ASTM E647-23

Standard Test Method for Measurement of Fatigue Crack Growth Rates

SIGNIFICANCE AND USE
5.1 Fatigue crack growth rate expressed as a function of crack-tip stress-intensity factor range, da/dN versus ΔK, characterizes a material's resistance to stable crack extension under cyclic loading. Background information on the ration-ale for employing linear elastic fracture mechanics to analyze fatigue crack growth rate data is given in Refs (1)4 and (2).  
5.1.1 In innocuous (inert) environments fatigue crack growth rates are primarily a function of ΔK and force ratio, R, or Kmax and R (Note 1). Temperature and aggressive environments can significantly affect da/dN versus ΔK, and in many cases accentuate R-effects and introduce effects of other loading variables such as cycle frequency and waveform. Attention needs to be given to the proper selection and control of these variables in research studies and in the generation of design data.
Note 1: ΔK, Kmax, and R are not independent of each other. Specification of any two of these variables is sufficient to define the loading condition. It is customary to specify one of the stress-intensity parameters (ΔK or Kmax) along with the force ratio, R.  
5.1.2 Expressing da/dN as a function of ΔK provides results that are independent of planar geometry, thus enabling exchange and comparison of data obtained from a variety of specimen configurations and loading conditions. Moreover, this feature enables da/dN versus ΔK data to be utilized in the design and evaluation of engineering structures. The concept of similitude is assumed, which implies that cracks of differing lengths subjected to the same nominal ΔK will advance by equal increments of crack extension per cycle.  
5.1.3 Fatigue crack growth rate data are not always geometry-independent in the strict sense since thickness effects sometimes occur. However, data on the influence of thickness on fatigue crack growth rate are mixed. Fatigue crack growth rates over a wide range of ΔK have been reported to either increase, decrease, or remain unaffected as specime...
SCOPE
1.1 This test method2 covers the determination of fatigue crack growth rates from near-threshold (see region I in Fig. 1) to Kmax  controlled instability (see region III in Fig. 1.) Results are expressed in terms of the crack-tip stress-intensity factor range (ΔK), defined by the theory of linear elasticity.  
1.9 Special requirements for the various specimen configurations appear in the following order:
The Compact Specimen  
Annex A1  
The Middle Tension Specimen  
Annex A2  
The Eccentrically-Loaded Single Edge Crack Tension Specimen  
Annex 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.11 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: Historical
• Publication Date: 31-Jan-2023
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: E08 - Fatigue and Fracture
• Drafting Committee: E08.06 - Crack Growth Behavior

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E647 − 23
Standard Test Method for
1
Measurement of Fatigue Crack Growth Rates
This standard is issued under the fixed designation E647; 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 The second part is composed of annexes that describe the
2 special requirements for various specimen configurations, spe-
1.1 This test method covers the determination of fatigue
cial requirements for testing in aqueous environments, and
crack growth rates from near-threshold (see region I in Fig. 1)
procedures for non-visual crack size determination. In addition,
to K controlled instability (see region III in Fig. 1.) Results
max
there are appendices that cover techniques for calculating
are expressed in terms of the crack-tip stress-intensity factor
da/dN, determining fatigue crack opening force, and guidelines
range (ΔK), defined by the theory of linear elasticity.
for measuring the growth of small fatigue cracks. General
1.2 Several different test procedures are provided, the opti-
information and requirements common to all specimen types
mum test procedure being primarily dependent on the magni-
are listed as follows:
tude of the fatigue crack growth rate to be measured.
Section
Referenced Documents 2
1.3 Materials that can be tested by this test method are not
Terminology 3
limited by thickness or by strength so long as specimens are of
Summary of Use 4
sufficient thickness to preclude buckling and of sufficient
Significance and Use 5
Apparatus 6
planar size to remain predominantly elastic during testing.
Specimen Configuration, Size, and Preparation 7
1.4 A range of specimen sizes with proportional planar Procedure 8
Calculations and Interpretation of Results 9
dimensions is provided, but size is variable to be adjusted for
Report 10
yield strength and applied force. Specimen thickness may be
Precision and Bias 11
varied independent of planar size. Special Requirements for Testing in Aqueous Environments Annex A4
Guidelines for Use of Compliance to Determine Crack Size Annex A5
1.5 The details of the various specimens and test configu-
Guidelines for Electric Potential Difference Determination of Annex A6
Crack Size
rations are shown in Annex A1 – Annex A3. Specimen
Recommended Data Reduction Techniques Appendix X1
configurations other than those contained in this method may
Recommended Practice for Determination of Fatigue Crack Appendix X2
be used provided that well-established stress-intensity factor
Opening Force from Compliance
Guidelines for Measuring the Growth Rates of Small Fatigue Appendix X3
calibrations are available and that specimens are of sufficient
Cracks
planar size to remain predominantly elastic during testing.
Recommended Practice for Determination of ACR-Based Appendix X4
Stress-Intensity Factor Range
1.6 Residual stress and crack closure may significantly
1.9 Special requirements for the various specimen configu-
influence the fatigue crack growth rate data, particularly at low
stress-intensity factors and low force ratios, although such rations appear in the following order:
variables are not incorporated into the computation of ΔK.
The Compact Specimen Annex A1
The Middle Tension Specimen Annex A2
1.7 Values stated in SI units are to be regarded as the
The Eccentrically-Loaded Single Edge Crack Tension Annex A3
standard. Values given in parentheses are for information only. Specimen
1.10 This standard does not purport to address all of the
1.8 This test method is divided into two main parts. The first
safety concerns, if any, associated with its use. It is the
part gives general information concerning the recommenda-
responsibility of the user of this standard to establish appro-
tions and requirements for fatigue crack growth rate testing.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1
This test method is under the jurisdiction of ASTM Committee E08 on Fatigue
1.11 This international standard was developed in accor-
and Fracture and is the direct responsibility of Subcommittee E08.06 on Crack
dance with internationally recognized principles on standard-
Growth Behavior.
Current edition approved Feb. 1, 2023. Published April 2023. Originally
ization established in the Decision on Principles for the
approved in 1978. Last previous approved in 2022 as E647 – 22b. DOI: 10.1520/
Development of International Standards, Guides and Recom-
E0647-23.
2 mendations issued by the World Trade Organization Technical
For additional information on this test method see RR: E24 – 1001. Available
from
...

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: E647 − 22b E647 − 23
Standard Test Method for
1
Measurement of Fatigue Crack Growth Rates
This standard is issued under the fixed designation E647; 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
2
1.1 This test method covers the determination of fatigue crack growth rates from near-threshold (see region I in Fig. 1) to K
max
controlled instability (see region III in Fig. 1.) Results are expressed in terms of the crack-tip stress-intensity factor range (ΔK),
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 and crack closure may significantly influence the fatigue crack growth rate data, particularly at low
stress-intensity factors and low force ratios, although such variables are not incorporated into the computation of ΔK.
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:
Section
1
This test method is under the jurisdiction of ASTM Committee E08 on Fatigue and Fracture and is the direct responsibility of Subcommittee E08.06 on Crack Growth
Behavior.
Current edition approved Sept. 15, 2022Feb. 1, 2023. Published March 2023April 2023. Originally approved in 1978. Last previous approved in 2022 as
E647 – 22a.E647 – 22b. DOI: 10.1520/E0647-22B.10.1520/E0647-23.
2 For additional information on this test method see RR: E24 – 1001. Available from ASTM Headquarters, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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E647 − 23
FIG. 1 Defined Regions of a Typical Fatigue Crack Growth Rate Curve
Referenced Documents 2
Terminology 3
Summary of Use 4
Significance and Use 5
Apparatus 6
Specimen Configuration, Size, and Preparation 7
Procedure 8
Calculations and Interpretation of Results 9
Report 10
Precision and Bias 11
Special Requirements for Testing in Aqueous Environments Annex A4
Guidelines for Use of Compliance to Determine Crack Size Annex A5
Guidelines for Electric Potential Difference Determination of Annex A6
Crack Size
Recommended Data Reduction Techniques Appendix X1
Recommended Practice for Determination of Fatigue Crack Appendix X2
Opening Force from Compliance
Guidelines for Measuring the Growth Rates of Small Fatigue Appendix X3
Cracks
Recommended Practice for Determination of ACR-Based Appendix X4
Stress-Intensity Factor Range
1.9 Special requirements for the various specimen configurations appear in the following order:
The Compact Specimen Annex A1
The Middle Tension Specimen Annex A2
The Eccentrically-Loaded Sing
...