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Detektion av kolvläge i hydraulcylinder med ultraljudsmetod
2015 (Swedish)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

This thesis explores the possibility to detect position of a piston inside hydraulic cylinders by ultrasonic measurements. The method consists of attaching a piezoelectric transducer onto the metallic cylinder and then send ultrasonic pulses into the cylinder. The echoes that arise due to reflections from different acoustic impedances are then read to determine the location of the piston.The methodology consisted of computer simulations in the program COMSOL Multiphysics, which is used to simulate physical processes with finite element methods. The report contains two simulations where the first is easier to calculate and analyze, and the other more realistic and complex and therefore require more time consuming calculations.In the simulations, one finds that the cylinder geometry are similar to the category of thin plates and therefore show ultrasonic wave forms according to that category. One also finds that under the made assumptions and simplifications it will be possible to detect the piston position. This is, however, contradicted by real measurements made on a similar setup.The different outcome between simulations and measurements can be the result of differences in the setup as, for example, different center frequency. The transducer in the simulations is made with a center frequency of 300 kHz - 500 kHz, while the measurements are made at a center frequency of 2.25 MHz. It may also be that the simplifications and assumptions made, to avoid simulations that are too costly, have been too damaging to get a reliable result.For future research, it is recommended to do detailed studies of the simplifications made and also run simulations with several different center frequencies to observe their effect on the results. One can also try to send wave forms other than the natural arising ones to determine whether they provide better detection. For example, Rayleigh waves.

Place, publisher, year, edition, pages
2015. , 44 p.
Keyword [en]
Keyword [sv]
Teknik, mätteknik, ultraljud, position, finita element
URN: urn:nbn:se:ltu:diva-53900Local ID: ae21fceb-2af2-491a-9e46-01bf48c94f0eOAI: diva2:1027277
Subject / course
Student thesis, at least 30 credits
Educational program
Engineering Physics, master's level
Validerat; 20150629 (global_studentproject_submitter)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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