互易法校准压电型声发射传感器的研究与实现

Realization of Piezoelectric Acoustic Emission Sensor Calibration by Reciprocity Method

声发射传感器的校准是实现声发射定量技术的前提，依据电声换能器互易原理，在计算互易常数的基础上，建立了适用于压电型声发射传感器表面波和纵波互易的校准系统。通过设置特定的激励信号波形，依据接收电压信号与激励电流信号之间的时间延迟，准确获取电流信号与电压信号对应的特征值，实现了声发射传感器的表面波和纵波互易校准。由于传感器的尺寸效应，传感器在高频时的表面波速度灵敏度低于纵波灵敏度，不确定度评定结果表明，声发射传感器速度灵敏度的互易法校准不确定度为1．2dB。

The calibration of acoustic emission （AE） sensors is the premise of achieving acoustic emission quantitative testing technology. In view of electro - acoustic transducer reciprocity principle, the reciprocal constant is calculated to establish a calibration system that applies to the reciprocity of piezoelectric AE sensor Rayleigh wave and longitudinal wave. With specific excitation signal waveform, in accordance with the time delay between the received voltage signal and the excitation current signal, the characteristic values of both signals could be captured accurately. Because of the aperture effect of the sensor, the velocity sensitivity of surface waves is lower than that of longitudinal waves while the sensor operates in high frequency. The uncertainty of reciprocity calibration on the velocity sensitivity of acoustic emission sensors is about 1.2 dB.