Phased array design for optimized directivity behavior in guided wave applications

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

“…In the above paragraphs, we considered the special case corresponding to W(m) = 1. For other cases of W(m) the same arguments as above and for equation (10) can be used to deduce similar inferences relative to equation (21). However, it will be useful from the point of view of evaluating numerical results to write the various versions of the Fourier transform of the general form of the annular PAT (equations ( 2) and ( 3)):…”

“…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.…”