无源无线应变传感器的模拟与测试

Passive and Wireless Strain Gauge Based on Patch Antenna:Simulation and Test

利用射频识别技术(RFID)设计了带芯片的贴片天线传感器以实现无源无线的结构应变监测。通过理论推导和数值模拟证实了贴片天线谐振频率与所受应变有着近似的线性关系,灵敏度系数为天线的初始谐振频率。实际应用中因剪力滞后效应导致天线与试件应变不一致,通过模拟和试验求解传递效率系数进而对传感器的灵敏度系数进行修正。设计拉伸试验,分别将贴片天线以纵向、横向方式粘贴在铝板上,采用无线测试方案测量天线在不同荷载作用下的谐振频率,试验表明,天线的谐振频率与天线长度方向上应变具有良好的线性关系,传感器灵敏度系数的实测值与理论计算值符合较好,可精确地用于应变检测。

Using radiofrequency identification(RFID)technology,passive and wireless strain gauge with ICchip is proposed based on patch antennas in this paper.Theoretically,the resonant frequency of patch antennasvaries with strain of antennas approximately linearly,and the sensitivity coefficient is the initial resonancefrequency of antennas bearing no strain.Due to shear lag effect,specimen cannot fully transfer the strain ontothe top surface of antennas.Therefore,sensitivity coefficient of stain gauges should be modified by strain transferefficiency coefficient,which is obtained by both simulation and tests.Finally,the specimen with patch antennasfor tension experiments are designed.Using the RFID reader,the resonant frequencies of antennas are measuredunder different levels of loads. The results show that the resonant frequency of the antennas has linearrelationship with its strain,and sensitivity coefficients of strain gauges obtained from experiments are consistentwith the calculation.The proposed RFID strain gauge can detect the strain wirelessly with great accuracy.