无源无线应变传感器中压电材料接触力学模型研究

针对现有无源无线传感器存在稳定性差,抗干扰能力不强,传输距离过短的问题,提出一种新型无源无线应变传感器。该传感器由两个线圈和一个体声波传感器组成,体声波传感器包括传力结构和石英晶片,其可将被测表面的应变转化为可检测的石英谐振频率偏移。 首先,建立了半椭圆接触模型,研究接触力、激励电压、接触元件形状对石英的影响,以提高传感器性能;其次,设计了石英加载装置,实现石英表面微力加载研究;最后,搭建了无源无线应变传感系统,传输距离可达 5 cm,分辨率约为 4. 2 Hz/ με,应变测量范围为 600 με,重复性实验显示 RSD 为 5. 47% 。 实验结果表明,该传感系统具有良好性能,在未来将与无人机结合为大型结构应变测量提供有效的解决方案。

Contact mechanics study of piezoelectric materials in passive wireless strain sensors

In order to solve the problems of poor stability, weak anti-interference ability and short transmission distance of existing passivewireless sensors, a new type of passive wireless strain sensor was proposed. The sensor consists of two coils and a volume acousticsensor, which includes a force transmission structure and a quartz wafer, which converts the strain on the measured surface into adetectable quartz resonant frequency shift. Firstly, a semi-elliptical contact model was established to study the effects of contact force,excitation voltage, and contact element shape on quartz to improve sensor performance. The second, design a quartz loading device torealize the loading of small forces on the quartz surface. Last, build a passive wireless strain sensing system, the transmission distancecan reach 5 cm, the resolution is about 4. 2 Hz/ με, the strain measurement range is 600 με, and the repeatability is 5. 47% . Theexperimental results show that the sensing system has good performance, and will be combined with UAVs in the future to provide aneffective solution for large-scale structural strain measurement.