ASTM D5766/D5766M-23

Standard Test Method for Open-Hole Tensile Strength of Polymer Matrix Composite Laminates

SIGNIFICANCE AND USE
5.1 Refer to Guide D8509.
SCOPE
1.1 This test method determines the open-hole tensile strength of multidirectional polymer matrix composite laminates reinforced by high-modulus fibers. The composite material forms are limited to continuous-fiber or discontinuous-fiber (tape or fabric, or both) reinforced composites in which the laminate is balanced and symmetric with respect to the test direction. The range of acceptable test laminates and thicknesses are described in 8.2.1.  
1.2 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.  
1.2.1 Within the text the inch-pound units are shown in brackets.  
1.3 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.  
1.4 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

• 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 D2734-23 - Standard Test Methods for Void Content of Reinforced Plastics
• Effective Date: 01-Oct-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D5229/D5229M-20 - Standard Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials
• Effective Date: 01-Mar-2020
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D3878-19a - Standard Terminology for Composite Materials
• Effective Date: 15-Oct-2019
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D3878-19 - Standard Terminology for Composite Materials
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM D2584-18 - Standard Test Method for Ignition Loss of Cured Reinforced Resins
• Effective Date: 15-Sep-2018
• Refers: ASTM D3878-18 - Standard Terminology for Composite Materials
• Effective Date: 01-Apr-2018

Overview

ASTM D5766/D5766M-23 is the internationally recognized standard test method for determining the open-hole tensile strength of multidirectional polymer matrix composite laminates reinforced with high-modulus fibers. Developed by ASTM International, this test method is essential for evaluating the mechanical performance of composite materials, particularly those used in structural applications where design features, such as holes or notches, are present. The standard applies to both continuous- and discontinuous-fiber reinforced composites, including tape or fabric laminates that are balanced and symmetric in the test direction.

By following ASTM D5766/D5766M-23, organizations ensure reliable, repeatable, and comparable test results, supporting robust material qualification, structural design, and quality assurance programs in demanding industries.

Key Topics

• Open-Hole Tensile Strength Testing: The method subjects a test specimen with a centrally located hole to uniaxial tension, simulating real-world conditions where structural components may be notched or contain fastener holes.
• Specimen Preparation: Guidance is provided for preparing specimens, including recommendations for laminate stacking sequences, hole preparation to avoid material damage, and specimen geometry.
• Measurement and Data: The method details how to measure and calculate the ultimate tensile strength, taking into account the gross cross-sectional area (excluding the hole) and important geometric ratios such as width-to-diameter and diameter-to-thickness.
• Failure Mode Assessment: Only failures that occur through the hole in the test specimen are considered valid, ensuring that the mechanical response is accurately characterized.
• Statistical Analysis: The standard requires reporting of individual and average strength values, as well as statistical parameters such as standard deviation and coefficient of variation.
• Significance and Use: Results from this test are vital for developing design allowables, verifying material consistency, supporting research and development, and managing structural integrity.

Applications

ASTM D5766/D5766M-23 is broadly applied across industries that demand high performance and reliability from composite materials, including:

• Aerospace and Defense: Assessing the open-hole tensile strength of composite laminate structures in aircraft or spacecraft, especially in areas such as fastener holes, notched panels, and damage tolerance studies.
• Automotive: Evaluating composite parts utilized in vehicles where holes or cutouts are necessary for assembly or weight reduction.
• Wind Energy: Testing the mechanical strength of wind turbine blades and other structural components manufactured from multidirectional laminates.
• Infrastructure and Industrial: Verifying the integrity and reliability of composite materials used in construction, marine, and industrial equipment applications.
• Material Research and Qualification: Generating data for material datasheets, supporting new material development, and qualifying suppliers.

Benefits of using ASTM D5766/D5766M-23:

• Provides reliable, industry-accepted procedures for open-hole tensile strength testing.
• Enables consistent comparison of different composite materials and lay-ups.
• Supports safety-, quality-, and compliance-driven material selection and validation processes.

Related Standards

To maximize the utility and consistency of results, ASTM D5766/D5766M-23 is often referenced alongside other key composite testing and terminology standards, including:

• ASTM D792 - Density and Specific Gravity of Plastics
• ASTM D3039/D3039M - Tensile Properties of Polymer Matrix Composite Materials
• ASTM D5229/D5229M - Moisture Absorption of Polymer Matrix Composite Materials
• ASTM D3171 - Constituent Content of Composite Materials
• ASTM D2584 - Ignition Loss of Cured Reinforced Resins
• ASTM D2734 - Void Content of Reinforced Plastics
• ASTM D3878 and ASTM D883 - Terminology for Composites and Plastics
• ASTM D8509 - Guide for Test Method Selection for Bolted Joint Properties

These standards ensure comprehensive support for composite material characterization, supporting accurate open-hole tensile testing and related engineering decisions.

Keywords

composite materials, open-hole tensile strength, polymer matrix laminates, ASTM D5766, mechanical testing, fiber-reinforced composites, tensile properties, aerospace composites, structural testing, material qualification

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: D5766/D5766M − 23
Standard Test Method for
Open-Hole Tensile Strength of Polymer Matrix Composite
Laminates
This standard is issued under the fixed designation D5766/D5766M; 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 tive Density) of Plastics by Displacement
D883 Terminology Relating to Plastics
1.1 This test method determines the open-hole tensile
D2584 Test Method for Ignition Loss of Cured Reinforced
strength of multidirectional polymer matrix composite lami-
Resins
nates reinforced by high-modulus fibers. The composite mate-
D2734 Test Methods for Void Content of Reinforced Plastics
rial forms are limited to continuous-fiber or discontinuous-fiber
D3039/D3039M Test Method for Tensile Properties of Poly-
(tape or fabric, or both) reinforced composites in which the
mer Matrix Composite Materials
laminate is balanced and symmetric with respect to the test
D3171 Test Methods for Constituent Content of Composite
direction. The range of acceptable test laminates and thick-
Materials
nesses are described in 8.2.1.
D3878 Terminology for Composite Materials
1.2 The values stated in either SI units or inch-pound units
D5229/D5229M Test Method for Moisture Absorption Prop-
are to be regarded separately as standard. The values stated in
erties and Equilibrium Conditioning of Polymer Matrix
each system may not be exact equivalents; therefore, each
Composite Materials
system shall be used independently of the other. Combining
D8509 Guide for Test Method Selection and Test Specimen
values from the two systems may result in non-conformance
Design for Bolted Joint Related Properties
with the standard.
E6 Terminology Relating to Methods of Mechanical Testing
1.2.1 Within the text the inch-pound units are shown in
E177 Practice for Use of the Terms Precision and Bias in
brackets.
ASTM Test Methods
1.3 This standard does not purport to address all of the
E456 Terminology Relating to Quality and Statistics
safety concerns, if any, associated with its use. It is the E691 Practice for Conducting an Interlaboratory Study to
responsibility of the user of this standard to establish appro-
Determine the Precision of a Test Method
priate safety, health, and environmental practices and deter-
E1309 Guide for Identification of Fiber-Reinforced
mine the applicability of regulatory limitations prior to use. Polymer-Matrix Composite Materials in Databases (With-
1.4 This international standard was developed in accor-
drawn 2015)
dance with internationally recognized principles on standard- E1434 Guide for Recording Mechanical Test Data of Fiber-
ization established in the Decision on Principles for the
Reinforced Composite Materials in Databases (Withdrawn
Development of International Standards, Guides and Recom- 2015)
mendations issued by the World Trade Organization Technical
3. Terminology
Barriers to Trade (TBT) Committee.
3.1 Definitions—Terminology D3878 defines terms relating
2. Referenced Documents
to high-modulus fibers and their composites. Terminology
D883 defines terms relating to plastics. Terminology E6 defines
2.1 ASTM Standards:
terms relating to mechanical testing. Terminology E456 and
D792 Test Methods for Density and Specific Gravity (Rela-
Practice E177 define terms relating to statistics. In the event of
a conflict between terms, Terminology D3878 shall have
This test method is under the jurisdiction of ASTM Committee D30 on precedence over the other standards.
Composite Materials and is the direct responsibility of Subcommittee D30.05 on
3.2 Definitions of Terms Specific to This Standard—Refer to
Structural Test Methods.
Guide D8509.
Current edition approved Sept. 1, 2023. Published September 2023. Originally
approved in 1995. Last previous edition approved in 2018 as D5766/
3.3 Symbols:
D5766M – 11 (2018). DOI: 10.1520/D5766_D5766M-23.
A = cross-sectional area of a specimen
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 last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5766/D5766M − 23
CV = coefficient of variation statistic of a sample population
for a given property (in percent)
D = hole diameter
h = specimen thickness
n = number of specimens per sample population
N = number of plies in laminate under test
OHTu
F = ultimate open-hole (notched) tensile strength in the
x
test direction
max
P = maximum force carried by test specimen prior to
failure
s = standard deviation statistic of a sample population for
n-1
a given property
S = repeatability (within laboratory precision) standard
r
deviation, calculated in accordance with Practice E691
S = reproducibility (between laboratory precision) standard
R
deviation, calculated in accordance with Practice E691
w = specimen width
x = test result for an individual specimen from the sample
i
population for a given property
x¯5 mean or average (estimate of mean) of a sample
population for a given property
σ = normal stress
4. Summary of Test Method
4.1 A uniaxial tension test of a balanced, symmetric lami-
nate is performed in accordance with Test Method D3039/
D3039M, although with a centrally located hole. Edge-
mounted extensometer displacement transducers are optional.
Refer to Guide D8509 for additional test details.
FIG. 1 Schematic of Open-Hole Tension Test Specimen
5. Significance and Use
to 0.160 in.], inclusive. Fabric laminates containing satin-type
5.1 Refer to Guide D8509.
weaves shall have symmetric warp surfaces, unless otherwise
noted in the report.
6. Interferences
NOTE 1—Typically a [45 /-45 /0 /90 ] tape or [45 /0 ] fabric lami-
i i j k ms i j ms
6.1 Refer to Guide D8509.
nate should be selected such that a minimum of 5 % of the fibers lay in
each of the four principal orientations. This laminate design has been
found to yield the highest likelihood of acceptable failure modes.
7. Apparatus
8.2.2 Configuration:
7.1 Apparatus shall be in accordance with Test Method
8.2.2.1 Configuration A—The width of the specimen is
D3039/D3039M. Additionally, a micrometer or gauge capable
36 mm 6 1 mm [1.50 in. 6 0.05 in.] and the length range is
of determining the hole diameter to 60.025 mm [60.001 in.]
200 mm to 300 mm [8.0 in. to 12.0 in.]. The notch consists of
is required.
a centrally located hole, 6 mm 6 0.06 mm [0.250 in. 6
0.003 in.] in diameter, centered by length to within 0.12 mm
8. Sampling and Test Specimens
[0.005 in.] and by width to within 0.05 mm [0.002 in.]. While
8.1 Sampling—Sampling shall be in accordance with Test
tabs may be used, they are not required and generally not
Method D3039/D3039M.
needed, since the open hole acts as sufficient stress riser to
8.2 Geometry—The specimen geometry shall be in accor- force failure in the notched region. Configuration A is preferred
dance with Test Method D3039/D3039M, as modified by the for the general laminate stacking sequences defined in 8.2.1
following, and illustrated by the schematic of Fig. 1. Any because it is long enough to ensure a uniform strain field is
variation of the stacking sequence, specimen width or length, achieved in the specimen outside of the influence of the hole.
or hole diameter from that specified shall be clearly noted in 8.2.2.2 Configuration B—The width of the specimen is
the report.
36 mm 6 1 mm [1.50 in. 6 0.05 in.] and the length range is
8.2.1 Stacking Sequence—The standard laminate shall have 150 mm to 200 mm [6.0 in. to 8.0 in.]. The notch consists of a
multidirectional fiber orientations (fibers shall be oriented in a centrally located hole, 6 mm 6 0.06 mm [0.250 in. 6
minimum of two directions), and balanced and symmetric 0.003 in.] in diameter, centered by length to within 0.12 mm
stacking sequences. Nominal thickness shall be 2.5 mm [0.005 in.] and by width to within 0.05 mm [0.002 in.]. While
[0.10 in.], with a permissible range of 2 mm to 4 mm [0.080 in. tabs may be used, they are not required and generally not
D5766/D5766M − 23
needed, since the open hole acts as sufficient stress riser to 11.2.2 If specific gravity, density, reinforcement volume or
force failure in the notched region. Configuration B is limited void volume are to be reported then obtain these samples from
to quasi-isotropic laminate stacking sequences, typically a the same panels being tension tested. Specific gravity and
[45 /–45 /0 /90 ] tape or [45 /0 ] fabric laminate, with a density may be evaluated by means of Test Methods D792.
m m m m ns m m ns
specimen grip length of 35 mm to 55 mm [1.4 in. to 2.0 in.] Volume percent of the constituents may be evaluated by one of
NOTE 2—The ungripped specimen length for Configuration B shall not
the matrix digestion procedures of Test Method D3171, or, for
be less than 75 mm [3.0 in.] as shorter ungripped lengths may result in an
certain reinforcement materials such as glass and ceramics, by
unacceptable influence upon failure at or near to the hole.
the matrix burn-off technique of Test Method D2584. The void
8.3 Specimen Preparation—Special care shall be taken to
content equations of Test Methods D2734 are applicable to
ensure that creation of the specimen hole does not delaminate
both Test Method D2584 and the matrix digestion procedures.
or otherwise damage the material surrounding the hole. Holes
11.2.3 Condition the specimens as required. Store the speci-
should be drilled undersized and reamed to final dimensions.
mens in the conditioned environment until test time, if the test
Record and report the specimen hole preparation methods.
environment is different than the conditioning environment.
Other specimen preparation techniques and requirements are
11.2.4 Following any conditioning, but before the tensile
noted in Test Method D3039/D3039M.
testing, measure and report the specimen hole diameter, D, to
the nearest 0.025 mm [0.001 in.]. Inspect the hole and areas
9. Calibration
adjacent to the hole for delaminations. Report the location and
size of any delaminations found. Perform other measurements
9.1 Calibration shall be in accordance with Test Method
in accordance with Test Method D3039/D3039M.
D3039/D3039M.
11.3 Tensile Testing—Perform other measurements, and the
10. Conditioning
tension test of the laminate specimen, in accordance with the
Procedure section of Test Method D3039/D3039M. If strain
10.1 The recommended pre-test condition is effective mois-
response local to the hole is to be determined, attach either one
ture equilibrium at a specific relative humidity as established
or two extensometers to the specimen edge(s) ensuring the hole
by Test Method D5229/D5229M; however, if the test requestor
is located within the extensometer gauge section.
does not explicitly specify a pre-test conditioning environment,
NOTE 5—When testing a conditional specimen at elevated temperature
no conditioning is required and the test specimens may be
with no fluid exposure control, the percentage moisture loss of the
tested as prepared.
specimen prior to test completion may be estimated by placing a
10.2 The pre-test specimen conditioning process, to include conditioned traveler coupon of known weight within the test chamber at
the same time the specimen is placed in the chamber. Upon completion of
specified environmental exposure levels and resulting moisture
the test, the traveler coupon is removed from the chamber, weighed, and
content, shall be reported with the test data.
the percentage weight calculated and reported.
NOTE 3—The term moisture, as used in Test Method D5229/D5229M,
includes not o
...

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: D5766/D5766M − 11 (Reapproved 2018) D5766/D5766M − 23
Standard Test Method for
Open-Hole Tensile Strength of Polymer Matrix Composite
Laminates
This standard is issued under the fixed designation D5766/D5766M; 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 test method determines the open-hole tensile strength of multidirectional polymer matrix composite laminates reinforced
by high-modulus fibers. The composite material forms are limited to continuous-fiber or discontinuous-fiber (tape or fabric, or
both) reinforced composites in which the laminate is balanced and symmetric with respect to the test direction. The range of
acceptable test laminates and thicknesses are described in 8.2.1.
1.2 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.
1.2.1 Within the text the inch-pound units are shown in brackets.
1.3 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.
1.4 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
D2584 Test Method for Ignition Loss of Cured Reinforced Resins
D2734 Test Methods for Void Content of Reinforced Plastics
D3039/D3039M Test Method for Tensile Properties of Polymer Matrix Composite Materials
D3171 Test Methods for Constituent Content of Composite Materials
D3878 Terminology for Composite Materials
D5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite
Materials
D8509 Guide for Test Method Selection and Test Specimen Design for Bolted Joint Related Properties
This test method 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 June 1, 2018Sept. 1, 2023. Published July 2018September 2023. Originally approved in 1995. Last previous edition approved in 20112018 as
D5766/D5766M – 11.D5766/D5766M – 11 (2018). DOI: 10.1520/D5766_D5766M-11R18.10.1520/D5766_D5766M-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
D5766/D5766M − 23
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
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1309 Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in Databases (Withdrawn 2015)
E1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases (Withdrawn 2015)
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 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 non-dimensional 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 diameter-to-thickness ratio, D/h [nd], n—in an open-hole specimen, the ratio of the hole diameter to the specimen thickness.
3.2.1.1 Discussion—The diameter-to-thickness ratio may be either a nominal value determined from nominal dimensions or an
actual value determined from measured dimensions.
3.2.2 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.
3.2.3 principal material coordinate system, n—a coordinate system with axes that are normal to the planes of symmetry inherent
to a material.
3.2.3.1 Discussion—Common usage, at least for Cartesian axes (123, xyz, and so forth), generally assigns the coordinate system
axes to the normal directions of planes of symmetry in order that the highest property value in a normal direction (for elastic
properties, the axis of greatest stiffness) would be 1 or x, and the lowest (if applicable) would be 3 or z. Anisotropic materials do
not have a principal material coordinate system due to the total lack of symmetry, while, for isotropic materials, any coordinate
system is a principal material coordinate system. In laminated composites, the principal material coordinate system has meaning
only with respect to an individual orthotropic lamina. The related term for laminated composites is “reference coordinate system.”
3.2.4 reference coordinate system, n—a coordinate system for laminated composites used to define ply orientations. One of the
reference coordinate system axes (normally the Cartesian x-axis) is designated the reference axis, assigned a position, and the ply
principal axis of each ply in the laminate is referenced relative to the reference axis to define the ply orientation for that ply.
3.2.5 specially orthotropic, adj—a description of an orthotropic material as viewed in its principal material coordinate system. In
laminated composites, a specially orthotropic laminate is a balanced and symmetric laminate of the [0 /90 ] family as viewed from
i j ns
the reference coordinate system, such that the membrane-bending coupling terms of the laminate constitutive relation are zero.
3.2.6 width-to-diameter ratio, w/D [nd], n—in an open-hole specimen, the ratio of the specimen width to the hole diameter.
3.2.6.1 Discussion—The width-to-diameter ratio may be either a nominal value determined from nominal dimensions or an actual
value determined from measured dimensions.
3.3 Symbols:
A = cross-sectional area of a specimen
CV = coefficient of variation statistic of a sample population for a given property (in percent)
D = hole diameter
The last approved version of this historical standard is referenced on www.astm.org.
D5766/D5766M − 23
h = specimen thickness
n = number of specimens per sample population
N = number of plies in laminate under test
OHTu
F = ultimate open-hole (notched) tensile strength in the test direction
x
max
P = maximum force carried by test specimen prior to failure
s = standard deviation statistic of a sample population for a given property
n-1
S = repeatability (within laboratory precision) standard deviation, calculated in accordance with Practice E691
r
S = reproducibility (between laboratory precision) standard deviation, calculated in accordance with Practice E691
R
w = specimen width
x = test result for an individual specimen from the sample population for a given property
i
x¯5 mean or average (estimate of mean) of a sample population for a given property
σ = normal stress
4. Summary of Test Method
4.1 A uniaxial tension test of a balanced, symmetric laminate is performed in accordance with Test Method D3039/D3039M,
although with a centrally located hole. Edge-mounted extensometer displacement transducers are optional. Ultimate strength is
calculated based on the gross cross-sectional area, disregarding the presence of the hole. While the hole causes a stress
concentration and reduced net section, it is common aerospace practice to develop notchedRefer to Guide D8509 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.for additional test details.
4.2 The only acceptable failure mode for ultimate open-hole tensile strength is one which passes through the hole in the test
specimen.
5. Significance and Use
5.1 This test method is designed to produceRefer to Guide D8509notched tensile strength data for structural design allowables,
material specifications, research and development, and quality assurance. Factors that influence the notched tensile strength and
should 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), specimen conditioning, environment of testing, specimen alignment and
gripping, speed of testing, time at temperature, void content, and volume percent reinforcement. Properties that may be derived
from this test method include the following:.
5.1.1 Open-hole (notched) tensile strength (OHT).
6. Interferences
6.1 Hole Preparation—Due to the dominating presence of the notch, and the lack of need to measure the material response, results
from this test method are relatively insensitive to parameters that would be of concern in an unnotched tensile property test.
However, since the notch dominates the strength, consistent preparation of the hole, without damage to the laminate, is important
to meaningful results. Damage due to hole preparation will affect strength results. Some types of damage, such as delaminations,
can blunt the stress concentration due to the hole, increasing the force-carrying capacity of the specimen and the calculated
strength. Other types of damage can reduce the calculated strength.
6.2 Specimen Geometry—Results are affected by the ratio of specimen width to hole diameter (w/D); this ratio should be
maintained at 6, unless the experiment is investigating the influence of this ratio. Results may also be affected by the ratio of hole
diameter to thickness (D/h); the preferred ratio is the range from 1.5 to 3.0 unless the experiment is investigating the influence of
this ratio. Results may also be affected by specimen length ; the preferred specimen length is in the range from 200 to 300 mm
[8.0 to 12.0 in.]. Shorter specimens (150 to 200 mm [6.0 to 8.0 in]) may be utilized in accordance with the limitations defined in
8.2.2. The equivalence of test results from Configurations A and B is contingent upon several factors, including fiber
strain-to-failure, resin strength and fracture toughness. Laminates with a propensity to develop sub-critical resin splits and cracks
could potentially be affected by a change in specimen length due to closer grip proximity to the hole (and any longitudinal cracks
that may develop).
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6.1 Material Orthotropy—The degree of laminateRefer to Guide D8509 orthotropy strongly affects the failure mode and measured
OHT strength. Valid OHT strength results should only be reported when appropriate failure modes are observed, in accordance
with 11.5.
6.4 Thickness Scaling—Thick composite structures do not necessarily fail at the same strengths as thin structures with the same
laminate orientation (that is, strength does not always remain constant independent of specimen thickness). Thus, data gathered
using this test method may not translate directly into equivalent thick-structure properties.
6.5 Other—Additional sources of potential data scatter in testing of composite materials are described in Test Method
D3039/D3039M.
7. Apparatus
7.1 Apparatus shall be in accordance with Test Method D3039/D3039M. Additionally, a micrometer or gagegauge capable of
determining the hole diameter to 60.025 mm [60.001 in.] is required.
8. Sampling and Test Specimens
8.1 Sampling—Sampling shall be in accordance with Test Method D3039/D3039M.
8.2 Geometry—The specimen geometry shall be in accordance with Test Method D3039/D3039M, as modified by the following,
and illustrated by the schematic of Fig. 1. Any variation of the stacking sequence, specimen width or length, or hole diameter from
that specified shall be clearly noted in the report.
FIG. 1 Schematic of Open-Hole Tension Test Specimen
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8.2.1 Stacking Sequence—The standard laminate shall have multidirectional fiber orientations (fibers shall be oriented in a
minimum of two directions), and balanced and symmetric stacking sequences. Nominal thickness shall be 2.5 mm [0.10 in.],
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.
Fabric laminates containing satin-type weaves shall have symmetric warp surfaces, unless otherwise noted in the report.
NOTE 1—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 ms i j ms
four principal orientations. This laminate design has been found to yield the highest likelihood of acceptable failure modes.
8.2.2 Configuration:
8.2.2.1 Configuration A—The width of the specimen is 36 6 1 mm [1.50 6 0.05 in.] 36 mm 6 1 mm [1.50 in. 6 0.05 in.] and
the length range is 200 to 300 mm [8.0 to 12.0 in.]. 200 mm to 300 mm [8.0 in. to 12.0 in.]. The notch consists of a centrally located
hole, 6 6 0.06 mm [0.250 6 0.003 in.] 6 mm 6 0.06 mm [0.250 in. 6 0.003 in.] in diameter, centered by length to within 0.12
mm [0.005 in.] 0.12 mm [0.005 in.] and by width to within 0.05 mm [0.002 in.]. 0.05 mm [0.002 in.]. While tabs may be used,
they are not required and generally not needed, since the open hole acts as sufficient stress riser to force failure in the notched
region. Configuration A is preferred for the general laminate stacking sequences defined in 8.2.18.2.1 because it is long enough
to ensure a uniform strain field is achieved in the specimen outside of the influence of the hole.
8.2.2.2 Configuration B—The width of the specimen is 36 6 1 mm [1.50 6 0.05 in.] 36 mm 6 1 mm [1.50 in. 6 0.05 in.] and
the length range is 150 to 200 mm [6.0 to 8.0 in.]. 150 mm to 200 mm [6.0 in. to 8.0 in.]. The notch consists of a centrally located
hole, 6 6 0.06 mm [0.250 6 0.003 in.] 6 mm 6 0.06 mm [0.250 in. 6 0.003 in.] in diameter, centered by length to within 0.12
mm [0.005 in.] 0.12 mm [0.005 in.] and by width to within 0.05 mm [0.002 in.]. 0.05 mm
...