報告題目: Nonlinear Oscillations - 100 years after Duffing
報告人: Prof.Joerg Wallaschek(Leibniz Universität Hannover，Dean of the Faculty of Mechanical Engineering，Director of the Institute of Dynamics and Vibration Research)
報告時間: 2017年1月5日下午2：00
報告地點: 18-529
主辦單位:機械結構力學及控制國家重點實驗室、國際交流合作處、航空宇航學院、科協
Bio:
Jörg Wallaschek，德國Leibniz Universität Hannover教授，Dean of the Faculty of Mechanical Engineering，Director of the Institute of Dynamics and Vibration Research
Jörg Wallaschek is Director of the Institute of Dynamics and Vibration Research at Leibniz University Hannover, Germany. He has over 25 years of professional research experience in the field of mechatronics, dynamics and vibration in both academia and industry. His research is focussed on piezoelectric systems and ultrasonic engineering, and he has contributed to the continuous development of ultrasonic vibration motors. During his academic career Jörg Wallaschek has supervised more than 60 successfully completed PhD projects. He has authored more than 150 scientific publications, including textbooks and contributed chapters on sensors and actuators, modelling of electromechanical systems and energy harvesting technologies. Jörg Wallaschek teaches courses on engineering mechanics and structural dynamics at Leibnis University Hannover, Germany and gives expert seminars on vibration technologies at Haus der Technik and VDI-Wissensforum. He is member of editorial boards of scientific journals (including Archive of Applied Mechanics and International Journal of Vibroengineering) and steering committees of international conferences. He is also member of the expert panel on Schwingungstechnik (vibration technologies) of VDI and DIN and serves as reviewer for public organisations and consultant for small, medium and large enterprises.
Abstract:
Design problems in mechanical engineering often require the study of nonlinear vibration. This lecture introduces typical sources of nonlinear system behavior encountered in mechanical and electromechanical systems, like e.g. material behavior, contact mechanics, friction, electromagnetic and fluid force fields. It adresses their relevance in the context of applications like drillstring dynamics, vibrations in turbomachinery, piezoelectric energy harvesting and ultrasonic process technologies. Analytical, numerical and experimental methods, including higher-order harmonic balance, nonlinear modal analysis and phase-controlled frequency response measurements will also be discussed. Special attention will be given to A) phenomena involving contact mechanics and friction, like the effect of friction reduction by superimposed ultrasonic vibrations, force generation in piezoelectric ultrasonic vibration motors, or frictional damping of turbine bladings by underplatform dampers and shroud interfaces, B) phenomena involving electromechanical coupling, like eddy-current damping and piezoelectric damping of turbine bladings or piezoelectric energy conversion in ultrasonic motors and energy harvesting devices. The lecture aims at providing a general understanding of the field of nonlinear vibrations in mechanical engineering rather than at giving a rigorous and detailed mathematical analysis of individual phenomena. Special focus will be given to modelling assumptions, their computational implementation and their experimental validation.
