Since their discovery, microelectromechanical systems (MEMS) has reached a certain level of maturity that, nowadays, they are being used in numerous daily-used machines ranging from all kind of sensors in automobiles to inertial sensors, accelerometers, and gyroscopes in the recent video games and smart mobile phones. Therefore, with the increasing demand for small sensors and actuators of distinguishing functionalities such as: large stroke, self-powering, self-calibration, high tunability, etc…, these tiny systems are expected to remain the exclusive technology in this regards for the coming years. However, with this growing demand come great challenges that these structures would have to withstand such as: the pull-in instability, all sort of internal resonances, auto-parametric resonances, mode localization, etc... Indeed, mode localization in MEMS has gathered significant attention over the past few years due to the potential to developing ultra-high sensitive micro-sensors. This dynamic phenomenon can be defined as the confinement of vibration energy to one of the modes of the coupled system in response to an external stimulus. Another phenomenon that is closely related in coupled systems exhibiting mode localization is the eigenvalue curve veering. Veering occurs when frequencies of two linearly coupled modes approach each other and deviate away interchanging the path trajectories as an external control parameter is varied. In the veering zone the respective mode-shapes of the two modes are affected by each other and get hybridized.
In this talk, the phenomenon of mode localization and mode veering will be discussed and explored for a specific MEMS design consisting of two electrostatically actuated and mechanically coupled microbeam based resonators. Continuous mechanical models will be used for the theoretical prediction of the dynamic responses of the two coupled resonators. The eigenvalue problem will be discussed under different stiffness perturbations and coupling strengths. The influence of the main input resonator electrode bias on the mode localization point will be also considered. The dynamics of the two coupled resonators will be presented and compared using their frequency response curves under different actuation, coupling strength, and output resonator stiffness perturbation scenarios.
Dr. Hassen M. Ouakad was born in Bizerte (Tunisia) in 1983. He received the B.Sc. degree, with honors, in Mechanics and Structures in 2007 from Tunisia Polytechnic School. In 2008 he received a master degree in Computational Mechanics from a joint graduate program between Tunisia Polytechnic School, Tunisia, and Virginia Tech, VA, USA. Then he joined the MEMS characterization and Motion Lab of the State University of New-York at Binghamton (NY, ISA), where he received the Ph.D. degree in 2010. In January 2011, he joined the Petroleum Engineering Department at the Texas A&M University in the Education City of Doha, State of Qatar, as a Postdoc Research Assistant. In September 2011 he joined the Mechanical Engineering Department of King Fahd University as an Assistant Professor. He got promoted to the rank of Associate Professor since April 2016. Since September 2018, he joined the Mechanical and Industrial Engineering Department of Sultan Qaboos University (SQU) in Oman as Associate Professor where he currently heads the Mechanical Systems Laboratory.
Dr. Ouakad is the recipient of the 2010 Excellence in research award granted by the Watson School of the State University of New-York at Binghamton, NY, USA. He was also awarded both the Excellence in Teaching and the Excellence in Academic Advising from the Engineering College of King Fahd University in May 2016 and April 2017 respectively. Moreover, He was awarded the Excellence in Research Award from the Deanship of Scientific Research at KFUPM back in May 2018. Dr. Ouakad developed and examined numerical/experimental techniques to characterize miniaturized devices rely on non-parallel plates electric actuating fields. He authored and co-authored more than ninety scientific articles published in highly ISI ranked international journals and referred conference proceedings. His work has been cited more than 1300 times and his H index is 15.
Dr. Ouakad is a member in the Institute of Electrical and Electronic Engineers (IEEE), and the American Society of Mechanical Engineering (ASME). He currently serves as an Associate Editor for the imminent journals of Vibration and Control, the IEEE ACCESS Journal, the Springer Microsystem Technologies. In addition, he served on few scientific committees of national and international symposiums and conferences.