Study of wave motion on tubulars using broad-band laser ultrasound

We investigate the transition characteristics of laser-generated ultrasonic waves propagating along the axial and circumferential directions in tubulars. The thermoacousto-photonic non-destructive evaluation technique is employed to initiate broad-band surface and guided waves in tubulars of several different outer diameters and wall thicknesses. A non-contact broad-band optical sensor known as fiber-tip interferometry is used for wave acquisition. Wave dispersion as a function of thickness to mean radius ratio is resolved using a Gabor wavelet transform based algorithm. The algorithm enables dispersion to be established through the deployment of just one sensing interferometer. This is in contrast to techniques which require multiple detection locations for the determination of wave dispersion.