Vibration and acoustic radiation characteristics of cylindrical piezoelectric transducers with circumferential steps

Cylindrical Piezoelectric PZT Transducers for Sensing and Actuation

“…As stated earlier, to employ the benefits of the curved and focused geometry of a cylindrical transducer as well as stepped-thickness characteristics for flat plates, which had shown advantages over uniform-thickness plates, previous work investigated both circumferentially and axially stepped-thickness piezoelectric PZT cylindrical transducers in an effort to amplify the generated acoustic field inside the transducer without the need to increase the input power [ 2 , 4 , 5 ]. This required a suitable constructive interference of the radiated waves inside the transducer and minimized the counter-phase vibrations at any cross-section along the length.…”

“…To achieve this, steps were introduced at equal intervals around the circumference to excite certain vibration mode shapes and create localized high vibration amplitudes. Figure 5 depicts an embodiment of a radially poled circumferentially stepped-thickness cylindrical PZT-5 transducer (with an outer diameter of 30 mm, an inner diameter of 26 mm and a length of 50 mm, driven at 31 kHz and having circumferential and axial mode numbers of six and one, respectively) in two views having six circumferential steps [ 2 ]. The delivered output acoustic pressure was, on average, more than 1.5 times greater than that of the identical uniform-thickness transducer driven at the same input power of 4.5 W.…”

“…Piezoelectric transducers have applications as sensors and actuators in numerous fields, including the biomedical, food industry and nondestructive testing (NDT), among many other industrial applications [ 1 ]. Depending on the application, requirements and material properties, a variety of geometries and configurations have been used, including but not limited to rectangular or circular plates, arrays of transducers and cylinders from micro- to macroscale [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. In spite of the fact that it has been endeavored to employ the most suitable material for each application, researchers have continuously been investigating various techniques to improve performance, which may include enhancing the transducer’s sensitivity for sensor and/or receiver applications or amplifying the acoustic field generated for actuation and/or transmission [ 2 ].…”

“…Depending on the application, requirements and material properties, a variety of geometries and configurations have been used, including but not limited to rectangular or circular plates, arrays of transducers and cylinders from micro- to macroscale [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. In spite of the fact that it has been endeavored to employ the most suitable material for each application, researchers have continuously been investigating various techniques to improve performance, which may include enhancing the transducer’s sensitivity for sensor and/or receiver applications or amplifying the acoustic field generated for actuation and/or transmission [ 2 ]. To achieve this, the effects of changing the shape and geometry of the transducer as well as its configurations have been studied [ 7 , 8 , 9 , 12 , 13 , 15 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”

“…Further, a combination of the curved focusing geometry of a cylinder and a stepped-thickness configuration to further eliminate the counter-phase radiation from various regions of a transducer seemed to have the potential for transducer applications where a focused amplified acoustic field with a relatively low power supply is desired. To this aim, both axially and circumferentially stepped-thickness cylindrical shells were investigated, proving that a suitably designed configuration of these steps can localize deformation within thin sections, control the mode of vibration and amplify the generated acoustic field at a low power input [ 2 , 4 , 5 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. Further research revealed that these transducers can be effectively employed for applications in biomedical areas; an example is for airway humidification or drug delivery purposes [ 3 ].…”