香港城市大学Peter W. Tse学术讲座

 

Abstract: Recently, guided ultrasonic waves (GW) based inspection technique has been proven effective in detecting structural defects. GW-based inspection system can enable long distance inspection, detect defects on the entire cross-section of the inspected object and determine the stress exerted on the object. In this seminar, the speaker will present the results obtained by using novel GW/Lamb waves to inspect the defects occurred in I-beams for construction and rails for trains. Moreover, the method and results of using laser-generated waves to detect cracks occurred in I-beams will be presented. Wave sensors, like the piezoelectric transducers and magnetostrictive sensors, are used to emit and measure the propagation and reflection of Lamb waves. However, they must be physically mounted on the inspected objects. Contrary to these contact type of sensors, a fully non-contact type of laser-based system was used to emit and receive the Lamb waves. This laser-based system is a new and foremost state-of-the-art inspection technique because it can be used where contactable sensors cannot be applied directly to the objects, such as those with high temperature surface, have limited access for mounting the sensors and are operating in a hazardous environment. In this research work, a new 3D scanning laser (3D-SLDV) was used to acquire high resolution time-space Lamb waves that were generated by I-beams. A high power and pulsed Nd:YAG laser was used to emit the required Lamb waves. The emission and sensing were performed simultaneously and the wave propagation data was recorded by scanning the surface of the I-beam sequentially. The 3D-SLDV measured the in-plane and out-of-plane displacements/velocities across a user-defined grid with sufficient resolutions in x-, y- and z-directions. The measured data was used to construct the wave patterns that were propagating in the I-beams at different time instants. Hence, the propagating waves become easily visualized. The Root-Mean-Square (RMS) values of the time-traces obtained at each scan point were computed in all the directions of wave propagation. Their graphic view clearly shows the location of crack in the I-beam. Additionally, the line profiles across the highest RMS values in x- and y-directions were extracted to evaluate the sizes of crack. From the results, the new 3D-SLDV possesses tremendous capability in revealing the location and the extent of cracks. Such capability is superior to that offered by contactable sensors. The results could be the first time that the waves propagating in a real I-beam can be visually observed, whilst in the past, it can only be visualized through simulation. The capability of using such totally laser-based 3D inspection system to reveal the characteristics of Lamb wave and its interaction with defects are substantial. After the success in applying laser-generated waves to inspect I-beams, the same system can be applied to the inspection of train rails because rails and I-beams possess a similar structures. This novel laser-generated wave inspection technique is non-contact, fast, and enables long-distance inspection with high sensitivity and efficiency. Waves can be emitted from an inspection train to inspect long length of track ahead of the moving train. The future success in designing a real-time and laser-generated wave inspection system for train rails will be a major breakthrough in railway research.

HIGHLIGHTS
 Classified by the Council of Canadian Academies as the author of Top 1% most highly cited papers in the related research field worldwide in year 2016 again.
 Honor Positions: a Fellow, the American Society of Mechanical Engineers (ASME), a Founding Fellow and a Board Director, International Society of Engineering Asset Management (ISEAM), a Foundation Fellow, International Institute of Utility Specialists (IIUS) and a Fellow of a number of other professional organizations. ISO O-Member in Technical Committees of TC108, 135 & 199
 Research Funding: Received various research funding for over $102 million HK dollars. Won several Innovation and Technology funds (ITF) from the HK SAR Government and a Theme based Research Scheme (TRS) project with a grant of $40,850,000 for developing advanced techniques to inspect trains’ rails and cables.
 Publications: As of today, the Scopus indexes for my h-index is 27 with 3,446 citations. The Google Scholar indexes for my published papers h-index is 31 with 4,757 citations. Some SCI journal papers have over 200 citations each. Published several books. Today, the number of publication is over 400 articles.
 Chair and Co-chair of a number of International Conference Organizing Committee, different Committee Member, Panel Member of many international conference, Invited Main speaker, invited Keynote speaker, Seminar Organizer etc., for many international and local conferences, symposiums and workshops.
 Vice-President of the Hong Kong Institute of Utility Specialists (HKIUS) and Member of the Appeal Board Panel (Amusement Rides (Safety)), Government Secretariat Home Affairs Bureau, Hong Kong SAR Government
 I have obtained consultancy, contract research and knowledge transfer projects with over 30 international and local companies. Examples are the world largest oil sand exploration company, the Syncrude Canada Ltd., which was formed by Exxon, Imperial Oil, Petro China etc., and MTR Corp., CLP Power, Towngas etc., which are the biggest public utilities companies in Hong Kong.

 


讲座邀请人:机械工程学院林天然教授