Acoustic Emission Testing

Transcription

1 Acoustic Emission Testing

2 Christian U. Grosse (Eds.) Acoustic Emission Testing 123

3 Christian U. Grosse Department of Non-destructive Testing and Monitoring Techniques Material Testing Institute MPA University of Stuttgart Pfaffenwaldring Stuttgart Germany christian.grosse@mpa.uni-stuttgart.de Graduate School of Science & Technology Kumamoto University Kurokami Kumamoto Japan ohtsu@gpo.kumamoto-u.ac.jp ISBN e-isbn DOI / Library of Congress Control Number: Springer-Verlag Berlin Heidelberg This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable for prosecution under the German Copyright Law. The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Typesetting: camera ready by the editors Production: le-tex publishing services ohg, Leipzig, Germany Cover design: estudiocalamar S.L., F. Steinen-Broo, Girona, Spain Printed on acid-free paper springer.com

4 Preface This book addresses one of the most interesting techniques used for the non-destructive evaluation of materials: The acoustic emission technique (AET). Compared to other non-destructive testing (NDT) methods, AET can monitor changes in materials behavior over a long time and without moving one of its components i.e. sensors. This makes the technique quite unique along with the ability to detect crack propagations occurring not only on the surface but also deep inside a material. Consequently, AET is an important addition to NDT methods surveying actively a structure by scanning for geometric defects as well as to visual inspection methods observing a materials surface. There are many reports on successful AE applications in engineering at a broad variety of materials, material compositions and structures. Applications to many different materials are addressed in this book, but the success of these applications does not necessarily mean that the AET is easy to be applied. Depending on the degree of heterogeneity of the material and the complexity of the structure under test there could exist a variety of problems that need to be solved. The status of applications ranges from scientific/experimental to industrial/routine. A monitoring experiment or application should therefore take the experience into account that is compiled in this book. Although the setup necessary to conduct AE measurements appear to be very easy on the forehand, many issues need to be solved to obtain reliable results and to interpret them in the right way. The introduction will give some ideas about techniques and the frame of applications addressed in this book. It will also draw boundaries to related techniques. Chap. 2 summarizes the historical backgrounds of AET and some names of the researchers being responsible for significant discoveries and improvements. Since the choice of sensors and instruments influences the quality of the recorded data, Chap. 3 is dedicated to these issues. Due to the complexity of the material or structure and vice versa, the degree of accuracy or detailing of information should vary in different classes of AE applications. Where the number of AE phenomena in a certain time period exceeds the amount of data where full signal waveforms can be recorded or analyzed, the online extraction of data called parameters out of these waveforms shall still give valuable information. The parametric AE analysis techniques to be performed are described in Chap. 4. Chap. 5 summarizes basics of signal-based analysis techniques.

5 VI Preface One of the most important features of AET is the ability to localize the source of an AE event. Following the evolution of source locations, the technique can lead to a better insight into the materials behavior under load resulting in the four-dimensional image of defect developments. Chap. 6 describes in detail most of the existing techniques and algorithms for the source localization. However, an AE signal contains much more information about the fracture process and source parameters. Therefore, the two following Chaps. 7 and 8 are dedicated to describe the mathematical and physical principles of AET. Additionally, this closed the first part of this book dealing more with the background and basic principles. The second part is mostly addressed to the practical engineer giving after some general remarks (Chap. 9) numerous examples of AET to applications including AE in concrete (Chap. 10), rock (Chap. 11) and wood (Chap. 12). These are followed by chapters dealing with superstructures (Chap. 13) and substructures (Chap. 14). Since the use of cables limits sometimes the number of successful AE applications, Chap. 15 describes AE methods based on wireless sensor networks. Wireless techniques demand a new class of data processing procedures that are called array techniques as summarized. Finally for applications, it is essential to be aware of the limitations and accuracy of AET as well as the necessary skills of the operators handling the equipment and analyzing the data. Chap. 16 will give an introduction to these issues. The editors hope that the subdivision of this book into the first part dealing more with basic principles and the second with a selection of applications is useful to the reader. In some chapters, redundancies of similar problems addressed by different authors are allowed with purpose. This should demonstrate the benefits of diverse approaches to problems. The described techniques have by far not reached their full potential and the developments in the field of microelectronics and sensing techniques will certainly lead to further improvements of these methods in the next years. The editors would like to acknowledge first of all the contributions by their colleagues acting as authors of the individual chapters. They certainly represent some of the most active and respected scientists in their field. The editors are also grateful for the help of Mrs. Anne Lehan, Mrs. Ingeborg Bathelt and Mrs. Lioba Elli-Meier that were hard working on the preparation and formatting of the manuscripts. This book would certainly not have been possible without their help. Finally are all readers encouraged to suggest corrections and additions to the editors that will be included in a future edition. April 2008 Christian U. Grosse and (Editors)

6 Authors Jürgen Eisenblätter Gesellschaft für Materialprüfung und Geophysik mbh, Dieselstr. 6a, Ober Mörlen, Germany Phone: Christian U. Grosse Department of Non-destructive Testing and Monitoring Techniques Material Testing Institute MPA, University of Stuttgart Pfaffenwaldring 4, Stuttgart; Germany Phone: + 49 (711) christian.grosse@mpa.uni-stuttgart.de Stefan Köppel Benzinger und Partner, formerly ETH Zürich Bellerivestr. 217, 8008 Zürich, Switzerland Phone: s.koeppel@bp-ing.ch Jochen H. Kurz Fraunhofer Institute Nondestructive Testing (IZfP), University Building 37, Saarbrücken, Germany Phone: +49 ( 681) jochen.kurz@izfp.fraunhofer.de Eric N. Landis Department of Civil and Environmental Engineering University of Maine, 5711 Boardman Hall Orono, Maine 04469, USA Phone: landis@maine.edu Lindsay M. Linzer PO Box Auckland Park 2006 Johannesburg, CSIR: NRE- Mining, SouthAfrica Phone: +27 (11) lindsay.linzer@gmail.com Gerd Manthei University of Applied Science Giessen Friedberg, Wiesenstr. 14, Gießen, Germany Phone: +49 ( 641) gerd.manthei@mmew.fh-giessen.de

7 VIII Graduate School of Science & Technology Kumamoto University Kurokami, Kumamoto , Japan phone +81 (96) Barbara Schechinger Formerly ETH Zürich Titlisstrasse Rombach, Switzerland phone: +41 (62) b.schechinger@gmx.net Mitsuhiro Shigeishi Associate Professor Department of Civil & Environmental Engineering Kumamoto University Kurokami, Kumamoto , Japan shigeishi@civil.kumamoto-u.ac.jp Tomoki Shiotani Department of Urban Management, Kyoto University, C-Cluster C1-2 Katsura Campus Phone: +81 (75) shiotani@toshi.kuciv.kyoto-u.ac.jp Thomas Vogel ETH Zürich, Institute für Baustatik und Konstruktionen, HIL E 33.3, Wolfgang-Pauli-Str. 15, 8093 Zürich, Switzerland Phone: +41 (44) vogel@ibk.bang.ethz.ch

8 Table of Contents Preface Authors V VII Part A Basics 1. Introduction... 3 Christian U. Grosse 2. History and Fundamentals Sensors and Instruments Parametric AE Analysis Tomoki Shiotani 5. Signal-Based AE Analysis Christian U. Grosse, Lindsay M. Linzer 6. Source Localization Jochen H. Kurz, Stefan Köppel, Lindsay Linzer, Barbara Schechinger, Christian U. Grosse 7. Source Mechanisms Moment Tensor Analysis.175

9 X Table of Contents Part B Applications 9. General Remarks on Applications AE in Concrete Acoustic Emission in Study of Rock Stability 239 Gerd Manthei, Jürgen Eisenblätter 12. AE in Wood 311 Eric N. Landis 13. Superstructures 323 Mitsuhiro Shigeishi 14. Substructures 341 Tomoki Shiotani 15. Wireless AE techniques 367 Christian U. Grosse 16. Opportunities, Limitations, Accuracy and Skill 383 Thomas Vogel, Barbara Schechinger Synonyms and often used Abbreviations 397 Index 399