Prof. Li CHENG (成利教授)
The Hong Kong Polytechnic University, Hong Kong
Dr. Li Cheng is currently a Chair Professor of Mechanical Engineering and the Director of Consortium for Sound and Vibration Research (CSVR) at the Hong Kong Polytechnic University. He received his BSc degree from Xi'an Jiaotong University, DEA and Ph.D. degrees from the Institut National des Sciences Appliquées de Lyon (INSA-Lyon), France. After two years in Sherbrooke University, he started his academic career at Laval University, Canada in 1992, rising from an assistant professor to Associate/Full Professor, before coming to Hong Kong in 2000, where he was promoted to Chair Professor in 2005 and was the Head of Department from 2011 to 2014. Dr. Cheng published extensively with more than 200 journal papers and 250 conference papers in the field of sound and vibration, structural health monitoring, smart structure and fluid-structure interaction. He also edited a few books and held 6 patents. He is an elected fellow of the Acoustical Society of America, Acoustical Society of China, IMechE, Hong Kong Institution of Engineers and Hong Kong Institute of Acoustics. He currently serves as Deputy Editor-in-Chief and Receiving Editor of Journal of Sound and Vibration, Associate Editor for the Journal of Acoustical Society of America, Associate Editor of Structural Health Monitoring: an International Journal and editorial board member of another 6 journals: International Journal of Applied Mechanics, Advances in Aircraft and Spacecraft Science: an International Journal, ACTA ACUSTICA Sinica, Chinese Journal of Acoustics, Vibration, Acoustics etc. Dr. Cheng also been a Plenary/Keynote Speaker at conferences in USA, UK, France, Japan, Greece, India, South Korea, Poland, Bangladesh as well as China, including some of the most prestigious conferences in his field such as 47th Inter-noise, 23rd ICSV, 13th RASD, 15th APVC and 12th ICOVP. He also served as the general Chair of the 46th International Congress on Noise Control Engineering (Inter-noise) and the Chair of 14th and 17th Asia Pacific Vibration Conference (APVC). Dr. Cheng is currently the President of the Hong Kong Society of Theoretical and Applied Mechanics. He is also a board director of both IIAV (International Institutes of Acoustics and Vibration) and I-INCE (International Institutes of Noise Control Engineering).
Speech Title: Vibration and Noise Control for Aeronautical and Aerospace Applications
Abstract: The issue of vibration and noise inside an enclosure is a typical vibroacoustic problem of great relevance to various aeronautical and aerospace applications, exemplified by noise inside aircraft cabin and space vehicles. The growing importance of the vibration/noise related problems and the necessity for their consideration at the design stage is being witnessed with an increasing awareness. To tackle the problem, a comprehensive set of technological know-how, including the development of efficient and flexible modelling and optimization tools, understanding of the underlying physics as well as the development of effective control means, is indispensable. This talk reviews and highlights some of the past and on-going work undertaken by the speaker and his team in this area. Topics include the discussions on the general structural-acoustic coupling problem, development of efficient simulation, analysis and optimization tools, design of light weight strictures as well as various passive and active control techniques, under the context of interior noise and vibration control for aircraft and space structures.
Prof. John Mo
Royal Melbourne Institute of Technology, Australia
John P. T. Mo is Professor of Manufacturing Engineering and former Head of Manufacturing and Materials Engineering at RMIT University, Australia, since 2007. He has been an active researcher in manufacturing and complex systems for over 35 years and worked for educational and scientific institutions in Hong Kong and Australia. From 1996, John was a Project Manager and Research Team Leader with Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) for 11 years leading a team of 15 research scientists. John has a broad research interest and has received numerous industrial research grants. A few highlights of the projects include: signal diagnostics for plasma cutting machines, ANZAC ship alliance engineering analysis, optimisation of titanium machining for aerospace industry, critical infrastructure protection modelling and analysis, polycrystalline diamond cutting tools on multi-axes CNC machine, system analysis for support of complex engineering systems John obtained his doctorate from Loughborough University, UK and is a Fellow of Institution of Mechanical Engineers (UK) and Institution of Engineers Australia.
Speech Title: Speedy tool sharpening – the key to efficient aircraft manufacture
Abstract: With more customers demanding fuel efficiency, modern aircraft uses high strength-to-weight materials to minimize weight with maximum strength. Two types of materials are now extensively used in aircraft design: Titanium alloy and composite fibre reinforced plastics (CFRP) materials. However, both types of materials are well-known to be difficult to machine (or drill). CFRP materials are prone to delamination and local breakage if it is machined with cutter tools that cannot maintain its sharpness through the cutting process. The unpredictable large variations in cutting forces due to fibre materials damage the cutting edges easily if the tool material is not hard enough. On the other hand, Titanium alloys are known to be chemically reactive to cutting tools. The machining process is prompt to be disrupted by the need of frequent tool renewal. To maintain good cutting conditions, polycrystalline diamond tools have been used, irrespective of its high cost. However, polycrystalline diamond material is the hardest tool material and is extremely hard to grind into the right form of cutting edges. In a complex product such as an aircraft, thousands of accurate holes are required to be drilled. Numerous unitized Titanium components are machined. Large number of cutters are required to be re-ground to ensure these machining processes are completed with precision. Polycrystalline diamond tools have traditionally been ground by machinist who have developed great skills and dexterity in using their grinding machines. Armed with experience and an intuitive feel for the pressure needed to be exerted on the tool, the grinding process can take anywhere from three to five hours for one cutter. While this exceptional skill is to be admired, such a time consuming and laborious process is clearly impractical to be duplicated for large scale production. Thus, there is a need for a more efficient automated process. This paper reviews the research to develop a computer numerically controlled grinding machine for polycrystalline diamond tools. Based on the principle of electric discharge erosion, several strategies for controlling the electric discharge process to produce high precision and reliable tools are discussed. Scientific findings and further research direction to advance the process are explained.