Professor Domingos A. Rade
Aeronautics Institute of Technology, Brazil
Plenary Session Title: Dynamic modeling of advanced composite materials
Abstract:
Due to recent advances in automated manufacturing technology, the so-called tow-steered laminates, in which the fibers in the layers are deposited following arbitrary curvilinear paths, have become viable. This extends the possibilities of improving the performance of composite structures in terms of bending, buckling, vibration and aeroelastic behavior, as compared to traditional unidirectional laminates. Nonetheless, the development of adequate modeling techniques and experimental validation are still in course. In this context, the author reviews studies devoted to the dynamics of tow-steered composite plates, encompassing: a) development of Rayleigh-Ritz and Finite Element Models; b) optimization of the dynamic and aeroelastic behavior accounting for manufacturing constraints and uncertainties in local fiber orientations; c) influence of fiber steering on damping; d) manufacturing and experimental testing. The results demonstrate the improved behavior of optimized tow-steered composite plates as compared to traditional unidirectional counterparts, and the necessity of appropriate managing of uncertainties and manufacturing-induced defects in the numerical models.
Biography:
Domingos A. Rade holds a Mechanical Engineering degree (Federal University of Uberlândia-UFU, Brazil, 1984), a Master of Science in Aeronautical Engineering (Aeronautics Institute of Technology ‐ ITA, Brazil, 1987), and Doctorate in Sciences for the Engineer (University of Bourgogne Franche‐Comté, France, 1994). He has been Associate Professor and Full Professor at the Federal University of Uberlândia (1985‐2015) and is currently Professor at the Aeronautics Institute of Technology. He has served as invited professor at the University of Bourgogne Franche‐Comté, National Institute of Applied Sciences of Rouen and National Engineering School of Mans, both in France. He has held the following administrative positions at UFU: head of the Physics Department, Coordinator of the undergraduate course of Aeronautical Engineering, and Director of the School of Mechanical Engineering. At ITA he is currently the head of the Department of Mechanical Design. He has been the vice‐coordinator of the National Institute of Science and Technology of Smart Structures in Engineering (2009‐2014) and member and coordinator of the Advising Board of Engineering and Architecture of the Minas Gerais Research Foundation ‐ FAPEMIG (2008‐2012). He is currently member of the Advising Board of Mechanical, Aerospace, Naval and Oceanic Engineering of the Brazilian Council for Research, Technology and Innovation – CNPq. His teaching and research activities are devoted to structural dynamics and vibrations, with emphasis on inverse problems, vibration control, probabilistic structural mechanics, smart materials and structures, and fluid‐structure interaction. He has co‐authored 46 refereed journal papers, 6 book chapters and 1 textbook published by Elsivier. He has advised 26 master dissertations and 16 doctorate theses.
Professor Li Cheng
The Hong Kong Polytechnic University, Hong Kong
Chair Professor of Mechanical Engineering
Ph.D, FASA, FASC, FIMechE, FHKIE
Plenary Session Title: Structural Wave Manipulation through Acoustic Black Holes
Abstract:
Acoustics Black Holes (ABH) effects can be achieved through manipulations of bending wave propagation inside a thin-walled structure with its thickness tailored according to a power-law variation. In doing so, the phase velocity of the bending wave gradually reduces alongside thickness thinning, eventually to zero in the ideal scenario at the wedge tip/indentation center, resulting in zero wave reflection and high energy concentration within a small localized area. The phenomenon attracts increasing attentions as a promising passive vibration control method because vibration energy can be channeled and only a very small amount of damping material is required within the energy focalization region to achieve efficient damping to flexural waves. In addition, the wave slowing phenomenon allows the creation of a subsonic region inside a supersonic structure, thus reducing the its overall sound radiation efficiency. These unique features point at a great potential of the ABH technology for various applications such as vibration control, sound radiation reductions and energy harvesting. This talk summarizes some of the recent progress made in the study of the ABH. Topics cover the semi-analytical modelling of the ABH structures; design and analysis of a double-layer compound ABH beam for improved static and dynamic properties; combination of locally resonant and Bragg scattering for broadband stopband creation;sound radiation of ABH structures with topology optimization as well as some examples of ABH for vibration and sound noise control applications.
Biography:
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: 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, 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).
Professor Gaetan Kerschen
University of Liège, Belgium
Professor of Aerospace Engineering
Director of the Space Structures and Systems Lab (S3L)
Plenary Session Title: Dynamic vibration absorbers: revisiting classical results and introducing new tuning strategies
Abstract:
The classical dynamic vibration absorber is an effective passive vibration mitigation device widely used in, e.g., civil and automotive applications. This presentation first revisits the well-known equal-peak method proposed by Den Hartog almost one century ago. We show how an exact closed-form solution to the H¥ optimization problem can be derived. In view of the narrow bandwidth of the dynamic vibration absorber, we then introduce new tuning strategies adapted to uncertain or nonlinear host structures. The second part of the presentation addresses novel practical designs of linear and nonlinear dynamic vibration absorbers, which include the joint use of topology optimization and additive manufacturing, and piezoelectric shunting with electrical and digital circuits.
Biography:
Gaëtan Kerschen completed his Ph.D. degree in Aerospace Engineering from the University of Liège in Belgium in 2003. In 2003 and 2004, he was a visiting postdoctoral fellow at National Technical University of Athens and at the University of Illinois at Urbana-Champaign. Since 2007, he has been a faculty member at the University of Liège, where he is a professor in the Department of Aerospace and Mechanical Engineering. His expertise is primarily in the area of structural dynamics and orbital mechanics. He is the recipient of two European Research Council (ERC) grants, namely an ERC Starting Grant and an ERC Proof of Concept Grant. He is currently an Associate Editor for the International Journal of Bifurcation and Chaos and Mechanical Systems and Signal Processing. He is the co-founder of NOLISYS, a startup company which provides solutions and software for nonlinear vibrating systems.
Dr John Macdonald
University of Bristol, UK
Reader in Structural Dynamics
M.A.(Cantab), Ph.D.(Bristol)
Plenary Session Title: Human-structure interaction: modelling, experiments and full-scale measurements
Abstract:
Human-induced vibrations of footbridges, cantilever grandstands and other vibration-sensitive structures has attracted increasing interest in recent years, partly in response to vibrations problems on high-profile structures such as the London Millennium Bridge (LMB). Apart from the challenges of characterising the variability of human dynamic loads and crowd behaviour, a key issue, which can have a major effect on the dynamic response, is human-structure interaction, whereby the structural motion affects the human behaviour, which modifies the dynamic loads. In certain cases this can lead to dynamic instability, as for lateral vibrations of the LMB and other long-span bridges. Results from simple biomechanical modelling, full-scale measurements and a state-of-the-art instrumented oscillating treadmill rig have shed light on the human-structure interaction mechanism in this case. It is found that that the primary effect is not synchronisation of the pedestrian walking frequency to the bridge motion, but that pedestrians effectively act as negative dampers to the motion, in a similar way to galloping or flutter of slender structures in the wind. However, ongoing research, based on treadmill data and biomechanical modelling, is investigating a weak tendency for phase pulling and potential synchronisation in certain cases, which may add to the instability of the structure. In other situations the human-structure interaction may be beneficial, such as for vertical vibrations of footbridges due to pedestrian walking and for grandstands subject to crowds bobbing or jumping on them at sporting events or pop concerts. Analysis of a simple jumping model exhibits chaos, similar to features observed in laboratory tests in which it was not possible to jump regularly at resonance with the structure.
Biography:
John Macdonald graduated with the Institution of Civil Engineers’ (ICE) student prize from the University of Cambridge in 1990. After 4 years with engineering consultants Scott Wilson (now part of AECOM), principally working in structural design, he commenced his research in structural dynamics at the University of Bristol. He was awarded his PhD in 2000, based on full-scale monitoring and analysis of vibrations of the Second Severn Crossing cable-stayed bridge. Part of this work directly contributed to a vibration mitigation solution for the bridge and was awarded an ICE prize. He is now Reader in Structural Dynamics in Bristol and has held an EPSRC Advanced Research Fellowship on aeroelastic and nonlinear structural dynamic interactions of slender structures. His research focuses on wind and human-induced vibrations, structural monitoring and vibration mitigation, on structures such as long-span bridges, cable structures, tall buildings and wind turbines. He is a member of the British Standards Institution committee for revisions to the Eurocode on wind actions on structures and has been Scientific Advisor to Fehmarnbelt / Danish Technical University and US Federal Highways Administration / National Research Council of Canada projects on wind-induced vibrations. He has acted as a consultant to industry for various structural dynamic issues including wind and pedestrian-induced vibrations of bridges, fatigue analysis of post-tensioned cables and occupancy comfort of tall buildings. He is Subject Editor for human and human-induced vibrations for the Journal of Sound and Vibration.
Dr Alain Berry
Université de Sherbrooke, Canada
Research Chair in Transport Sector Vibro-Acoustics
M.Sc & Ph.D (Sherbrooke)
Plenary Session Title: Time-space indentification of dynamic transverse loads on plane elastic structures
Abstract:
The identification of dynamic loads acting on structures is a key aspect of several engineering problems involving structure-borne sound and vibration problems, stress analysis, or the study of fatigue-induced structural damages. This work is concerned with the reconstruction of various types of excitations on plates and membranes from their measured full-field vibration response. The force identification problem is solved using the so-called Virtual Fields Method (VFM), an approach based on the principle of virtual work and piecewise virtual displacement functions.
The full-field vibration response measurement was performed by the authors using Scanning Laser Doppler vibrometry (LDV) or Optical Deflectometry (OD). While LDV generally involves time-consuming measurements over a coarse spatial grid and are limited to stationary excitations in both space and frequency, OD measurements are resolved in both space and time over very dense spatial grids, enabling the study of non-stationary excitations.
The OD measurement technique and VFM post-processing method will be reviewed and load reconstruction results will be presented in the case of transient or continuous, spatially-correlated excitations such as diffuse acoustic fields or turbulent flows over bending plates and membranes.
Biography:
Alain Berry received his MSc and PhD degrees from Université de Sherbrooke, Canada in 1988 and 1991, respectively. He is a Full Professor in the Department of Mechanical Engineering, Université de Sherbrooke, a member of GAUS (Groupe d'Acoustique de l'Université de Sherbrooke) and of CIRMMT (Center for Interdispinary Research on Music Media and Technology, based at McGill University, Montreal). He currently holds a Canada Research Chair in Vibroacoustics applied to the transport sector. His research interests are structural acoustics, active noise and vibration control, sound field reproduction, acoustic imaging and musical acoustics. He is currently collaborating with various companies in the aerospace and automotive sectors on environmental acoustic as well as cabin acoustic comfort issues.