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The effect of waveguide material and shape on AE transmission characteristics Part 2: Frequency and joint-time frequency characteristics

This paper presents the effects of varying waveguide material and/or shape on the frequency and joint-time-frequency characteristics of pulsed acoustic emission (AE) events. Forty-eight solid cylindrical waveguides were fabricated from alumina ceramic, mild steel, stainless steel (SS316), 2024-T3 aluminium or extruded Delrin. Three different lengths, two diameters and four sensor face angles were tested. The effects of a point at the source end of the waveguide were also verified. Analysis methods included continuous wavelets, short time Fourier transforms and standard Fourier transforms. Results showed that detected signals are dominated by the resonant harmonics of the waveguides, particularly with commonly used waveguide materials such as aluminium and steel.