Amplitude controlled array transducers for mode selection and beam steering of guided waves in plates

Analysis of annular phased array transducers for ultrasonic guided wave mode control

“…However, no restrictions are imposed in the wavenumber domain(s) throughout this paper. As will be seen later, and as previously achieved in [20][21][22], this lack of a restriction on the wavenumber domain facilitates the prediction of whether multiple modes might propagate in the structure at a given frequency and time delay; and whether countermeasures may be taken to avoid such a scenario.…”

“…The multimodality of guided waves at any given frequency means that generation techniques that selectively generate the chosen mode are important. There are several techniques for guided wave mode selection, including (a) fixed and variable angle wedges based on Snell's law [4], (b) one and two-dimensional transducer combs [5][6][7][8][9] and (c) phased array transducers [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Fixed and variable wedges can be bulky and are prone to mechanical wear and tear.…”

“…Ultrasonic guided wave mode control using phased array transducers (PATs) is an increasingly important research topic for (SHM) and (NDE) of plate-like structures [10][11][12][13][14][15][16][17][18][19][20][21]. PATs consist of an array of transducers similar to comb transducers, each of which is excited with a distinct time delay and by the principle of interference of waves; both mode selection and steering of guided waves can be accomplished and controlled electronically.…”

“…PATs consist of an array of transducers similar to comb transducers, each of which is excited with a distinct time delay and by the principle of interference of waves; both mode selection and steering of guided waves can be accomplished and controlled electronically. Mode selection by amplitude control of transducer arrays has also been introduced recently [22] and can be used in a manner similar to PATs. A detailed review of several kinds of PATs is presented in [23].…”

“…In [20,21] it was shown, using a spatio-temporal filter approach, that contrary to their intended purposei.e., generation of a single guided wave mode-PATs may lead to the generation of multiple modes. A similar analysis is extended to the analysis of annular PATs.…”