Improving the air coupling of bulk piezoelectric transducers with wedges of power-law profiles: A numerical study |
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Authors: | Marcel C Remillieux Brian E Anderson Pierre-Yves Le Bas TJ Ulrich |
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Institution: | Geophysics Group EES-17, Los Alamos National Laboratory, MS D446, Los Alamos, NM 87545, USA |
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Abstract: | An air-coupled ultrasonic transducer is created by bonding a bulk piezoelectric element onto the surface of a thick plate with a wedge of power-law profile. The wedge is used to improve the ultrasonic radiation efficiency. The power-law profile provides a smooth, impedance-matching transition for the mechanical energy to be transferred from the thick plate to the air, through the large-amplitude flexural waves observed in the thinnest region of the wedge. The performance of the proposed transducer is examined numerically and compared to that of a design where the piezoelectric element is isolated and where it is affixed to a thin plate of uniform thickness. The numerical analysis is first focused on the free-field radiation of the transducers. Then, time-reversal experiments are simulated by placing the transducers inside a cavity of arbitrary shape with some perfectly reflecting boundaries. In addition to time-reversal mirrors, the proposed concept could be integrated in the design of phased arrays and parametric arrays. |
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Keywords: | Piezoelectric transducers Air-coupled ultrasound Acoustic-structure interaction Finite-element analysis Time-reversed acoustics |
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