Design Of Acceleration Switches And Energy Harvesters Based On Multistable Mechanisms

Integrated with spatial arranged permanent magnets, the magnetic-mechanical coupled multistable mechanism can maintain many separate stable states without external powers within its travelling range. Possessing the advantages of precise positioning, low energy cost and fast response, multistable mechanisms have great potential applications in various engineering fields such as smart driving, sensors, multi-threshold switches, and relays. According to the dynamic analysis of the multistable mechanism(MPMM), a mathematic model for analyzing the static and dynamic characteristics of the multithreshold acceleration switches was established. The good agreement between the numerical and the experimental results effectively validated the reliability of the new proposed model. Meanwhile, by using the nonlinear snap-through mechanics of the multistable mechanisms, an amplitude dependent energy harvester with variable resonance frequencies was designed, which can effectively improve the energy harvesting efficiency. The paper mainly includes the following topics:(1)A design method of a line-MPMM with non-asymmetrical arranged magnets was proposed. The nonlinear snap-through model was analyzed. By optimization algorithm, a novel P-M based pen-stable mechanism with multi-thresholds was designed. The nonlinear coupling relation among parameters including magnet number, arrangement form, flexible mechanism parameters and thresholds, steady state number has been analyzed. A method of controlling mechanical characteristics of MPMM was gained.(2)To solve the present problems of acceleration switches, such as single threshold, low contact stability and slow response, based on the penstable mechanism a model of a novel self-lock acceleration switch with magnetic attract contact beam was designed,, the static and dynamic mechanics character of the switch was analyzed. Researches showed that the switch has4static thresholds in two directions and6or4dynamic threshold characteristics under given excitation pulse width. Experimental results showed that the static force-displacement curve was basically the same with the theoretical results. And under given excitation, the contact beam could make a quick response and keep closed with stable contact. A reliably theoretical basis for a novel smart acceleration switch was proved by this paper.(3)By using the nonlinear snap-through mechanics of the multi-stable mechanisms, an amplitude dependent energy harvester with variable resonance frequencies was designed, the relationship between the amplitude of the harmonic excitation and the resonant frequency of the harvester has been studied, the output voltage of the harvester under different excitation was analyzed. Simulation result shows that, with the help of MPMM, the energy harvesting efficiency can be effectively improved.Give special thanks to National Natural Science Foundation of China which greatly supported this paper.(51105059,11372063).