Karakterizacija materijala temeljem frekvencijske analize ultrazvučnih odziva

master's thesis

• Title (english): Material characterization based on frequency analysis of ultrasonic pulses
• Author: Anja Brlek
• Mentor: Damir Markučič (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2020-12-03, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Ultrazvuk predstavlja jednu od metoda nerazornih ispitivanja koja ima brojne primjene u različitim
područjima znanosti i tehnike, a u ovom diplomskom radu fizikalni princip ultrazvuka koristit će
se u svrhu provedbe karakterizacije materijala. Karakterizacija materijala pruža podatke o
značajkama sastava i strukture materijala (uključujući nepravilnosti i nedostatke unutar materijala)
čije poznavanje je važno za određenu upotrebu ili provedbu ispitivanja. Kao predmet rada korišten
je uzorak izrezan iz zavarenog spoja dviju ploča od nehrđajućeg čelika debljine 60 mm. Budući da
je prilikom zavarivanja materijala većih debljina prisutan različit unos topline u različitim
dijelovima materijala, razlikuju se mikro- i makrostrukture u različitim dijelovima volumena.
Pretpostavka je da će se ultrazvučni odzivi dobiveni od osnovnog materijala, zone utjecaja topline
i metala zavara značajno razlikovati. Na temelju snimljenih odziva u vremenskoj domeni te
frekvencijskih značajki korištenih sondi provodi se frekvencijska analiza pomoću tzv. FFT ili brze
Fourierove transformacije. Analiza i usporedba rezultata pokazat će sličnosti i odstupanja
karakterističnih parametara u frekvencijskom spektru svakog snimljenog odziva.

Abstract (english)

Ultrasonic measurement is one of the methods of non-destructive testing that has numerous
applications in various fields of science and technology, and in this thesis the physical principle of
ultrasound will be used to implement the characterization of the material. Material characterization
provides information on the characteristics of the composition and structure of the material
(including irregularities and defects within the material) whose knowledge is important for the
particular use or study. A sample cut out from a welded joint of two stainless steel plates 60 mm
thick was used as the subject of the paper. Since different heat inputs are present in different parts
of the material when welding materials of larger thicknesses, micro- and macrostructures in
different parts of the volume differ. It is assumed that the ultrasonic responses obtained from the
base material, the zone of influence of heat and the weld metal will differ significantly. Based on
the recorded responses in the time domain and the frequency characteristics of the used probes,
the frequency analysis is performed using the FFT or fast Fourier transform. Analysis and
comparison of the results will show the similarities and deviations of the characteristic parameters
in the frequency spectrum of each recorded response.

• Keywords: karakterizacija materijala; ultrazvuk; ultrazvučni odziv; frekvencijska analiza; ultrazvučna frekvencijska analiza; frekvencijski spektar; brza Fourierova transformacija; FFT
• Keywords (english): material characterization; ultrasound; ultrasonic response; frequency analysis; ultrasonic frequency analysis; frequency spectrum; fast Fourier transform; FFT
• Language: croatian
• URN:NBN: urn:nbn:hr:235:327411
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Repository: Repository of Faculty of Mechanical Engineering and Naval Architecture University of Zagreb
• Created on: 2020-11-27 09:59:28