Astm stp 1122 1992

STP 1122 Advances in Fatigue Lifetime Predictive Techniques M R Mitchell and R W Landgraf, editors ASTM Publication Code Number (PCN): 04-011220-30 ASTM 1916 Race Street Philadelphia, PA 19103 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Library of Congress Cataloging-in-Publication Data Advances in fatigue lifetime predictive techniques/M R Mitchell and R W Landgraf, editors p c m - - ( S T P ; 1122) Includes bibliographical references and index ISBN 0-8031-1423-0 Materials Fatigue Fracture mechanics Service life (Engineering) I Mitchell, M R (Michael R.), 1941II Landgraf, R W III Series: ASTM special technical publications; 1122 TA409.A39 1991 620.1'126 dc20 91-36055 CIP Copyright 1992 A M E R I C A N SOCIETY F O R TESTING A N D M A T E R I A L S , Philadelphia, PA All rights reserved This material may not be reproduced or copied, in whole or in part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of the publisher Photocopy Rights Authorization to photocopy items for internal or personal use, or the internal or personal use of specific clients, is granted by the A M E R I C A N SOCIETY F O R TESTING A N D M A T E R I A L S for users registered with the Copyright Clearance Center (CCC) Transactional Reporting Service, provided that the base fee of $2.50 per copy, plus $0.50 per page is paid directly to CCC, 27 Congress St., Salem, M A 01970; (508) 744-3350 For those organizations that have been granted a photocopy license by CCC, a separate system of payment has been arranged The fee code for users of the Transactional Reporting Service is 0-8031-1423-0 92 $2.50 + 50 Peer Review Policy Each paper published in this volume was evaluated by three peer reviewers The authors addressed all of the reviewers' comments to the satisfaction of both the technical editor(s) and the ASTM Committee on Publications The quality of the papers in this publication reflects not only the obvious efforts of the authors and the technical editor(s), but also the work of these peer reviewers The ASTM Committee on Publications acknowledges with appreciation their dedication and contribution to time and effort on behalf of ASTM Printed in Baltimore, Md January 1992 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Foreword The A S T M Symposium on Advances in Fatigue Lifetime Predictive Techniques was held on 24 April 1990 in San Francisco, California ASTM Committee E-9 on Fatigue sponsored the event The symposium chairmen and editors of this volume were M R Mitchell, Rockwell International, Scienc~ Center, Thousand Oaks, California, and R W Landgraf, Virginia Polytechnic Institute and State University, Blacksburg, Virginia Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions au Contents Overview GENERAL APPROACHES Fatigue Mechanics: An Assessment of a Unified Approach to Life Prediction-J C N E W M A N , JR.~ E P P H I L L I P S , M, H S W A I N , A N D R A E V E R E T T , JR A Fracture Mechanics Based Model for Cumulative Damage Assessment As Part of Fatigue Life Prediction M V O R M W A L D , P, H E U L E R , A N D T S E E G E R 28 ELEVATED TEMPERATURE PHENOMENA Thermo-Mechanical Fatigue Life Prediction Methods H SEHITOGLU 47 Evaluation of the Effect of Creep and Mean Stress on Fatigue Life Using a Damage Mechanics Approach N M ABUELFOUTOUH 77 Cumulative Creep-Fatigue Damage Evolution in an Austenitic Stainless Steel-84 M A M c G A W Application of a Thermal Fatigue Life Prediction Model to High-Temperature Aerospace Alloys B1900 + H f and Haynes 188 G R HALFORD, J F S A L T S M A N , M J V E R R I L L I , A N D V A R Y A 107 Thermomechanical and Bithermal Fatigue Behavior of Cast BI900 + Hf and Wrought Haynes 188 G R H A L F O R D , M J V E R R I L E I , S K A L L U R I , F J R I T Z E R T , R E D U C K E R T , A N D F A H O L L A N D 120 Elevated Temperature Crack Growth in Aircraft Engine Materials T NICHOLAS 143 A N D S M A L L SPECTRUM LOADING Near-Threshold Fatigue Crack Growth Prediction under Spectrum L o a d i n g - R S U N D E R 161 Contribution of Individual Load Cycles to Crack Growth under Aircraft Spectrum Loading R SUNDER 176 Fatigue Crack Growth from Narrow-Band Gaussian Spectrum Loading in 6063 Aluminum Alloy P s VEERS A N D J A VAN D E N A V Y L E 191 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Modeling High Crack Growth Rates under Variable Amplitude Loading-D J D O U G H E R T Y , A U DE KON1NG, A N D B M H I L L B E R R Y 214 A Probabilistic Fracture Mechanics Approach for Structural Reliability Assessment of Space Flight Systems s S U T H A R S H A N A , M CREAGER, D EBBELER, A N D N MOORE 234 MULTIAXIAL BEHAVIOR A Multiaxial Fatigue Life Estimation Technique J A BANNANTINE AND 249 D F SOCIE Small Crack Growth in Multiaxial Fatigue s c REDDY AND A FATEMI 276 Failure Modes in a Type 316 Stainless Steel under Biaxial Strain Cycling-299 S Y ZAMR1K, D C DAVIS, A N D P J K U L O W I T C H Nonproportional Fatigue of Welded Structures A SILJANDER, P KURATH, AND 319 F V L A W R E N C E , JR APPLICATIONS Damage Evaluation in Composite Materials Using Thermographic Stress Analysis D Z H A N G A N D B I SANDOR 341 Fatigue Life Prediction and Experimental Verification for an Automotive Suspension Component Using Dynamic Simulation and Finite Element Analysis w K BAEK AND R I STEPHENS 354 Plasticity and Fatigue Damage Modeling of Severely Loaded Tubing s M TIPTON A N D D A N E W B U R N 369 Electric-Potential-Drop Studies of Fatigue Crack Development in Tensile-Shear Spot Welds M H SWELLAM, P KURATH, AND F V LAWRENCE 383 Life Prediction of Circumferentially Grooved Components under Low-Cycle Fatigue K HATANAKA, X FUJIMITSU, S SH1RA1SHI, AND J OMORI Reliability Centered Maintenance for Metallic Airframes Based on a Stochastic Crack Growth Approach s O M A N N I N G , J N Y A N G , F L PRETZER, J E MARLER On the Prediction of the Fatigue Propagation of Semi-Elliptical Defects-W O SOBOYEJO 402 AND 422 435 Analytical and Experimental Investigation of Fatigue in Lap Joints-D V SWENSON~ C C H I H - C H I E N , A N D T G DERBER 449 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Fatigue Lifetime Monitoring in Power Piants P c RICCARDELLA, A F D E A R D O R F F , A N D T J G R I E S B A C H 460 Fatigue Analysis Techniques for Vintage Steam Turbine/Generator Components H R J H A N S A L E A N D D R M c C A N N 474 Author Index 491 Subject Index 493 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP1122-EB/Jan 1992 Overview The ability to predict accurately the service performance of engineering structures subjected to fatigue loading, always a formidable challenge, has become a goal of increasing importance throughout the design community Few industries have escaped the intense competitive pressures to develop safer, more durable products, in less time, and at reduced cost The situation is further complicated by the increasing sophistication of engineering structures and the use of higher performance, but often less forgiving, materials Fatigue is of particular concern because it is, arguably, the most prevalent failure mode in practice and one of the more difficult to deal with Fortunately, materials and mechanics researchers remain active in this important field, and the last decade has seen significant improvements in our understanding of fatigue phenomena and in our ability to deal with it in engineering practice Some impressive new tools and techniques are becoming available to assist designers in more reliably assessing the fatigue performance of a variety of components and structures Such a capability provides the opportunity to develop more optimized designs by anticipating potential problem areas and by allowing consideration of a broader range of alternatives Nearly all major industries aerospace, power generation, ground transportation are in the process of integrating such new methods into their respective design procedures The intent of the ASTM Symposium on Advances in Fatigue Lifetime Predictive Techniques, the first on this topic, was to bring together a cross-section of fatigue researchers and practitioners to review, in detail, recent progress in the development of methods to predict fatigue performance of materials and structures and to assess the extent to which these new methods are finding their way into practice A major challenge associated with the development of these advanced technologies is to insure that they are transferred to the engineering community in a timely manner Coverage is purposely broad and includes a range of materials, mechanics, and structures viewpoints and approaches to the fatigue analysis problem Contemporary strain-based fatigue and fatigue crack propagation methodologies are represented, and problems in the areas of high temperature behavior, spectrum loading, and multiaxial fatigue are addressed Significantly, a number of papers are concerned with applications of modern methods in engineering practice, thus providing an important perspective on the overall utility of modern techniques to real-world problem solving The first two papers provide valuable overviews of current efforts to develop general analysis approaches, incorporating both crack initiation and propagation considerations, to fatigue life prediction These methods incorporate our latest understanding of short crack behavior and the influence of crack closure phenomena in explaining a variety of mean stress, threshold, and load interaction effects Such developments represent an interesting and productive blend of cyclic deformation and fracture mechanics concepts to handle the difficult problem of cracks growing in plastic strain fields Next, six papers cover a range of elevated temperature phenomena and serve to effectively review progress and problems associated with thermomechanical fatigue, creep-fatigue, thermal fatigue, and cycle- and time-dependent crack growth While considerable progress is evident, there remain a number of unresolved issues in this area before truly general design approaches are available Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by Copyright Washington 1992 by ASTM International www.aslm.org University of (University of Washington) pursuant to License Agreement No further reproductions authorized ADVANCESIN FATIGUE LIFETIME PREDICTIVE TECHNIQUES The many problems associated with predicting lifetimes under spectrum loading conditions are addressed in the following five papers Here much attention is focused on crack closure behavior to explain overload and varying R-ratio effects that are characteristic of service spectrum The application of probabilistic fracture mechanics to structural reliability assessment is also covered In the area of multiaxial fatigue, a series of four papers give evidence there has been significant progress in observing and understanding initiation and propagation processes under in-phase and out-of-phase loading This is providing the basis for more rational and useful design approaches by focusing attention on critical shear planes at local regions in a structure to which damage accumulation models are applied Recent efforts dealing with biaxial fatigue at elevated temperature and welds under non-proportional loading are also included in the coverage Finally, a series of ten application papers provide evidence that considerable progress is being made in transferring new techniques into practice, often with encouraging results Coverage includes automotive, airframe, and power generation structures with detailed treatments of pressurized tubes, spot welds, lap joints, and various notched geometries Thermographic stress analysis techniques are also covered along with residual stress effects on stress intensities In total, the 27 papers contained in this volume provide a valuable review and update of progress and opportunities in this continually evolving field One is left with a sense of optimism that many of the challenging problems relating to material and structural fatigue performance are solvable, and that substantial progress is being made in developing and implementing the requisite technologies Of particular significance is the profound influence that modern experimental and analytical tools have had in contributing to this progress The capability to study and evaluate materials and components in the laboratory under simulated service conditions has been a boon to the experimentalists Likewise, rapid advances in computational power are providing the vehicle for making the often sophisticated analytical approaches a reality We would be remiss if we were to fail to mention the two papers that shared the ASTM Committee E-9 Award for Best Symposium Paper: ~ Crack Growth from NarrowBand Gaussian Spectrum Loading in 6063 Aluminum Alloy" by P S Veers and J A Van Den Avyle, and "Elevated Temperature Crack Growth in Aircraft Engine Materials" by T Nicholas and S Mall We congratulate both sets of authors Finally, the value of establishing and maintaining cross-industrial and cross-disciplinary forums of this type deserves special mention The complexities of structural fatigue problems necessitate broad interdisciplinary approaches and much is to be gained from a continuing dialogue between industry and academia, researchers and practitioners, and the spectrum of materials, mechanics, and structures specialists This helps assure that the right problems are being addressed by researchers and provides ready channels for technology transfer It is hoped that this symposium may have served as a useful step in promoting a broader view of fatigue lifetime prediction, in establishing a focal point for information dissemination, and in providing a platform from which to plan future related symposia Michael R Mitchell Rockwell International Science Center Thousand Oaks, CA 91360 Symposium Chairman and Editor Ronald W Landgraf Virginia Polytechnic Institute & State University Blacksburg, VA 24061 Symposium Chairman and Editor Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authori General Approaches Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authoriz JHANSALE AND MC CANN ON STEAM TURBINE/GENERATOR COMPONENTS 481 Input Load Histories The input load history is in one of two forms: (1) Rain Flow Counted Histogram or (2) Sequential Peak-Valleys (ASTM E 1049) A Rain Flow Counted Histogram allows a simple and rapid cumulative damage analysis But, since the sequence of the history is lost, the local mean stress and its effect cannot be evaluated However, reasonable upper and lower bound estimations can be made on the basis of the maximum overload excursion experienced either during the history, initial manufacture or proof test conditions Sequential PeakValley History preserves the sequence and therefore allows calculation of local mean stress and its effect on life Analysis of Rain Flow Counted Histogram Data For each level of (As/2)i, and the corresponding number of full cycles N i, the damage Di is calculated from the solution matrix as follows: D~ = 2N/(2NI) ~ (4) Using the linear damage summation rule that total damage is given by D, = D, (5) i Analysis of Sequential Peak-Valley Data A material stress-strain model is used to determine the actual local stress and strain amplitude and means This model is similar to the one developed by Wetzel [6] A brief description of this model is given in the Appendix Following stress-strain analysis, the cumulative damage analysis is performed in one of two ways One way is to reduce the predicted local stress-strain history into a histogram and apply the same procedure as in the analysis of Rain Flow Counted data Alternatively, the cumulative damage analysis is performed using a real-time incremental damage procedure as part of material stress-strain simulation (see Appendix) Creep-Fatigue Analysis Creep-fatigue cumulative damage analysis is especially utilized to evaluate potential problem areas or components prior to outage A linear time-cycles fraction damage summation rule, similar to A S M E [7], which defines the total damage as the sum of creep and fatigue damages is used as follows: D, = D< + D r (6) Dc = t~/Ty~ (7) where and D r = (ni/N~)Cold + ( n / N i ) W a r m + (ng/Nf)Hot + (n/Ns-) load change (8) Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authoriz 482 ADVANCES IN FATIGUE LIFETIME PREDICTIVE TECHNIQUES Creep damage calculations are based on both mean and minimum stress rupture properties Fatigue damage calculations are based on lower bound cyclic stress-strain and strain-life properties using the techniques described earlier When the total damage D, reaches a value of 0.5 for creep or 1.0 for creep-fatigue (whichever comes first), a warning point is indicated This means that either crack initiation or severe creep damage may have occurred and a close inspection is required Table shows a typical output from a creep-fatigue damage analysis on a main stop valve which was performed in 1984 From the output it can be seen that a creep warning point is indicated by 1989 Actual inspections in 1990, which included analysis of replicas, showed no damage Small material samples were also removed and creep tests are in progress So far the creep-fatigue analysis appears to be conservative Cumulative damage analysis is also used for the outer surface regions, especially the high temperature blade grooves of high pressure turbine rotor where cracking has been frequently experienced The FEM is utilized to more accurately determine the temperatures and stresses in these locations, and design modifications are made to reduce the stresses and future fatigue damage accumulation Figure shows such an example The rotor is first analyzed using a coarse two-dimensional axisymmetric finite element model, followed by another with a localized fine mesh model for both the present and redesigned geometries The design modifications in the example shown include a change in the blade groove geometry and the TABLE Example of typical creep-fatigue cumulative damage analysis of a main stop valve C R E E P A N D LOW C Y C L E F A T I G U E D A M A G E A N A L Y S E S COMPONENT: STOP VALVE MATERIAL: 2.25CR-IMO (2) P L A C E D IN S E R V I C E ,YR: 1961 A N A L Y S I S T H R O U G H YR: 2014 USAGE PAST FUTURE(YEARLY) HOURS 158561 6600 STARTS COLD: 150 6.00 WARM: 327 12.00 HOT: 43 2.00 LD CHG: .000 N O M I N A L STRESSES: KT= 2.0 D.R.= i STRESS, KSI AMP MEAN COLD: 10.00 00 WARM: 7.20 00 HOT: 5.60 00 L D C H G : ( S E E TEXT) C U M U L A T I V E D A M A G E FROM 1961 T H R O U G H Y E A R I N D I C A T E D B E L O W LOW CYCLE FATIGUE YEAR CREEP COLD WARM HOT LDCHG TOTAL 1984 1985 1986 1987 1988 1989 1990 1991 415 432 450 467 484 502 519 536 2011 2012 2013 2014 -W .882 899 917 934 057 059 062 064 066 068 071 034 035 036 037 039 040 041 002 002 002 002 002 002 ~ -~Juo-~ ~-~.003 000 000 000 000 000 000 507 528 549 570 591 612 / 0 000 1.030 116 066 004 000 1.051 119 121 123 126 067 068 069 071 004 004 004 004 000 000 000 000 1.071 1.092 1.113 1.134 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductio JHANSALE AND MC CANN ON STEAM TURBINE/GENERATOR COMPONENTS i I 483 z T l , , I I I FIG (top) Two-dimensional axisymmetric coarse mesh finite element model of a typical high pressure turbine spindle (center) Local fine mesh model of the original first reaction blade groove region (bottom) Local fine mesh model of the revised first reaction blade groove and stress relief groove regions introduction of a stress relief groove ahead of the blade groove These modifications resulted in reducing the stresses by a factor of about two and the future damage rate by a factor of at least ten As part of machining the relief groove region, a ring sample was also obtained for material testing and evaluation Burst Condition Analysis Rotor shafts, turbine disks, and generator rotor coil support rings have to be analyzed for potential burst condition Existing subcritical flaws may grow by fatigue, creep, and/or stress corrosion cracking to reach critical size where a burst condition could occur Thus it Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions a 484 ADVANCES IN FATIGUE LIFETIME PREDICTIVE TECHNIQUES aer=f(~ )" KIC2~ KIC ~ cr /- 0o o,t,o I]ME FIG Schematic illustration o f Ne burst condition o f a steam turbine spindle with an axial bore during a cold start is necessary to define the burst condition in order to calculate the remaining life Using the linear elastic fracture mechanics (LEFM) criterion, it is assumed that a fracture condition occurs when the applied maximum stress intensity factor (Kraal) reaches K~c, the fracture toughness However, the applied Kma is a function of time from startup and location in the component K~c is a function of temperature and therefore is also a function of time and location Therefore analysis of each location and time step after startup is required to determine the critical time and location which results in the minimum critical flaw size This defines the burst condition for the component From LEFM, the ratio of K~c to applied stress is a function of the critical flaw size Using this idea, the ANSYS postprocessor is utilized to map out the component and determine the time and location corresponding to the minimum KIo/a ratio Figure shows a schematic illustration of a burst condition for a high pressure turbine rotor containing an axial bore The bore circumferential stress (~), the fracture toughness (KI~), and the critical crack size (a~r) change with time (and temperature) during a cold start During a cold start when the bore is cold and when the high temperature steam hits the outside surface, a high tangential thermal stress is induced at the bore The mechanical stress due to rotation is negligible since the speed is usually low The fracture toughness is also low since the material temperature at the bore is also low As the rotor is speeded up to the operating speed, and the rotor temperature increases towards a steady-state, the thermal stress reduces but the mechanical stress increases Since the bore temperature is also increasing, the fracture toughness also increases Therefore the minimum critical crack size, which is a function of the ratio of K~c to ~, could occur well before the steady-state is reached and when the rotor is at full speed If the present flaws as determined from the nondestructive examinations are of the magnitude of the critical flaw sizes, then they are removed by overboring and/or the startup procedure is revised The revised startup procedure could include prewarming of the rotor Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproduct JHANSALE AND MC CANN ON STEAM TURBINE/GENERATOR COMPONENTS 485 and/or a slower startup to increase the minimum critical flaw size via increased fracture toughness and/or reduced stress As part of the overboring operation ring samples are removed for material testing and evaluation Smaller subcritical flaws are evaluated by performing fatigue crack growth analysis as a function of start-stop and over speed test cycles to determine the remaining useful life A fracture mechanics program, N A S C R A C | [8], is utilized for this analysis Conclusions State-of-the-art finite element, fatigue, and fracture mechanics techniques described in this paper have been applied to nearly 300 steam turbine/generator rotors and numerous other power generator components These techniques have been extremely useful in performing remaining life evaluation and condition improvement of vintage steam turbinegenerator components in service Our experience has also shown that the required fatigue creep and fracture properties can be evaluated from small material samples obtained from these components APPENDIX Material Stress-Strain Simulation Model A spring-slider model as shown in Fig adequately simulates the history-dependent stressstrain behavior of structural metals By choosing an appropriate number of spring-slider elements, stiffnesses for the springs and friction stresses for the sliders, the nonlinear stressstrain characteristic of the material can be matched as closely as desired with precise linear approximation Wetzel [6] developed a set of simple rules to essentially reproduce this model behavior Based on this idea, the following procedure was developed and used in our computer program, The stress-strain curve is assumed to be identical in tension or compression and is represented by precise linear segments as illustrated in Fig Figure shows a five-segment approximation for illustration The rules are stated as follows: The availability of a segment during the current loading path which is either tensile or compressive depends on the prior loading history and is denoted by an "availability coefficient" in that direction E E1 Ei En ~I ~n E Elastic Spring with Modulus, E (7 Solid Friction Slider, with Friction Stress, ~' FIG Spring-slider model for stress-strain simulation of structural metals Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 486 ADVANCES IN FATIGUE LIFETIME PREDICTIVE TECHNIQUES o- C I / /B | A v a i l a b i l i t y C o e f f i c i e n t of E l e m e n t s OA AB BC | Q Loading Path | Q | T C T C T C T C T C S 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 E 0,0 2.0 0.0 2.0 0.0 2.0 0.2 1.8 1.0 1.0 S 0.0 2.0 0.0 2.0 0.0 2.0 0.2 1.8 1.0 L0 E 2.0 0.0 1.3 0.7 0.0 2.0 0.2 1.8 1.0 1.0 S 2.0 0.0 1.3 0.7 0.0 2.0 0,2 1.8 1.0 1.0 E 0.0 2.0 0.0 2.0 0.0 2.0 0.0 2.0 0.0 2.0 T C T (S - S t a r t , E - E n d , T - T e n s i o n C - Compression, Unused E l e m e n t s U n d e r l i n e d ) F I G V Example to illustrate simulation of stress-strain hysteresis behavior by the method of rules after Wetzel [6] Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions auth JHANSALE AND MC CANN ON STEAM TURBINE/GENERATOR COMPONENTS 487 The absolute sum of the availability coefficients in the tensile and compressive directions for each segment is always equal to two The initial availability coefficient in tension or in compression for each segment is one During a specific loading, the stress-strain path is defined by segments, starting with the first, and proceeding in consecutive order to the extent that the segments are available in the direction of loading until the desired stress or strain limit is reached The availability of a segment in a given direction (tension or compression) decreases to the extent it is used in that direction, but increases by that amount in the opposite direction in conformity with rule In brief, the procedure amounts to a simple bookkeeping operation of the availability coefficients as illustrated in Fig When the tensile loading sequence OA begins, one unit of each segment is available in tension and compression Hence, the stress-strain path OA consists of one unit lengths of elements to and 0.8 unit of 4; at this stage, point A is reached The availability coefficients of these segments in tension are reduced by the amounts of these element lengths, but at the same time their availability coefficients in compression are correspondingly increased by the same amount The availability coefficients of segment are unaltered, since that segment was not used The next loading sequence, A B , which is compressive uses the two available units of segment and 1.3 units of segment 2; at this stage, the desired limit B is reached The next sequence, BC, which is tensile, uses the two units of 1, 1.3 units of 2, none of 3, 0.2 units of 4, and one unit of 5; at this stage, point C is reached i-1 0" - -%1 FIG 1llustration of incremental damage summation procedure in one reversal Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 488 ADVANCES IN FATIGUE LIFETIME PREDICTIVE TECHNIQUES In an actual application, the stress-strain curve is represented by many segments similar to those shown in the solution matrix in Table The first column represents the node number The third, fourth, sixth, and seventh columns respectively represent the local strain, local stress, nominal stress for a given K, and the damage values corresponding to these nodes Methods of incorporating cyclic hardening/softening and cyclic relaxation/creep behavior and a generalized isotropic-kinematic plasticity formulation have been developed [9,10] However, transient phenomena are not included in the present computer program Only the stabilized cyclic stress-strain curve is used The damage accumulated during each reversal is calculated as follows Considering that a tensile reversal in a cyclic history starts at in Fig 8, the damage caused by using the ith R-C I:~[IPrIDtT S ~ V I ~ CO~ E)'GD,E ~ S;E)~Irr~ smrlcE3 I ' ~ BRT~F~R FwrI~LE~ ~IE: - ~ I~011 ~ ~'IR.~IS F'RTZo r I:IIq.I'SZS ~ ERll[ ~ Ti~(t1000 1~'l'Z0h'~ C~I~HEIIt:SH~q" S ~ : TI3~IL~ S'm~,J1~: 11~SlU[ S'II~Ob'IH: X RE~ucrI~'(R~O~: G.iqSI"ICrI0~LLUS: CYG.IC ~ CCE}-r.: CY(:LIC S I I ~ H~RD E3~.: FI~'IGLE S'IRE~b'~ CC~'T : F~IGUC ~ ~.: FR ' TZGUC~.CTILITYCC~'X.: F~TIGU[ DUCTILI"IY ~ P : FOR e'RTER,T.FI ~Ie,t-'~CO,CE),II1RRTICH ~nrCTICt,i 'llnB(tlBSI ~ O v , I' ~ SH~" K 9.B T: K SUBF: II~1D~R.:4138 11D,SZI ( ~ : 696 I'PR S~L.(Cg~ PR00~]LTTY CF ~.~,,RVI~L rcR ~ 413a 696 1,1129; I ~ 6"7 ~ 1~B9 13 1Z76 MF~ -.EE5 ~Z -.63 P,(Mq ,108 -3~0 LCCR LCO:L 676.~6G -T:28.434 010~15 -6.159~Z[-~3 -4.70067E ~ -.OIE3B15 -~0 ~9 ,-676.~6~ 6~.~,1 328.449 676.366 300 ~B8 41B8 * ~OIOT~ ~ ' i ' I J ' ~ t ~ V~.LI[ TOT~ 6.1~'~41E- ~3 4." ~ - B 91~3815 E3TI~II~ ~.O0(S TO F'~ILU~ E~:L ~ D~TQ ~ X 0 ~'.6~0@E -0,4 2.6'~06E-04 ~ t ~ ' - 7.1~,~[-04 "t 1~324(-e4 3.369",'6E-0,4 ~6976E-0,4 4.4~697E-04 6.6~205~-04 9.910~-64 8.8~56.c~-~1 ~ 6.6~1C.-~4 E}'F[CT: 11ZZ.29 [STII~TI~ ELOG(S TO FAILUR[ IMCL ~#~( PF.qrt :}le~.~ E~r~CT: 11Z4.14 [STIM~'~ EL0CXSTO FAILU~: 1123.ZI 8.~ F~ " SItILt.AII~DHOT(>IROOTSTRE~VS STRAIN ~ tlqT~IQL: 413B(TIE3~ILESII~3~TH:E~J61'I~) 6.0@ 4.~ S T Z.~ R s S S e.00 ~-Z.00 A ~.00 -6.00 ~It'E]D~It~ So~Ie'F~ -8.00 Tg~(t 1000 ITICI~VICrW,1 -0.20~.16 B.12 -0.00 -~.04 0.00 STRRIM 0.04 0.00 0.1Z 0.16 I 0.28 (-01 FIG Simple example of material stress-strain and damage simulation (top left) Material properties (top right) Output of fatigue analysis results assuming that the last six sequential peak-valleys are repeated until failure (bottom) Plot of simulated notch root stress-strain response Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized JHANSALE AND MC CANN ON STEAM TURBINE/GENERATOR COMPONENTS 489 segment is calculated as 8D i = ~ d , - ~-14 where d~ and di_ 1are nodal damage values precalculated in the solution matrix corresponding to nodes i and i - respectively and f~ and f,._ ~ are corresponding mean stress effect factors Using Morrow's criterion f~ is given by f, = (1 - aoj%.) ~/b where aoi is the mean stress corresponding to the ith node in the present reversal The total damage in any given reversal is a summation of the damages caused by the usage of all the segments in this reversal For example, the damage D of the present reversal up to the ith node is given by f,d~ because D = 8D1 + 8D2 + = faD1 + (f2d2 - - + 8D~ f~dl) + (fAi - f~ 14-1) = Ld, The procedure is repeated for each reversal in the history Figure shows a simple example of material stress-strain response simulation and damage accumulation under seven sequential peak-valley nominal stress This real-time incremental damage summation procedure was originally developed as part of the doctoral research of one of the authors [11,12] It appropriately accounts for the nonlinear damage accumulation during each part of the cycle References [1] McCann, D R and Jhansale, H R., "Condition Assessment of Over 250 Steam Turbine and Generator Rotors," in Proceedings, Electric Power Research Institute NDE Workshop, Charlotte, N.C., 12-15 Sept 1989 [2] ANSYS, available from Swanson Analysis Systems, Houston, Pa [3] Rice, R C et al (Eds.), Fatigue Design Handbook, AE-10, 2nd ed., Society of Automotive Engineers, 1988 [4] Morrow, JoDean, Fatigue Properties of Metals, Manual, ISC Division, Society of Automotive Engineers, 1964 [5] Smith, K N., Watson, P., and Topper, T H., "A Stress-Strain Function for the Fatigue of Materials," Journal of Materials, Vol 5, No 4, Dec 1970, pp 767-778 [6] Wetzel, R M., "A Method of Fatigue Damage Analysis," Technical Report SR 71-107, Scientific Research Staff, Ford Motor Company, Dearborn, Mich., Aug 1971 [7] ASME Pressure Vessel Code, Section III, Code Case N-47, 1974 [8] BIGIF, Electric Power Research Institute, Palo Alto, Calif [9] Jhansale, H R., "A Unified Approach for Modelling Inelastic Behavior of Structural Metals under Complex Cyclic Loadings," Technical Report CERL-TR-M-214, U.S Army Construction Engineering Research Laboratory, Champaign, II1., May 1977, NTIS Ref AD-A040 741/1GA [10] Sharma, S K and Jhansale, H R., "A Plasticity Formulation for Cyclic Inelastic Structural Analysis," Interim Report M-202, U.S Army Construction Engineering Research Laboratory, Champaign, Ill., Feb 1977 [11] Jhansale, H R., "Inelastic Deformation and Fatigue Response of Spectrum Loaded Strain Controlled Axial and Flexural Members," Ph.D thesis, University of Waterloo, Waterloo, Ontario, Canada, March 1971 [12] Jhansale, H R., "Evaluation of Deformation Phenomena of Metals for Fatigue Analysis," Journal of Testing and Evaluation, Vol 3, No 5, Sept 1975, pp 348-355 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP1122-EB/Jan 1992 Author Index A Abuelfoutouh, Nader Mohamed, 77 Arya, V., 107 K Kalluri, S., 120 Kulowitch, P J., 299 Kurath, P., 383,319 B Baek, W K., 354 Bannantine, J A., 249 Landgraf, Ronald W., Lawrence, F V., 383,319 C Chih-Chien, Chia, 449 Creager, M., 234 D Davis, D C., 299 de Koning, A U., 214 Deardorff, Arthur F., 460 Derber, Thomas G., 449 Dougherty, D J., 214 Duckert, R E., 120 M Mall, Shankar, 143 Manning, S D., 422 Marler, J E., 422 McGaw, Michael A., 84 Mitchell, Michael R., Moore, N., 234 N Newburn, Dale A., 369 Newman, Jr., J C., Nicholas, Theodore, 143 O Ebbeler, D., 234 Everett, Jr., R A., F Fatemi, Ali, 276 Fujimitsu, Tatsuro, 402 Omori, Junji, 402 Phillips, E P., Pretzer, F L., 422 R G Griesbach, Timothy J., 460 Reddy, Satish C., 276 Riccardella, Peter C., 460 Ritzert, F J., 120 It Halford, G R., 107, 120 Hatanaka, Kenji, 402 Heuler, P., 28 Hillberry, B M., 214 Holland, F A., 120 Saltsman, J F., 107 Sandor, Bela I., 341 Seeger, T., 28 Sehitoglu, Huseyin, 47 Shiraishi, Susumu, 402 491 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by Copyright Washington 1992by ASTM International www.astm.org University of (University of Washington) pursuant to License Agreement No further reproductions authorized 492 ADVANCESIN FATIGUE LIFETIME PREDICTIVETECHNIQUES Siljander, Aslak, 319 Soboyejo, W O., 435 Socie, D F., 249 Stephens, R I., 354 Sunder, R., 161, 176 Sutharshana, S., 234 Swain, M H., Swellam, M H., 383 Swenson, Daniel V., 449 u Van Den Avyle, James A., 191 Veers, Paul S., 191 Verrilli, M J., 107, 120 Vormwald, M., 28 Y Yang, J N., 422 T Z Tipton, Steven M., 369 Zamrik, S Y., 299 Zhang, Daqing, 341 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP1122-EB/Jan 1992 Subject Index A Adhesives, lap joints, 449 Aircraft airframe inspection, 422 engine materials, 143 load spectra, 176 Aluminum alloy, variable amplitude loading, 214 6063 Aluminum alloy, crack growth, 191 Automotive suspension component, life prediction, 354 B Bending stress, out-of-phase, 319 B1900 + Hf thermal fatigue life prediction model, 107 thermomechanical and bithermal fatigue, 120 Biaxial fatigue, 276 Biaxial strain cycling, failure modes, 299 Bithermal fatigue, 107, 120 C Carbon steel, circumferentially grooved components, 402 Circumferential crack, 402 CircumferentiaIly grooved components, life prediction, 402 Composite materials, thermographic stress analysis, 341 Coplanar cracks, 435 Crack closure, 28 6063 aluminum alloy, 191 model, 176 stress-based model, 161 Crack growth 6063 aluminum alloy, 191 analytical model, 143 damage distribution, 176 high-temperature, 143 hold time effects, 143 lap joints, 449 near-threshold, 161 small cracks, 276 subcritical, 234 variable amplitude loading, 214 Crack growth model stochastic, 234, 422 two-component, 214 Crack initiation, 5, 28, 249 high-temperature low-cycle fatigue, 299 severely loaded tubing, 369 tensile-shear spot welds, 383 Crack-opening load, 191 Crack propagation, semielliptical cracks, 435 tensile-shear spot welds, 383 Creep fatigue, 77, 107 cumulative damage, 84 Type 316 stainless steel, 84 Critical plane, 249 severely loaded tubing, 369 Cumulative damage aircraft spectrum loading, 176 creep fatigue, 84 severely loaded tubing, 369 Cyclic creep rupture, 77 Cyclic J-integral range, 402 D Damage accumulation, 28 Damage Coupling, 84 Damage mechanics, life prediction, 77 Damage theory, 84 Damage tolerance, 422 Defects, Ductile tearing, 214 Dynamic simulation, life prediction, 354 E Elastoplastic fracture mechanics, 28 Electric-potential-drop studies, tensileshear spot welds, 383 Endurance limit, 28 Failure behavior, 120 Failure modes, Type 316 stainless steel, 299 493 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 494 ADVANCESIN FATIGUE LIFETIME PREDICTIVETECHNIQUES Fatigue analysis, steam turbine/generator components, 474 Fatigue damage mechanisms, composite materials, 341 Fatigue damage modeling, 369 Fatigue lifetime monitoring, power plants, 469 Fatigue mechanics, FatiguePro, 460 Findley model, nonproportional loading, 319 Finite element analysis lap joints, 449 life prediction, 354 semielliptical cracks, 435 Flexural bending, 369 Flow behavior, 107, 120 Fractography, 214 Fracture mechanics semielliptical cracks, 435 steam turbine/generator components, 474 Fracture modes, 299 steam turbine/generator components, 474 thermo-mechanical fatigue, 47 unified approach, welded structures, 319 Load condensation, 191 Load history, 354 Low-cycle fatigue, 107, 120 biaxial strain cycling, 299 circumferentially grooved components, 402 H N Haynes 188 thermal fatigue life prediction model, 107 thermomechanical and bithermal fatigue, 120 High-temperature fatigue, 107, 120 1045 HR steels, small crack growth, 276 Hydrostatic stress, severely loaded tubing, 369 M Material memory, 214 Mean stress, 77 Mises effective stress amplitude, 319 Monitoring, power plants, 460 Multiaxial fatigue life prediction, 249 severely loaded tubing, 369 small cracks, 276 Multiaxial loading, local stress damage, 319 Non-coplanar cracks, 435 Nonlinear damage, severely loaded tubing, 369 O Oxidation, high temperature isothermal and thermomechanical fatigue, 47 Oxide cracking, 47 P Inconel 718, crack growth rate, 143 small cracks, 276 Inelastic strain, 120 Inspection, 422 Intergranular cracking, 47 Intergranular creep, 47 Isothermal fatigue, 47 L Lap joints, 449 Life prediction, 28 circumferentially grooved components, 402 damage mechanics, 77 dynamic simulation and finite element analysis, 354 multiaxial fatigue, 249 Plasticity, 214 modeling, 369 nonproportional, 249 Plastic zones, 214 Power plants, fatigue lifetime monitoring, 460 Pressure vessels and piping, 460 Pressurized tubing, 369 Preventive maintenance, 422 Probabilistic failure assessment, 234 Probabilistic fracture mechanics, 234 R Racetrack filter, 191 Rainflow analysis, 161 Reliability assessment, 234 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized SUBJECT INDEX Reliability Centered Maintenance Analysis, 422 Ren6 80, fatigue life, 77 Risk analysis, 422 Rivets, lap joints, 449 495 Superalloys nickel-based, 143 thermal fatigue life prediction model, 107 T SAE 1045 steel, multiaxial fatigue life prediction, 249 Semielliptical cracks, 402 propagation, 435 Shear stress maximum amplitude, 319 out-of-phase, 319 Shear-type fatigue damage, 319 Small cracks growth behavior, 28 multiaxial fatigue, 276 Spectrum loading, 161 crack growth, 176 narrow-band Gaussian, 191 random, 191 variable amplitude, 249 Spot welds, tensile-shear, 383 Steam turbine/generator components, fatigue analysis, 474 Strain-life method, 249 Strainrange partitioning, 120 Stress analysis, Stress history, 354 Stress intensity, lap joints, 449 Stress intensity factor, 5, 191 Structural durability, 107 Structural integrity, monitoring, 460 Structural reliability, 422 Tensile-shear spot welds, electric-potentialdrop studies, 383 Thermal fatigue life prediction model, 107 Thermal stress, power plants, 460 Thermoelasticity theory, 341 Thermographic stress analysis, composite materials, 341 Thermomechanical fatigue, 107 life prediction, 47 superalloys, 120 Threshold stress intensity, 161 Titanium aluminide, crack growth rate, 143 TMF/TS-SRP, 107 Total-life analysis, crack propagation, Toughness testing, steam turbine/generator components, 474 Tubing, severely loaded, 369 Type 316 stainless steel creep fatigue, 84 failure modes, 299 V Variable amplitude loading, 28 W Welded structures, nonproportional fatigue, 319 Copyright by ASTM Int'l (all rights reserved); Wed Dec 23 18:52:01 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized