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dc.contributor.authorPrøytz, Celine
dc.date.accessioned2022-05-04T23:34:10Z
dc.date.available2022-05-04T23:34:10Z
dc.date.issued2022-03-30
dc.date.submitted2022-05-04T22:00:15Z
dc.identifier.urihttps://hdl.handle.net/11250/2994251
dc.description.abstractThe main objective of this thesis is to construct and characterize ultrasonic transducers. The transducers are constructed to get the information needed for finite element simulations with the wanted accuracy since commercial transducers do not provide sufficient information regarding the material data, dimensions and materials involved. The goal is to get a reasonable agreement between the measurements and simulations. These transducers are constructed for use in guided ultrasonic waves studies at 300 to 1000 kHz. In this work, ultrasonic piezoelectric transducers with ka numbers of 17 and 46 with a thickness mode $f_{TE1}$, at 500 kHz is constructed and characterized. These transducers are constructed for being used in studies for ultrasonic beam transmission through solid steel plates, to see how the leaky lamb waves are induced in the steel plate with different ka numbers. Pz27 disks is used with dimensions ($D_p$ x $T_p$) of 44 x 4 mm and 16 x 4 mm. Three transducers with a ka number of $17$ and three with a ka number of $46$ are made with one front layer, a backing layer, a steel casing and a UHF connector at the back. A thorough and detailed description of each of the steps in the transducer construction process is given. After each step, electrical measurements are conducted and simulated using finite element modelling. As well, acoustic measurements in water have been conducted for two of the constructed transducers. The results have shown that the most critical part of the construction process has been soldering a wire to the piezoelectric disks back electrode, and attaching the disk to a front layer using conductive adhesive. Multiple disks have been soldered to get enough reasonable results. As well, it has been shown that it is harder to solder the disks with ($D_p$ x $T_p$) of 16 x 4 mm than the disks with ($D_p$ x $T_p$) of 44 x 4 mm. The conductance measurements after the disk with ($D_p$ x $T_p$) of 16 x 4 mm are soldered have deviated more from the conductance measurements conducted before the disk have been soldered than the disks with ($D_p$ x $T_p$) of 44 x 4 mm. More deviations are also seen between the measurements and simulations after front layers are attached to disks with ($D_p$ x $T_p$) of 16 x 4 mm, than to disks with ($D_p$ x $T_p$) of 44 x 4 mm. Thirteen disks have been attached to a front layer. Different methods have been tried to finally find a method that has given a reasonable agreement between the measurements and simulations. A tungsten epoxy backing layer has been used, where the mixture has been dried inside the casing, and an air cone is made in the back. This method of attaching the backing layer inside the casing has given little control over the material parameters of the backing layer. Even though the same mass ratio has been used for mixing the tungsten epoxy backing layers, by comparing the measurements to the simulations, it has been shown that the impedance of the backing layer has not been the same in the transducers. The finished prototype transducers have achieved a reasonable agreement between the electrical and acoustic measurements and simulations. The source sensitivity has been measured for one transducer with a piezoelectric disk with ($D_p$ x $T_p$) of 44 x 4 mm and one transducer with a piezoelectric disk with ($D_p$ x $T_p$) of 16 x 4 mm from 200 to 1000 kHz. In addition, the directivity pattern at 575 kHz has been measured, but a steady-state region was not obtained.
dc.language.isoeng
dc.publisherThe University of Bergen
dc.rightsCopyright the Author. All rights reserved
dc.subjectTransducer construction
dc.subjectFinite-Element Modelling
dc.subjectAcoustics
dc.titleUnderwater Ultrasonic Transducer Technology. Construction, Characterization and Finite-Element Modelling.
dc.typeMaster thesis
dc.date.updated2022-05-04T22:00:15Z
dc.rights.holderCopyright the Author. All rights reserved
dc.description.degreeMasteroppgave i havteknologi
dc.description.localcodeHTEK399
dc.description.localcode5MAMN-HTEK
dc.description.localcodeMAMN-HTEK
dc.subject.nus752999
fs.subjectcodeHTEK399
fs.unitcode12-24-0


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