ASTM D6484/D6484M-23

Standard Test Method for Open-Hole Compressive 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 compressive 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 Several related ASTM standards reference the procedures and apparatus described within this test method. In particular, the support fixture described in 7.2 is used by several other standards to stabilize compression-loaded test specimens. These include Practice D6742/D6742M, which covers filled-hole compression testing; Practice D7615/D7615M, which covers open-hole fatigue testing; and Practice D8066/D8066M, which covers unnotched laminate compression testing.  
1.3 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.  
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 D6484/D6484M-20 - Standard Test Method for Open-Hole Compressive Strength 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 D2734-23 - Standard Test Methods for Void Content of Reinforced Plastics
• Effective Date: 01-Oct-2023
• Refers: ASTM D6742/D6742M-23 - Standard Practice for Filled-Hole Tension and Compression Testing of Polymer Matrix Composite Laminates
• Effective Date: 01-Sep-2023
• Refers: ASTM D7615/D7615M-23 - Standard Practice for Open-Hole Fatigue Response of Polymer Matrix Composite Laminates
• Effective Date: 01-Sep-2023
• Refers: ASTM D883-22 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2022
• Refers: ASTM E456-13a(2022) - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D7615/D7615M-19 - Standard Practice for Open-Hole Fatigue Response of Polymer Matrix Composite Laminates
• Effective Date: 01-Apr-2019
• Refers: ASTM D6742/D6742M-17 - Standard Practice for Filled-Hole Tension and Compression Testing of Polymer Matrix Composite Laminates
• Effective Date: 15-Oct-2017
• Refers: ASTM D2734-16 - Standard Test Methods for Void Content of Reinforced Plastics
• Effective Date: 01-Sep-2016
• Referred By: ASTM D6856/D6856M-03(2016) - Standard Guide for Testing Fabric-Reinforced “Textile” Composite Materials
• 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 D6484/D6484M-23 is a standardized test method developed by ASTM International for determining the open-hole compressive strength (OHC) of multidirectional polymer matrix composite laminates reinforced by high-modulus fibers. This standard addresses the specific evaluation of composite laminates with either continuous or discontinuous fiber reinforcements-such as tape or fabric-requiring laminates to be balanced and symmetric in relation to the direction of testing.

The primary use of this test method is to generate reliable compressive strength data for composite materials with intentional holes or notches, as found in structural applications such as aerospace fastener holes, free edges, or inherent defects. The test is critical for research and development, quality assurance, and for establishing structural design allowables for composite materials.

Key Topics

• Open-Hole Compressive Strength (OHC): This standard specifies procedures to determine the ultimate compressive strength of polymer matrix composites containing a centrally located hole, reflecting realistic service conditions in structural components.
• Applicable Materials: Restricted to balanced, symmetric, multidirectional laminates reinforced with high-modulus fibers (continuous or discontinuous) in forms like tape or fabric.
• Test Specimen Geometry: Emphasizes maintenance of specific width-to-diameter (w/D) and diameter-to-thickness (D/h) ratios to ensure consistency and comparability of results.
• Test Procedures: Provides two procedures (A and B), utilizing either hydraulic wedge grips or end-loading platens with a supportive fixture designed to stabilize the specimen during compression.
• Failure Criteria: Only failure modes that pass through the centrally located hole are considered valid for ultimate open-hole compressive strength assessment.
• Data and Reporting: In addition to compressive strength, the test method outlines requirements for reporting test specimen fabrication, geometry, machining, material properties, and observed failure modes.

Applications

The ASTM D6484/D6484M-23 test method is widely applicable in industries where composite structures are subjected to localized stress concentrations resulting from holes or notches. Key application areas include:

• Aerospace: Critical for evaluating the strength of composite panels with fastener holes, providing data for design allowables and safety assessments of aircraft structures.
• Automotive: Useful for lightweight composite components with mounting holes or cutouts, ensuring structural performance under compressive loads.
• Marine and Construction: Supports the assessment of composite structures exposed to compressive forces and potential damage from manufacturing or operational defects.
• Research and Development: Facilitates material comparison, quality assurance, and process optimization for composite manufacturing.

The standard helps manufacturers, researchers, and quality control professionals to understand the structural integrity of composite laminates when subjected to open-hole compressive loading, a common real-world scenario.

Related Standards

Several ASTM standards complement or use procedures and apparatus from ASTM D6484/D6484M-23:

• ASTM D6742/D6742M: Practice for filled-hole tension and compression testing of polymer matrix composite laminates.
• ASTM D7615/D7615M: Practice for open-hole fatigue response testing in polymer matrix composite laminates.
• ASTM D8066/D8066M: Practice for unnotched compression testing of polymer matrix composite laminates.
• ASTM D3039/D3039M: Test method for tensile properties of polymer matrix composites.
• ASTM D5687/D5687M: Guide for preparation of flat composite panels and specimen fabrication.
• ASTM D5229/D5229M: Test method for moisture absorption in polymer matrix composites.

By following ASTM D6484/D6484M-23, organizations ensure reliable, repeatable measurement of open-hole compressive strength, supporting the safe and efficient use of advanced composites in structural applications.

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: D6484/D6484M − 23
Standard Test Method for
Open-Hole Compressive Strength of Polymer Matrix
Composite Laminates
This standard is issued under the fixed designation D6484/D6484M; 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 test method determines the open-hole compressive
strength of multidirectional polymer matrix composite lami-
2. Referenced Documents
nates reinforced by high-modulus fibers. The composite mate-
2.1 ASTM Standards:
rial forms are limited to continuous-fiber or discontinuous-fiber
D792 Test Methods for Density and Specific Gravity (Rela-
(tape or fabric, or both) reinforced composites in which the
tive Density) of Plastics by Displacement
laminate is balanced and symmetric with respect to the test
D883 Terminology Relating to Plastics
direction. The range of acceptable test laminates and thick-
D2584 Test Method for Ignition Loss of Cured Reinforced
nesses are described in 8.2.1.
Resins
1.2 Several related ASTM standards reference the proce-
D2734 Test Methods for Void Content of Reinforced Plastics
dures and apparatus described within this test method. In
D3039/D3039M Test Method for Tensile Properties of Poly-
particular, the support fixture described in 7.2 is used by
mer Matrix Composite Materials
several other standards to stabilize compression-loaded test
D3171 Test Methods for Constituent Content of Composite
specimens. These include Practice D6742/D6742M, which
Materials
covers filled-hole compression testing; Practice D7615/
D3878 Terminology for Composite Materials
D7615M, which covers open-hole fatigue testing; and Practice
D5229/D5229M Test Method for Moisture Absorption Prop-
D8066/D8066M, which covers unnotched laminate compres-
erties and Equilibrium Conditioning of Polymer Matrix
sion testing.
Composite Materials
1.3 Units—The values stated in either SI units or inch- D5687/D5687M Guide for Preparation of Flat Composite
pound units are to be regarded separately as standard. The
Panels with Processing Guidelines for Specimen Prepara-
values stated in each system are not necessarily exact equiva-
tion
lents; therefore, to ensure conformance with the standard, each D6742/D6742M Practice for Filled-Hole Tension and Com-
system shall be used independently of the other, and values
pression Testing of Polymer Matrix Composite Laminates
from the two systems shall not be combined. D7615/D7615M Practice for Open-Hole Fatigue Response
1.3.1 Within the text, the inch-pound units are shown in
of Polymer Matrix Composite Laminates
brackets. D8066/D8066M Practice Unnotched Compression Testing
of Polymer Matrix Composite Laminates
1.4 This standard does not purport to address all of the
D8509 Guide for Test Method Selection and Test Specimen
safety concerns, if any, associated with its use. It is the
Design for Bolted Joint Related Properties
responsibility of the user of this standard to establish appro-
E4 Practices for Force Calibration and Verification of Test-
priate safety, health, and environmental practices and deter-
ing Machines
mine the applicability of regulatory limitations prior to use.
E6 Terminology Relating to Methods of Mechanical Testing
1.5 This international standard was developed in accor-
E83 Practice for Verification and Classification of Exten-
dance with internationally recognized principles on standard-
someter Systems
ization established in the Decision on Principles for the
E122 Practice for Calculating Sample Size to Estimate, With
Development of International Standards, Guides and Recom-
Specified Precision, the Average for a Characteristic of a
Lot or Process
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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2023. Published October 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1999. Last previous edition approved in 2020 as D6484/D6484M – 20. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6484_D6484M-23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6484/D6484M − 23
E177 Practice for Use of the Terms Precision and Bias in and fixture are end-loaded. The portion of the force initially
ASTM Test Methods transferred into the support fixture is transmitted by shear into
E456 Terminology Relating to Quality and Statistics the test specimen.
E691 Practice for Conducting an Interlaboratory Study to
5. Significance and Use
Determine the Precision of a Test Method
5.1 Refer to Guide D8509.
3. Terminology
3.1 Definitions—Terminology D3878 defines terms relating 6. Interferences
to high-modulus fibers and their composites. Terminology
6.1 Refer to Guide D8509.
D883 defines terms relating to plastics. Terminology E6 defines
terms relating to mechanical testing. Terminology E456 and
7. Apparatus
Practice E177 define terms relating to statistics. In the event of
7.1 Micrometers and Calipers—A micrometer with a 4 mm
a conflict between terms, Terminology D3878 shall have
to 8 mm [0.16 in. to 0.32 in.] nominal diameter ball interface or
precedence over the other terminologies.
a flat anvil interface shall be used to measure the specimen
3.2 Definitions of Terms Specific to This Standard—Refer to
thickness. A ball interface is recommended for thickness
Guide D8509.
measurements when at least one surface is irregular (for
example, a coarse peel ply surface which is neither smooth nor
3.3 Symbols:
flat). A micrometer or caliper with a flat anvil interface shall be
A—cross-sectional area of a specimen
used for measuring length, width, and other machined surface
CV—coefficient of variation statistic of a sample population
dimensions. The use of alternative measurement devices is
for a given property (in percent)
permitted if specified (or agreed to) by the test requestor and
B —edgewise percent bending
z
reported by the testing laboratory. The accuracy of the instru-
D—hole diameter
ments shall be suitable for reading to within 1 % of the
h—specimen thickness
specimen dimensions. For typical specimen geometries, an
n—number of specimens per sample population
instrument with an accuracy of 60.0025 mm [60.0001 in.] is
N—number of plies in laminate under test
ohcu
adequate for the thickness measurement, while an instrument
F —ultimate open hole (notched) compressive strength
x
with an accuracy of 60.025 mm [60.001 in.] is adequate for
in the test direction
measurement of length, width, and other machined surface
P —maximum force carried by test specimen before
max
dimensions. Additionally, a micrometer or gauge capable of
failure
determining the hole diameter to 60.025 mm [60.001 in.]
r—95 % repeatability confidence limit, equal to 2.8 times
shall be used.
the repeatability standard deviation
R—95 % reproducibility confidence limit, equal to 2.8 times
7.2 Support Fixture—The fixture is a face-supported com-
the reproducibility standard deviation
pressive test fixture as shown in Fig. 1. The fixture consists of
S —standard deviation statistic of a sample population for
n–1
two short-grip/long-grip assemblies, two support plates, and
a given property
steel shims as required to maintain a nominally zero (0.00 mm
S —repeatability (within laboratory precision) standard
r
to 0.12 mm [0.000 in. to 0.005 in.] tolerance) gap between
deviation, calculated in accordance with Practice E691
support plates and long grips. If this gap does not meet the
S —reproducibility (between laboratory precision) standard
R
minimum requirement, shim the contact area between the
deviation, calculated in accordance with Practice E691
support plate and the short grip with steel shim stock. If the gap
w—specimen width
is too large, shim between the support plate and the long grip,
x —test result for an individual specimen from the sample
holding the shim stock on the support plate with tape. Fig. 2
population for a given property
shows shim requirements. The fixture should be checked for
x¯—mean or average (estimate of mean) of a sample popu-
conformity to engineering drawings. Each short-grip/long-grip
lation for a given property
assembly is line-drilled as shown in Figs. A2.1 and A1.1 and
σ—normal stress
must be used as a matched set. The threading of the support
plate is optional. Standard test specimens are 36 mm by
4. Summary of Test Method
300 mm [1.5 in. by 12 in.]. In Procedure A, the fixture is
4.1 A uniaxial compression test of a balanced, symmetric
hydraulically gripped on each end and the compressive force is
laminate is performed with a centrally located hole. Edge-
transmitted by means of friction through the fixture and into the
mounted extensometer displacement transducers are optional.
test specimen. In Procedure B, the fixture is placed between flat
Refer to Guide D8509 for additional test details.
platens and loaded in compression at each end; force intro-
4.2 The test specimen is face-supported in a multi-piece duced into the fixture is transmitted by means of friction into
bolted support fixture. Two acceptable test procedures are the test specimen. A cutout exists on both faces of the fixture
provided. In Procedure A, the specimen/fixture assembly is for a thermocouple, fastener, or extensometer, if required by
clamped in hydraulic wedge grips. The force is transmitted by the requesting organization. The long and short fixtures have an
shear into the support fixture and then is transmitted by shear undercut along the corner of the specimen grip area so that
into the test specimen. In Procedure B, the specimen/fixture specimens are not required to be chamfered and to avoid
assembly is placed between flat platens, such that the specimen damage caused by the radius. The fixtures also allow a slight
D6484/D6484M − 23
FIG. 1 Support Fixture Assembly
clearance between the fixture and the gauge section of the
specimen, in order to minimize grip failures and friction
effects.
7.2.1 Support Fixture Details—The detailed drawings for
manufacturing the support fixture are contained in Figs. A2.2-
A1.5. An optional threaded support plate is shown in Figs. A2.6
and A1.6, to be used instead of the support plate shown in Figs.
A2.5 and A1.5 and the nuts called out in Fig. 1. Other fixtures
that meet the requirements of this section may be used (for
example, MTS Open Hole Compressive Fixture Model
605.21A or Wyoming Test Fixtures, Inc. Models CU-OH and
WTF-OH). The following general notes apply to these figures:
7.2.1.1 Machine surfaces to a 3.2 [125] finish unless other-
wise specified.
7.2.1.2 Break all edges.
7.2.1.3 Specimen-gripping area shall be thermal sprayed
using high-velocity oxygen fueled (HVOF), electrospark de-
position (ESD), or equivalent process.
7.2.1.4 The test fixture may be made of low-carbon steel for
ambient temperature testing. For non-ambient environmental
conditions, the recommended fixture material is a nonheat-
treated ferritic or precipitation-hardened stainless steel (heat
treatment for improved durability is acceptable but not re-
quired).
7.2.1.5 Additional fasteners may be installed in the gripping
area (shown in Figs. A2.1 and A1.1) when using Procedure B.
The presence of such fasteners is not required to perform an
FIG. 2 Support Fixture—Shim Requirements
end-loaded test successfully. However, they can be beneficial
D6484/D6484M − 23
in suppressing unacceptable failure modes (such as end fail- testing laboratory conditions. This chamber shall be capable of
ures) in certain circumstances (high temperature testing, for maintaining the test specimen and fixture at the required test
example) by ensuring that the specimen is well-supported by environment during the mechanical test. The test temperature
the fixture. shall be maintained within 63 °C [65 °F] of the required
temperature, and the relative humidity level shall be main-
NOTE 1—Experience has shown that fixtures may be damaged in use,
tained to within 63 % RH of the required humidity level.
thus periodic reinspection of the fixture dimensions and tolerances is
important.
8. Sampling and Test Specimens
7.3 Testing Machine—The testing machine shall be in ac-
8.1 Sampling—Test at least five specimens per test condi-
cordance with Practices E4 and shall satisfy the following
tion unless valid results can be gained through the use of fewer
requirements:
specimens, as in the case of a designed experiment. For
7.3.1 Testing Machine Configuration—The testing machine
statistically significant data, consult the procedures outlined in
shall have both an essentially stationary head and a movable
Practice E122. Report the method of sampling.
head. A short loading train, and either rigidly mounted hydrau-
8.2 Geometry:
lic grips or flat end-loading platens, shall be used.
8.2.1 Stacking Sequence—The standard tape and fabric
7.3.2 Grips—If Procedure A is used, each head of the testing
laminates shall have multidirectional fiber orientations (fibers
machine shall be capable of holding one end of the test
shall be oriented in a minimum of two directions) and balanced
assembly so that the direction of force applied to the specimen
and symmetric stacking sequences. The nominal thickness
is coincident with the longitudinal axis of the specimen.
shall be 4 mm [0.160 in.], with a permissible range from 3 mm
Hydraulic wedge grips shall apply sufficient lateral pressure to
to 5 mm [0.125 in. to 0.200 in.], inclusive. Fabric laminates
prevent slippage between the grip face and the support fixture.
containing satin-type weaves shall have symmetric warp
7.3.3 Flat Platens—If Procedure B is used, the test machine
surfaces, unless otherwise specified and noted in the report.
shall be mounted with well-aligned, fixed (as opposed to
spherical seat) flat platens. The platen surfaces shall be parallel
NOTE 2—Typically, a [45 /–45 /0 /90 ] tape or [45 /0 ] fabric lami-
i i j k ms i j ms
nate should be selected such that a minimum of 5 % of the fibers lay in
within 0.03 mm [0.001 in.] across the test fixture base length of
each of the four principal orientations. This laminate design has been
80 mm [3.0 in]. If the platens are not sufficiently hardened, or
found to yield the highest likelihood of acceptable failure modes.
simply to protect the platen surfaces, a hardened plate (with
8.2.2 Specimen Configuration—The geometry of the speci-
parallel surfaces) can be inserted between each end of the
men is shown in Figs. 3 and 4.
fixture and the corresponding platen. A rectangle should be
drawn on the center of the lower platen, to help center the test
8.3 Specimen Preparation—Guide D5687/D5687M pro-
fixture between the platens.
vides recommended specimen preparation practices and should
7.3.4 Drive Mechanism—The testing machine drive mecha- be followed where practical.
nism shall be capable of imparting to the movable head a
8.3.1 Panel Fabrication—Control of fiber alignment is criti-
controlled velocity with respect to the stationary head. The cal. Improper fiber alignment will reduce the measured prop-
velocity of the movable head shall be capable of being
erties. The panel must be flat and of uniform thickness to
regulated in accordance with 11.3. ensure even loading. Erratic fiber alignment will also increase
7.3.5 Load Indicator—The testing machine load-sensing the coefficient of variation. Report the panel fabrication
method.
device shall be capable of indicating the total force being
carried by the test specimen. This device shall be essentially 8.3.2 Machining Methods—Specimen preparation is ex-
tremely important for this specimen. Take precautions when
free from inertia lag at the specified rate of testing and shall
indicate the force with an accuracy over the force range(s) of cutting specimens from plates to avoid notches, undercuts,
rough or uneven surfaces, or delaminations due to inappropri-
interest of within 61 % of the indicated value.
ate machining methods. Obtain final dimensions by water-
7.3.6 Extensometers—The extensometer gauge length shall
lubricated precision sawing, milling, or grinding. The use of
be 25 mm [1.0 in.]. Extensometers shall satisfy, at a minimum,
diamond tooling has been found to be extremely effective for
Practice E83, Class B-1 requirements for the strain range of
many material systems. Edges should be flat and parallel
interest, and shall be calibrated over that range in accordance
within the specified tolerances. Holes should be drilled under-
with Practice E83. The extensometers shall be essentially free
sized and reamed to final dimensions. Take special care to
of inertia lag at the specified speed of testing.
ensure that creation of the specimen hole does not delaminate
7.4 Conditioning Chamber—When conditioning materials
or otherwise damage the material surrounding the hole. Ma-
at non-laboratory environments, a temperature/vapor-level
chining tolerances and surface finish requirements are as noted
controlled environmental conditioning chamber is required that
in Figs. 3 and 4. Record and report the specimen cutting and
shall be capable of maintaining the required temperature to
hole preparation methods.
within 63 °C [65 °F] and the required relative humidity level
8.3.3 If specific gravity, density, reinforcement volume
to within 63 % RH. Chamber conditions shall be monitored
fraction, or void volume fraction are to be reported, then obtain
either on an automated continuous basis or on a manual basis
these samples from the same panels being tested. Specific
at regular intervals.
gravity and density may be evaluated by means of Test Method
7.5 Environmental Test Chamber—An environmental test D792. Volume percent of the constituents may be evaluated by
chamber is required for test environments other than ambient one of the matrix digestion procedures of Test Method D3171
D6484/D6484M − 23
FIG. 3 Open Hole Compression Test Specimen (Inch-Pound Version)
FIG. 4 Open Hole Compression Test Specimen (SI Version)
or, for certain reinforcement materials such as glass and
ceramics, by the matrix burn-off technique of Test Method
D6484/D6484M − 23
D2584. The void content equations of Test Method D2734 are 1 % of the dimension. Record the dimensions to three signifi-
applicable to both Test Method D2584 and the matrix digestion cant figures in units of millimetres [inches].
procedures.
NOTE 5—The test requester may request that additional measurements
8.3.4 Labeling—Label the specimens so that they will be
be performed after the machined specimens have gone through any
distinct from each other and traceable back to the raw material,
conditioning or environmental exposure.
and will neither influence the test nor be affected by it.
11.2.3 Condition the specimens as required. Store the speci-
mens in the conditioned environment until test time, if the test
9. Calibration
environment is different than the conditioning environment.
9.1 The accuracy of all measuring equipment shall have
11.3 Speed of Testing—Set the speed of testing so as to
certified calibrations that are current at the time of use of the
produce failure within 1 min to 10 min. If the ultimate strength
equipment.
of the material cannot be reasonably estimated, initial trials
should be conducted using standard speeds until the ultimate
10. Conditioning
strength of the material and the compliance of the system are
10.1 The recommended pre-test condition is effective mois-
known, and speed of testing can be adjusted. The suggested
ture equilibrium at a specific relative humidity as established
standard head displacement rate is 2 mm/min [0.05 in./min].
by Test Method D5229/D5229M; however, if the test requestor
11.4 Test Environment—If possible, test the specimen under
does not explicitly specify a pre-test conditioning environment,
the same fluid exposure level used for conditioning. However,
no conditioning is required and the test specimens may be
cases such as elevated temperature testing of a moist specimen
tested as prepared.
place unrealistic requirements on the capabilities of common
10.2 The pre-test specimen conditioning process, to include
testing machine environmental chambers. In such cases, the
specified environmental exposure levels and resulting moisture
mechanical test environment may need to be modified, for
content, shall be reported with the test data.
example, by testing at elevated temperature with no fluid
NOTE 3—The term “moisture,” as used in Test Method D5229/
exposure control, but with a specified limit on time to failure
D5229M, includes not only the vapor of a liquid and its condensate, but
the liquid itself in large quantities, as for immersion. from withdrawal from the conditioning chamber. Record an
...

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: D6484/D6484M − 20 D6484/D6484M − 23
Standard Test Method for
Open-Hole Compressive Strength of Polymer Matrix
Composite Laminates
This standard is issued under the fixed designation D6484/D6484M; 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 compressive 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 Several related ASTM standards reference the procedures and apparatus described within this test method. In particular, the
support fixture described in 7.2 is used by several other standards to stabilize compression-loaded test specimens. These include
Practice D6742/D6742M, which covers filled-hole compression testing; Practice D7615/D7615M, which covers open-hole fatigue
testing; and Practice D8066/D8066M, which covers unnotched laminate compression testing.
1.3 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in
each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.
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
D2584 Test Method for Ignition Loss of Cured Reinforced Resins
D2734 Test Methods for Void Content of Reinforced Plastics
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 Oct. 1, 2020Sept. 1, 2023. Published November 2020October 2023. Originally approved in 1999. Last previous edition approved in 20142020
as D6484/D6484M – 14.D6484/D6484M – 20. DOI: 10.1520/D6484_D6484M-20.10.1520/D6484_D6484M-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
D6484/D6484M − 23
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
D5687/D5687M Guide for Preparation of Flat Composite Panels with Processing Guidelines for Specimen Preparation
D6742/D6742M Practice for Filled-Hole Tension and Compression Testing of Polymer Matrix Composite Laminates
D7615/D7615M Practice for Open-Hole Fatigue Response of Polymer Matrix Composite Laminates
D8066/D8066M Practice Unnotched Compression Testing of Polymer Matrix Composite Laminates
D8509 Guide for Test Method Selection and Test Specimen Design for Bolted Joint Related Properties
E4 Practices for Force Calibration and Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E83 Practice for Verification and Classification of Extensometer Systems
E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or
Process
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
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 terminologies.
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 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 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 width-to-diameter ratio, w/D [nd], n—in an open-hole specimen, the ratio of the specimen width to the hole diameter.
3.2.3.1 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)
B —edgewise percent bending
z
D—hole diameter
h—specimen thickness
n—number of specimens per sample population
N—number of plies in laminate under test
ohcu
F —ultimate open hole (notched) compressive strength in the test direction
x
P —maximum force carried by test specimen before failure
max
r—95 % repeatability confidence limit, equal to 2.8 times the repeatability standard deviation
R—95 % reproducibility confidence limit, equal to 2.8 times the reproducibility standard deviation
D6484/D6484M − 23
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
x¯—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 compression test of a balanced, symmetric laminate is performed 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 test specimen is face-supported in a multi-piece bolted support fixture. Two acceptable test procedures are provided. In
Procedure A, the specimen/fixture assembly is clamped in hydraulic wedge grips. The force is transmitted by shear into the support
fixture and then is transmitted by shear into the test specimen. In Procedure B, the specimen/fixture assembly is placed between
flat platens, such that the specimen and fixture are end-loaded. The portion of the force initially transferred into the support fixture
is transmitted by shear into the test specimen.
4.3 The only acceptable failure mode for ultimate open-hole compressive 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 compressive strength data for structural design
allowables, material specifications, research and development, and quality assurance. Factors that influence the notched
compressive strength 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), specimen conditioning, environment of testing,
specimen alignment and gripping, loading procedure, speed of testing, time at temperature, void content, and volume percent
reinforcement. Properties that may be derived from this test method include open-hole (notched) compressive strength (OHC).
6. Interferences
6.1 Hole Preparation—Because of 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 compressive
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 caused by hole preparation will affect strength results. Some types of damage, such
as longitudinal splitting and delamination, can blunt the stress concentration caused by 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 the ratio of ungripped specimen length to specimen width; this ratio should be
maintained at 2.7, unless the experiment is investigating the influence of this ratio.
6.3 Support Fixture—Results are affected by the amount of lateral pressure applied to the test specimen by the support fixture.
Sources of variation in this lateral pressure include fixture bolt torque, hydraulic gripping pressure, and fixture shimming choices,
and should be controlled and reported as required in the Procedure and Report sections. The support fixture can inhibit the growth
of delamination damage by inhibiting out-of-plane deformation beyond the cutout, and by relieving force from the specimen via
friction effects. This may result in non-conservative data.
D6484/D6484M − 23
6.1 Material Orthotropy—The degree of laminateRefer to Guide D8509 orthotropy strongly affects the failure mode and measured
OHC strength. Valid OHC strength results should only be reported when appropriate failure modes are observed, in accordance
with 11.9.
6.5 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 scale linearly with thickness). Thus, data gathered using this test method may
not translate directly into equivalent thick-structure properties.
6.6 Type of Loading—Differences in force versus crosshead displacement and force versus extensometer strain response may be
observed when comparing hydraulic grip-loaded specimens with end-loaded specimens. Hydraulic grip-loaded data typically
exhibit linear behavior at the onset of loading. At high force levels, some nonlinear behavior may be observed due to grip slippage.
End-loaded data typically display some initial nonlinear behavior at low force levels, due to seating of the specimen/fixture
assembly underneath the load platens, but then exhibit linear behavior to failure.
7. Apparatus
7.1 Micrometers and Calipers—A micrometer with a 44 mm to 8 mm [0.16[0.16 in. to 0.32 in.] nominal diameter ball interface
or a flat anvil interface shall be used to measure the specimen thickness. A ball interface is recommended for thickness
measurements when at least one surface is irregular (for example, a coarse peel ply surface which is neither smooth nor flat). A
micrometer or caliper with a flat anvil interface shall be used for measuring length, width, and other machined surface dimensions.
The use of alternative measurement devices is permitted if specified (or agreed to) by the test requestor and reported by the testing
laboratory. The accuracy of the instruments shall be suitable for reading to within 1 % of the specimen dimensions. For typical
specimen geometries, an instrument with an accuracy of 60.0025 mm [60.0001 in.] is adequate for the thickness measurement,
while an instrument with an accuracy of 60.025 mm [60.001 in.] is adequate for measurement of length, width, and other
machined surface dimensions. Additionally, a micrometer or gagegauge capable of determining the hole diameter to 60.025 mm
[60.001 in.] shall be used.
7.2 Support Fixture—The fixture is a face-supported compressive test fixture as shown in Fig. 1. The fixture consists of two
FIG. 1 Support Fixture Assembly
D6484/D6484M − 23
short-grip/long-grip assemblies, two support plates, and steel shims as required to maintain a nominally zero (0.00(0.00 mm to
0.12 mm [0.000[0.000 in. to 0.005 in.] tolerance) gap between support plates and long grips. If this gap does not meet the minimum
requirement, shim the contact area between the support plate and the short grip with steel shim stock. If the gap is too large, shim
between the support plate and the long grip, holding the shim stock on the support plate with tape. Fig. 2 shows shim requirements.
The fixture should be checked for conformity to engineering drawings. Each short-grip/long-grip assembly is line-drilled as shown
in Figs. 3A2.1 and 4A1.1 and must be used as a matched set. The threading of the support plate is optional. Standard test specimens
are 36 by 300 mm [1.5 by 12 in.]. 36 mm by 300 mm [1.5 in. by 12 in.]. In Procedure A, the fixture is hydraulically gripped on
each end and the compressive force is transmitted by means of friction through the fixture and into the test specimen. In Procedure
B, the fixture is placed between flat platens and loaded in compression at each end; force introduced into the fixture is transmitted
by means of friction into the test specimen. A cutout exists on both faces of the fixture for a thermocouple, fastener, or
extensometer, if required by the requesting organization. The long and short fixtures have an undercut along the corner of the
specimen grip area so that specimens are not required to be chamfered and to avoid damage caused by the radius. The fixtures also
allow a slight clearance between the fixture and the gagegauge section of the specimen, in order to minimize grip failures and
friction effects.
7.2.1 Support Fixture Details—The detailed drawings for manufacturing the support fixture are contained in Figs. 5-A2.2-12A1.5.
An optional threaded support plate is shown in Figs. 13A2.6 and 14A1.6, to be used instead of the support plate shown in Figs.
11A2.5 and 12A1.5 and the nuts called out in Fig. 1. Other fixtures that meet the requirements of this section may be used (for
example, MTS Open Hole Compressive Fixture Model 605.21A or Wyoming Test Fixtures, Inc. Models CU-OH and WTF-OH).
The following general notes apply to these figures:
7.2.1.1 Machine surfaces to a 3.2 [125] finish unless otherwise specified.
7.2.1.2 Break all edges.
7.2.1.3 Specimen-gripping area shall be thermal sprayed using high-velocity oxygen fueled (HVOF), electrospark deposition
(ESD), or equivalent process.
FIG. 2 Support Fixture—Shim Requirements
D6484/D6484M − 23
7.2.1.4 The test fixture may be made of low-carbon steel for ambient temperature testing. For non-ambient environmental
conditions, the recommended fixture material is a nonheat-treated ferritic or precipitation-hardened stainless steel (heat treatment
for improved durability is acceptable but not required).
7.2.1.5 Additional fasteners may be installed in the gripping area (shown in Figs. 3A2.1 and 4A1.1) when using Procedure B. The
presence of such fasteners is not required to perform an end-loaded test successfully. However, they can be beneficial in
suppressing unacceptable failure modes (such as end failures) in certain circumstances (high temperature testing, for example) by
ensuring that the specimen is well-supported by the fixture.
NOTE 1—Experience has shown that fixtures may be damaged in use, thus periodic reinspection of the fixture dimensions and tolerances is important.
7.3 Testing Machine—The testing machine shall be in accordance with Practices E4 and shall satisfy the following requirements:
7.3.1 Testing Machine Configuration—The testing machine shall have both an essentially stationary head and a movable head. A
short loading train, and either rigidly mounted hydraulic grips or flat end-loading platens, shall be used.
7.3.2 Grips—If Procedure A is used, each head of the testing machine shall be capable of holding one end of the test assembly
so that the direction of force applied to the specimen is coincident with the longitudinal axis of the specimen. Hydraulic wedge
grips shall apply sufficient lateral pressure to prevent slippage between the grip face and the support fixture.
7.3.3 Flat Platens—If Procedure B is used, the test machine shall be mounted with well-aligned, fixed (as opposed to spherical
seat) flat platens. The platen surfaces shall be parallel within 0.03 mm [0.001 in.] across the test fixture base length of 80 mm [3.0
in]. If the platens are not sufficiently hardened, or simply to protect the platen surfaces, a hardened plate (with parallel surfaces)
can be inserted between each end of the fixture and the corresponding platen. A rectangle should be drawn on the center of the
lower platen, to help center the test fixture between the platens.
7.3.4 Drive Mechanism—The testing machine drive mechanism shall be capable of imparting to the movable head a controlled
velocity with respect to the stationary head. The velocity of the movable head shall be capable of being regulated in accordance
with 11.3.
7.3.5 Load Indicator—The testing machine load-sensing device shall be capable of indicating the total force being carried by the
test specimen. This device shall be essentially free from inertia lag at the specified rate of testing and shall indicate the force with
an accuracy over the force range(s) of interest of within 61 % of the indicated value.
7.3.6 Extensometers—The extensometer gagegauge length shall be 25 mm [1.0 in.]. Extensometers shall satisfy, at a minimum,
Practice E83, Class B-1 requirements for the strain range of interest, and shall be calibrated over that range in accordance with
Practice E83. The extensometers shall be essentially free of inertia lag at the specified speed of testing.
7.4 Conditioning Chamber—When conditioning materials at non-laboratory environments, a temperature/vapor-level controlled
environmental conditioning chamber is required that shall be capable of maintaining the required temperature to within 63 °C
[65 °F] and the required relative humidity level to within 63 % RH. Chamber conditions shall be monitored either on an
automated continuous basis or on a manual basis at regular intervals.
D6484/D6484M − 23
7.5 Environmental Test Chamber—An environmental test chamber is required for test environments other than ambient testing
laboratory conditions. This chamber shall be capable of maintaining the test specimen and fixture at the required test environment
during the mechanical test. The test temperature shall be maintained within 63 °C [65 °F] of the required temperature, and the
relative humidity level shall be maintained to within 63 % RH of the required humidity level.
8. Sampling and Test Specimens
8.1 Sampling—Test at least five specimens per test condition unless valid results can be gained through the use of fewer specimens,
as in the case of a designed experiment. For statistically significant data, consult the procedures outlined in Practice E122. Report
the method of sampling.
8.2 Geometry:
8.2.1 Stacking Sequence—The standard tape and fabric laminates shall have multidirectional fiber orientations (fibers shall be
oriented in a minimum of two directions) and balanced and symmetric stacking sequences. The nominal thickness shall be 4 mm
[0.160 in.], with a permissible range from 3 to 5 mm [0.125 to 0.200 in.], 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 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 Specimen Configuration—The geometry of the specimen is shown in Figs. 153 and 164.
8.3 Specimen Preparation—Guide D5687/D5687M provides recommended specimen preparation practices and should be
followed where practical.
8.3.1 Panel Fabrication—Control of fiber alignment is critical. Improper fiber alignment will reduce the measured properties. The
panel must be flat and of uniform thickness to ensure even loading. Erratic fiber alignment will also increase the coefficient of
variation. Report the panel fabrication method.
FIG. 3 Open Hole Compression Test Specimen (Inch-Pound Version)
D6484/D6484M − 23
FIG. 4 Open Hole Compression Test Specimen (SI Version)
8.3.2 Machining Methods—Specimen preparation is extremely important for this specimen. Take precautions when cutting
specimens from plates to avoid notches, undercuts, rough or uneven surfaces, or delaminations due to inappropriate machining
methods. Obtain final dimensions by water-lubricated precision sawing, milling, or grinding. The use of diamond tooling has been
found to be extremely effective for many material systems. Edges should be flat and parallel within the specified tolerances. Holes
should be drilled undersized and reamed to final dimensions. Take special care to ensure that creation of the specimen hole does
not delaminate or otherwise damage the material surrounding the hole. Machining tolerances and surface finish requirements are
as noted in Figs. 153 and 164. Record and report the specimen cutting and hole preparation methods.
8.3.3 If specific gravity, density, reinforcement volume fraction, or void volume fraction are to be reported, then obtain these
samples from the same panels being tested. Specific gravity and density may be evaluated by means of Test Method D792. Volume
percent of the constituents may be evaluated by one of the matrix digestion procedures of Test Method D3171 or,
...