弹簧连接质量块压电悬臂梁低频和超宽频性能优化

Low and ultra-wideband performance optimization of spring-connected mass piezoelectric cantilever

针对压电悬臂梁因固有频率过高、频带窄等原因导致的振动能量采集效率低、实际应用效果不佳的问题,通过欧拉-伯努利梁的特征频率方程,分析悬臂梁收集能量的特性和振动学特性,得到影响压电悬臂梁固有频率的3个参数:有效刚度、有效质量和自由端惯性矩。提出一种通过改变整体有效刚度来优化悬臂梁的弹簧连接质量块式结构,并进一步通过改变结构的惯性矩得出多自由度弹簧悬臂梁,降低了梁的固有频率,并在仿真实验中得到验证。仿真实验中发现由于两阶谐振频率间距减小而产生频带叠加的现象,通过两阶频带分解解释其产生的可能性。实验结果得出弹簧连接质量块式悬臂梁结构较传统而言,输出电压提高30%,频带拓宽为原来的2.5倍;虽然与质量块悬臂梁相比改善效果不明显,但引入多自由度后输出电压最高能提高60%,频带拓宽最高为质量块悬臂梁的3.3倍。

Aiming at the problems of low vibration energy collection efficiency and poor practical application effect caused by high natural frequency and narrow frequency band of piezoelectric cantilever beam,the characteristics of energy collection and vibration characteristics of cantilever beam were analyzed by the characteristic frequency equation of Euler-Bernoulli beam,and three parameters affecting the natural frequency of piezoelectric cantilever beam were obtained:effective stiffness,effective mass and free end inertia moment.A spring-connected mass block structure was proposed to optimize the cantilever beam by changing the overall effective stiffness,and the multi-degree-of-freedom spring cantilever beam was obtained by changing the inertia moment of the structure,which reduced the natural frequency of the beam and was verified in the simulation experiment.In the simulation experiment,it was found that the frequency band superposition phenomenon occured?due to the decrease of the two-order resonant frequency spacing,and the possibility of its generation was explained by the two-order frequency band decomposition.The experimental results showed that the output voltage of the spring-connected mass block cantilever beam structure was increased by 30%and the frequency band was widened by 2.5 times compared with the traditional structure.Although the improvement effect was not obvious compared with the mass cantilever beam,the output voltage can be increased by 60%and the frequency band width can be increased by 3.3 times after the introduction of multi-degree of freedom.