ASTM E647-13a
(Test Method)Standard Test Method for Measurement of Fatigue Crack Growth Rates
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, d a/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)5 and (2).
5.1.1 In innocuous (inert) environments fatigue crack growth rates are primarily a function of ΔK and force ratio, R, or K max 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 d a/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 to Kmax controlled instability. 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/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 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 ...
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Designation: E647 − 13a
StandardTest 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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope special requirements for various specimen configurations, spe-
2
cial requirements for testing in aqueous environments, and
1.1 This test method covers the determination of fatigue
proceduresfornon-visualcracksizedetermination.Inaddition,
crack growth rates from near-threshold to K controlled
max
there are appendices that cover techniques for calculating
instability. Results are expressed in terms of the crack-tip
da/dN,determiningfatiguecrackopeningforce,andguidelines
stress-intensity factor range (∆K), defined by the theory of
for measuring the growth of small fatigue cracks. General
linear elasticity.
information and requirements common to all specimen types
1.2 Several different test procedures are provided, the opti-
are listed as follows:
mum test procedure being primarily dependent on the magni-
Section
tude of the fatigue crack growth rate to be measured.
Referenced Documents 2
Terminology 3
1.3 Materials that can be tested by this test method are not
Summary of Use 4
limited by thickness or by strength so long as specimens are of
Significance and Use 5
Apparatus 6
sufficient thickness to preclude buckling and of sufficient
Specimen Configuration, Size, and Preparation 7
planar size to remain predominantly elastic during testing.
Procedure 8
Calculations and Interpretation of Results 9
1.4 A range of specimen sizes with proportional planar
Report 10
dimensions is provided, but size is variable to be adjusted for
Precision and Bias 11
yield strength and applied force. Specimen thickness may be Special Requirements for Testing in Aqueous Environments Annex A4
Guidelines for Use of Compliance to Determine Crack Size Annex A5
varied independent of planar size.
Guidelines for Electric Potential Difference Determination of Annex A6
Crack Size
1.5 The details of the various specimens and test configu-
Recommended Data Reduction Techniques Appendix X1
rations are shown in Annex A1 – Annex A3. Specimen
Recommended Practice for Determination of Fatigue Crack Appendix X2
configurations other than those contained in this method may
Opening Force From Compliance
Guidelines for Measuring the Growth Rates Of Small Fatigue Appendix X3
be used provided that well-established stress-intensity factor
Cracks
calibrations are available and that specimens are of sufficient
Recommended Practice for Determination Of ACR-Based Appendix X4
planar size to remain predominantly elastic during testing.
Stress-Intensity Factor Range
1.9 Special requirements for the various specimen configu-
1.6 Residualstress/crackclosuremaysignificantlyinfluence
rations appear in the following order:
the fatigue crack growth rate data, particularly at low stress-
intensity factors and low stress ratios, although such variables
The Compact Specimen Annex A1
The Middle Tension Specimen Annex A2
are not incorporated into the computation of ∆K.
The Eccentrically-Loaded Single Edge Crack Tension Annex A3
1.7 Values stated in SI units are to be regarded as the Specimen
standard.Values given in parentheses are for information only.
1.10 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.8 Thistestmethodisdividedintotwomainparts.Thefirst
responsibility of the user of this standard to establish appro-
part gives general information concerning the recommenda-
priate safety and health practices and determine the applica-
tions and requirements for fatigue crack growth rate testing.
bility of regulatory limitations prior to use.
The second part is composed of annexes that describe the
2. Referenced Documents
3
2.1 ASTM Standards:
1
This test method is under the jurisdiction ofASTM Committee E08 on Fatigue
and Fracture and is the direct responsibility of Subcommittee E08.06 on Crack E4Practices for Force Verification of Testing Machines
Growth Behavior.
Current edition approved Oct. 15, 2013. Published February 2014. Originally
3
approved in 1978. Last previous approved in 2013 as E647–13. DOI: 10.1520/ For referenced ASTM standards, visit the ASTM website, www.astm.org, or
E0647-13A. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
2
For additional information on this test method see RR: E24–1001. Available Standards volume information, refer to the standard’s Document Summary page on
fromASTM Headquarters, 100 Barr Harbor Drive,West Conshohocken, PA19428. the ASTM websit
...
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.
´1
Designation: E647 − 13 E647 − 13a
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
ε NOTE—3.2.3 and 10.1.1 were editorially revised in May 2013.
1. Scope
2
1.1 This test method covers the determination of fatigue crack growth rates from near-threshold to K controlled instability.
max
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/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 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,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
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
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 Jan. 15, 2013Oct. 15, 2013. Published January 2013February 2014. Originally approved in 1978. Last previous approved in 20122013 as
E647 – 12.E647 – 13. DOI: 10.1520/E0647-13E01.10.1520/E0647-13A.
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 − 13a
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 Single Edge Crack Tension Annex A3
Specime
...
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