Analiza signala akustične emisije i vibracija u postupcima bušenja

master's thesis

• Title (english): Acoustic emission and vibrations signal analysis in drilling processes
• Author: Stipe Skroče
• Mentor: Josip Kasać (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2015-12-02, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

U okviru ovog diplomskog rada analizirani su signali vibracija i akustične emisije nastalih prilikom bušenja čelika i aluminija, u svrhu karakterizacije materijala koji se buši i/ili stupnja istrošenosti svrdla. Pri bušenju, kao postupku obrade odvajanjem čestica (rezanjem), dolazi do prodiranja svrdla u materijal, pri čemu se dio energije bušenja pretvara u vibracije i akustično emisiju. Signali su snimljeni pri naizmjeničnom bušenju rupa aluminija i čelika prilikom čega su korišteni različiti režimi rada. Pomoću programskog paketa Matlab, signali su filtrirani za korekciju šuma te naknadno uz pomoć Furierovih tranformacija prikazani i analizirani na mogućnost postojanja korelacije frekvencijskih karakteristika i tvrdoće materijala. Prikazane su pojedinačne nefiltrirane i filtrirane snimke pojedinih mjerenja te srednja vrijednost snimki određenog režima bušenja. Na temelju analize vidljivo je da se može odrediti tvrdoća materijala putem vibracija, dok akustična emisija nije pružila dovoljno parametara za karakteriziranje materijala. Glavni nedostatak ove metode je problematika odabira optimalnog režima rada neovisno o materijalu i posljedice krivo odabranih režima.

Abstract (english)

In this thesis acoustic emission and vibration signals, produced during drilling into steel and aluminum, were analyzed for the purpose of characterization of material that is being drilled and/or the stage of auger deterioration. When drilling, cutting process, the auger penetrates the material and part of the energy used for drilling is being converted into vibrations and acoustic emissions. Signals were recorded during random drilling of holes in aluminum and steel, while using different work patterns. With the help of Matlab program, signals were filtered for noise correction. Later they were shown using Furier's transformations and analyzed for the possibility of existence of the correlation between frequency characteristics and hardness of the material. Single unfiltered and filtered recordings are shown, as well as the arithmetic mean of recordings of distinct drill pattern. Based on the analysis it is clear that the hardness of the materials can be determi- ned by vibrations, while acoustic emission didn't provide enough parameters for material characterization. The main disadvantage of this method is the issue of selection of the optimal work pattern regardless of the material, and the consequences of wrongly selected patterns.

• Keywords: Bušenje; neizravna mjerenja; akustična emisija; vibracije; spektralna analiza; digitalni filteri; karakterizacija materijala
• Language: croatian
• URN:NBN: urn:nbn:hr:235:203201
• 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
• Created on: 2019-05-22 15:22:55