Optimization Design And Energy Harvesting Efficiency Of Piezoelectric Energy Harvester For A Double-beam Structure Undergoing Coupled Bending-torsion Vibrations

The available vibration energy around the environment represents a potential renewable energy source,and the low power demand of microelectronic device is a driving force to promote the development of this research field.Piezoelectric energy harvesters are widely researched as an alternative power source because of their advantages of easy miniaturization in structure,high output power density,high output voltage,and simple structure.The traditional research is mainly focused on the piezoelectric energy harvester undergoing bending vibration,but there are two disadvantages of the lower energy harvesting efficiency and the narrower frequency bandwidth.The introduction of coupled bending-torsion vibrations can effectively solve the problem of narrow frequency band bandwidth.The principle is to use the coupled bending-torsion vibrations to bring the first two modes of the energy harvesting system closer to each other,which is suitable for multiple-frequency environmental vibration.Secondly,many studies have shown that the width splitting method is used to reduce the damping of the system for the piezoelectric energy harvester undergoing bending vibration,so that the output voltage is improved,but the width splitting method is rarely reported on the coupled bending-torsion vibrations system in the literature.In addition,some researchers use the orthogonal experiments to optimize the structural parameters of the piezoelectric energy harvester,so as to obtain higher energy harvesting performance.In summary,the application of the width splitting method for the piezoelectric energy harvester undergoing coupled bending-torsion vibrations has the potential to solve the shortcomings of low energy harvesting efficiency and narrow frequency bandwidth,and the orthogonal test can effectively analyze the cross-effect between multiple factors and optimize the structural parameters.The content of this article is as follows:?1?By introducing different types of masses,the coupled bending-torsion energy harvesting systems induced by non-equilibrium mass and L-type mass are constructed.The orthogonal experiment based on simulation,the manufactures of piezoelectric energy harvester undergoing bending-torsion vibrations,the construction of the mechanical experimental test system and the mechanical experimental test are successively completed.?2?The width splitting method is applied into the piezoelectric energy harvester undergoing coupled bending-torsion induced by non-equilibrium mass for single beam structure,and so the double beam structure is established.The multiple-factor analysis based on orthogonal test was carried out on coupled bending-torsion system of the double-beam structure and the optimized parameter combination is d=6 mm,t_s=0.4 mm,L=30 mm.Compared with the single beam structure of piezoelectric energy harvester,the output voltages of coupled bending-torsion energy harvester induced by non-equilibrium mass are increased by 23.6%at the first mode and13.1%at the second mode,while the output power are increased by 52.8%and 28%.The maximum error is 14.6%,and the minimum error is 2.2%.?3?The width splitting method is applied into piezoelectric energy harvester undergoing coupled bending-torsion induced by L-mass mass for the single-beam,and the L-type mass double-beam structure is established.The orthogonal experiment analysis of the piezoelectric energy harvester for double-beam structure was carried out to optimize its structural parameters,and the optimized parameter combination is d=5 mm,t_s=0.5 mm and t_m2=2.5 mm.The numerical results show that the total output voltage of coupled bending-torsion system induced by L-type mass the for double-beam is increased by 126%compared to bending system induced by L-type mass for the single-beam.For piezoelectric energy harvester undergoing coupled bending-torsion vibration,the output voltages of double-beam structure are increased by 24.8%at the first mode and 31.1%at the second mode compared with single-beam structure.