About the Lecturer

Wang Ji, Chair Professor of Qianjiang Scholars at Ningbo University, is the leader of the founding group for Electromagnetic Devices Mechanics of the Chinese Society of Theoretical and Applied Mechanics, an expert at the Technical Committee of the International Electrotechnical Commission (IEC), the founding director of Ningbo Key Laboratory of Piezoelectric Device Technology, and the editor-in-chief of Structural Longevity, an international journal. Wang has been engaging in the researches on the structural design and analysis theory of the piezoelectric acoustic wave devices, and has obtained many US patents and Chinese invention patents for his research work related to quartz crystal resonators. The quartz crystal research project led by him won the second prize of the scientific research at Seiko Epson, Japan.

About the Lecture

Mechanical components of devices and fine machinery are increasingly subject to significant accelerations in normal services and operations with highly mobile platforms such as vehicles, aircrafts, rockets, missiles, satellites, and other moving environments. With large accelerations, it is inevitable that mechanical vibrations can be driven to nonlinear states, resulting strong variations of vibration characteristics including frequency and modes shapes. Naturally, applications of many devices can be affected if these modified vibrations are not considered in the monitoring systems configuration and correction of signals.The general principle of evaluation of acceleration effect is to consider the nonlinear deformation of vibrations and the external acceleration is treated as the additional stresses. In this study, we start from the exact equations of motion with an external acceleration in the thickness-shear vibrations of an infinite isotropic plate, and the approximate solutions of frequency and displacements due to the acceleration are obtained. The vibration frequency under acceleration is obtained through the deformation due to acceleration by approximation with the perturbation method. The analytical solution with good accuracy is obtained and the frequency variation is evaluated with the simple relationship between deformation, acceleration, and frequency. This study provides an analytical solution to such problems in addition to the popular finite element method in a consistent manner.