Lepljeni in hibridni prekrovni spoji z ogljikovimi vlakni ojačanega polimernega kompozita in aluminija 2017-T4

Markovič, Filip (author), Šturm, Roman (mentor), Bergant, Zoran (co-mentor)

Kompozitni materiali se pogosto spajajo z lepljenjem. Problem lepljenih spojev pa je, da so nezanesljivi, saj lahko pride do nenadne porušitve. Lepljene spoje zato pogosto predimenzioniramo, delno pa lahko ta problem rešimo s hibridnimi spoji, kar pomeni, da lepljeni spoj ojačamo z mehanskimi pritrdilnimi elementi, ki delujejo kot varnostni člen v spoju in prenašajo del obremenitev. V tem delu smo izdelali in natezno testirali različne kombinacije lepljenih in hibridnih enojnih prekrovnih spojev z lepljenci iz aluminija 2017-T4 in kompozitnega polimera, ojačanega z ogljikovimi vlakni. Ugotovili smo, da lepljeni spoj z dvema kompozitnima lepljencema prenese približno 2-krat večjo obremenitev, če sta se lepljenca utrdila skupaj z lepilom, kot če se je lepilo utrdilo posebej. Ugotovili smo tudi, da ima kombinacija lepljencev vpliv na trdnost spoja, in sicer lepljeni spoj kompozit-aluminij prenese ~21 % večjo obremenitev, kompozit-kompozit pa ~50 % večjo obremenitev v primerjavi z lepljenim spojem aluminij-aluminij. Trdnost hibridnih spojev, ki smo jih dodatno zavarovali s kompozitnimi zatiči iz ogljikovih vlaken, ni bila višja od lepljenih spojev. Pri spojih z zatiči iz aramidnih vlaken pa se je trdnost povečala v manjši meri. Pri obeh vrstah pa sta zatiča nekaj časa vzdrževala oba spajana dela skupaj tudi po porušitvi lepljenega spoja, pri čemer se je razteznost spoja podaljšala.

• Language: Slovenian
• Keywords: polimerni kompoziti, lepljeni spoj, hibridni spoj, epoksi, kompozitni zatič
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [F. Markovič]
• Year: 2021
• Number of pages: XXIV, 78 str.
• PID: 20.500.12556/RUL-127231
• UDC: 678.6:62-419.3:621.886(043.2)
• COBISS.SI-ID: 70019331
• Publication date in RUL: 27.05.2021

Secondary language

• Language: English
• Title: Adhesive and hybrid single lap joints with carbon fiber reinforced polymer composite and aluminium 2017-T4

Abstract

Composite materials are often joined together by adhesive bonding. However, the problem is the unreliability of adhesive joints, which means they can suddenly fracture. Due to this, adhesive joints are often overdesigned, but the problem can be partially solved by using hybrid joints. This means that the adhesive joint is reinforced with mechanical fasteners, which serve as a safety element and carry a part of the load. In our research, we have created and tested different combinations of adhesive and hybrid single lap joints with adherends of aluminium 2017-T4 and carbon fiber reinforced composite. Our research shows that the adhesive joint with two composite adherends can carry approximately 2-times greater load if the adherends have been cured together with the adhesive, compared to the adherends and the adhesive being cured separately. Our research also shows that the combination of adherends has an effect on joint strength, namely composite-aluminium can carry a ~21 % greater load, while composite-composite a ~50 % greater load in comparison to the adhesive joint aluminium-aluminium. We have not found any improvement by using composite pins made out of carbon fiber, and only a small improvement of the maximal load that the hybrid joint can take by using a pin made out of aramid fibers in comparison to adhesive joint. However, both types of pins have kept the joined parts together even after adhesive failed, resulting in higher joint strain.

• Keywords: polymer composites, adhesive joint, hybrid joint, epoxy, composite pin