Study On Nonlinear Broadband Vibration And Rotational Energy Harvesting Based On Piezoelectric Beam Structure

With the development of the Internet of Things,wireless sensors network are widely used in all work of life.A large number of wireless sensor devices have been applied to various places,nowadays electrochemical battery is mainly power source of the wireless sensor devices,but there are some shortcomings of electrochemical battery,such as limited life-time,high replacement cost,and environmental pollution,etc.Thus self-powered wireless sensor devices is becoming a new technology for wireless sensor network.In self-powered sensor device research field,vibration energy harvesting has becoming a hot research topic,this is because ubiquitous vibration energy distribute in our environment.The operational wideband of traditional linear energy harvester is very narrow,it is not suitable to harvest the environmental vibration energy with wideband and time-varying frequency.Therefore,nonlinear vibrational energy harvesters are developed with wide response bandwidth.At the same time,monitoring the operation condition of rotational machine is very important to our daily life,it is meaningful and feasible to use rotational energy to power the wireless sensor devices which are mounted on the rotational machine.This paper proposed two T-shaped piezoelectric energy harvesting systems and a magnetically coupled dual-cantilevers energy harvesting system by utilizing nonlinear technique,and through the theoretical model,numerical simulation and experiments to study the output performance of the proposed energy harvesting systems.In this paper,an impact-based bistable piezoelectric energy harvesting system is presented,the response performance of this energy harvesting system has been analyzed by using numerical simulation.Finally,this paper developed two rotational energy harvesting systems which are based on bistable buckled beam,the output characteristics of the two energy harvesting systems are investigated through the theoretical analysis,numerical simulation and experiment.The main research works and achievements are as follow:(1)Two novel nonlinear T-shaped beam piezoelectric energy harvesting systems are proposed.For the first weak nonlinear two-degree-of-freedom T-shaped beam energy harvesting system,the electromechanical coupled control equations are deduced based on energy method and Hamilton principle.Theoretical and experimental results indicate that there are two resonance bands of the T-shaped energy harvesting system with 1:3 internal resonance in the first resonance band.In order to further wide the resonance bands,a magnetically coupled buckled T-shaped beam piezoelectric energy harvesting system is proposed.The electromechanical coupled control equations are established by using lumped parameter method.Theoretical and experimental results demonstrate that there are two nonlinear hardening resonance bands with 1:2:3:4internal resonance in the first resonance band.(2)An asymmetric monostable dual-cantilever piezoelectric energy harvesting system is proposed by using magnetically coupled method.The electromechanical coupled control equations are deduced based on energy method and Hamilton principle.The dynamic response of the proposed energy harvesting system is investigated by utilizing numerical simulation and experiment.The theoretical and experimental results demonstrate that comparing with the traditional symmetric bistable dual-cantilever energy harvesting system,the proposed energy harvesting system has the ability to realize higher output voltage with lower strain level,thus the developed energy harvesting system has higher energy conversion efficiency.(3)The dynamical characteristics of the traditional magnetically coupled bistable cantilever piezoelectric energy harvesting system under impact excitation is studied.The Hertz collision force model is used to establish the contact force model of the energy harvesting system.The electromechanical coupled control equations are established by using lumped parameter method.The dynamic response of the proposed energy harvesting system under harmonic and random excitations are investigated based on numerical simulation.The results demonstrate that the proposed energy harvesting system has wideband resonance responses under both of harmonic and random excitations.(4)Two bistable buckled beam rotational energy harvesting systems are developed.The first piezoelectric rotational energy harvesting system consist of a clamped-clamped buckled beam and a noncontact magnetic force excitation system.The electromechanical coupled control equations are established by using lumped parameter method.The dynamic response of the proposed rotational energy harvesting system is investigated by utilizing numerical simulation and experiment.The theoretical and experimental results indicate that the developed rotational energy harvesting system can realize wide rotational band response.The second rotational energy harvesting system is composed of a buckled beam with axial magnetically coupled and a noncontact magnetic force excitation system.The electromechanical coupled control equations are deduced based on energy method and Hamilton principle.The dynamic response of the developed rotational energy harvesting system is studied by utilizing numerical simulation and experiment.It is found that the proposed rotational energy harvesting system can realize wide rotational band response under smaller rotational excitation force.