ASTM E647-13 PDF

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 (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, 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 Documents2 Terminology3 Summary of Use4 Significance and Use5 Apparatus6 Specimen Configuration, Size, and Preparation7 Procedure8 Calculations and Interpretation of Results9 Report10 Precision and Bias11 Special Requirements for Testing in Aqueous EnvironmentsAnnex A4 Guidelines for Use of Compliance to Determine Crack SizeAnnex A5 Guidelines for Electric Potential Difference Determination of Crack SizeAnnex A6 Recommended Data Reduction TechniquesAppendix X1 Recommended Practice for Determination of Fatigue Crack Opening Force From ComplianceAppendix X2 Guidelines for Measuring the Growth Rates Of Small Fatigue CracksAppendix X3 Recommended Practice for Determination Of ACR-Based Stress-Intensity Factor RangeAppendix X4

1.9 Special requirements for the various specimen configurations appear in the following order:

The Compact SpecimenAnnex A1 The Middle Tension SpecimenAnnex A2 The 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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Published :	01/15/2013
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