**Meet the editor**

Wojciech Sikorski was born in Poland in 1977. In 2001 he graduated from the Electrical Faculty in the Poznan University of Technology with an MSc degree in high voltage engineering and in 2005 with a PhD degree in electrical engineering. He worked as a visiting researcher at the University of Stuttgart, Germany (2003), University of Manitoba (postdoctoral fellowship), Winnipeg,

Canada (2007) and CG Power Systems Canada Inc. (2007). He participated in a few international and national research projects supported by the European Union and Polish Government. He has published over 50 papers in journals and international conferences, mainly on measurement, diagnostics and on-line monitoring of power transformers with the use of the acoustic emission (AE) method. He also carried out a number of technical activities for the electric power industry in the field of AE. Currently he specializes in the development of AE signal source localization techniques. He is an active member of the Association of Polish Electrical Engineers and the Polish Society for Theoretical and Applied Electrical Engineering.

Contents

**Preface VII**

Rúnar Unnþórsson

Chapter 1 **Hit Detection and Determination in AE Bursts 1**

**Freeze and Thaw Cycles 21** Hyun-Do Yun and Wonchang Choi

Alessandrini and Francesco Bianchi

Chapter 4 **Acoustic Emission Application for Monitoring**

Chapter 5 **Power Transformer Diagnostics Based on Acoustic**

Wojciech Sikorski and Krzysztof Walczak

Franciszek Witos and Zbigniew Gacek

Chapter 7 **Acoustic Emission in Drying Materials 147**

**Fruits and Vegetables 175**

Artur Zdunek

Chapter 6 **Testing of Partial Discharges and Location of Their Sources in Generator Coil Bars by Means of Acoustic Emission and**

Stefan Jan Kowalski, Jacek Banaszak and Kinga Rajewska

Chapter 8 **Application of Acoustic Emission for Quality Evaluation of**

Zahari Taha and Indro Pranoto

**Bearing Defects 71**

**Emission Method 91**

**Electric Methods 117**

Chapter 2 **Acoustic Emission to Detect Damage in FRP Strength Under**

Chapter 3 **Structural Ageing of a Cable-Stayed Bridge During Load-Test: The Overall Effect Monitored by Acoustic Emission 35** Giovanni P. Gregori, Giuliano Ventrice, Sebastiano Pinori, Genesio

## Contents

#### **Preface XI**


#### Chapter 9 **Otoacoustic Emissions 203** Giovanna Zimatore, Domenico Stanzial and Maria Patrizia Orlando

Preface

of its application.

and failure.

emission hits in burst waveforms.

metal viaduct and a concrete or brick or wood viaduct.

Acoustic emission (AE) is a phenomenon in which elastic or stress waves are emitted from rapid, localized change of strain energy in material. The practical application of the AE first emerged in the 1950's, but only in the last 20 years the science, technology and applications of AE have progressed significantly. Currently AE has become one of the most important non-destructive testing techniques, which is widely applied in: fatigue cracks detection and location in pressure vessels and pipelines, partial discharge sources detection and location in power transformers and rotating machinery, damage assessment in fibre-reinforced poly‐ mer-matrix composites, monitoring welding applications and corrosion processes, on-line monitoring of civil-engineering structures (e.g. highway bridges, skyscrapers, dams etc.). This interdisciplinary book consists of nine chapters, which is a proof of the fact that the AE method is continuously and intensively developing and scientists still find some new areas

**Chapter 1** presents diverse methods and algorithms for detecting and determining acoustic

**Chapter 2** discusses the application of acoustic emission to detect damage in FRP strength under freeze and thaw cycles. The strengthening performance and evaluation of the damage caused by acoustic emission activities for RC beams strengthened in shear with CFRP are examined under various freezing and thawing cycles with and without shear strengthening. Number of research proved that the significant increase in acoustic emission activities (event, energy, amplitude, and frequency) is observed at each damage level that corre‐ sponds to the initiation of the crack, propagation of diagonal cracking, de-bonding of CFRP

**Chapter 3** presents the example of application of the AE method to structural ageing detec‐ tion of a cable-stayed bridge during load-test before its opening to public use. Apart from detailed analysis of the obtained research results, the authors answered many important questions, such as: what parameter should be monitored, which measuring procedure is op‐ timal in bridge monitoring using AE technology or what is the relevant difference between a

**Chapter 4** focuses on the application of the AE characteristics to detect defects in ball bear‐ ings. Simulated defects were introduced in the balls and inner race. The research results

**Chapters 5** and **6** concern the application of the acoustic emission in electrical power engi‐ neering. **Chapter 5** discusses different techniques of defects location in large power trans‐ formers. Additionally, there are presented some examples of implementation of partial

validated the use of AE RMS and AE Counts in detecting bearing defects.
