Professor Steven W. Shaw Steven W. Shaw is Professor of Mechanical Engineering at Florida Institute of Technology.  He is also Adjunct Professor of Physics and Astronomy and University Distinguished Professor Emeritus of Mechanical Engineering at Michigan State University.  He received an AB in Physics (1978) and an MSE in Applied Mechanics (1979) from the University of Michigan and a PhD in Theoretical and Applied Mechanics (1983) from Cornell University. His current research interests include vibration absorbers and micro/nano-scale resonators, with an emphasis on nonlinear and noisy behavior and applications to timekeeping, sensing, and torsional vibrations.  He has held visiting appointments at Cornell University, the University of Michigan, Caltech, the University of Minnesota, the University of California-Santa Barbara, and McGill University.  Steve is a Fellow of ASME (1995) and recipient of the Henry Ford Customer Satisfaction Award (1986), the ASME Henry Hess Award (1986), the SAE Arch T. Colwell Merit Award (1997), the ASME N. O. Myklestad Award (2013), the ASME T. K. Caughey Dynamics Award (2019), and the ASME J. P. Den Hartog Award (2023).

Reducing Torsional Vibration Using Order Tuned Absorbers – Theory and Applications

Centrifugal pendulum vibration absorbers consist of masses that are movably suspended to a rotor in a manner such that their response under the action of the rotor dynamics reduces engine-order torsional vibrations.  These devices have been in wide use in light aircraft engines since the 1930’s and recently have seen extensive application in automotive powertrain components where they are used to improve fuel economy and enhance passenger comfort.  There is a long history of investigations of these absorbers that includes detailed analyses of the paths along which the absorbers travel relative to the host rotor.  This path dictates linear and nonlinear pendulum tuning and plays an essential role in absorber effectiveness.  Theoretical and experimental studies have solidified our understanding of these systems and provided approaches for designing paths to optimize performance.  In this presentation I will review this history and discuss some recent developments that have enhanced the use of pendulum absorbers.  These include: (i) the dynamics of absorbers immersed in fluid, such as those used in automotive torque converters, and (ii) the design of absorbers that rotate relative to the host rotor to enhance their effective inertia.  Absorber tuning strategies that account for these effects will be presented.  Finally, difficulties associated with implementing these absorbers for other applications, such as the gear systems used in electric vehicles, will also be briefly discussed.

Professor Seyyed M. Hasheminejad Professor Seyyed M. Hasheminejad was born in Tehran, Iran, on July 6, 1962.   He received the B.S. degree in mechanical engineering from California State University, Chico, in 1983, the M.S. degree in mechanical engineering from Santa Clara University, Santa Clara, CA, in 1985, and the Ph.D. degree in mechanical engineering from University of Colorado, Boulder, in 1992. Since 1993, he has been a full time faculty member at the Mechanical Engineering Department, Iran University of Science and Technology (IUST), Tehran, Iran.   He has conducted (consulted in) various national research projects, including design and construction of high-power underwater piezoelectric transducers, automotive and industrial exhaust vent acoustic silencers, sound absorbers (acoustic foams) and insulators, vibration damping treatments, pneumatic mounts, and broadcasting studios; and noise and vibration control in automobiles, airplanes, trains, residential, and various industrial environments.    He has also been involved in development of national standards, specifications, and guidelines on environmental noise and vibration control.   Professor Hasheminejad is a member of various professional societies in Iran such as the Iranian Society of Mechanical Engineers and the Iranian Society of Aerospace Engineers.   He is an active reviewer for a number of international journals and evaluating boards as well as a member of several technical committees in academic and professional societies.

A review of three decades of research studies in the field of fluid-structure interaction (FSI) in the Acoustics Research Laboratory (ARL) of Iran University of Science and Technology (IUST)

Abstract: Fluid–Structure Interaction (FSI) is a challenging interdisciplinary topic that has involved a vast variety of research conducted by the experts in the fields of fluid dynamics and acoustics. In this phenomenon any acoustic pressure in the fluid environment could result in dynamic response of the nearby structures which can in turn affect the associated flow and/or acoustic fields. This phenomenon can be observed in many natural and manmade structures in different scales. The interaction between the submerged structures and surrounding fluid, trees and wind, underwater plants and water stream, swimming of micro-organisms, and the interaction of underground water stream with the soil are some examples of this topic.   In particular, there are numerous FSI examples in engineering applications. For instance, modelling the hydro-elastic response of the offshore platforms with ocean, aero-elastic interactions and fluttering of aerial structures and turbine blades, liquid sloshing in dams and storage tanks, the dynamics of artificial heart valves and blood flow in biomedical engineering, vibrations of bridges and sky scrapers in civil engineering, interactions of risers and offshore platforms in ocean engineering, design of wind turbines in energy engineering, and sonic crystals and arrays of carbon nanotubes. A wide range of theoretical and numerical methodologies have been adopted to analyse these problems.  The present speech is a brief overview on over three decades of FSI-related research carried out in the Acoustic Research Laboratory of Iran University of Science and Technology. 

 

 

 

Professor Reza N. Jazar Dr. Jazar is a professor of Mechanical Engineering and is the Deputy Head of School for Mechanical and Automotive Engineering at the School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Melbourne, Australia. He received his MS in Mechanical Engineering from Tehran Polytechnic (1990) in Robotics, and his PhD from Sharif University of Technology (1997) in Nonlinear Vibrations and Applied Mathematics. Working at several universities around the world has made him familiar with many different successful academic disciplines and methods. Professor Jazar has several years of work experience in Automotive industries around the world. He has worked as a researcher and manager of several projects for famous automotive manufacturers in Japan, Korea, Germany, France, and the USA. His research interests are: Nonlinear Vibrations and Nonlinear Dynamics. He is the author of more than 300 scientific papers and monographs, and the author of 30 technical and textbooks.

Tire-Road Separation in Vehicle Vibrations

Reza Jazar, Reza.Jazar@rmit.edu.au

School of  Engineering, RMIT University, Melbourne, Australia

KEYWORDS: Tire-Road Separation, Mathematical Modeling, Vehicle Vibrations, Road-Vehicle Interaction.

Abstract

Research on vehicle vibrations usually operates on the assumption that the vehicle is in contact with the road (Jazar 2017). In practice, however, cars may lose contact with the road for various reasons (Nguyen et al. 2022). In the literature on separation dynamics, a separation phenomenon between the wheel and the ground has recently been proven to provide a system closer to the real system (Nguyen et al. 2021a, b, c, 2022; Khazaie et al. 2018). These studies focused on the tire–road separation of suspension systems with 2 degrees of freedom (DOF), which is good enough to provide a basic understanding of vibration dynamics. A quarter-car model is useful only for studying the vertical responses of vehicles (Jazar 2022) because it investigates one corner of the vehicle and does not observe the geometrical effects of the full vehicle during the examination of longitudinal and lateral interconnections (Gillespie 1992). Therefore, it simulates only the body bounce while ignoring pitch and roll modes (Wong 2008). To investigate these modes, we might apply the separation assumption to a general vibrating model of a vehicle, also known as the full-car model. However, solving the governing equations related to its discontinuous state is more complicated because of various wheel and suspension constraints. Thus, speech looks into how the separation progress affects the vertical and pitch dynamics of a 4 DOF bicycle-car model and validates the special condition of the ride comfort of the system.

Reference

Reza N. Jazar, Hormoz Marzbani , (2024), Vehicle Vibrations: Theory and Application, Springer, New York.