Prof. Paolo Ermanni – ETH Zurich
Structural approaches for adaptive biomedical and aerospace systems
Abstract: High performance fiber reinforced polymers (FRP) are layered anisotropic materials. The fiber architecture can be tuned to tailor material properties and deformation behavior, thus allowing the realization of structural systems with amazing structural features, including extreme deformability, shape deformation and reconfigurability. The talk is presenting and discussing various design approaches, mechanisms, and applications for adaptive composite-based load-carrying systems. The presented concepts consider selective inner compliance, as well as passive and semi-active variable stiffness solutions. Controlled elastic instability and integration of multi-stable elements provide additional mechanisms to induce nonlinear variable stiffness response and therefore achieving selective deformability in load-carrying lightweight structures. The integration of FRPs elements into mechanical metamaterials is further expanding the potential of composite materials for multi-functional lightweight applications, by adding additional geometrical parameters and tunability of the repeating unit cell. A promising concept is relying on FRP shell metastructures consisting of a thin FRP-frame and a pre-stretched soft polymer membrane. The instability of the initially flat component is inducing a rich multi-stable behavior, being a first step towards the realization of programmable structures, which can morph to multiple 3D shapes from an initial flat configuration upon an external stimulus. Finally, we are currently exploring the mechanical behavior and the potential of very thin composite shells made from continuously fiber reinforced Polyether ether ketone (PEEK). Those composite materials are capable of withstanding large bending curvatures without failure and are therefore pre-destined for applications, which require a high degree of deformability for shape adaptation and deployment purposes. Applicability of thin fiber reinforced PEEK shells in selected biomedical and space systems will be discussed.
Bio: Paolo Ermanni has been Professor and Director of the Laboratory of Composite Materials and Adaptive Structures (CMASLab) in the Department of Mechanical and Process Engineering of ETH Zurich since 1998 (Associate Professor until March 2003 and Full Professor thereafter). Ermanni holds a master’s degree in mechanical engineering and a Doctoral degree from ETH Zurich. He spent more than five years at Airbus in Hamburg (D) as a senior engineer and later on, as a project manager, mainly dealing with structural and technological challenges related to the realisation of a second generation of civil supersonic aircraft. In 1997, he took on a new position as a strategic consultant-manager at Kearney in Milan (Italy). Ermanni’s research is inspired by real-world engineering problems and is concerned with the exploration of innovative designs, material architectures and advanced manufacturing processes. Ultimate goal is to improve the efficiency and reliability of high-performance composite materials and lightweight structural systems. Current research interests include shape adaptation for morphing and reconfigurable systems, composite metamaterials and advanced processing routes for high performance thermoplastic composites.
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Prof. Diann Brei – University of Michigan
Adaptive inflatable structures for avant garde automotive and medical applications
Abstract: We are on the advent of the next technological revolution. All around us our world is undergoing rapid transformative change, from mobility to medical breakthroughs. The field of adaptive structures is well positioned to play a pivotal role by providing crucial capabilities in morphing, energy absorption, active deployment, and many more. While the structures and machines from the industrial revolution were inherently hard and inflexible in nature, emerging inflatable adaptive structures can radically change their properties, shapes and behavior in a “softer” controlled manner. Combining soft inflatable structures with rigid and tensile constraint elements provides more and unique functionality with higher structural performance. One example of this is tendon-constrained inflatable interior walls within autonomous vehicles that can actively deploy to softly capture occupants and cargo while absorbing harmful energy. Similarly, an active inflatable cowling can gently cover windshield wipers from leaves and snow, yet as needed can open rigidly against aerodynamic loads using an advanced tile-based layered-bladder approach. Adaptive inflatable structures can also be used to enhance the quality of life in medical applications. A good example of where adaptive inflatable structural properties can be tailored is tendon-constrained headrest for wheelchairs that can support neck flexion stabilizing the head, while enabling rotation or other directional motions with only light resistance enabling users to move in directions that they have muscular strength. Through highlighting several avant garde applications within the automotive and medical sector, this talk will explore inflatable adaptive structures and their underlying behavioral science to understand the highly tailorable functionality gained through advanced internal architectural arrangements such as tendon-constrained and novel tile and constrained-layer techniques.
Bio: Dr. Diann Brei Professor of Mechanical Engineering and former Chair of the Integrative Systems + Design Division at the University of Michigan. She received her PhD (1993) in Mechanical Engineering and her BSE (1988) in Computer Systems Engineering (1988). Her research is focused on the underling design science for device innovation using smart materials. Her smart material architectural models along with her multi-domain, multi-stage design methods have set the foundation for a successful translational research and development paradigm adopted by industries in the automotive, medical and aerospace sectors. Dr. Brei who is an ASME Fellow and AIAA Associate Fellow, has been an active leader in the smart materials and structures community recognized by the ASME Machine Design Award, ASME Adaptive Structures and Material Systems Award, SPIE Lifetime Achievement Award SSM and the ASME Distinguished Service Award.
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Prof. Norman M. Wereley – University of Maryland
Energy absorption strategies for occupant protection
Abstract: The ability to dissipate energy in vehicle systems, especially with the goal of protecting occupants from potentially injurious vibration, repetitive shock, crash and blast loads, is becoming a critical issue as the cumulative impact of these load spectra on chronic health and acute injury are becoming better understood. The objective of this talk is to discuss what properties are optimal for energy absorption (EA) applications such impact or shock load mitigation. Two primary strategies will be discussed in this talk: passive vs. semi-active energy absorbers. The first focus is the use of crushable materials to absorb energy. Two classes of passive materials will be discussed for EA applications including sintered and composite hollow glass foam materials, as well as elastomeric or plastic cellular materials. The second focus is the use of magnetorheological fluids (MRFs) in EA applications. The properties of the MRF can be optimized for a particular application. A number of key nondimensional parameters can be used to gain insight into how to define optimality for various applications including: Bingham number, Hedstrom number, Reynolds number, Mason number, dynamic range. Also, the trade-offs associated in designing an optimal MRF for a particular application are discussed. The advantages of passive versus semi-active EA strategies will be discussed.
Bio: Dr. Wereley is the Minta Martin Professor in the Department of Aerospace Engineering at University of Maryland. His current research interests are focused on active and passive vibration and shock mitigation (especially occupant protection systems) using primarily magnetorheological materials, and soft actuators and soft robotic systems. Dr. Wereley has published over 260 journal articles, 20 book chapters, over 275 conference articles, and over 20 patents. Dr. Wereley is the Editor-in-Chief of SAMPE Journal and Editor of the Journal of Intelligent Material Systems and Structures. He also serves as an associate editor of Smart Materials and Structures, MDPI Actuators, and others. Dr. Wereley is the recipient of the ASME Adaptive Structures and Material Systems Prize (2012) and the SPIE Smart Structures and Materials Lifetime Achievement Award (2013). Dr. Wereley is a Fellow of AIAA, RAeS, VFS, ASME, SPIE, and the Institute of Physics. He is also a Senior Member of IEEE. Dr. Wereley has a B.Eng. (1982) from McGill University and M.S. (1987) and Ph.D. (1990) from the Massachusetts Institute of Technology.
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Prof. Wei-Hsin Liao – The Chinese University of Hong Kong
Auxetic structures for energy absorption and harvesting
Abstract: Auxetic structures have been applied in the energy absorption field due to the unique mechanical properties. Inspired by foam filled structures, we investigate a thin-walled structure filled with double arrowed auxetic structure and investigates the energy absorption characteristics. The gradient configuration is introduced to improve the energy absorption performance. A theoretical model is also established to predict the energy absorption to quantify the energy dissipated due to thin-walled tubes, gradient auxetic structures and their interactions. On the other hand, auxetic structures are utilized to increase the power output of piezoelectric energy harvesting. We design a gradient auxetic piezoelectric energy harvester, which combines a cantilever beam and a gradient auxetic structure. Compared with the normal uniform auxetic structure, the gradient auxetic structure can contribute to a more uniform strain distribution of the piezoelectric cantilever beam; thus, the proposed gradient auxetic energy harvester can produce higher power than the uniform auxetic energy harvester without increasing the stress concentration at the same time. Our related work in auxetic structures for energy absorption and harvesting will be presented.
Bio: Wei-Hsin Liao received his Ph.D. in Mechanical Engineering from The Pennsylvania State University, University Park, USA. Since August 1997, Dr. Liao has been with The Chinese University of Hong Kong, where he is Choh-Ming Li Professor of Mechanical and Automation Engineering and the Department Chairman. His research has led to publications of about 400 technical papers and 27 patents. As the General Chair, he organized the 20th International Conference on Adaptive Structures and Technologies (ICAST 2009). He was the Conference Chair for the Active and Passive Smart Structures and Integrated Systems, SPIE Smart Structures/NDE in 2014 and 2015. He received the T A Stewart-Dyer/F H Trevithick Prize 2005, the ASME 2017 Best Paper Award in Mechanics and Material Systems, the ASME 2021 Energy Harvesting Best Paper Award, and the ASME 2023 Best Paper Award in Structures and Structural Dynamics. He is the recipient of the 2018 SPIE Smart Structures and Materials Lifetime Achievement Award and the 2020 ASME Adaptive Structures and Material Systems Award. Dr. Liao currently serves as an Associate Editor for Journal of Intelligent Material Systems and Structures, and on the Executive Editorial Board of Smart Materials and Structures. Dr. Liao is a Fellow of ASME, HKIE, and IOP.