Effect of wave propagation and transfer of a sensor on detected acoustic emission signal

Abstract

One of the biggest challenge for acoustic emission (AE) signal classification on real constructions is transfer from laboratory measurement on specimens to full scale. Detected AE responses are (among other factors) strongly influenced by propagation of waves in material and transfer function of sensor used. Propagation of elastic stress waves in plate of AISI 304 stainless steel was investigated in this work. Two types of wave excitation were used: broad band HSU-Nielsen source and artificial narrow band source via Vallen VS150-M transducer. AE responses were detected with use of 3 different AE transducers to take into account the effect of sensor transfer function on detected response. Attenuation curves were constructed from extracted amplitudes and digitalized signal was recorded for subsequent advanced analysis. Description of detected wave modes and separation of reflected waves was successfully done with use of combination of voltage-time dependency, wavelet transform (WT) and dispersion curves. Effect of wave propagation and transfer function of a sensor on signal maximum amplitude was discussed.