FRACTURE MECHANICS Proceedings of the Thirteenth National Symposium on Fracture Mechanics A symposium sponsored by ASTM Committee E-24 on Fracture Testing of Metals AMERICAN SOCIETY FOR TESTING AND MATERIALS Philadelphia, Pa., 16-18 June 1980 ASTM SPECIAL TECHNICAL PUBLICATION 743 Richard Roberts Lehigh University editor ASTM Publication Code Number (PCN) 04-743000-30 €f» AMERICAN SOCIETY FOR TESTING AND MATERIALS 1916 Race Street, Philadelphia, Pa 19103 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:02:15 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: 81-65836 NOTE The Society is not responsible, as a body, for the statements and opinions advanced in this publication Printed in Baltimore, Md November 1981 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:02:15 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Foreword This publication, Fracture Mechanics, contains papers presented at the Thirteenth National Symposium on Fracture Mechanics which was held 16-18 June 1980 at Philadelphia, Pennsylvania The American Society for Testing and Materials' Committee E-24 on Fracture Testing of Metals sponsored the symposium Richard Roberts, Lehigh University, presided as symposium chairman and editor of this publication Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:02:15 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Related ASTM Publications Tables for Estimating Median Fatigue Limits, STP 731 (1981), $15.00, 04731000-30 Fatigue of Fibrous Composite Materials, STP 723 (1981), $30.00, 04-72300023 Crack Arrest Methodology and Applications, STP 711 (1980), $44.74, 04711000-30 Commercial Opportunities for Advanced Composites, STP 704 (1980), $13.50, 04-704000-33 Fracture Mechanics (Twelfth Conference), STP 700 (1980), $53.25, 04700000-03 Nondestructive Evaluation and Flaw Criticality for Composite Materials, STP 696 (1979), $34.50, 04-696000-33 Composite Materials: Testing and Design (Fifth Conference), STP 674 (1979), $52.50, 04-674000-33 Advanced Composite Materials—Environmental Effects, STP 658 (1978), $26.00, 04-658000-33 Fatigue of Filamentary Composite Materials, STP 636 (1977), $26.50, 04636000-33 Composite Materials: Testing and Design (Fourth Conference), STP 617 (1977), $51.75, 04-617000-33 Thermal Fatigue of Materials and Components, STP 612 (1976), $27.00, 04-612000-30 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:02:15 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 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 12:02:15 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 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 12:02:15 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorize Contents Introduction Fatigue Cracii Growth Behavior and Life Predictions for 2219-T851 Aluminum Subjected to Variable-Amplitude Loadings— J B CHANG, R M ENGLE, AND J STOLPESTAD Effect of Residual Stress on Fatigue Crack Growth Rate Measurement—R J BUCCI 28 Benefits of Overload for Fatigue Cracking at a Notch— J H UNDERWOOD AND J A KAPP 48 A Simple Crack Closure Model for Prediction of Fatigue Crack Growth Rates Under Variable-Amplitude Loading— A U DE KONING 63 A Model for Representing and Predicting the Influence of Hold Time on Fatigue Crack Growth Behavior at Elevated Temperature— A SAXENA, R S ViTILLIAMS, AND T T SHIH 86 Fatigue Growth of Initially Physically Short Cracks in Notched Aluminum and Steel Plates—B N LEIS AND T P FORTE 100 Fatigue Fracture Micromechanisms in Poly(Methyl Methacrylate) of Broad Molecular Weight Distribution—x JANISZEWSKI, R W HERTZBERG, AND J A MANSON 125 Fatigue Crack Growth Rates as a Function of Temperature— GUNTER MARCl 147 A Fracture Mechanics Study of Stress-Corrosion Cracking of Some Austenitic and Austeno-Ferritic Stainless Steels— p BALLADON, J FREYCENON, AND I HERITIER 167 An Experimental* Investigation of Creep Crack Growth in INIOO— R C DONATE, T NICHOLAS, AND L S FU Copyright by ASTM Int'l (all rights reserved); Mon Dec Downloaded/printed by University of Washington (University of Washington) pursuant 186 21 12:02:15 to License EST 2015 Agreement No A Fracture Toughness Correlation Based on Charpy Initiation Energy—D M NORMS, I E REAUGH, AND W L SERVER 207 Anomaly of Toughness Behavior with Notch-Root Radius— K P DATTA AND W E WOOD 218 Final Stretch Model of Ductile Fracture—M P WNUK AND S SEDMAK 236 Strength/Toughness Relationship for Interstitially Strengthened AISI 304 Stainless Steels at K Temperature—R L TOBLER, D T READ, AND R P REED 250 Some Problems in the Application of Fracture Mechanics— W G CLARK, JR Fracture Mechanics Technology Applied to Individual Aircraft Tracking—A G DENYER 269 288 Dependence of Strength on Particle Size in Graphite—E P KENNEDY AND C R KENNEDY 303 Fracture Behavior of a Thick-Section Graphite/Epoxy Composite— T T SHIH AND W A LOGSDON 316 Fracture Control in Ballistic-Damaged Graphite/Epoxy Wing Structure—j G AVERY, S J BRADLEY, AND K M KING 338 An R-Curve for a Surface Crack in Titanium—j c LEWIS AND G SINES 360 Stress-Intensity Factors for Complete Circumferential Interior Surface Cracks in Hollow Cylinders—D O HARRIS AND E Y LIM Effect of Higher-Order Stress Terms on Mode-I Caustics in Birefringent Materials—j w PHILLIPS AND R J SANFORD 375 387 Influence Functions for Stress-Intensity Factors at a Nozzle Comer— J HELIOT, R LABBENS, AND F ROBISSON 403 Stress-Intensity Distributions for Natural Flaw Shapes Approximating 'Benchmark' (reometries—c w SMITH, W H PETERS, G C KIRBY, AND A ANDONIAN 422 Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:02:15 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further Stress-Intensify Factor for a Comer Crack at the Edge of a Hole in a P l a t e — S S PALUSAMY AND M RAYMUND 438 Short Rod and Short Bar Fracture Toughness Specimen Geometries and Test Methods for Metallic Materials—L M BARKER 456 Estimations on J-Integral and Tearing Modulus T from a Single Specimen Test Record—H A ERNST, P C PARIS, AND J D LANDES 476 A More Basic Approach to the Analysis of Multiple-Specimen RCurves for Determination of/j.—K W CARLS ON AND J A WILLIAMS 503 An Experimental Evaluation of Tearing Instability Using the Compact Specimen—J A JOYCE AND M G VASSILAROS Relationship Between Critical Stretch Zone Width, Crack-Tip Opening Displacement, and Fracture Energy Criterion: Application to SA-516-70 Steel Plates—PHUC NGUYEN-DUY 525 543 Single-Specimen Tests for//^ Determination—Revisited— G A CLARKE 553 Small-Specimen Brittle-Fracture Toughness Testing—w R ANDREWS, V KUMAR, AND M M LITTLE 576 Effect of Cyclic Frequency on the Corrosion-Fatigue Crack-Initiation Behavior of ASTM A 517 Grade F Steel—M E TAYLOR AND J M BARSOM 599 Evaluation of Crack Growth Gages for Service Life Tracking— C R SAFE AND D R HOLLOWAY 623 Summary 641 Index 647 Copyright by Downloaded/printed University of ASTM by Washington Int'l (all (University rights of reserved); Washington) Mon pursuant Dec to SAFF AND HOLLOWAY ON CRACK GROWTH GAGES 635 gage crack length, and the Faxfilm impressions make a good record of measurements Comparisons of predicted and measured crack growth in the gages are shown in Fig 14 In general, the agreement between predicted and measured crack lengths is good In those cases in which the gages separated from the wing skin, measured crack growth was close to that predicted until the gages separated Crack Growth Gi^e as Usage Monitor Use of the crack growth gage as an aircraft fatigue life usage monitor is complicated by the fact that the relationship of potential crack growth in the structure to crack growth in the gage is predicted to vary markedly for small changes in usage (Fig 15) This variation is due to the difference in crack growth retardation between the crack in the structure and the crack in the gage In order for the relationship of potential crack growth in the structure to crack growth in the gage to be unique, unaffected by spectrum changes, the stress state at the tip of the gage crack must be similar to that at the tip of the crack in the structure The difference in material thickness between gage and structure precludes similitude at the crack tips and, Thousands of Spectrum Hours FIG 14—Comparison of gage crack length measurements from fatigue test article with predicted lengths Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:02:15 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorize 636 FRACTURE MECHANICS: THIRTEENTH CONFERENCE 0.2 100,000 0.4 0.6 0.8 1.0 Predicted Crack Length in Gage • in - -' ~10,000 1,000 100 _ ~ - / /— Severe < ~ y-i iseline Mild.^ = - 10 20 40 60 80 Wi 100 120 Peak Stress, Percent of Lirriit Stress FIG 15—Relationship of potential crack growth in structure to gage crack growth varies with aircraft usage consequently, precludes development of a unique relationship between gage crack length and crack length in the structure A procedure was developed to account for the variation in structure/gage flaw growth relationship based on predictions of crack growth in the gage and in the structure for a baseline spectrum under several limit stress levels Relationships between potential crack growth from a hole and crack Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:02:15 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized SAFF AND HOLLOWAY ON CRACK GROWTH GAGES 637 growth in the gage were determined for each stress level, Fig 16 These relationships were used to predict potential flaw growth from a hole based on the crack length in the gage at a given time As an example of this technique for service life monitoring using the crack growth gage, five variations of an F-4 wing load spectrum were considered: baseline, mild, and severe variations used in the earlier evaluations (Fig 15), the baseline with the maximum load per 1000 h increased to 125 percent of limit, and the baseline clipped at 80 percent of limit load The latter spectrum variations were among the most severe of those reported in Ref 13 The predictions of crack growth from the hole based on gage analyses were compared with straightforward crack growth predictions using the contact-stress model for each of the spectrum variations Comparison of the two predictions (Fig 17) is reasonably good and indicates that gage crack growth interpretations will be consistent with the trends, at least, of potential crack growth in the structure, as long as the gage remains attached to the structure The comparison of predictions shown in Fig 17 is the only available measure of the ability of the gage to monitor service usage The comparison must be substantiated by test before acceptance of the gage as a usage monitor The predictions of crack growth from a hole are based on improved analyses of the test results reported in Ref 13 The predictions of gage response are based on test results for limit stress levels between 28.6 and 33 MN/m^^^ (26 and 30 ksi) and are subject to greater question at limit stress levels that are higher or lower 0.4 I 0.3 e 20 ksi Xl ' = X2 =2 0.2 / / Predicted by interpolation 0.1 y^ 10 20 Thousands of Spectrum Hours 30 ' " ' ksi 10 20 Thousands of Spectrum Hours 30 FIG 16—Crack growth from hole prediction interpolated from gage crack growth Copyright by ASTM Int'l (all rights reserved); Mon Dec 21 12:02:15 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 638 FRACTURE MECHANICS: THIRTEENTH CONFERENCE 1.0 1/ / / I CI pped Spectrum / / \ 0.8 / / Severe / ' Spectrum ' ' / / ^ Interpolated Results Based on Gage Analysis Growth Analysis ~— ^ / f // // [ in = 2.54 cm y /Baseline Spectrum f / // A P/ / / / / /I ll Jl , '/ 0.4 / / /X y ^ Mild Spectrum