Statistics
brackets.
3. Terminology
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.1 Definitions—Terminology D3878 defines terms relating
responsibility of the user of this standard to establish appro-
to high-modulus fibers and their composites. Terminology
priate safety, health, and environmental practices and deter-
D883 defines terms relating to plastics. Terminology E6 defines
mine the applicability of regulatory limitations prior to use.
terms relating to mechanical testing. Terminology E456 and
1.5 This international standard was developed in accor-
Practice E177 define terms relating to statistics. In the event of
dance with internationally recognized principles on standard-
a conflict between terms, Terminology D3878 shall have
ization established in the Decision on Principles for the
precedence over the other standards.
Development of International Standards, Guides and Recom-
3.2 Definitions of Terms Specific to This Standard—Refer to
Guide D8509.
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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2023. Published September 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2001. Last previous edition approved in 2017 as D6742/D6742M – 17. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6742_D6742M-23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6742/D6742M − 23
3.3 Symbols: reported. This value may be a measured torque or a specifica-
A = cross-sectional area of a specimen tion torque for fasteners with lock-setting features. If washers
d = fastener diameter
are used, the washer type, number of washers, and washer
D = specimen hole diameter location(s) shall be specified as initial test parameters and
d = countersink depth
reported. Reuse of fasteners is not recommended because of
csk
d = countersink flushness
potential differences in through-thickness clamp-up for a given
fl
f = distance, perpendicular to loading axis, from hole edge to
torque level, caused by wear of the threads.
closest side of specimen
fhcu 7.3 Torque Wrench—If using a torqued fastener, the torque
F = ultimate filled-hole compressive strength in the test
x
wrench used to tighten the fastener shall be capable of
direction
fhtu determining the applied torque to within 610 % of the desired
F = ultimate filled-hole tensile strength in the test direc-
x
value.
tion
g = distance, parallel to loading axis, from hole edge to end
8. Sampling and Test Specimens
of specimen
h = specimen thickness
8.1 Sampling—For tension tests, sampling shall be in accor-
max
P = maximum force carried by test specimen prior to
dance with Test Method D5766/D5766M. For compression
failure
tests, sampling shall be in accordance with Test Method
w = specimen width
D6484/D6484M.
4. Summary of Practice 8.2 Geometry:
8.2.1 Stacking Sequence—The standard laminates shall
4.1 Filled-Hole Tensile Strength—In accordance with Test
have multidirectional fiber orientations (fibers shall be oriented
Method D5766/D5766M, but with a close-tolerance fastener or
in a minimum of two directions) and balanced and symmetric
pin installed in the hole, perform a uniaxial tension test of a
stacking sequences. For tension specimens, nominal thickness
balanced, symmetric laminate with a centrally located hole.
shall be 2.5 mm [0.10 in.], with a permissible range of 2 mm to
4.2 Filled-Hole Compressive Strength—In accordance with
4 mm [0.080 in. to 0.160 in.], inclusive. For compression
Test Method D6484/D6484M, but with a close-tolerance fas-
specimens, nominal thickness shall be 4 mm [0.160 in.], with
tener or pin installed in the hole, perform a uniaxial compres-
a permissible range of 3 mm to 5 mm [0.125 in. to 0.200 in.],
sion test of a balanced, symmetric laminate with a centrally
inclusive. Fabric laminates containing satin-type weaves shall
located hole.
have symmetric warp surfaces, unless otherwise specified and
NOTE 1—For both test methods, ultimate strength is calculated based on
noted in the report.
the gross cross-sectional area, disregarding the presence of the filled hole.
While the filled hole causes a stress concentration and reduced net section,
NOTE 2—Typically, a [45 /−45 /0 /90 ] tape or [45 /0 ] fabric lami-
i i j k ns i j ns
it is common aerospace practice to develop notched design allowable
nate should be selected such that a minimum of 5 % of the fibers lay in
strengths based on gross section stress to account for various stress
each of the four principal orientations. This laminate design has been
concentrations (fastener holes, free edges, flaws, damage, and so forth) not
found to yield the highest likelihood of acceptable failure modes. Consult
explicitly modeled in the stress analysis.
Practice D6507 for information on fiber orientation codes.
8.2.2 Specimen Configuration—For tension tests, the test
5. Significance and Use
specimen configuration shall be in accordance with Test
5.1 Refer to Guide D8509.
Method D5766/D5766M. For compression tests, the test speci-
men configuration shall be in accordance with Test Method
6. Interferences
D6484/D6484M. The nominal hole diameter may vary from
6.1 Refer to Guide D8509.
that specified in Test Methods D5766/D5766M and D6484/
D6484M depending upon the type of fastener used.
7. Apparatus
8.3 Specimen Preparation—For tension tests, specimens
7.1 General Apparatus—General apparatus shall be in ac-
shall be prepared in accordance with Test Method D5766/
cordance with Test Methods D5766/D5766M (for tension tests)
D5766M. For compression tests, specimens shall be prepared
and D6484/D6484M (for compression tests), although with a
in accordance with Test Method D6484/D6484M. Use appro-
fastener or pin installed in the specimen hole. The micrometer
priate hole preparation procedures specified by the test re-
or gauge used shall be capable of determining the hole and
questor.
fastener diameters to 68 μm [60.0003 in.].
8.4 If specific gravity, density, reinforcement volume, or
7.2 Fastener—The fastener or pin type shall be specified as
an initial test parameter and reported. The nominal fastener void volume are to be reported, then obtain these samples from
the same panels being tested. Specific gravity and density may
diameter shall be 6 mm [0.25 in.], unless a range of diameters
is being investigated. Some fastener types (for example blind be evaluated by means of Test Method D792. Volume percent
of the constituents may be evaluated by one of the matrix
bolts) may not be available in this diameter; for these, it is
recommended to use a fastener for which the diameter is as digestion procedures of Test Method D3171, or, for certain
close as possible to 6 mm [0.25 in.]. The installation torque (if reinforcement materials such as glass and ceramics, by the
applicable) shall be specified as an initial test parameter and matrix burn-off technique of Test Method D3171.
D6742/D6742M − 23
9. Calibration g, shall also be measured. The accuracy of all measurements
shall be within 1 % of the dimension, unless otherwise speci-
9.1 The accuracy of all measuring equipment shall have
fied in this practice. Dimensions shall be recorded to three
certified calibrations that are current at the time of use of the
significant figures in units of millimetres [inches].
equipment.
NOTE 4—The test requester may request that additional measurements
10. Conditioning
be performed after the machined specimens have gone through any
conditioning or environmental exposure.
10.1 The recommended pre-test condition is effective mois-
11.2.3 Cleaning—The specimen hole, surrounding clamp-
ture equilibrium at a specific relative humidity as established
ing area, and fastener shank shall be cleaned. If the fastener
by Test Method D5229/D5229M; however, if the test requestor
threads are required to be lubricated, the lubricant shall be
does not explicitly specify a pre-test conditioning environment,
applied to the nut threads instead of the fastener threads.
no conditioning is required and the test specimens may be
Extreme care shall be taken not to accidentally transfer any of
tested as prepared.
the lubricant to the fastener shank, the specimen hole, or to the
10.2 The pre-test specimen conditioning process, to include
clamping area during assembly and torquing. The cleaning
specified environmental exposure levels and resulting moisture
method and lubricant used (if any) shall be recorded and
content, shall be reported with the test data.
reported.
NOTE 3—The term moisture, as used in Test Method D5229/D5229M,
11.2.4 Specimen Assembly—Assemble test specimen with
includes not only the vapor of a liquid and its condensate, but the liquid
itself in large quantities, as for immersion.
fastener or pin (and washers if used), in accordance with the
fastener installation procedures specified by the test requestor.
10.3 If no explicit conditioning process is performed the
11.2.5 Fastener Torquing—If using a torqued fastener, the
specimen conditioning process shall
...

This document is not 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. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: D6742/D6742M − 17 D6742/D6742M − 23
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 (´) indicates an editorial change since the last revision or reapproval.
1. 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 D5766/D5766M (for tension testing) and D6484/D6484M (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. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
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 responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
D883 Terminology Relating to Plastics
D3171 Test Methods for Constituent Content of Composite Materials
D3878 Terminology for Composite Materials
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.
Current edition approved Oct. 15, 2017Sept. 1, 2023. Published October 2017September 2023. Originally approved in 2001. Last previous edition approved in 20122017
as D6742/D6742M – 12.D6742/D6742M – 17. DOI: 10.1520/D6742_D6742M-17.10.1520/D6742_D6742M-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6742/D6742M − 23
D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite
Materials
D5766/D5766M Test Method for Open-Hole Tensile Strength of Polymer Matrix Composite Laminates
D6484/D6484M Test Method for Open-Hole Compressive Strength of Polymer Matrix Composite Laminates
D6507 Practice for Fiber Reinforcement Orientation Codes for Composite Materials
D8509 Guide for Test Method Selection and Test Specimen Design for Bolted Joint Related Properties
E6 Terminology Relating to Methods of Mechanical Testing
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E456 Terminology Relating to Quality and Statistics
3. Terminology
3.1 Definitions—Terminology D3878 defines terms relating to high-modulus fibers and their composites. Terminology D883
defines terms relating to plastics. Terminology E6 defines terms relating to mechanical testing. Terminology E456 and Practice
E177 define terms relating to statistics. In the event of a conflict between terms, Terminology D3878 shall have precedence over
the other standards.
3.2 Definitions of Terms Specific to This Standard: Standard—
NOTE 1—If the term represents a physical quantity, its analytical dimensions are stated immediately following the term (or letter symbol) in fundamental
dimension form, using the following ASTM International standard symbology for fundamental dimensions, shown within square brackets: [M] for mass,
[L] for length, [T] for time, [θ] for thermodynamic 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.Refer to Guide D8509.
3.2.1 nominal value, n—a value, existing in name only, assigned to a measurable property for the purpose of convenient
designation. Tolerances may be applied to a nominal value to define an acceptable range for the property.
3.2.2 countersink flushness, n—depth or protrusion of countersunk fastener head relative to the laminate surface after installation.
A positive value indicates protrusion of the fastener head above the laminate surface; a negative value indicates depth below the
surface.
3.2.3 countersink depth, n—depth of countersinking required to properly install a countersunk fastener, such that countersink
flushness is nominally zero. Countersink depth is nominally equivalent to the height of the fastener head.
3.3 Symbols:
A = cross-sectional area of a specimen
d = fastener diameter
D = specimen hole diameter
d = countersink depth
csk
d = countersink flushness
fl
f = distance, perpendicular to loading axis, from hole edge to closest side of specimen
fhcu
F = ultimate filled-hole compressive strength in the test direction
x
fhtu
F = ultimate filled-hole tensile strength in the test direction
x
g = distance, parallel to loading axis, from hole edge to end of specimen
h = specimen thickness
max
P = maximum force carried by test specimen prior to failure
w = specimen width
4. Summary of Practice
4.1 Filled-Hole Tensile Strength—In accordance with Test Method D5766/D5766M, but with a close-tolerance fastener or pin
installed in the hole, perform a uniaxial tension test of a balanced, symmetric laminate with a centrally located hole.
4.2 Filled-Hole Compressive Strength—In accordance with Test Method D6484/D6484M, but with a close-tolerance fastener or
pin installed in the hole, perform a uniaxial compression test of a balanced, symmetric laminate with a centrally located hole.
NOTE 1—For both test methods, ultimate strength is calculated based on the gross cross-sectional area, disregarding the presence of the filled hole. While
D6742/D6742M − 23
the filled hole causes a stress concentration and reduced net section, it is common aerospace practice to develop notched design allowable strengths based
on gross section stress to account for various stress concentrations (fastener holes, free edges, flaws, damage, and so forth) not explicitly modeled in the
stress analysis.
5. Significance and Use
5.1 This practice provides supplemental instructions that allow Test Methods Refer to Guide D5766/D5766MD8509 (for tension
testing) and .D6484/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 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:
fhtu
5.1.1 Filled-hole tensile (FHT) strength, F .
x
fhcu
5.1.2 Filled-hole compressive (FHC) strength, F .
x
6. Interferences
6.1 Fastener-Hole Clearance—Compression test results, in particular, are affected by the clearance arising from the difference
between hole and fastener diameters. A 25−μm [0.001−in.] change in clearance can change the observed failure mode and affect
strength results by as much as 25 % Refer (1). For this reason, both the hole and fastener diameters must be accurately measured
and recorded. A typical aerospace tolerance on fastener-hole clearance is +75/−0 μm [+0.003/−0.000 in.] for structural fastener
holes. Filled-hole specimen behavior is also affected by clearance under tensile loading, but to ato Guide D8509lesser degree than
under compressive forces.(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 and recorded.
6.2 Fastener Torque/Preload—Results are affected by the installed fastener preload (clamping pressure). Laminates can exhibit
significant differences in both failure force and failure mode because of changes in fastener preload under both tensile and
compressive loading. The critical preload condition (either high or low clamping pressure) can vary depending upon the type of
loading, 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 the
material system, stacking sequence, test environment, and amount of fastener torque (6). Notched tensile strengths can be high
torque critical for some layups and low torque (or open hole) critical for others, depending upon the characteristics of the material
system (resin brittleness, fiber strain to failure, and so forth), the test environment, and the modes of failure that arise. Filled-hole
compressive (FHC) strengths are almost always higher than the corresponding open-hole compressive (OHC) strengths, although
high versus low clamp-up criticality can vary depending upon the material system, stacking sequence, and test environment (5).
6.3 Fastener Type/Hole Preparation—Results 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 Environment—Results are affected by the environmental conditions under which the tests are conducted. Laminates tested in
various environments can exhibit significant differences in both failure force and failure mode. Experience has demonstrated that
cold temperature environments are generally critical for filled-hole tensile strength, while elevated temperature, humid
environments are generally critical for filled-hole compressive strength. However, critical environments must be assessed
independently for each material system, stacking sequence, and torque condition tested.
6.5 Specimen Geometry—In addition to the geometrical interferences documented in Test Methods D5766/D5766M and
D6484/D6484M, results may be affected by the ratio of countersunk (flush) head depth to thickness; the preferred ratio is the range
of 0.0 to 0.7 unless the experiment is investigating the influence of this ratio. Results may also be affected by the ratio of specimen
width to fastener diameter, which may vary from the preferred ratio of 6 depending upon the particular fastener and hole diameters
used. Results may also be affected if the hole is not centered by length or width.
D6742/D6742M − 23
6.6 Material Orthotropy—The degree of laminate orthotropy strongly affects the failure mode and measured FHT and FHC
strengths. Valid FHT and FHC strength results should only be reported when appropriate failure modes are observed, according
to 11.6.
6.7 Other—Additional sources of potential data scatter are documented in Test Method D5766/D5766M for tension tests and in
Test Method D6484/D6484M for compression tests.
7. Apparatus
7.1 General Apparatus—General apparatus shall be in accordance with Test Methods D5766/D5766M (for tension tests) and
D6484/D6484M (for compression tests), although with a fastener or pin installed in the specimen hole. The micrometer or
gagegauge used shall be capable of determining the hole and fastener diameters to 68 μm [60.0003 in.].
7.2 Fastener—The fastener or pin type shall be specified as an initial test parameter and reported. The nominal fastener diameter
shall be 6 mm [0.25 in.], unless a range of diameters is being investigated. Some fastener types (for example blind bolts) may not
be available in this diameter; for these, it is recommended to use a fastener for which the diameter is as close as possible to 6 mm
[0.25 in.]. The installation torque (if applicable) shall be specified as an initial test parameter and reported. This value may be a
measured torque or a specification torque for fasteners with lock-setting features. If washers are used, the washer type, number of
washers, and washer location(s) shall be specified as initial test parameters and reported. Reuse of fasteners is not recommended
because of potential differences in through-thickness clamp-up for a given torque level, caused by wear of the threads.
7.3 Torque Wrench—If using a torqued fastener, the torque wrench used to tighten the fastener shall be capable of determining the
applied torque to within 610 % of the desired value.
8. Sampling and Test Specimens
8.1 Sampling—For 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 Sequence—The standard laminates shall have multidirectional fiber orientations (fibers shall be oriented in a
minimum of two directions) and balanced and symmetric stacking sequences. For tension specimens, nominal thickness shall be
2.5 mm [0.10 in.], with a permissible range of 2 to 4 mm [0.080 to 0.160 in.], 2 mm to 4 mm [0.080 in. to 0.160 in.], inclusive.
For compression specimens, nominal thickness shall be 4 mm [0.160 in.], with a permissible range of 3 to 5 mm [0.125 3 mm to
5 mm [0.125 in. to 0.200 in.], inclusive. Fabric laminates containing satin-type weaves shall have symmetric warp surfaces, unless
otherwise specified and noted in the report.
NOTE 2—Typically, a [45 /−45 /0 /90 ] tape or [45 /0 ] fabric laminate should be selected such that a minimum of 5 % of the fibers lay in each of the
i i j k ns i j ns
four principal orientations. This laminate design has been found to yield the highest likelihood of acceptable failure modes. Consult Practice D6507 for
information on fiber orientation codes.
8.2.2 Specimen Configuration—For tension tests, the test specimen configuration shall be in accordance with Test Method
D5766/D5766M. For compression tests, the test specimen configuration shall be in accordance with Test Method D6484/D6484M.
The nominal hole diameter may vary from that specified in Test Methods D5766/D5766M and D6484/D6484M depending upon
the type of fastener used.
8.3 Specimen Preparation—For tension tests, specimens shall be prepared in accordance with Test Method D5766/D5766M. For
compression tests, specimens shall be prepared in accordance with Test Method D6484/D6484M. U
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