Design And Experimental Research Of Snap-through Triboelectric Nanogenerator And Its Multiple Mechanism

Coordinating and promoting both of the traditional infrastructure and new infrastructure construction have been put forward by the 14th Five-Year Plan and the Outline of 2035Long-range Goals,in order to create a modernize infrastructure system with a complete,efficient and practical,intelligent green,safe and reliable system.As the hardware foundation for infrastructure intelligence and digitalization,the sensors are widely applied in different complex environments,however how powering the sensors,especially in difficult-to-maintain areas or unattended remote areas has become one of bottleneck problems for self-powered wireless sensor technology.Triboelectric nanogenerator(TENG)can convert mechanical energy in the environment into electrical energy,so that the mechanical energy harvesting technologies could be used to realize self-powered sensors.TENG might be applied in a low-carbon,environment-friendly,flexible,convenient,stable and sustainable way,however it still has a great distance from application due to low output performance,poor environmental adaptability,and weak reliability etc.To this end,the bistable mechanism of snap-through TENG is developed to design a snap-through TENG in this dissertation,and a snap-through hybrid triboelectric-piezoelectric rotational energy harvester is designed after clarifying the relationship among the snap-through bistable mechanism,the triboelectric boundary modulation mechanism and the large deformation of piezoelectric beam.Hybrid triboelectric-piezoelectric-electromagnetic wind energy method using snap-through bistable mechanism is proposed to enhance the efficiency of electromechanical energy conversion and the output performance of wind energy harvester,and realize self-powered the flow rate measurement of the wireless sensor.And the main contents are as follows:(1)Aiming at the problems of low working frequency,small bandwidth,and difficulty in matching with multi-frequency environment,a segmented electrode mechanism is proposed to apply in a multi-layer piezoelectric cantilever structure,and avoiding modal displacement cancellation in high-order vibration modes is used to improve the electromechanical conversion efficiency.The electrical output performance is researched on the bent-torsion dual-modal piezoelectric cantilever beam in multi-frequency excitation environment.Compared with the conventional single-mode piezoelectric cantilever,the dual-mode piezoelectric cantilever beam can not only reduce the first-order vibration frequency,but also narrow the first two-order vibration frequency difference.The results of simulation and experiment verified that the effective deformation of the piezoelectric cantilever beam could be increased by using asymmetric structure and average width division method,which provides theoretical support for optimizing the piezoelectric cantilever structure to improve the output performance in multi-frequency environment.(2)In order to solve the problems of TENG materials wear and environmental pollution,we propose the snap-through TENG with magnetic coupling and buckled bistable mechanism to harvest rotational energy.Based on snap-through bistable mechanism a large deformation is created by enhancing the contact impact force between the buckled beam and buckled boundary,so that it is used to significantly improve the electrical output through increasing the friction contact degree of the electrodes.The electromechanical coupling dynamic model is established to analyze the electrical output performances under the different magnet layout modes,and the performances are in good agreement with the experiment results.When the prototype with two pairs of staggered magnets is arranged under the third mode at d=16 mm and V_A=20×10×10 mm~3,the maximum voltage of 1235 V and maximum average power of778μW are achieved at the rotating speeds of 150 r/min and 800 r/min respectively.(3)Aiming at the damage of piezoelectric patches caused by the excessive deformation of cantilever beam,a snap-through hybrid triboelectric-piezoelectric rotational energy harvester is designed by using bistable mechanism and TENG boundary modulation mechanism,in order that it can improve energy conversion efficiency and reliability.The mechanical and electronic coupling dynamic model is established,and the relationship is clarified among bistable mechanism,TENG boundary modulation mechanism and large deformation of piezoelectric cantilever beam.Compared with the output performances for the prototypes of single and bistable mechanisms,the total energy density of the prototype with bistable mechanism is 29.04 W/m~3,and it is 2.65 times as high as the prototype with single mechanism.Combining with bistable mechanism and TENG boundary modulation mechanism,PEH can not only works at low speed but also greatly improves the electrical output performance at high speed,in order that the working speed range of PEH has been broaden.(4)The wind energy harvester using hybrid triboelectric-piezoelectric-electromagnetic is proposed based on snap-through bistable mechanism,in order to solve the problems of low energy conversion efficiency and low stability of the fluid energy harvester.Based on the wind-turbine-electric coupling dynamic model,the snap-through bistable motion can be regulated through rationally designing the magnets layout,so that it can enhance the electromechanical energy conversion efficiency and the output performance of the wind energy harvester.The results of theoretical analysis and experimental measurement show that the maximum total output power density of the snap-through TENG with hybrid mechanism is 83.97 W/m~3,and it is 6.88 times as high as the TENG with single mechanism.Furthermore,the self-powered flow rate sensor is realized to provide a new idea for self-powered energy wireless health monitoring system of infrastructure.