Piezoelectric Electromechanical Transducers for Underwater Sound, Parts III & IV

The book presents a broad-scope analysis of piezoelectric electromechanical transducers and the related aspects of practical transducer design for underwater applications. It uses an energy method for analyzing transducer problems that provides the physical insight important for the understanding of electromechanical devices. Application of the method is first illustrated with transducer examples that can be modeled as systems with a single degree of freedom, (such as spheres, short cylinders, bars and flexural disks and plates made of piezoelectric ceramics). Thereupon, transducers are modeled as devices with multiple degrees of freedom. In all these cases, results of modeling are presented in the form of equivalent electromechanical circuits convenient for the calculation of the transducers’ operational characteristics. Special focus is made on the effects of coupled vibrations in mechanical systems on transducer performance. The book also provides extensive coverage of acoustic radiation including acoustic interaction between the transducers. The book is inherently multidisciplinary. It provides essential background regarding the vibration of elastic passive and piezoelectric bodies, piezoelectricity, acoustic radiation, and transducer characterization. Scientists and engineers working in the field of electroacoustics and those involved in education in the field will find this material useful not only for underwater acoustics, but also for electromechanics, energy conversion and medical ultrasonics

Capacitive ultrasonic transducers fabricated using microstereolithography

Air-coupled thin-membrane capacitive ultrasonic transducers have been developed that use microstereolithography fabrication with architectures comprised entirely of partially metalised photopolymer. These devices derive considerable advantages from rapid prototyping technology, in that they are cheap to produce, and benefit from the design-to-product lead times inherent in the production of components using stereolithography. To date membranes have been produced with thicknesses ranging from 30 to 90 μm with aspect ratios in the range of 100 - 1000. These devices have been shown to operate both as transmitters and as receivers of ultrasound, and have a bandwidth approaching 100% with a centre frequency of 100 kHz. The method of fabricating these devices allows for easy modification for various applications including structural health monitoring and immersion, as well as affording the possibility of integrated focussing or wave-guiding architecture and packaging that can be incorporated into a single build. Fundamental or subtle changes to a given transducer design may be achieved incurring little additional cost or time. This novel approach to transducer fabrication enables the bespoke manufacture of specific transducer architectures from a computer aided design package using polymers that exhibit different material properties to materials used in silicon micromachining, but at the same time allow for fabrication on a scale that is approaching that of microfabrication. The versatility of 3-D rapid prototyping allows the realisation of more complicated structures than was possible previously. This work examines these transducers in terms of their characterisation and their operation in conjunction with other transduction architecture, such as focussing parabolic mirrors that were also produced using the same manufacturing technology. In addition, their operation in contacting acoustics and the reception of surface acoustic waves has been demonstrated. Immersion studies using these devices have found that that they hold promise for operation in a variety of different media. These transducers are seen as an important prototype development tool in the field of capacitive ultrasonic transduction and microphone-speaker design

Capacitive ultrasonic transducers fabricated using microstereolithography

Air-coupled thin-membrane capacitive ultrasonic transducers have been developed that use microstereolithography fabrication with architectures comprised entirely of partially metalised photopolymer. These devices derive considerable advantages from rapid prototyping technology, in that they are cheap to produce, and benefit from the design-to-product lead times inherent in the production of components using stereolithography. To date membranes have been produced with thicknesses ranging from 30 to 90 μm with aspect ratios in the range of 100 - 1000. These devices have been shown to operate both as transmitters and as receivers of ultrasound, and have a bandwidth approaching 100% with a centre frequency of 100 kHz. The method of fabricating these devices allows for easy modification for various applications including structural health monitoring and immersion, as well as affording the possibility of integrated focussing or wave-guiding architecture and packaging that can be incorporated into a single build. Fundamental or subtle changes to a given transducer design may be achieved incurring little additional cost or time. This novel approach to transducer fabrication enables the bespoke manufacture of specific transducer architectures from a computer aided design package using polymers that exhibit different material properties to materials used in silicon micromachining, but at the same time allow for fabrication on a scale that is approaching that of microfabrication. The versatility of 3-D rapid prototyping allows the realisation of more complicated structures than was possible previously. This work examines these transducers in terms of their characterisation and their operation in conjunction with other transduction architecture, such as focussing parabolic mirrors that were also produced using the same manufacturing technology. In addition, their operation in contacting acoustics and the reception of surface acoustic waves has been demonstrated. Immersion studies using these devices have found that that they hold promise for operation in a variety of different media. These transducers are seen as an important prototype development tool in the field of capacitive ultrasonic transduction and microphone-speaker design.EThOS - Electronic Theses Online ServiceGBUnited Kingdo