报告题目: Analytical and experimental investigation of the centrifugal softening and stiffening effects in rotational energy harvesting

报告人：Dr. Shitong Fang，The Chinese University of Hong Kong

邀请人：黄冬梅

报告时间：2021年10月15日10:00-11:00

腾讯会议ID：835 657 678

报告人简介：Dr. Shitong Fang received her B.S. degree from the Sun Yat-sun University in 2017 and Ph.D. degree from the Chinese University of Hong Kong in 2021. She is now the postdoctoral researcher at the Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong. Dr. Fang published more than 10 papers in international journals including Journal of Sound and Vibration, Applied Physics Letters, Mechanical Systems and Signal Processing, Nonlinear Dynamics, and Smart Materials and Structures, and one featured article selected by Applied Physics Letters and reported by the famous science highlight AIP Scilight by AIP Publishing. She is currently the reviewer for Journal of Intelligent Material Systems and Structures and Mechanical Systems and Signal Processing. Her research interests include energy harvesting technique, plucking and impact frequency-up conversion, bistability/multistability, centrifugal-softening and -stiffening effects and other nonlinear dynamics.

Abstract：Depending on its mounting orientation, the rotational piezoelectric harvester can be subjected to the centrifugal softening or stiffening effects, which may pose a positive or negative influence on the energy harvesting performance. This lecture firstly presents the comprehensive comparison of the centrifugal softening and stiffening harvesters with a unified dimensionless analytical model. The analytical expressions of the optimum short-circuit and open-circuit rotational frequencies, the optimum resistances and the optimum centrifugal coefficients are derived to reveal the influence mechanism of the centrifugal effects. The proposed model is validated experimentally and used for case studies to compare the centrifugal softening and stiffening harvesters. Results illustrate that the centrifugal softening harvester has a superior energy harvesting performance at low rotational frequencies while the centrifugal stiffening harvester is better at high rotational frequencies. Furthermore, the peak power of the centrifugal softening harvester is higher while the frequency bandwidth of the centrifugal stiffening harvester is wider. In addition, it is found that the centrifugal stiffening harvester is more sensitive to the centrifugal coefficient. Based on the centrifugal stiffening effect, the self-tuning harvester can be achieved with a wide frequency bandwidth. Meanwhile, this requires that the centrifugal coefficient is precisely determined, and the fundamental natural frequency of the harvester without the centrifugal force should be low enough when operating at low rotational frequencies. Compared with the centrifugal stiffening effect, the centrifugal softening effect may be more suitable to be used in MEMS/NEMS applications since it can reduce the fundamental resonant frequency of the harvester during the rotation.