title: Flutter Phenomenon in Flow Driven Energy Harvester-A Unified Theoretical Model for "Stiff" and "Flexible" Materials.
abstract: Here, we report a stable and predictable aero-elastic motion in the flow-driven energy harvester, which is different from flapping and vortex-induced-vibration (VIV). A unified theoretical frame work that describes the flutter phenomenon observed in both "stiff" and "flexible" materials for flow driven energy harvester was presented in this work. We prove flutter in both types of materials is the results of the coupled effects of torsional and bending modes. Compared to "stiff" materials, which has a flow velocity-independent flutter frequency, flexible material presents a flutter frequency that almost linearly scales with the flow velocity. Specific to "flexible" materials, pre-stress modulates the frequency range in which flutter occurs. It is experimentally observed that a double-clamped "flexible" piezoelectric P(VDF-TrFE) thin belt, when driven into the flutter state, yields a 1,000 times increase in the output voltage compared to that of the non-fluttered state. At a fixed flow velocity, increase in pre-stress level of the P(VDF-TrFE) thin belt up-shifts the flutter frequency. In addition, this work allows the rational design of flexible piezoelectric devices, including flow-driven energy harvester, triboelectric energy harvester, and self-powered wireless flow speed sensor.
authors.affiliation: Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, #16-16 Connexis, 138632, Singapore.|International R&D center of Micro-nano Systems and New Materials Technology, Key Laboratory of Optoelectronic Technology &amp;Systems, Ministry of Education, Chongqing University, Chongqing 400044, P.R. China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.affiliation: International R&D center of Micro-nano Systems and New Materials Technology, Key Laboratory of Optoelectronic Technology &amp;Systems, Ministry of Education, Chongqing University, Chongqing 400044, P.R. China.|Institute of Microelectronics, Agency for Science, Technology and Research, 2 Fusionopolis Way, #08-02 Innovis Tower, 138634, Singapore.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Mu
authors.affiliation: Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117583, Singapore.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: DHI Water &Environment (S) Pte Ltd, 1 Cleantech Loop, #03-05 CleanTech One, 637141, Singapore.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Ren
authors.affiliation: Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, P.R. China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, P.R. China.|School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors.forename: Zhong Lin
authors.initials: ZL
authors.lastname: Wang
authors.affiliation: Institute of Microelectronics, Agency for Science, Technology and Research, 2 Fusionopolis Way, #08-02 Innovis Tower, 138634, Singapore.
authors.forename: Chengliang
authors.initials: C
authors.lastname: Sun
authors.affiliation: Institute of Microelectronics, Agency for Science, Technology and Research, 2 Fusionopolis Way, #08-02 Innovis Tower, 138634, Singapore.
authors.forename: Alex Yuandong
authors.initials: AY
authors.lastname: Gu