Acoustic Emission And Acousto Ultrasonic Techniques For Wood And Wood Based Composites

Considerable activity in the acoustics of wood has occurred since the first edition of this book in 1995. An informal survey of a number of the published articles and papers presented at international conferences revealed that the interest of the wood science community is continually increasing. In this context, I felt c- pelled to revise the text in accordance with newer findings and this prompted the addition in the present book of 159 new references added to the existing 850 in the first edition. As a result of the favorable comments upon the first edition, from students and colleagues, I have included a part on mathematical theory related to wave pro- gation in orthotropic solids in the general text, in order to enable the interested reader to follow the essentially physical aspects of the subject. A new chapter related to “acousto-ultrasonics” is introduced; Chapters 4, 5, 6, 8, 9, 10, 11, and 12 have been considerably expanded and a significant redistribution of the subject matter from the earlier edition has been made.

In the last quarter century, delamination has come to mean more than just a failure in adhesion between layers of bonded composite plies that might affect their load-bearing capacity. Ever-increasing computer power has meant that we can now detect and analyze delamination between, for example, cell walls in solid wood. This fast-moving and critically important field of study is covered in a book that provides everyone from manufacturers to research scientists the state of the art in wood delamination studies. Divided into three sections, the book first details the general aspects of the subject, from basic information including terminology, to the theoretical basis for the evaluation of delamination. A settled terminology in this subject area is a first key goal of the book, as the terms which describe delamination in wood and wood-based composites are numerous and often confusing. The second section examines different and highly specialized methods for delamination detection such as confocal laser scanning microscopy, light microscopy, scanning electron microscopy and ultrasonics. Ways in which NDE (non-destructive evaluation) can be employed to detect and locate defects are also covered. The book’s final section focuses on the practical aspects of this defect in a wide range of wood products covering the spectrum from trees, logs, laminated panels and glued laminated timbers to parquet floors. Intended as a primary reference, this book covers everything from the microscopic, anatomical level of delamination within solid wood sections to an examination of the interface of wood and its surface coatings. It provides readers with the perspective of industry as well as laboratory and is thus a highly practical sourcebook for wood engineers working in manufacturing as well as a comprehensively referenced text for materials scientists wrestling with the theory underlying the subject.

Recent advances in power electronics greatly benefit the multidisciplinary field of modern ultrasonics. More powerful, compact, and versatile electronic chips and software enable new computer-based devices for real-time data capture, storage, analysis, and display and advance the science and technology employed in commercial systems and applications of ultrasound. Reviewing the scientific basis behind these improvements, Ultrasonics: Fundamentals, Technologies, and Applications, Third Edition discusses them in detail, with new and additional figures and references, offering a completely revised and expanded examination of the state of modern ultrasonics. This new edition of a bestselling industry reference discusses the full breadth of ultrasonics applications for industrial and medical use and provides the fundamentals and insights gathered over the authors’ collective 80 years in the field. It provides a unique and comprehensive treatment of the science and technology behind the latest advancements and applications in both low and high power implementations. Coverage combines fundamental physics, a review and analysis of sensors and transducers, and the systems required for the full spectrum of industrial, nondestructive testing and medical and biomedical uses. It includes citations of numerous references and covers both main stream and the more unusual and obscure applications of ultrasound. Ultrasonics is ubiquitous in its industrial applications for sensing, NDT, and process measurements, in high power forms for processing and sonochemistry, as well as in medical procedures where it is used for diagnosis, therapy and surgery. This book provides a complete overview of the field, presenting numerous applications, cutting-edge advancements and improvements, additional figures and references, and a look at future directions.

Finding and slzmg cracks and other crack-like discontinuities has been the center of attention for scientists and engineers developing and using nondestructive evaluation (NDE) technology. However, with advanced mate rials being "engineered" and used in critical structural components, a new for NDE has emerged. Whereas many traditional engineering materi challenge als fail due to the initiation and self-similar propagation of a crack, reinforced composite materials degrade and fail in a manner more analogously to the collapse of a structure. Consequently the NDE of such materials involves assessing the combined effect of the material's damaged condition rather than identifying and sizing single critical imperfection. In 1979 Alex Vary, seeking to address the challenge confronting the NDE of advanced fiber reinforced composite materials began work on a new method of materials characterization. Focusing on the problem of evaluating graphite fiber reinforcedl epoxy laminated plates; Vary used a piezoelectric transducer to excite a mechanical disturbance in a plate and, with a sensi tive piezoelectric transducer monitored the disturbance on the same surface of the plate. (Placing the transducers on the same surface was primarily for practical purpose but their displacement in the direction of anticipated service load was of fundamental significance!) To quantify this observation, he counted the number of excursions, of the resulting electrical signal, above a arbitrary voltage threshold; a procedure frequently used for acoustic emission signal analysis.