Analiza pucanja zavarenih spojeva aluminijskih okvira za bicikle

undergraduate thesis

• Title (english): Analysis of weld failure on aluminium bicycle frame
• Author: Antonio Satinović
• Mentor: Ivica Garašić (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2015-03-03, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; Production Mechanical Engineering

Abstract

Danas su na tržištu dostupne različite aluminijske legure. Većina biciklističkih tvrtki profile cijevi daje izraditi prema vlastitim specifikacijama. Odgovarajuće dizajnirani aluminijski okviri nude važne prednosti: malu težinu, visoku otpornost koroziji i nisku cijenu. Također su jednostavni za proizvodnju, budući da se cijevi mogu izvlačiti, savijati, i oblikovati u gotovo svaki oblik. Međutim, glavni problemi kod aluminijskih okvira proizlaze iz pada čvrstoće legura nakon zavarivanja, te kraći vijek trajanja aluminija uslijed dinamičkog opterećenja u usporedbi s ostalim materijalima koji se koriste u proizvodnji okvira za bicikle. U prvom dijelu rada navedena je podjela aluminijskih legura, postupci zavarivanja koji se najčešće koriste za njihovo zavarivanje, problemi koji se javljaju pri zavarivanju i nerazorne metode kojima se zavari ispituju, te ukratko o tipičnom dizajnu okvira bicikla, te legurama koje se koriste za izradu i njihova mehanička svojstva. Drugi dio rada temelji se na ispitivanju pukotine i reparaturi zavarenog spojana aluminijskom okviru izrađenom od legure EN AW-7005, koja je jedna od najčešćih legura koje se koriste u biciklističkoj industriji. Ekspreiment se sastoji od ispitivanja napuklog zavara metodom penetranata, reparature pukotine TIG postupkom zavarivanja, te naknadnog ispitivanja penetrantima kako bi se utvrdilo da je reparatura kvalitetno izvršena. Na temelju tog ekspreimenta donesen je zaključak o isplativosti i mogućnostima reparature aluminijskog okvira bicikla.

Abstract (english)

Today on the market we have a range of many different aluminium alloys. Most bicycle companies make tubes for the frame by their own specifications. Adequately designed aluminium frames give essential advantages: low weight, high resistance to corrosion and low price. Also, they are simple to manufacture, because tubes can be drawn, bent, and shaped in almost any form. However, main problem with aluminium frames come from their strength loss due to welding, and in comparison with other frame materials, aluminium is more susceptible to fatigue failure at lower cycle counts and has finite fatigue life. In the first part of the work are presented aluminium alloys and their division into series, welding procedures that are generally used for welding of aluminium and its alloys, weldability problems and non-destructive methods of testing, as well as shortly described typical bicycle frame design, and alloys that are used in its manufacturing. Second part of the work is based on the examination of the crack and repair welding of joint on the aluminium bicycle frame made out of the EN AW-7005 alloy, which is one of the most common alloys used in bicycle industry. The experiment was composed of non destructive testing of the weld using penetrant method, repairing the crack using TIG procedure, and afterwards testing the repair weld again using the penetrant method to establish that the repair was performed correctly. After the experiment was done, the conclusion was made about possibility and profitability when repairing the damaged aluminium frame.

• Keywords: aluminium; aluminium alloys; welding; bicycle frame; weld failure
• Keywords (english): aluminij; aluminijske legure; zavarivanje; okvir bicikla; pucanje zavara
• Language: croatian
• URN:NBN: urn:nbn:hr:235:674671
• Study programme: Title: Mechanical Engineering; 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
• Created on: 2019-05-22 12:38:13