Study On Calibration Of Acoustic Emission Sensors

Acoustic Emisson technology is widely used in the inspection of pressure vessels and other large-scale structural components. Piezoelectrical acoustic emission sensors are the important parts of the acoustic emission technology.The calibration of acoustic emission sensors is the precondition for the quantificational techonology of acoustic emission.Now in China the AE sensors can not trace to the national standard source.The dissertation build diferent calibration systems according to deferent wave mode, including reciprocity calibration system for surface wave and longitudinal wave, comparison calibration system for surface wave and face-to-face calibration system.At first, the existing methods and standards of AE sensor calibration were reviewed. The principle of reciprocity calibration was explained and the reciprocity constant of surface wave and longitudinal wave were deduced, The surface wave reciprocity calibration system and longitudinal wave reciprocity calibration system were built respectively. The test results shouwed that the uncertainty of calibration system is 12%(k=2) from 100 kHz to 1 MHz.The reciprocity systems realized the acoustic emission transducers'primary calibrationSecondary, capillary and lead with different dimension,as well as the transducer with its inverse photoelectric effect, were used as AE source and the signal's characterics of time-domain and frequency-domain were analysed. According to ISO 12714 the secondary calibration system,namely comparison calibration system, was build, It can promise the repeatability less than 2% and the uncertainty less than 16%. The comparion system supplied the convinect means to calibration the acoustic emission sensors.Besides,the face-to-face calibration system was built and it can ensure the uncertainty less than 15%. It provides a convenient way to calibrate sensors on-line.In the acoustic emission calibration technology, the reference sensor is important. The reference campacity sensor and the laser Doppler method are the follow-up research directions.