ASTM D5766/D5766M-95
(Test Method)Standard Test Method for Open Hole Tensile Strength of Polymer Matrix Composite Laminates
Standard Test Method for Open Hole Tensile Strength of Polymer Matrix Composite Laminates
SCOPE
1.1 This test method determines the open hole tensile strength of polymer matrix composite laminates reinforced by high-modulus fibers. The composite material forms are limited to continuous-fiber or discontinuous-fiber reinforced composites in which the laminate is balanced and symmetric with respect to the test direction. The standard test laminate is of the [45/0/-45/90] ns stacking sequence family, where the sublaminate repeat index is adjusted to yield a laminate thickness within the range discussed in 8.2.1. Other laminates may be tested provided the laminate configuration is reported with the results, however, the test method is unsatisfactory for unidirectional tape laminates containing only one ply orientation.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text the inch-pound units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 5766/D 5766M – 95
Standard Test Method for
Open Hole Tensile Strength of Polymer Matrix Composite
Laminates
This standard is issued under the fixed designation D 5766/D 5766M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 3171 Test Method for Fiber Content of Resin-Matrix
Composites by Matrix Digestion
1.1 This test method determines the open hole tensile
D 3878 Terminology of High-Modulus Reinforcing Fibers
strength of polymer matrix composite laminates reinforced by
and Their Composites
high-modulus fibers. The composite material forms are limited
E 6 Terminology Relating to Methods of Mechanical Test-
to continuous-fiber or discontinuous-fiber reinforced compos-
ing
ites in which the laminate is balanced and symmetric with
E 177 Practice for Use of the Terms Precision and Bias in
respect to the test direction. The standard test laminate is of the
ASTM Test Methods
[45/0/−45/90]ns stacking sequence family, where the sublami-
E 456 Terminology Relating to Quality and Statistics
nate repeat index n is adjusted to yield a laminate thickness
E 691 Practice for Conducting an Interlaboratory Study to
within the range discussed in 8.2.1. Other laminates may be
Determine the Precision of a Test Method
tested provided the laminate configuration is reported with the
E 1309 Guide for Identification of Composite Materials in
results, however, the test method is unsatisfactory for unidi-
Computerized Material Property Databases
rectional tape laminates containing only one ply orientation.
E 1434 Guide for Development of Standard Data Records
1.2 This standard does not purport to address all of the
for Computerization of Mechanical Test Data for High-
safety concerns, if any, associated with its use. It is the
Modulus Fiber-Reinforced Composite Materials
responsibility of the user of this standard to establish appro-
E 1471 Guide for Identification of Fibers, Fillers and Core
priate safety and health practices and determine the applica-
Materials in Computerized Material Property Databases
bility of regulatory limitations prior to use.
1.3 The values stated in either SI units or inch-pound units
3. Terminology
are to be regarded separately as standard. Within the text the
3.1 Definitions—Terminology D 3878 defines terms relating
inch-pound units are shown in brackets. The values stated in
to high-modulus fibers and their composites. Terminology
each system are not exact equivalents; therefore, each system
D 883 defines terms relating to plastics. Terminology E 6
must be used independently of the other. Combining values
defines terms relating to mechanical testing. Terminology
from the two systems may result in nonconformance with the
E 456 and Practice E 177 define terms relating to statistics. In
standard.
the event of a conflict between terms, Terminology D 3878
2. Referenced Documents shall have precedence over the other standards.
3.2 Definitions of Terms Specific to This Standard::
2.1 ASTM Standards:
D 792 Test Methods for Density and Specific Gravity (Rela-
NOTE 1—If the term represents a physical quantity, its analytical
tive Density) of Plastics by Displacement
dimensions are stated immediately following the term (or letter symbol) in
fundamental dimension form, using the following ASTM standard sym-
D 883 Terminology Relating to Plastics
bology for fundamental dimensions, shown within square brackets: [M]
D 2584 Test Method for Ignition Loss of Cured Reinforced
3 for mass, [L] for length, [T] for time, [u] for thermodynamic temperature,
Resins
and [nd] for non-dimensional quantities. Use of these symbols is restricted
D 2734 Test Methods for Void Content of Reinforced Plas-
to analytical dimensions when used with square brackets, as the symbols
tics
may have other definitions when used without the brackets.
D 3039/D 3039M Test Method for Tensile Properties of
3.2.1 balanced laminate, n—laminate in which all laminae
Polymer Matrix Composite Materials
at angles other than 0 degrees or 90 degrees occur only in 6
pairs, though each ply of a pair is not required to be located
adjacent to the other.
This test method is under the jurisdiction of ASTM Committee D-30 on High
Modulus Fibers and Their Compositesand is the direct responsibility of Subcom-
3.2.2 nominal value, n—a value, existing in name only,
mittee D30.05on Structural Test Methods.
Current edition approved Aug. 15, 1995. Published October 1995.
Annual Book of ASTM Standards, Vol 08.01.
3 5
Annual Book of ASTM Standards, Vol 08.02. Annual Book of ASTM Standards, Vol 03.01.
4 6
Annual Book of ASTM Standards, Vol 15.03. Annual Book of ASTM Standards, Vol 14.02.
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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 5766/D 5766M
assigned to a measurable property for the purpose of conve- strength data for material specifications, research and develop-
nient designation. Tolerances may be applied to a nominal ment, and quality assurance. Factors that influence the notched
value to define an acceptable range for the property. tensile strength and should therefore be reported include the
3.2.3 ply orientation, u,n—the angle between a reference following: material, methods of material fabrication, accuracy
direction and the ply principal axis. The angle is expressed in of lay-up, laminate stacking sequence and overall thickness,
degrees, is never greater than 90°, and is shown as a positive specimen geometry, specimen preparation (especially of the
quantity when taken from the reference direction to the ply hole), specimen conditioning, environment of testing, speci-
principal axis, following the right-hand-rule. men alignment and gripping, speed of testing, void content,
3.2.3.1 Discussion—The reference direction is usually re- and volume percent reinforcement. Properties that may be
lated to a primary load-carrying direction. derived from this test method include the following:
3.2.4 ply principal axis, n—the coordinate axis in the plane 5.1.1 Open hole (notched) tensile strength.
of a lamina that is used as the reference direction for that
6. Interferences
lamina.
6.1 Hole Preparation—Due to the dominating presence of
3.2.4.1 Discussion—The ply principal axis will, in general,
be different for each ply of a laminate. The direction of this axis the notch, and the lack of need to measure the material
response, results from this test method are relatively insensitive
relative to some reference axis is defined by the ply orientation.
The convention is to align the ply principal axis with a material to parameters that would be of concern in an unnotched tensile
property test. However, since the notch dominates the strength,
feature that is the direction of maximum stiffness (such as the
fiber direction for unidirectional tape or the warp direction for consistent preparation of the hole, without damage to the
fabric reinforced material). Conventions for other laminated laminate, is important to meaningful results. Damage due to
hole preparation will affect strength results. Some types of
material forms have not yet been established.
3.2.5 symmetric laminate, n—is one in which the orienta- damage, such as delaminations, can blunt the stress concentra-
tion because of the hole, increasing the load-carrying capacity
tion, form, and material (and warp surface, for satin-type
fabrics) for the plies located on one side of the midplane is the of the coupon and the calculated strength.
6.2 Geometry—Results are affected by the ratio of specimen
mirror image of the stacking sequence on the other side of the
midplane. width to hole diameter; this ratio should be maintained at 6,
unless the experiment is investigating the influence of this
3.2.6 warp surface, n—the side of a woven fabric, in a
satin-type weave pattern, which is dominated by the warp ratio. Results may also be affected by the ratio of hole diameter
to thickness; the preferred ratio is the range of 1.5–3.0 unless
yarns.
3.3 Symbols: the experiment is investigating the influence of this ratio.
6.3 Other—Additional sources of potential data scatter in
3.3.1 A—cross-sectional area of a coupon.
3.3.2 CV—coefficient of variation statistic of a sample testing of composite materials are described in Test Method
D 3039/D 3039M.
population for a given property (in percent).
3.3.3 D—hole diameter.
7. Apparatus
3.3.4 h—coupon thickness.
7.1 Apparatus shall be in accordance with Test Method
3.3.5 n—number of coupons per sample population.
D 3039/D 3039M. However, the procedure herein does not
3.3.6 N—number of plies in laminate under test.
OHTu
measure material response, so strain or deflection measurement
3.3.7 F —ultimate tensile strength in the test direction.
x
max
related discussions in Test Method D 3039/D 3039M do not
3.3.8 P —maximum load carried by test coupon prior to
apply. Additionally, a micrometer or gage capable of determin-
failure.
ing the hole diameter to 60.025 mm [60.001 in.] is required.
3.3.9 s —standard deviation statistic of a sample popula-
n−1
tion for a given property.
8. Sampling and Test Specimens
3.3.10 w—coupon width.
8.1 Sampling—Sampling shall be in accordance with Test
3.3.11 x —test result for an individual coupon from the
i
Method D 3039/D 3039M.
sample population for a given property.
8.2 Geometry—The coupon geometry shall be in accor-
3.3.12 x¯—mean or average (estimate of mean) of a sample
dance with Test Method D 3039/D 3039M, as modified by the
population for a given property.
following, and illustrated by the schematic of Fig. 1. Any
3.3.13 s—normal stress.
variation of the stacking sequence, specimen width or length,
4. Summary of Test Method
or hole diameter from that specified shall be clearly noted in
4.1 A uniaxial tension test of a balanced, symmetric lami- the report.
8.2.1 Stacking Sequence—The normal laminate shall have a
nate is performed in accordance with Test Method D 3039/
balanced and symmetric stacking sequence of [45/0/−45/90]ns,
D 3039M, although with a centrally located hole and without
where n is selected to keep the laminate thickness as close as
strain or displacement transducers. Ultimate strength is calcu-
possible to 2.5 mm [0.10 in.], with a permissible range of 2–4
lated based on the gross cross-sectional area, disregarding the
mm [0.080–0.160 in.], inclusive. Laminates containing satin-
presence of the hole.
type weaves shall have symmetric warp surfaces, unless
5. Significance and Use
otherwise noted in the report.
5.1 This test method is designed to produce notched tensile 8.2.2 Dimensions—The width of the specimen is 36 6 1
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 5766/D 5766M
11.1.1 The tension specimen sampling method, coupon type
and geometry, and conditioning travelers (if required).
11.1.2 The tensile properties and data reporting format
desired.
NOTE 2—Determine specific material property, accuracy, and data
reporting requirements prior to test for proper selection of instrumentation
and data recording equipment. Estimate the coupon strength to aid in
transducer selection, calibration of equipment, and determination of
equipment settings.
11.1.3 The environmental conditioning test parameters.
11.1.4 If performed, the sampling method, coupon geom-
etry, and test parameters used to determine density and
reinforcement volume.
11.2 General Instructions:
11.2.1 Report any deviations from this test method, whether
intentional or inadvertent.
11.2.2 If specific gravity, density, reinforcement volume or
void volume are to be reported then obtain these samples from
the same panels being tension tested. Specific gravity and
density may be evaluated by means of Test Methods D 792.
Volume percent of the constituents may be evaluated by one of
the matrix digestion procedures of Test Method D 3171, or, for
certain reinforcement materials such as glass and ceramics, by
the matrix burn-off technique of Test Method D 2584. The void
content equations of Test Methods D 2734 are applicable to
both Test Method D 2584 and the matrix digestion procedures.
11.2.3 Following any conditioning, but before the tensile
FIG. 1 Schematic of Open Hole Tension Test Coupon testing, measure and report the specimen hole diameter to the
nearest 0.025 mm [0.001 in.]. Inspect the hole and areas
mm [1.50 6 0.05 in.] and the length range is 200–300 mm adjacent to the hole for delaminations. Report the location and
[8.0–12.0 in.]. The notch consists of a centrally located hole,
size of any delaminations found. Perform other measurements
66 0.06 mm [0.250 6 0.003 in.] diameter, placed within 0.1
in accordance with Test Method D 3039/D 3039M.
mm [0.005 in.] of the axial centerline of the coupon. While tabs
11.3 Tensile Testing—Perform other measurements, and the
may be used, they are not required and generally not needed,
tension test of the laminate coupon, in accordance with the
since the open hole acts as sufficient stress riser to force failure
Procedure section of Test Method D 3039/D 3039M.
in the notched region.
11.4 Failure Modes—The failure is often heavily influenced
8.3 Specimen Preparation—Care must be taken in prepara-
by delamination and the failure mode may exhibit much
tion of the hole so as not to delaminate the material. The most
delamination. Failures that do not occur at the hole are not
common successful hole preparation technique begins by
acceptable failure modes and the data shall be noted as invalid.
drilling an undersized hole, with backup plates on both
Fig. 2 illustrates the two acceptable failure modes. Three-place
surfaces and coolant; and finishes by reaming to the final
failure mode descriptors for these modes, following those
desired hole diameter. The finished hole shall be clean and
given in Test Method D 3039/D 3039M and summarized in
smooth with sharp unbeveled edges, but not polished. The
Table 1 shall be used. This notation uses the first place to
specimen shall not have any delamination damage. Other
describe failure type, the second to describe failure area, and
specimen preparation techniques and requirements are noted in
the last to describe failure location. Failure mode codes for
Test Method D 3039/D 3039M.
valid tests for this test method are limited to ___ GM, where
...
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