Study On Structure Optimization Method Of The Piezoelectric Vibrator For Harvesting Vehicle Noise Energy

The rise of vehicle population results in increasingly serious noise pollution,which can be of harm for the public.For Micro-Electro-Mechanical Systems in which wireless sensor nodes are embedded,it is a feasible method to harvest acoustic energy for the realization of self-powered modes.Meanwhile,cutting down the usage of chemical batteries as well as gaining access to economic benefits.In this paper,the analytical,simulative and experimental methods are proposed to promoting the acoustic-to-electric efficiency for piezoelectric vibrators.Firstly,the analytical modeling under quasi-transient state is established on basis of Euler-Bernoulli beam theory.The influence of load distributions,electrical connection mode,position degree,geometric parameters and material properties on the energy recovery density is analyzed analytically.The obtained results may be of theoretical reference for structural design and materials selection in piezoelectric energy harvesting.Secondly,the dynamic modeling of bimorphs connected in series is achieved both analytically and experimentally.The results indicate that the piezoelectric transducers exhibit the best performance when operating around the 1st mode.The greater the load impedance,the more desirable output voltage would be generated,along with the larger resonant frequency.There exists the worst thickness of piezoelectric ceramic,which leads to the greatest short-open resonant frequency shift and the worst adaptability to external impedance as well.The conclusions can be used for the structure optimization of the piezoelectric vibrator in acoustic energy harvesting.Then,experimental validations are performed to study energy conversion characteristics of aluminum-based piezoelectric transducers.It is found that excellent agreements are exhibited between experimental and analytical results,which verify the analytical predictions of voltage frequency response.Finally,the MATLAB toolbox based on the SQP algorithm is used to globally optimize the piezoelectric vibrators.To promote the quasi-static output capacity,the charge density is regarded as optimization objective,structural dimensions and material properties as optimization variables,yield limit as optimization constraint.The results exhibit about 68 times higher than the initial piezoelectric vibrator.Similarly,for the dynamic response,the resonant frequency shift,structural parameters and overall volume are viewed as optimization objective,variables and constraint,respectively.It is found that the resonant frequency shift is reduced by about 9 times compared with that of the original ones.This paper proposes a type of vehicle noise energy harvesting method.The conclusions can be extended to the field of environmental noise harvesting,which could be of certain theoretical value and instructive significance.