Professor Xingjian Jing
Xingjian Jing (M’13, SM’17) received the B.S. degree from Zhejiang University, China, the M.S. degree and PhD degree in Robotics from Shenyang Institute of Automation, Chinese Academy of Sciences, respectively. He also achieved the PhD degree in nonlinear systems and signal processing from University of Sheffield, U.K. .
He is now a Professor with the Department of Mechanical Engineering, City University of Hong Kong. Before joining in CityU, he was a Research Fellow with the Institute of Sound and Vibration Research, University of Southampton, followed by assistant professor and associate professor with Hong Kong Polytechnic University. His current research interests include: Nonlinear dynamics, Vibration, Control and Robotics, with a series of 200+ publications of 10000+ citations and H-index 51 (in Google Scholar), with a number of patents filed in China and US. He is one of the top 2% highly cited world scientists and a senior IEEE member.
Prof Jing is the recipient of a number of academic and professional awards including 2016 IEEE SMC Andrew P. Sage Best Transactions Paper Award, 2017 TechConnect World Innovation Award in US, 2017 EASD Senior Research Prize in Europe, 2017 the First Prize of HK Construction Industry Council Innovation Award, and 2019 HKIE outstand paper award etc.
He currently serves Associate Editors of Mechanical Systems and Signal Processing, IEEE Transactions on Industrial Electronics, & IEEE Transactions on Systems, Man, Cybernetics -Systems, and served as Technical Editor of IEEE/ASME Trans. on Mechatronics during 2015-2020. He was the lead editor of a special issue on “Exploring nonlinear benefits in engineering” published in Mechanical Systems and Signal Processing during 2017-2018 and is the lead editor of the other special issue on “Next-generation vibration control exploiting nonlinearities” published in MSSP during 2021-2022.
Beneficial Nonlinear Design in Engineering:
The X-Structure/Mechanism Approach
Department of Mechanical Engineering, City University of Hong Kong
Nonlinearity can take an important and critical role in engineering systems and thus cannot be simply ignored in structural design, dynamic response analysis, and parameter selection. A key issue is how to analyze and design potential nonlinearities introduced to or inherent in a system of under study, which is greatly demanded in many practical applications involving vibration control, energy harvesting, sensor systems and robots etc. This talk will present an up-to-date review on a cutting-edge method for manipulation and employment of nonlinearity in engineering systems developed in recent years, named as the X-structure or mechanism approach. The method is inspired from animal leg/limb skeletons and can provide passive low-cost high-efficiency adjustable and beneficial nonlinear stiffness (high static & ultra-low dynamic), nonlinear damping (dependent on resonant frequency and vibration excitation amplitude) and nonlinear inertia (low static & high dynamic) individually or simultaneously. The X-shaped structure or mechanism is a generic and considerably simple structure or mechanism representing a class of beneficial geometric nonlinearity with realizable and flexible linkage mechanism or structural design of different variants or forms (quadrilateral, diamond, polygon, K/Z/S/V-shape, or others) which all share similar geometric nonlinearity and thus similar nonlinear stiffness/damping properties, flexible in design and easy to implement. This talk systematically reviews the research background & motivation, essential bio-inspired ideas, advantages of this novel method, beneficial nonlinear properties in stiffness, damping and inertia, and potential applications, and ends with some remarks and conclusions.
Professor Saeed Ziaei-Rad
Bsc: Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran (1988)
2005-2009 Associate Professor
2001-2005 Assistant Professor
1997-2001 Postdoctoral Researcher
Iranian Society of Vibration and Acoustic
Honors and Awards
Outstanding Researcher of Isfahan province in the Year of 2012 (Honored by the Isfahan governor)
Dynamic Characteristics and Energy Harvesting from Bi-stable Composite Plates
Department of Mechanical Engineering, Isfahan University of Technology
The bi-stable composite structures are a group of composite materials which have different applications, especially in morphing structures, because of having two stable states and no need to spend any energy to stay in each one of these stable modes. So they have attracted the attention of many researchers and aerospace forums. The bi-stability property of these laminates is caused by the application of thermal residual stresses and the existence of differences in the mechanical characteristics of the constituent layers. Bi-stable composite sheets can be divided into laminates with straight fibers, laminates with curved fibers hybrid laminates, and mosaic laminates. The most common type of bi-stable laminates is bi-stable composite sheets with straight fibers. Unlike laminates with straight fibers, laminates with curved fibers have variable extension, bending, and extension-bending coupling stiffness. By adjusting the effective angles in bi-stable composite laminates with curved fibers, the design goals can be met. Hybrid bi-stable composite laminates are created by combining bi-stable composite laminates with metals. Also, mosaic bi-stable composite laminates are created by connecting a number of bi-stable composite laminates and composite laminates with a symmetrical arrangement.
Snap-through between stable states, which is a non-linear phenomenon, causes the bi-stable composite laminate to experience a large deformation during the jump. This special feature differentiates bi-stable composite laminates from other composite counterparts. Another important application of the bi-stable composite laminates is their use in energy harvesting systems. One of the limitations of the linear energy harvesting systems is their narrow frequency bandwidth. The snap-through phenomenon, the nonlinear behavior of bi-stable composite laminates and also the presence of various non-linear vibration regimes motivated researchers to use them as appropriate candidates to substitute linear energy harvesters. Also, due to the occurrence of large deformations during the snap-through process, energy harvesting systems based on the bi-stable composite laminates have the ability to produce more power than their linear counterparts.
In our research group at Isfahan University of Technology (IUT), many studies have been conducted on static, dynamic behavior and vibration energy harvesting of different types of bi-stable composite laminates. These studies have included carrying out experimental tests, developing semi-analytical models for small to medium sized laminates, developing a geometrically exact model for laminates with arbitrary dimensions, developing a comprehensive formulation of finite element method, as well as modeling and simulation in ABAQUS and ANSYS commercial software. In the experimental studies carried out by our group, the force and the base acceleration required for snap-through between stable states have been obtained in static and dynamic analyses, respectively. Also, in experimental tests, various non-linear vibration regimes were observed. In part of the experimental studies, the effect of the presence of magnets on the dynamic response of bi-stable composite laminate with straight fibers was investigated. The results showed that adding magnets to the laminate reduced the base acceleration required for snap-through. Our experimental and analytical studies show that laminate hybridization increases the required force for snap-through. Therefore, hybrid bi-stable composite laminates perform better in applications such as aerospace morphing structures than traditional bi-stable composite laminates. The accuracy of numerical models was measured with the help of experimental results. The obtained results showed a good agreement between numerical models and experimental tests.
A brief explanation of bi-stable applications, methods and techniques will be presented.