ELECTROMAGNETIC METHOD OF ELASTIC WAVE EXCITATION FOR CALIBRATION OF ACOUSTIC EMISSION SENSORS AND APPARATUS

摘要

We propose a new sensor testing technique, which may be a good candidate for the absolute sensor calibration, for the routine laboratory and in-field sensor response checking and for selecting the sensors with similar responses for AE source location problems. We suggest utilizing the energy of the high power electromagnetic field in a coaxial transfer line with a specific geometry to excite a mechanical wave at the surface of a conducting media. Theoretical modeling approach is discussed and the experimental validation of the proposed method is presented. Advantages of this method are as follows: ⅰ) the extremely high stability of the elastic wave at the epicentral point where the AE sensor is attached; ⅱ) the field of mechanical displacements produced by the magnetic field pressure is computable as a function of time with an aid of finite element method; ⅲ) dimensions are small, installation is easy and convenient both for the academic laboratory experiments and for the everyday NDT practice; ⅳ) low cost and simple maintenance.