ASTM E1922-97
(Test Method)Standard Test Method for Translaminar Fracture Toughness of Laminated Polymer Matrix Composite Materials
Standard Test Method for Translaminar Fracture Toughness of Laminated Polymer Matrix Composite Materials
SCOPE
1.1 This test method covers the determination of translaminar fracture toughness, KTL, for laminated polymer matric composite materials of various ply orientations using test results from monotonically loaded notched specimens.
1.2 This test method is applicable to room temperature laboratory air environments.
1.3 Composite materials that can be tested by this test method are not limited by thickness or by type of polymer matrix or fiber, provided that the specimen sizes and the test results meet the requirements of this test method. This test method was developed primarily from test results of various carbon fiber - epoxy matrix laminates and from additional results of glass fiber - epoxy matrix and carbon fiber - bismaleimide matrix laminates (1-4).
1.4 A range of eccentrically loaded, single-edge-notch tension, ESE (T), specimen sizes with proportional planar dimensions is provided, but planar size may be variable and adjusted, with associated changes in the applied test load. Specimen thickness is a variable, independent of planar size.
1.5 Specimen configurations other than those contained in this test method may be used, provided that stress intensity calibrations are available and that the test results meet the requirements of this test method. It is particularly important that the requirements discussed in 5.1 and 5.4 regarding contained notch-tip damage be met when using alternative specimen configurations.
1.6 Values stated in SI units are to be regarded as the standard.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E 1922 – 97
Standard Test Method for
Translaminar Fracture Toughness of Laminated Polymer
Matrix Composite Materials
This standard is issued under the fixed designation E 1922; 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 2. Referenced Documents
1.1 This test method covers the determination of translami- 2.1 ASTM Standards:
nar fracture toughness, K , for laminated polymer matrix D 883 Terminology Relating to Plastics
TL
composite materials of various ply orientations using test D 3039 Test Method for Tensile Properties of Polymer
results from monotonically loaded notched specimens. Matrix Composite Materials
1.2 This test method is applicable to room temperature D 3878 Terminology of High-Modulus Reinforcing Fibers
laboratory air environments. and their Composites
1.3 Composite materials that can be tested by this test D 5229 Test Method for Moisture Adsorption Properties
method are not limited by thickness or by type of polymer and Equilibrium Conditioning of Polymer Matrix Com-
matrix or fiber, provided that the specimen sizes and the test posite Materials
results meet the requirements of this test method. This test D 5528 Test Method for Mode I Interlaminar Fracture
method was developed primarily from test results of various Toughness of Unidirectional Fiber-Reinforced Polymer
carbon fiber – epoxy matrix laminates and from additional Matrix Composites
results of glass fiber – epoxy matrix and carbon fiber – E 4 Practices for Force Verification of Testing Machines
bismaleimide matrix laminates (1-4). E 6 Terminology Relating to Methods of Mechanical Test-
1.4 A range of eccentrically loaded, single-edge-notch ten- ing
sion, ESE(T), specimen sizes with proportional planar dimen- E 83 Practice for Verification and Classification of Exten-
sions is provided, but planar size may be variable and adjusted, someters
with associated changes in the applied test load. Specimen E 399 Test Method for Plane-Strain Fracture Toughness of
thickness is a variable, independent of planar size. Metallic Materials
1.5 Specimen configurations other than those contained in E 1681 Test Method for Determining a Threshold Stress
this test method may be used, provided that stress intensity Intensity Factor for Environment-Assisted Cracking of
calibrations are available and that the test results meet the Metallic Materials Under Constant Load
requirements of this test method. It is particularly important E 1823 Terminology Relating to Fatigue and Fracture Test-
that the requirements discussed in 5.1 and 5.4 regarding ing
contained notch-tip damage be met when using alternative
3. Terminology
specimen configurations.
3.1 Definitions:
1.6 Values stated in SI units are to be regarded as the
standard. 3.1.1 Terminology E 6, E 1823, and D 3878 are applicable
to this test method.
1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.2 Definitions of Terms Specific to This Standard:
3.2.1 notch-mouth displacement, V [L]—the Mode I (also
responsibility of the user of this standard to establish appro-
n
priate safety and health practices and to determine the called opening mode) component of crack or notch displace-
ment due to elastic and permanent deformation. The displace-
applicability of regulatory limitations prior to use.
ment is measured across the mouth of the notch on the
specimen surface (see Fig. 1).
This test method is under the jurisdiction of ASTM Committee E–8 on Fatigue
and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
Deformation and Fatigue Crack Formation.
Current edition approved Dec. 10, 1997. Published February 1998. Annual Book of ASTM Standards, Vol 08.01.
2 4
The boldface numbers in parentheses refer to the list of references at the end of Annual Book of ASTM Standards, Vol 15.03.
this standard. Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1922
FIG. 1 Test Arrangement for Translaminar Fracture Toughness Tests
3.2.2 notch length, a [L]—the distance from a reference 5. Significance and Use
n
plane to the front of the machined notch. The reference plane
5.1 The parameter K determined by this test method is a
TL
depends on the specimen form, and normally is taken to be
measure of the resistance of a polymer matrix composite
either the boundary, or a plane containing either the load line or
laminate to notch-tip damage and effective translaminar crack
the centerline of a specimen or plate. The reference plane is
growth under opening mode loading. The result is valid only
defined prior to specimen deformation (see Fig. 2).
for conditions in which the damage zone at the notch tip is
3.2.3 normalized notch size, a /W [nd]—the ratio of notch
n
small compared with the notch length and the in-plane speci-
length, a , to specimen width, W.
n
men dimensions.
3.2.4 For additional information, see Terminology D 883
5.2 This test method can serve the following purposes. In
and Test Methods D 3039, D 5229, and D 5528.
research and development, K data can quantitatively estab-
TL
lish the effects of fiber and matrix variables and stacking
4. Summary of Test Method
sequence of the laminate on the translaminar fracture resistance
4.1 This test method involves tension testing of eccentri-
of composite laminates. In acceptance and quality control
cally loaded, single-edge-notch, ESE(T), specimens in opening
specifications, K data can be used to establish criteria for
TL
mode loading. Load versus displacement across the notch at
material processing and component inspection.
the specimen edge, V , is recorded. The load corresponding to
n
5.3 The translaminar fracture toughness, K , determined by
a prescribed increase in normalized notch length is determined, TL
this test method may be a function of the testing speed and
using the load-displacement record. The translaminar fracture
temperature. This test method is intended for room temperature
toughness, K , is calculated from this load using equations
TL
and quasi-static conditions, but it can apply to other test
that have been established on the basis of elastic stress analysis
conditions provided that the requirements of 9.2 and 9.3 are
of the modified single-edge notched specimen.
met. Application of K in the design of service components
4.2 The validity of translaminar fracture toughness, K ,
TL
TL
should be made with awareness that the test parameters
determined by this test method depends on maintaining a
specified by this test may differ from service conditions,
relatively contained area of damage at the notch tip. To
possibly resulting in a different material response than that seen
maintain this suitable notch-tip condition, the allowed increase
in service.
in notch-mouth displacement near the maximum load point of
the tests is limited to a small value. Small increases in 5.4 Not all types of laminated polymer matrix composite
notch-mouth displacement are more likely for relatively thick materials experience the contained notch-tip damage and
samples and for samples with a significant proportion of the effective translaminar crack growth of concern in this test
near surface reinforcing fibers aligned parallel to the direction method. For example, the notch-tip damage may be more
of the notch. extensive and may not be accompanied by any significant
NOTE 1—All dimensions +/– 0.01 W, except as noted.
NOTE 2—A surfaces perpendicular and parallel as applicable within 0.01 W.
FIG. 2 Translaminar Fracture Toughness Test Specimen
E 1922
amount of effective translaminar crack growth. Typically, 8. Procedure
lower strength composite materials and those with a significant
8.1 Number of Tests— It is required that enough tests be
proportion of reinforcing fibers aligned in a direction perpen-
performed to obtain three valid replicate test results for each
dicular to the notch axis may not experience the contained
material condition. If material variations are expected, five
notch-tip damage required for a valid test.
tests are required.
8.2 Specimen Measurement—Three specimen measure-
6. Apparatus
ments are necessary to calculate applied K: notch length, a ;
n
thickness, B; and width, W. Complete separation of the
6.1 Loading—Specimens shall be loaded in a testing ma-
specimen into two pieces often occurs during a test, so it is
chine that has provision for simultaneous recording of the load
required that the specimen measurements be done prior to
applied to the specimen and the resulting notch-mouth dis-
testing. Also, exercise care to prevent injury to test personnel.
placement. A typical arrangement is shown in Fig. 1. Pin-
8.2.1 Measure the notch length, a , to the nearest 0.1 mm
loading clevises of the type used in Test Method E 399 are used
n
on each side of the specimen. Use the average of the two notch
to apply the load to the specimen. The accuracies of the load
measuring and recording devices should be such that load can length measurements in the calculations of applied K.
8.2.2 Measure the thickness, B, to the nearest 0.002 W,atno
be determined with an accuracy of 61 %. (For additional
fewer than three equally spaced positions around the notch.
information see Practices E 4).
Record the average of the three measurements as B for that
6.2 Displacement Gage—A displacement gage shall be used
specimen. Composite fabrication methods result in variations
to measure the displacement at the
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