压电双晶片悬臂梁结构用于结冰探测的研究

 采用一种压电双晶片悬臂梁结构作为结冰探测的传感元件,使用有限元方法(FEM)计算其在有水附着与结冰两种状态下的谐振频率变化,同时使用Agilent 35670A动态信号分析仪与传统的传输法进行实验测量,通过误差对比检验计算结果的正确性,并找出谐振频率的变化与压电梁局部质量和刚度等结构特征改变之间的联系,发现随着结冰的发生以及厚度的增加,相应的局部质量和刚度的改变对谐振频率的综合影响多变。针对压电双晶片悬臂梁结构的特殊性,采用一种反馈法接线进行测量,并与传输法测量结果以及FEM计算结果进行比较,证明这种测量方法的准确性。最后根据计算与实验测量结果确定合适的工作模态,总结整个结冰过程对该模态谐振频率的影响。结果表明,压电双晶片悬臂梁结构用于结冰探测是可行的,它能够准确检测出不同结冰状态对其结构特征的影响,并且结构简单、便于测量。

Study of Bimorph Piezoelectric Cantilever Structure Used on Icing Detection

A bimorph piezoelectric cantilever structure is introduced as sensor for icing detection. First of all, the resonant frequencies of the piezoelectric cantilever with water droplet and ice attached are calculated by using the finite element method (FEM), and the results are inspected through error evaluation with the help of an Agilent 35670A dynamic signal analyzer and a traditional transmission measuring method. In this way, the relationship between the variation of resonant frequencies and the change of piezoelectric cantilever structure, such as partial mass and stiffness, is revealed. The result shows that the combined effects of corresponding partial mass and stiffness on resonant frequencies of a piezoelectric cantilever are multivariant with the occurrence of freezing and accretion of ice. Then a substituted feedback measuring method based on the special structure of the bimorph piezoelectric cantilever is employed to obtain the resonant frequencies. The effectiveness of this measuring method is confirmed by comparing its results with those of the transmission measuring method and FEM. Finally, an appropriate operational mode is determined according to previous measured and calculated results, and the variation of the resonant frequency of the sensor throughout the icing process is summarized as well. The conclusions indicate that the employment of bimorph piezoelectric cantilevers on icing detection is feasible. It is simple in structure and measurement, yet it can effectively detect the existence of different icing conditions.