Razvoj algoritma za procjenu visokocikličkog zamora iz stohastičke povijesti naprezanja u vremenskoj i frekvencijskoj domeni

undergraduate thesis

• Title (english): Development of an algorithm for the estimation of high-cycle fatigue from the stochastic stress history in the time and frequency domains
• Author: Marko Matijević
• Mentor: Zvonimir Tomičević (mentor)
• Mentor: Damjan Čakmak (komentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2021-09-30, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Ovaj rad bavi se analizom zamora materijala. Usmjeren je na tri metode brojanja ciklusa iz ASTM norme: metoda brojanja prelaska nivoa (engl. Level-Crossing Counting), metoda brojanja vrhova (engl. Peak Counting) te metoda brojanja raspona (engl. Range Counting). Ovim metodama se pojednostavljuju složene povijesti naprezanja različitih amplituda na niz jednostavnih ciklusa naprezanja konstantnih amplituda.
Na početku rada opisan je zamorni lom, Wöhlerova krivulja te S-N metoda proračuna zamora.
Nadalje nabrojane su i opisane metode brojanja ciklusa navedene u normi ASTM E1049-85 (2011.)
U sljedećem dijelu opisani su frekvencijska domena, načini pretvorbe signala iz frekvencijske u vremensku domenu i obrnuto. Također su opisane karakteristike stohastičkog signala te uvjeti da bi on bio stohastičan. Opisane su metode brojanja ciklusa u frekvencijskom području za tri slučaja kojima je usmjeren ovaj rad.
U završnom dijelu prikazani su rezultati analize zamora stohastičkog signala različitih frekvencija i veličine naprezanja. Analiza je provedena pomoću algoritma napisanog u računalnom programu MATLab R2017b.

Abstract (english)

This thesis deals with the analysis of material fatigue. It focuses on three ASTM standards cycle counting methods: Level-Crossing Counting, Peak Counting and Range Counting. These methods simplify complex stress histories variable amplitudes into a series of simple constant amplitude stress cycles.
At the beginning of the thesis, fatigue fracture, Wöhler curve and S-N method of fatigue calculation are described.
The next section lists and describes cycle counting methods listed in ASTM E1049-85 (2011) standard.
The following section describes the frequency domain, ways to convert signals from frequency to time domain, and vice versa. The characteristics of the stochastic signal and the conditions to be stochastic are also described. Methods of counting cycles in the frequency range for three cases are described, which are the focus of this thesis.
The final part presents the results of the analysis of stochastic signal fatigue of different frequencies and stress sizes. The analysis was performed using an algorithm written in the computer program MATLab R2017b.

• Keywords: Zamorni lom; brojanje vrhova; brojanje raspona; brojanje prelaska nivoa; stohastička povijest naprezanja; vremenska domena; frekvencijska domena
• Keywords (english): Fatigue fracture; peak counting; range counting; level crossing counting; stochastic stress history; time domain; frequency domain
• Language: croatian
• URN:NBN: urn:nbn:hr:235:510209
• Study programme: Title: Mechanical Engineering; specializations in: Design, Process and Energy Engineering, Production Engineering, Engineering Modelling and Computer Simulation, Marine Engineering, Industrial Engineering and Management, Materials Engineering; Course: Design; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2023-09-23
• Created on: 2021-09-22 20:05:42