FATIGUE CRACK GROWTH MEASUREMENT AND DATA ANALYSIS A symposium sponsored by ASTM Committees E-9 on Fatigue and E-24 on Fracture Testing AMERICAN SOCIETY FOR TESTING AND MATERIALS Pittsburgh, Pa., 29-30 Oct 1979 ASTM SPECIAL TECHNICAL PUBLICATION 738 S J Hudak, Jr., Southwest Research Institute, and R J BuccI, Alcoa Laboratories, editors ASTM Publication Code Number (PCN) 04-738000-30 AMERICAN SOCIETY FOR TESTING AND MATERIALS 1916 Race Street, Philadelphia, Pa 19103 • Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:01:06 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Copyright © by AMERICAN SOCIETY FOR TESTING AND MATERIALS 1981 Library of Congress Catalog Card Number: 80-70650 NOTE The Society is not responsible, as a body, for the statements and opinions advanced in this publication Printed in Baltimore Md July 1981 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:01:06 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authoriz Foreword The Symposium on Fatigue Crack Growth Measurement and Data Analysis, sponsored by ASTM Committees E-9 on Fatigue and E-24 on Fracture Testing, was held in Pittsburgh, Pa., on 29-30 Oct 1979 S J Hudak, Jr., Southwest Research Institute, and R J Bucci, Alcoa Laboratories, served as symposium chairmen and also edited this publication Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:01:06 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorize Related ASTM Publications Part-Through Crack Fatigue Life Prediction, STP 687 (1979), $26.25, 04-687000-30 Fatigue Mechanisms, STP 675 (1979), $65.00, 04-675000-30 Service Fatigue Lxjads Monitoring, Simulation, and Analysis, STP 671 (1979), $29.50, 04-671000-30 Cyclic Stress-Strain and Plastic Deformation Aspects of Fatigue Crack Growth, STP 637 (1977), $25.00, 04-637000-30 Fatigue Crack Growth Under Spectrum Loads, STP 595 (1976), $34.50, 04-595000-30 Effect of Load Spectrum Variables on Fatigue Crack Initiation and Propagation, STP 714 (1980), $27.00, 04-714000-30 Crack Arrest Methodology and Applications, STP 711 (1980), $44.75, 04-711000-30 Fracture Mechanics, STP 700 (1980), $53.25, 04-700000-30 Flaw Growth and Fracture, STP 631 (1977), $49.75, 04-631000-30 Commercial Opportunities for Advanced Composites, STP 704 (1980), $13.50, 04-704000-33 Nondestructive Evaluation and Flaw Criticality for Composite Materials, STP 696 (1979), $34.50, 04-696000-33 Evaluations of the Elevated Temperature Tensile and Creep Rupture Properties of 12 to 27 Percent Chromium Steels, DS 59 (1980), $24.00, 05-059000-40 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:01:06 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized A Note of Appreciation to Reviewers This publication is made possible by the authors and, also, the unheralded efforts of the reviewers This is a body of technical experts whose dedication, sacrifice of time and effort, and collective wisdom in reviewing the papers must be acknowledged The quality level of ASTM publications is a direct function of their respected opinions On behalf of ASTM we acknowledge with appreciation their contribution ASTM Committee on Publications Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:01:06 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions aut Editorial Staff Jane B Wheeler, Managing Editor Helen M Hoersch, Senior Associate Editor Helen P Mahy, Senior Assistant Editor Allan S Kleinberg, Assistant Editor Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:01:06 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Contents Introduction GENERAL TEST PROCEDURES Development of a Proposed ASTM Standard Test Method for NearThreshold Fatigue Crack Growth Rate Measurement— R J BUCCI Influence of Various Parameters on the Determination of the Fatigue Crack Arrest Threshold—c AMZALLAG, P RABBE, C BATHIAS, D BENOIT, AND M TRUCHON 29 Discussion 43 Specimen Size Considerations in Fatigue Crack Growth Rate Testing—L A JAMES 45 Automatic Decreasing Stress-Intensity Fatigue Crack Growth Rate Testing Using Low-Cost Circuitry—R C BROWN AND N E DOWLING 58 An Evaluation of the Round Compact Specimen for Fatigue Crack Growth Rate Testing—L A JAMES AND W I MILLS 70 REMOTE CRACK MONITORING TECHNIQUES Procedures for Precision Measurement of Fatigue Crack Growth Rate Using Crack-Opening Displacement Techniques— G R YODER, L A COOLEY, AND T W CROOKER 85 Discussion 101 An Assessment of A-C and D-C Potential Systems for Monitoring Fatigue Crack Growth—R P WEI AND R L BRAZILL 103 Quantitative Measurements of the Growth Kinetics of Small Fatigue Cracks in lONi Steel—R P GANGLOFF 120 Detecting Acoustic Emission During Cyclic Crack Growth in Simulated BWR Environment—H NAKAJIMA, T SHOJI, M KIKUCHI, H NIITSUMA, AND M SHINDO 139 Discussion Copyright by Downloaded/printed University of 159 ASTM by Washington Int'l (all (University rights of reserved); Washington) Mon pursuant Dec to STATISTICAL ANALYSIS AND REPRESENTATION OF DATA Statistical Analysis of Fatigue Crack Growth—F BASTENAIRE, H.-p LIEURADE, L REGNIER, AND M TRUCHON 163 Analysis of Fatigue Crack Growth Rate Data from Different Laboratories—i T FONG AND N E DOWLING 171 Effect of Aa-Increment on Calculating da/dN from a versus N Data—D F OSTERGAARD, I R THOMAS, AND B M H I L L B E R R Y 194 Discussion 203 An Analysis of Several Fatigue Crack Growth Rate (FCGR) Descriptions—M S MILLER AND J P GALLAGHER 205 ENGINEERING APPLICATIONS Prediction of Structural Crack Growth Behavior under Fatigue Loading—s w HOPKINS AND C A RAU, JR 255 A Practical Probabilistic Method for Evaluating the Fall-Safeness of Structures that May Fail Due to Fatigue—i R GEBMAN AND P C PARIS 271 The Use of Fatigue Crack Growth Technology in Fracture Control Plans for Nuclear Components—w H BAMFORD AND D P JONES 281 Fatigue Considerations for Steel Bridges—i M BARSOM 300 APPENDIXES Appendix I—ASTM Method E 647-78 T 321 Appendix II—Proposed ASTM Test Method for Measurement of Fatigue Crack Growth Rates 340 SUMMARY Summary 359 Index 367 Copyright by Downloaded/printed University of ASTM by Washington Int'l (all (University rights of reserved); Washington) Mon pursuant Dec to STP738-EB/JUI 1981 Introduction The application of fracture mechanics concepts to fatigue crack growth has made substantial progress since its inception nearly two decades ago Much of this progress is recorded in previous ASTM Special Technical Publications (STPs) The current STP presents the proceedings of the ASTM Symposium on Fatigue Crack Growth Measuremdht and Data Analysis which was held in Pittsburgh, Pa., on October 29 and 30, 1979 This symposium, sponsored jointly by ASTM Committees E-9 on Fatigue and E-24 on Fracture Testing, summarized the 1979 state of the art of fatigue crack growth rate testing The planning of the symposium was linked to the establishment in 1978 of the first industry-wide, consensus standard for fatigue crack growth rate testing—ASTM Method E 647-78 T on ConstantLoad-Amplitude Fatigue Crack Growth Rates Above 10~* m/Cycle The symposium objectives were to (7) document background information which formed the basis for ASTM E 647, (2) provide a forum for exchanging experiences with ASTM E 647, (3) assess new developments in fatigue crack growth rate testing, and (4) exchange ideas and define problems in the use of fatigue crack growth rate information in materials' evaluation, design, and reliability assessment The success of the symposium is evidenced by the quality of the papers in this publication They provide information on specimen size requirements, optimum procedures for fatigue threshold and low growth rate measurements, remote crack monitoring systems, data processing procedures, statistical characterization of primary and processed data, mathematical models for data representation and interpolation, and use of fatigue crack growth information in fracture control plans Information presented in this STP should be useful to engineers involved in measuring and applying fatigue crack growth rate information to structural design Researchers engaged in the study of materials' behavior and in elucidating fatigue mechanisms will also find this information useful in designing experiments which are free of confounding effects arising from improper specimen design or testing procedures Since many of the papers in this publication cite and discuss sections of ASTM E 647, this test method is conveniently reprinted as Appendix I of this STP Appendix II is a document, developed within ASTM Committee E-24, which expands ASTM E 647 to include procedures for near-threshold fatigue crack growth rate measurements The latter document represents one stage Copyright by Downloaded/printed Copyright' 1981 University of by ASTM Int'l (all A S Tby M International www.astin.org Washington (University rights of reserved); Washington) Mon pursuant Dec 21 to L 356 FATIGUE CRACK GROWTH MEASUREMENT AND DATA ANALYSIS References [/] Paris, P C and Erdogan, F., Journal of Basic Eiigineeiing Transactions of the ASME, Series D December 1963, pp 528-534 [2] Paris, P C in Proceedings JOth Sagamore Army Materials Research Conference Syracuse University Press, 1964, pp 107-132 [3] Clark, W G., Jr., Experimental Mechanics September 1971, pp 1-8 [4\ Hoeppner, D W and Krupp, W E., Engineering Fracture Mechanics Vol 6, 1974, pp 47-70 [5] Fatigue Crack Growth Under Spectrum Loads ASTM STP 595 American Society for Testing and Materials, 1976 |6] Hudak, S J., Jr., Bucci, R J., Saxenda, A., and Malcolm, R C , "Development of Standard Methods of Testing and Analyzing Fatigue Crack Growth Rate Data — Third SemiAnnual Report," Westinghouse Research Report 77-9E7-AFCGR-R1, Westinghouse Research Laboratories, Pittsburgh, Pa., AFML Contract F33615-75-C-5064, March 1977 [7] Clark, W G., Jr., and Hudak, S J., Jr Journal o/ Testing and Evaluation Vol 3, No 6, 1975, pp 454-476 [fi] Saxena, A., Hudak, S J., Jr., Donald, J K., and Schmidt, D W Journal o) Testing and Evaluation Vol 6, No 3, 1978, pp 167-174 [9] Clark, W G., Jr., and Hudak, S J., Jr., "The Analysis of Fatigue Crack Growth Rate Data," Westinghouse Scientific Paper 75-9E7-AFCGR-P1, Westinghouse Research Laboratories, Pittsburgh, Pa.; to be published in Proceedings 22nd Sagamore Army Materials Research Conference on Application of Fracture Mechanics to Design \I0\ Newman, J C Jr in Fracture Analysis ASTM STP 560 American Society for Testing and Materials, 1974, pp 105-121 [//] Srawley, J E., International Journal of Fracture Vol 12, June 1976, pp 475-476 \I2] Feddersen, C E in Plane Strain Crack Toughness Testing of High-Strength Metallic Materials ASTM STP 410 American Society for Testing and Materials, 1967, pp 77-79 [13] Bucci, R J in Fatigue Crack Growth Measurement and Data Analysis ASTM STP 738, American Society for Testing and Materials, 1981, pp 5-28 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:01:06 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Summaxy Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:01:06 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP738-EB/JUI 1981 Summary The papers contained in this publication inherently fall into four groups: (/) General Test Procedures—information on optimum test procedures for measuring near-threshold fatigue crack growth rates, problem areas in nearthreshold testing, specimen size requirements for testing low-strength materials at high growth rates, and alternative specimens for fatigue crack growth rate (FCGR) testing; (2) Remote Crack Monitoring Techniques— descriptions of equipment and discussions of procedures to measure crack extension using elastic compliance (or COD), a-c and d-c electrical potential, and acoustic emission; (3) Statistical Analysis and Representation of Data— application of regression analysis to FCGR data, analysis of variance for reproducibility within a laboratory and repeatability between laboratories, and a summary of mathematical representations of wide-range FCGR data including effects of load ratio; and (4) Engineering Applications—utilization of FCGR data in probabilistic design and reliability analyses, fatigue crack growth considerations in the Boiler and Pressure Vessel Code of the American Society of Mechanical Engineers, and problem areas in the use of fracture mechanics to predict the fatigue life of welded structures Papers in the first two groups are closely tied to two ASTM methods for FCGR testing The first of these is ASTM Method for Constant-LoadAmplitude Fatigue Crack Growth Rates Above 10"^ m/Cycle (E 647-78 T), which was developed by ASTM Task Group E24.04.01 on Fatigue Crack Growi;h The second is a working document of ASTM Task Group E24.04.03 on Near-Threshold Fatigue Crack Growth This document, a modification of ASTM E 647, contains specialized techniques for near-threshold testing In order to provide for convenient reference, these documents are respectively provided in Appendixes I and II of this publication Papers in the last two groups provide much needed information to bridge the gap between generation of materials' FCGR properties in the laboratory and application of this information to the design and reliability assurance of structures The following sections summarize the papers from each of the four groups General Test Procedures Information which provided the basis for the proposed test procedures for fatigue crack growth rates below 10~® m/cycle is summarized by Bucci The key feature of these procedures is a /^-decreasing technique which involves Copyright by Downloaded/printed Copyright' 1981 University of 359 by ASTM Int'l (all A S Tby M International www.astin.org Washington (University rights of reserved); Washington) Mon pursuant Dec 21 to L 360 FATIGUE CRACK GROWTH MEASUREMENT AND DATA ANALYSIS generating data while the applied load, and therefore stress-intensity factor, is decreased, either continuously or in step-wise fashion The advantage of this procedure is that it eliminates the tedious and costly precracking period The importance of controlling the nominal rate at which K is decreased is demonstrated by comparing FCGR data obtained under /C-decreasing and /C-increasing (constant-load-amplitude) conditions Decreasing K at too fast a rate causes anomalously high growth rates and, consequently, low values of the threshold stress intensity (AAr^h) Testing under conditions of nominally constant \/K (dK/da) appears to be an optimum, since it corresponds to a constant nominal rate of change of the crack-tip plastic zone Data on several materials show that comparable /f-decreasing and /^-increasing results are obtained provided l/K (dK/da) > —0.08 mm""' This limiting value of the normalized /f-gradient appears to be appropriate for tests at low load ratios, although it may be unnecessarily restrictive for tests at high load ratios; that is, it may be acceptable to decrease K and the plastic-zone size more rapidly in high load ratio tests Additional tests are needed on a larger variety of materials to better define this limit, particularly for high load ratios and in the presence of various aggressive environments Bucci also discusses problems associated with transient growth rates which can cause FCGR data to be dependent on crack size, load history, and environment Although these effects are generally not well understood, guidelines are presented for their control or elimination, or both, during testing The second paper (Amzallag et al) which addresses near-threshold crack growth testing summarizes results from a cooperative interlaboratory test program conducted by the Fatigue Commission of the French Metallurgical Society Ten laboratories participated in the program which involved nearthreshold FCGR testing on a 2618-T651 aluminum alloy and a 316 stainless steel The results demonstrate the marked differences in near-threshold FCGR behavior which can occur for different materials A clearly definable A/L th'value was observed in the aluminum alloy but not in the steel These results also provide a useful documentation of the difficulties which can be encountered in interpreting results due to crack "tunneling" in specimens having too large a thickness-to-width ratio {B/W) The significant "tunneling" encountered in compact-type (CT) specimens having B/W = '/2 supports the need for the current ASTM recommendation oiB/W ^ V4 In fact, this ratio may need to be decreased for near-threshold testing where "tunneling" problems are often accentuated Post-test corrections for this phenomenon are often ineffective, since adequate data on crack front profiles are difficult to acquire because tunneling often changes throughout the course of a test and, in addition, can vary from material to