ASTM E647-99
(Test Method)Standard Test Method for Measurement of Fatigue Crack Growth Rates
Standard Test Method for Measurement of Fatigue Crack Growth Rates
SCOPE
1.1 This test method covers the determination of fatigue crack growth rates from near-threshold to Kmax controlled instability. Results are expressed in terms of the crack-tip stress-intensity factor range ( K), defined by the theory of linear elasticity.
1.2 Several different test procedures are provided, the optimum test procedure being primarily dependent on the magnitude of the fatigue crack growth rate to be measured.
1.3 Materials that can be tested by this test method are not limited by thickness or by strength so long as specimens are of sufficient thickness to preclude buckling and of sufficient planar size to remain predominantly elastic during testing.
1.4 A range of specimen sizes with proportional planar dimensions is provided, but size is variable to be adjusted for yield strength and applied force. Specimen thickness may be varied independent of planar size.
1.5 The details of the various specimens and test configurations are shown in Annex A1 - Annex A3. Specimen configurations other than those contained in this method may be used provided that well-established stress-intensity factor calibrations are available and that specimens are of sufficient planar size to remain predominantly elastic during testing.
1.6 Residual stress/crack closure may significantly influence the fatigue crack growth rate data, particularly at low stress-intensity factors and low stress ratios, although such variables are not incorporated into the computation of K.
1.7 Values stated in SI units are to be regarded as the standard. Values given in parentheses are for information only.
1.8 This test method is divided into two main parts. The first part gives general information concerning the recommendations and requirements for fatigue crack growth rate testing. The second part is composed of annexes that describe the special requirements for various specimen configurations, special requirements for testing in aqueous environments, and procedures for non-visual crack size determination. In addition, there are appendices that cover techniques for calculating da/dN, determining fatigue crack opening force, and guidelines for measuring the growth of small fatigue cracks. General information and requirements common to all specimen types are listed as follows:
SectionReferenced Documents2Terminology3Summary of Use4Significance and Use5Apparatus6Specimen Configuration, Size, and Preparation7Procedure8Calculations and Interpretation of Results9Report10Precision and Bias11Special Requirements for Testing in Aqueous EnvironmentsAnnex A4Guidelines for Use of Compliance to Determine Crack SizeAnnex A5Guidelines for Electric Potential Difference Determination of Crack SizeAnnex A6Recommended Data Reduction TechniquesAppendix X1Recommended Practice for Determination of Fatigue Crack Opening Force From ComplianceAppendix X2Guidelines for Measuring the Growth Rates Of Small Fatigue CracksAppendix X3
1.9 Special requirements for the various specimen configurations appear in the following order:
The Compact Tension SpecimenAnnex A1The Middle Tension SpecimenAnnex A2The Eccentrically-Loaded Single Edge Crack Tension SpecimenAnnex A3
1.10 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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Standards Content (Sample)
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Designation: E 647 – 99
Standard Test Method for
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Measurement of Fatigue Crack Growth Rates
This standard is issued under the fixed designation E 647; 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.
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1. Scope E 4 Practices for Force Verification of Testing Machines
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E 6 Terminology Relating to Methods of Mechanical Test-
1.1 This test method covers the determination of steady-
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ing
state fatigue crack growth rates from near-threshold to K
max
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E 8 Test Methods for Tension Testing of Metallic Materials
controlled instability using either compact tension, C(T), (Fig.
E 337 Test Method for Measuring Humidity with a Psy-
1) middle-tension, M(T), (Fig. 2) or eccentrically loaded single
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
edge crack tension, ESE(T), (Fig. A4.1) specimens. Results are
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peratures)
expressed in terms of the crack-tip stress-intensity factor range
E 338 Test Method for Sharp-Notch Tension Testing of
(DK), defined by the theory of linear elasticity.
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High-Strength Sheet Materials
1.2 Several different test procedures are provided, the opti-
E 399 Test Method for Plane-Strain Fracture Toughness of
mum test procedure being primarily dependent on the magni-
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Metallic Materials
tude of the fatigue crack growth rate to be measured.
E 467 Practice for Verification of Constant Amplitude Dy-
1.3 Materials that can be tested by this test method are not
namic Loads on Displacements in an Axial Load Fatigue
limited by thicknesses or by strength so long as specimens are
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Testing System
of sufficient thickness to preclude buckling and of sufficient
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E 561 Practice for R-Curve Determination
planar size to remain predominantly elastic during testing.
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E 616 Terminology Relating to Fracture Testing
1.4 A range of specimen sizes with proportional planar
E 813 Test Method for J , A Measure of Fracture Tough-
Ic
dimensions is provided, but size is variable to be adjusted for
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ness
yield strength and applied load. Specimen thickness may be
E 1012 Practice for Verification of Specimen Alignment
varied independent of planar size.
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Under Tensile Loading
1.5 Specimen configurations other than those contained in
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E 1150 Definitions of Terms Relating to Fatigue
this method may be used provided that well-established stress-
intensity factor calibrations are available and that specimens
3. Terminology
are of sufficient planar size to remain predominantly elastic
3.1 The terms used in this test method are given in Termi-
during testing.
nology E 6, Definitions E 1150, and Terminology E 616. Wher-
1.6 Residual stress/crack closure may significantly influence
ever these terms are not in agreement with one another, use the
the fatigue crack growth rate data, particularly at low stress-
definitions given in Terminology E 616 which are applicable to
intensity factors and low stress ratios, although such variables
this test method.
are not incorporated into the computation of DK.
3.2 Definitions:
1.7 Values stated in SI units are to be regarded as the
3.2.1 crack length, a[L], n—See crack size.
standard. Values given in parentheses are for information only.
3.2.2 crack size, a[L], n—a linear measure of a principal
1.8 This standard does not purport to address all of the
planar dimension of a crack. This measure is commonly used
safety concerns, if any, associated with its use. It is the
in the calculation of quantities descriptive of the stress and
responsibility of the user of this standard to establish appro-
displacement fields and is often also termed crack length or
priate safety and health practices and determine the applica-
depth.
bility of regulatory limitations prior to use.
3.2.2.1 Discussion—In the C(T) specimen, a is measured
2. Referenced Documents from the line connecting the bearing points of load application;
in the M(T) specimen, a is measured from the perpendicular
2.1 ASTM Standards:
bisector of the central crack; in the ESE(T) specimen, a is
measured from the specimen front face.
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3.2.2.2 Discussion—In fatigue testing, crack length is the
This test method is under the jurisdiction of ASTM Committee E-8 on Fatigue
and Fracture and is the direct responsibility of Subcommittee E08.06 on Crack physical crack size. See physical crack size in Terminology
Growth Behavior.
E 616.
Current edition approved May 10, 1999. Published September 1999. Originally
published as E 647 – 78 T. Last previous edition E 647 – 95a.
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For additional information on this test method see RR: E 24 – 1001. Available Annual Book of ASTM Standards, Vol 03.01.
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