Design And Simulation Of Piezoelectric Acceleration Sensor For Middle And High Frequency Differential Measurement

Medium and high-frequency shock vibration caused by short-wave damage of high-speed railway wheel-rail has significant effects on driving safety and ride comfort.Measuring the vibration acceleration of the axle box provides the main means of diagnosing and identifying wheel-rail damage.However,the current commercial piezoelectric acceleration sensors are difficulty meeting the high measurement accuracy,high natural frequency,and high sensitivity required for medium to high-frequency vibration.Therefore,this study designed a differential piezoelectric acceleration sensor with high measurement accuracy,high voltage sensitivity,and high natural frequency based on the high sensitivity of the differential piezoelectric sensor and the vibration characteristics of the axle box under the wheel-rail short-wave excitation.The dynamic characteristics of the sensor were verified by simulation experiments.The main research contents are as follows:(1)Structure design and analysis of the piezoelectric acceleration sensor for differential measurement.In order to measure the vibration acceleration of the middle and high-frequency axle box,different piezoelectric materials and sensor structures were compared and analyzed.The vibration model and equivalent dynamic model of the piezoelectric acceleration sensor were established to derive the theoretical calculation method of the dynamic sensing characteristics.The proposed structural design scheme considered the sensitivity of the output voltage and the natural frequency of the sensor.(2)Simulation analysis and parameter optimization of the piezoelectric acceleration sensor for differential measurement.The finite element simulation software ANSYS was used to establish the finite element model of the differential measurement piezoelectric acceleration sensor.Combining theoretical calculation and simulation analysis,the influence and mutual relationship of the sensor’s structural dimension parameters on its measurement error,natural frequency,damping ratio,voltage sensitivity,linearity,and lateral anti-interference characteristics were analyzed.The optimal structure parameters,such as the pedestal,the piezoelectric element,the conductive films,and the quality,were determined to satisfy the demands of the high-frequency vibration test in the axle box,ultimately determine the sensor size and performance indicators.(3)Simulation test of the piezoelectric acceleration sensor for differential measurement.Based on multi-body dynamics and finite element co-simulation technology,the dynamic simulation model of the high-speed wheel-rail rolling vibration test stand and the differential measurement piezoelectric acceleration sensor coupling finite element model with axle box were constructed.The axle box vibration acceleration signals under different wheel-rail damage conditions were obtained by using the high-speed wheel-rail rolling vibration test bench model,which were converted into an array form and imported into the sensor-axle box coupling finite element model,and the dynamic characteristics of the sensor under different axle box vibration acceleration excitation were analyzed.The results show that the sensor output voltage peak increases linearly with the increase of operating speed,polygonal harmonic order and wear depth,which has a good linear relationship.The sensor voltage sensitivity at the three measuring points is not affected by vehicle speed changes,wheel polygon harmonic order and the wear depth,and the slope of the fitted line is consistent with the theoretical calculation value of voltage sensitivity,which has good stability.