METHODS AND MODELS FOR PREDICTING FATIGUE CRACK GROWTH UNDER RANDOM LOADING

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2 METHODS AND MODELS FOR PREDICTING FATIGUE CRACK GROWTH UNDER RANDOM LOADING Sponsored by ASTM Subcommittee E24.06 on Fracture Mechanics Applications AMERICAN SOCIETY FOR TESTING AND MATERIALS ASTM SPECIAL TECHNICAL PUBLICATION 748 J. B. Chang, Rockwell International Corporation, and C. M. Hudson, NASA-Langley Research Center, editors ASTM Publication Code Number (PCN) h AMERICAN SOCIETY FOR TESTING AND MATERIALS 1916 Race Street, Philadelphia, Pa

3 Copyright by AMERICAN SOCIETY FOR TESTING AND MATERIALS 1981 Library of Congress Catalog Card Number: NOTE The Society is not responsible, as a body, for the statements and opinions advanced in this publication. Printed in Baltimore, Md. October 1981

4 Foreword The papers in this volume present in detail the methodology and procedure utilized by each individual in the prediction of the fatigue crack growth behaviors and lives for random flight spectrum test cases used in the roundrobin analysis conducted by ASTM Task Group E on Application of Fracture Data to Life Prediction. The objective of this round-robin analysis was to assess whether data from constant-amplitude fatigue crack growth tests on center-cracked-tension (CCT) specimens can be used to predict fatigue crack growth lives of CCT specimens subjected to random load sequences.

5 Related ASTM Publications Fatigue Crack Growth Measurement and Data Analysis, STP 738 (1981), $39.00, Effect of Load Spectrum Variables on Fatigue Crack Initiation and Propagation, STP 714 (1980), $27.00, Part-Through Crack Fatigue Life Prediction, STP 687 (1979), $26.25, Fatigue Mechanisms, STP 675 (1979), $65.00, Service Fatigue Loads Monitoring, Simulation, and Analysis, STP 671 (1979), $29.50, Fatigue Testing of Weldments, STP 648 (1978), , Corrosion-Fatigue Technology, STP 642 (1978), $32.00, Cyclic Stress-Strain and Plastic Deformation Aspects of Fatigue Crack Growth, STP 637 (1977), $25.00, Fatigue Crack Growth Under Spectrum Loads, STP 595 (1976), $34.50, Handbook of Fatigue Testing, STP 566 (1974), $17.25,

6 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

7 Editorial Staff Jane B. Wheeler, Managing Editor Helen M. Hoersch, Senior Associate Editor Helen P. Mahy, Senior Assistant Editor Allan S. Kleinberg, Assistant Editor

8 Contents Introduction 1 Round-Robin Crack Growth Predictions on Center-Craclted Tension Specimens under Random Spectrum Loading i. B. CHANG 3 A Root-Mean-Square Approach for Predicting Fatigue Crack Growth under Random Loading c. M. HUD SON 41 A Crack-Closure Model for Predicting Fatigue Crack Growth under Aircraft Spectrum Loading i. c. NEWMAN, IR. 53 Multi-Parameter Yield Zone Model for Predicting Spectrum Crack Growth w. s. JOHNSON 85 Crack Growth Behavior of Center-Cracked Panels under Random Spectrum Loading i. L. RUDD AND R. M. ENGLE, JR. 103 Random Spectrum Fatigue Crack Life Predictions With or Without Considering Load Interactions j. B. CHANG, M. SZAMOSSI, AND K-W. LIU 115 Summary 133 Index 137

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