TRANSFER FUNCTIONS OF ACOUSTIC EMISSION SENSORS

We have obtained the transfer functions of a wide range of AE sensors commonly available and utilized. These were determined by the excitation of input waves using an ultrasonic transmitter or pulse-laser in conjunction with a transfer block, a laser interferometer and a deconvolution procedure typically in the frequency domain. Sensor responses depend on the wave types; i.e., plane waves, and spherical waves with different radius of curvature. Using typical source waveforms and a convolution procedure, one can then visualize waveforms expected out of these AE sensors. Some sensors showed displacement response, while another gave velocity response. These response types also depended on incident wave types, requiring additional characterization steps in sensor calibration procedures.