fatigue testing and analysis theory and practice

TeAM YYePG Digitally signed by TeAM YYePG DN: cn=TeAM YYePG, c=US, o=TeAM YYePG, ou=TeAM YYePG, email=yyepg@msn.com Reason: I attest to the accuracy and integrity of this document Date: 2005.02.15 06:00:47 +08'00' Fatigue Testing and Analysis (Theory and Practice) LEE: FATIGUE TESTING AND ANALYSIS Final Proof 21.6.2004 6:19pm page i This page intentionally left blank Fatigue Testing and Analysis (Theory and Practice) Yung-Li Lee DaimlerChrysler Jwo Pan University of Michigan Richard B. Hathaway Western Michigan University Mark E. Barkey University of Alabama AMSTERDAM . BOSTON . HEIDELBERG . LONDON . NEW YORK OXFORD . PARIS . SAN DIEGO . SAN FRANCISCO . SINGAPORE SYDNEY . TOKYO LEE: FATIGUE TESTING AND ANALYSIS Final Proof 21.6.2004 6:19pm page iii Elsevier Butterworth–Heinemann 200 Wheeler Road, Burlington, MA 01803, USA Linacre House, Jordan Hill, Oxford OX2 8DP, UK Copyright ß 2005, Elsevier Inc. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone: (þ44) 1865 843830, fax: (þ44) 1865 853333, e-mail: permissions@elsevier.com.uk. You may also complete your request on- line via the Elsevier homepage (http://www.elsevier.com), by selecting ‘‘Customer Support’’ and then ‘‘Obtaining Permissions.’’ Recognizing the importance of preserving what has been written, Elsevier prints its books on acid-free paper whenever possible. Library of Congress Cataloging-in-Publication Data ISBN 0-7506-7719-8 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. (Application submitted) For information on all Butterworth–Heinemann publications visit our Web site at www.bh.com 04050607080910 10987654321 Printed in the United States of America LEE: FATIGUE TESTING AND ANALYSIS Final Proof 21.6.2004 6:19pm page iv Thank our families for their support and patience. To my parents and my wife Pai-Jen. - Yung-Li Lee To my Mom and my wife Michelle. - Jwo Pan To my wife Barbara. - Richard B. Hathaway To my wife, Tammy, and our daughters Lauren and Anna. - Mark E. Barkey LEE: FATIGUE TESTING AND ANALYSIS Final Proof 21.6.2004 6:19pm page v This page intentionally left blank Preface Over the past 20 years there has been a heightened interest in improving quality, productivity, and reliability of manufactured products in the ground vehicle industry due to global competition and higher customer demands for safety, durability and reliability of the products. As a result, these products must be designed and tested for sufficient fatigue resistance over a large range of product populations so that the scatters of the product strength and loading have to be quantified for any reliability analysis. There have been continuing efforts in developing the analysis techniques for those who are responsible for product reliability and product design. The purpose of this book is to present the latest, proven techniques for fatigue data acquisition, data analysis, test planning and practice. More specifically, it covers the most comprehensive methods to capture the component load, to characterize the scatter of product fatigue resistance and loading, to perform the fatigue damage assessment of a product, and to develop an accelerated life test plan for reliability target demonstration. The authors have designed this book to be a useful guideline and reference to the practicing professional engineers as well as to students in universities who are working in fatigue testing and design projects. We have placed a primary focus on an extensive coverage of statistical data analyses, concepts, methods, practices, and interpretation. The material in this book is based on our interaction with engineers and statisticians in the industry as well as based on the courses on fatigue testing LEE: FATIGUE TESTING AND ANALYSIS Final Proof 21.6.2004 6:19pm page vii vii and analysis that were taught at Oakland University, University of Michigan, Western Michigan University and University of Alabama. Five major con- tributors from several companies and universities were also invited to help us enhance the completeness of this book. The name and affiliation of the authors are identified at the beginning of each chapter. There are ten chapters in this book. A brief description of these chapters is given in the following. Chapter 1 (Transducers and Data Acquisition) is first presented to address the importance of sufficient knowledge of service loads/stresses and how to measure these loads/stresses. The service loads have significant effects on the results of fatigue analyses and therefore accurate measurements of the actual service loads are necessary. A large portion of the chapter is focused on the strain gage as a transducer of the accurate measurement of the strain/stress, which is the most significant predictor of fatigue life analyses. A variety of methods to identify the high stress areas and hence the strain gage placement in the test part are also presented. Measurement for temperature, number of temperature cycles per unit time, and rate of temperature rise is included. The inclusion is to draw the attention to the fact that fatigue life prediction is based on both the number of cycles at a given stress level during the service life and the service environments. The basic data acquisition and analysis techniques are also presented. In Chapter 2 (Fatigue Damage Theories), we describe physical fatigue mech- anisms of products under cyclic mechanical loading conditions, models to describe the mechanical fatigue damages, and postulations and practical implementations of these commonly used damage rules. The relations of crack initiation and crack propagation to final fracture are discussed in this chapter. In Chapter 3 (Cycle Counting Techniques), we cover various cycle counting methods used to reduce a complicated loading time history into a series of simple constant amplitude loads that can be associated with fatigue damage. Moreover the technique to reconstruct a load time history with the equivalent damage from a given cycle counting matrix is introduced in this chapter. In Chapter 4 (Stress-Based Fatigue Analysis and Design), we review methods of determining statistical fatigue properties and methods of estimating the fatigue resistance curve based on the definition of nominal stress amplitude. These methods have been widely used in the high cycle fatigue regime for decades and have shown their applicability in predicting fatigue life of notched shafts and tubular components. The emphasis of this chapter is on LEE: FATIGUE TESTING AND ANALYSIS Final Proof 21.6.2004 6:19pm page viii viii Preface the applications of these methods to the fatigue design processes in the ground vehicle industry. In Chapter 5 (Strain-Based Fatigue Analysis and Design), we introduce the deterministic and statistical methods for determining the fatigue resistance parameters based on a definition of local strain amplitude. Other accompan- ied techniques such as the local stress-strain simulation and notch analysis are also covered. This method has been recommended by the SAE Fatigue Design & Evaluation Committee for the last two decades for its applicability in the low and high cycle fatigue regimes. It appears of great value in the application of notched plate components. In Chapter 6 (Fracture Mechanics and Fatigue Crack Propagation), the text is written in a manner to emphasize the basic concepts of stress concen- tration factor, stress intensity factor and asymptotic crack-tip field for linear elastic materials. Stress intensity factor solutions for practical cracked geometries under simple loading conditions are given. Plastic zones and requirements of linear elastic fracture mechanics are then discussed. Finally, fatigue crack propagation laws based on linear elastic fracture mechanics are presented. In Chapter 7 (Fatigue of Spot Welds), we address sources of variability in the fatigue life of spot welded structures and to describe techniques for calculat- ing the fatigue life of spot-welded structures. The load-life approach, struc- tural stress approach, and fracture mechanics approach are discussed in details. In Chapter 8 (Development of Accelerated Life Test Criteria), we provide methods to account for the scatter of loading spectra for fatigue design and testing. Obtaining the actual long term loading histories via real time measurements appears difficult due to technical and economical reasons. As a consequence, it is important that the field data contain all possible loading events and the results of measurement be properly extrapolated. Rainflow cycle counting matrices have been recently, predominately used for assessing loading variability and cycle extrapolation. The following three main features are covered: (1) cycle extrapolation from short term measurement to longer time spans, (2) quantile cycle extrapolation from median loading spectra to extreme loading, and (3) applications of the extrapolation techniques to accelerated life test criteria. In Chapter 9 (Reliability Demonstration Testing), we present various statis- tical-based test plans for meeting reliability target requirements in the accel- erated life test laboratories. A few fatigue tests under the test load spectra should be carried out to ensure that the product would pass life test criteria. LEE: FATIGUE TESTING AND ANALYSIS Final Proof 21.6.2004 6:19pm page ix Preface ix [...]... University of Alabama He has conducted research in the areas of spot weld fatigue testing and analysis, multiaxial fatigue and cyclic plasticity of metals, and multiaxial notch analysis Prior to his current position, he was a Senior Engineering in the Fatigue Synthesis and Analysis group at General Motors Mid-Size Car Division 1 Transducers and Data Acquisition Richard Hathaway Western Michigan University... Transducers and Data Acquisition Richard B Hathaway, Western Michigan University Kah Wah Long, DaimlerChrysler 1 2 Fatigue Damage Theories Yung-Li Lee, DaimlerChrysler 57 3 Cycle Counting Techniques Yung-Li Lee, DaimlerChrysler Darryl Taylor, DaimlerChyrysler 77 4 Stress-Based Fatigue Analysis and Design 103 Yung-Li Lee, DaimlerChrysler Darryl Taylor, DaimlerChyrysler 5 Strain-Based Fatigue Analysis and Design... for the choice of a test plan including sample size and life test target are the subject of our discussion In Chapter 10 (Fatigue Analysis in the Frequency Domain), we introduce the fundamentals of random vibrations and existing methods for predicting fatigue damage from a power spectral density (PSD) plot of stress response This type of fatigue analysis in the frequency domain is particularly useful... DaimlerChrysler 10 Fatigue Analysis in the Frequency Domain Yung-Li Lee, DaimlerChrysler 369 About the Authors Dr Yung-Li Lee is a senior member of the technical staff of the Stress Lab & Durability Development at DaimlerChrysler, where he has conducted research in multiaxial fatigue, plasticity theories, durability testing for automotive components, fatigue of spot welds, and probabilistic fatigue and fracture... Department of Mechanical Engineering at Oakland University, Rochester, Michigan Dr Jwo Pan is a Professor in Department of Mechanical Engineering of University of Michigan, Ann Arbor, Michigan He has worked in the area of yielding and fracture of plastics and rubber, sheet metal forming, weld residual stress and failure, fracture, fatigue, plasticity theories and material modeling for crash simulations... unit time, and rate of temperature rise may be included Fatigue life prediction is based on knowledge of both the number of cycles the part will experience at any given stress level during that 1 2 Transducers and Data Acquisition life cycle and other influential environmental and use factors Section 1.2 begins with a review of surface strain measurement, which can be used to predict stresses and ultimately... funded by Ford Motor Company and Director for Center for Advanced Polymer Engineering Research at University of Michigan He is a Fellow of American Society of Mechanical Engineers (ASME) He is on the editorial boards of International Journal of Fatigue and International Journal of Damage Mechanics Dr Richard B Hathaway is a professor of Mechanical and Aeronautical engineering and Director of the Applied... Hongtae Kang (University of Michigan-Dearborn), Yen-Kai Wang (ArvinMeritor), Paul Lubinski (ArvinMeritor), and Tana Tjhung (DaimlerChrysler) Finally, we would like to thank our wives and children for their love, patience, and understanding during the past years when we worked most of evenings and weekends to complete this project Yung-Li Lee, DaimlerChrysler Jwo Pan, University of Michigan Richard... Mechanics and Fatigue Crack Propagation 237 Jwo Pan, University of Michigan Shih-Huang Lin, University of Michigan 7 Fatigue of Spot Welds Mark E Barkey, University of Alabama Shicheng Zhang, DaimlerChrysler AG 8 Development of Accelerated Life Test Criteria 285 313 Yung-Li Lee, DaimlerChrysler Mark E Barkey, University of Alabama 9 Reliability Demonstration Testing 337 Ming-Wei Lu, DaimlerChrysler 10 Fatigue. .. bridge output, and Eex the bridge excitation: ! eoCV N Â GF Â e ¼ (1:4:4) 4 Eex 1.5 gage and lead-wire compensation Lead wires and lead-wire temperature changes affect the balance and the sensitivity of the bridge If temperature changes occur during measurement, drift will occur Dummy gages are used to compensate for component temperature variations that occur during the test 19 Gage and Lead-Wire . attest to the accuracy and integrity of this document Date: 2005.02.15 06:00:47 +08'00' Fatigue Testing and Analysis (Theory and Practice) LEE: FATIGUE TESTING AND ANALYSIS Final Proof. with engineers and statisticians in the industry as well as based on the courses on fatigue testing LEE: FATIGUE TESTING AND ANALYSIS Final Proof 21.6.2004 6:19pm page vii vii and analysis that. spot weld fatigue testing and analysis, multiaxial fatigue and cyclic plasticity of metals, and multiaxial notch analysis. Prior to his current position, he was a Senior Engineering in the Fatigue