Svojstva ojačanih lameliranih hrastovih okvirnica

master's thesis

• Title (english): Propereties of reinforced laminated oak wood scantlings
• Author: Luka Lučić
• Mentor: Vjekoslav Živković (mentor)
• Committee member: Vjekoslav Živković (predsjednik povjerenstva)
• Committee member: Goran Mihulja (član povjerenstva)
• Committee member: Hrvoje Turkulin (član povjerenstva)
• Granter: University of Zagreb; Faculty of Forestry and Wood Technology; (Institute of Furniture and Wood in Construction); Zagreb
• Defense date and country: 2024-09-25, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Wood Technology

Abstract

U ovom radu cilj je bio ispitati mogućnost povećanja mehaničkih svojstava lameliranih hrastovih elemenata pomoću mreža od staklenih i karbonskih vlakana u kombinaciji s poliuretanskim ljepilom, umjesto uobičajene epoksidne smole koja je složena za industrijsku primjenu. Istraživanje je provedeno na lameliranim hrastovim gredicama dimenzija 60 x 70 x 1000 mm koje su ojačane prednapregnutim vlaknima i spojene poliuretanskim ljepilom, a njihova mehanička svojstva testirana su metodom savijanja u četiri točke uz praćenje deformacija optičkim 3D sustavom ARAMIS. Rezultati su pokazali značajna poboljšanja u mehaničkim svojstvima ojačanih uzoraka u odnosu na neojačane, s povećanjem krajnje sile loma za 29-41% i smanjenjem pomaka pri maksimalnom opterećenju za 4-15%, dok je efektivna krutost uzoraka povećana za 37-56%, ovisno o vrsti i količini ojačanja. Optimalnim se pokazalo ojačanje s jednim slojem karbonskih vlakana zbog najboljeg omjera poboljšanja svojstava i utroška materijala, a istraživanje je također pokazalo da poliuretansko ljepilo može biti učinkovita zamjena za epoksidnu smolu, pružajući zadovoljavajuću čvrstoću i adheziju bez potrebe za složenim postupcima i visokim troškovima. Ovi rezultati sugeriraju da bi se lamelirani drveni elementi ojačani karbonskim i staklenim vlaknima, uz uporabu poliuretanskog ljepila, mogli koristiti u raznim konstrukcijskim primjenama gdje su potrebna visoka mehanička svojstva i estetska kvaliteta.

Abstract (english)

The aim of this study was to examine the possibility of enhancing the mechanical properties of laminated oak elements using glass and carbon fiber meshes in combination with polyurethane adhesive, instead of the commonly used epoxy resin, which is complex for industrial application. The research was conducted on laminated oak beams with dimensions of 60 x 70 x 1000 mm, reinforced with pre-stressed fibers and bonded with polyurethane adhesive. Their mechanical properties were tested using the four-point bending method while tracking deformations with the ARAMIS optical 3D system. The results showed significant improvements in the mechanical properties of the reinforced samples compared to the non-reinforced ones, with an increase in the ultimate breaking force by 29-41% and a reduction in displacement at maximum load by 4-15%. The effective stiffness of the samples increased by 37-56%, depending on the type and amount of reinforcement. The reinforcement with a single layer of carbon fiber proved optimal due to the best ratio of property improvement to material consumption. The study also demonstrated that polyurethane adhesive can be an effective substitute for epoxy resin, providing satisfactory strength and adhesion without the need for complex procedures and high costs. These results suggest that laminated wood elements reinforced with carbon and glass fibers, using polyurethane adhesive, could be used in various structural applications where high mechanical properties and aesthetic quality are required.

• Keywords: Lamelirani elementi; hrastovina; ojačanja; karbonska vlakna; staklena vlakna; poliuretansko ljepilo
• Keywords (english): Laminated elements; oak wood; reinforcements; carbon fibers; glass fibers; polyurethane adhesive.
• Language: croatian
• URN:NBN: urn:nbn:hr:108:300793
• Study programme: Title: Graduate Studies of Wood Technology Processes; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra inženjer/inženjerka drvne tehnologije (sveučilišni/a magistar/magistra inženjer/inženjerka drvne tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-10-10 10:45:37