| Abstract | Primjena polimernih materijala ojačanih raznim vlaknima u modernoj industriji izrazito je popularna. U usporedbi s konvencionalnim metalnim materijalima, polimerni materijali ojačani vlaknima imaju povoljna materijalna svojstva, kao što su visoka čvrstoća, mala masa te odlično prigušenje buke i vibracija. S obzirom na sve veću potražnju za ugljičnim vlaknima te istovremeno sve većom brigom za okoliš, u proizvodnji se sve više koriste reciklirana ugljična vlakna koja su jeftinija te kao što je spomenuto ekološki prihvatljivija, a istovremeno su sličnih materijalnih karakteristika kao i novo proizvedena vlakna. S druge strane, dostupnost lanenih vlakana na visokoj je razini, a njihova prerada predstavlja jednostavniji proces kada se uspoređuju s drugim vlaknima. Spadaju među najčvršća prirodna vlakna, čija čvrstoća, zbog upijanja vlage, u mokrom stanju poprima još veće vrijednosti. U ovom radu razmatran je kompozit s polilaktičnom PLA (eng. Poly-Lactic Acid) matricom, ojačanom recikliranim ugljičnim vlaknima te vlaknima lana. Optimalna mehanička svojstva kompozitnih materijala ovise o odabiru orijentacije vlakana, mehaničkim svojstvima i udjelu materijalnih faza kompozita. Matrica osigurava kompaktnost dok vlakna povećavaju čvrstoću samog kompozita i njegovu nosivost.
Zahvaljujući naprednim numeričkim metodama, kao što je u ovom radu korištena metoda konačnih elemenata, moguće je odrediti materijalno ponašanje kompozita s različitim udjelom vlakana. U konvencionalnoj primjeni vrlo je bitno poznavati konstitutivno ponašanje materijala od kojih se izrađuju različiti proizvodi, kako bi se ti proizvodi što točnije numerički opisali i promatrali. Stoga se ovaj radi bavi numeričkim modeliranjem konstitutivnog ponašanja kompozita s polilaktičnom matricom ojačanom recikliranim ugljičnim vlaknima i vlaknima lana.
Kompozitni materijali, promatrani materijal te njegove materijalne faze opisane su u drugom poglavlju. Zatim je dan pregled modeliranja elastoplastičnog ponašanja materijala te loma materijala. Potom je opisana numerička metoda korištena za dobivanje materijalnih parametara, a zatim i provedena sama numerička analiza u programskom paketu Abaqus, te su prikazani dobivenim rezultati na temelju kojih je donesen zaključak. |
| Abstract (english) | The application of polymer materials reinforced with various fibers is highly popular in modern industry. Compared to conventional metallic materials, fiber-reinforced polymer materials possess favorable material properties, such as high strength, low weight, and excellent noise and vibration damping. Due to the increasing demand for carbon fibers and the growing concern for the environment, recycled carbon fibers, which are cheaper and, as mentioned, more environmentally friendly, are increasingly being used in production. At the same time, they have material characteristics similar to newly produced fibers. On the other hand, flax fibers are readily available and easier to process compared to other fibers. They are among the strongest natural fibers, with strength that increases in wet conditions due to moisture absorption. This paper examines a composite with a polylactic acid (PLA) matrix, reinforced with recycled carbon fibers and flax fibers. The optimal mechanical properties of composite materials depend on the choice of fiber orientation, mechanical properties, and the proportion of material phases in the composite. The matrix provides compactness, while the fibers increase the strength and load-bearing capacity of the composite itself.
Thanks to advanced numerical methods, such as the finite element method used in this study, it is possible to determine the material behavior of composites with different fiber proportions. In conventional applications, it is essential to understand the constitutive behavior of materials used to manufacture various products to describe and observe these products as accurately as possible numerically. Therefore, this study focuses on the numerical modeling of the constitutive behavior of a composite with a polylactic acid matrix reinforced with recycled carbon fibers and flax fibers.
Composite materials, observed material of this thesis, and its material phases are described in the second chapter. Then, an overview of the modeling of elastoplastic behavior and material fracture is given. Next, the numerical method used to obtain material parameters is described, followed by the numerical analysis conducted in the Abaqus software package, and the obtained results are presented, upon which the conclusion is drawn. |
| 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, Mechanics and Robotics, Autonomous Systems, Mechatronics and Robotics
Course: Engineering Modelling and Computer Simulation
Study programme type: university
Study level: graduate
Academic / professional title: sveučilišni/a magistar/magistra inženjer/inženjerka strojarstva (sveučilišni/a magistar/magistra inženjer/inženjerka strojarstva) |
