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Microstructure characterization of intermetallic compounds in the welded joint of Hilumin and aluminium
No full textOsnovni cilj ovog rada bila je karakterizacija intermetalnih spojeva u zavarenom spoju čelika prevučenog niklom (Hilumin) i aluminijske legure 1050. U teorijskom dijelu rada opisano lasersko zavarivanje raznorodnih materijala i utjecajni faktori pri zavarivanju. Detaljno su opisani intermetalni spojevi koji se mogu formirati prilikom zavarivanja aluminija i čelika.
U eksperimentalnom dijelu rada provedena je analiza makrostrukture i mikrostrukture te mjerenje mikrotvrdoće HV0,01 i HV0,025 zavarenih spojeva na disk laseru. Mikrostruktura je analizirana na svjetlosnom i pretražnom elektronskom mikroskopu. Također je provedena energetski disperzivna spektrometrija kako bi se odredili udjeli kemijskih elemenata u intermetalnim spojevima formiranim u metalu zavara. Utvrđeno je da se navedenim postupcima mogu pouzdano identificirati različiti intermetalni spojevi u metalu zavara.The main objective of this thesis was the characterization of intermetallic compounds in the welded joint of nickel-plated steel (Hilumin) and aluminium alloy 1050. The theoretical part of the thesis describes laser welding of dissimilar materials and influential factors in dissimilar materials welding. Intermetallic compounds that can be formed during welding of aluminium and steel are described in detail.
In the experimental part of the thesis, macrostructure and microstructure analysis, as well as microhardness measurements HV0.01 and HV0.025 of disk laser welded joints, were performed. The microstructure was analysed using a light and scanning electron microscope. Energy dispersive spectrometry was also performed to determine the compositions of chemical elements in intermetallic compounds formed in the weld metal. It has been determined that the above methods can reliably identify various intermetallic compounds in the weld metal
Development of test case design procedure for virtual testing of control units using artificial intelligence methods
No full textU ovom radu, opisan je razvoj procedure kreiranja testnih skripti pomoću umjetne inteligencije za testiranje kontrolnih jedinica unutar simulacijskog hardver u petlji (engl. Hardware in the Loop, HiL) okruženja. Jedan od ključnih koraka u procesu HiL testiranja je interpretacija testnih zahtjeva unutar određenog softverskog rješenja. Testni zahtjevi napisani su od strane različitih domenskih eksperata. Upravo zbog toga što je više osoba uključeno u proces pisanja testnih zahtjeva, svaka osoba ima svoj stil pisanja, automatizacija ovog dijela procesa je izazovna. Ideja je razviti metodologiju za kreiranje testnih skripti iz testnih zahtjeva koristeći velike jezične modele (engl. Large Language Model, LLM). Prvo je dan generalni uvod o HiL-ovima i LLM-ovima. Zatim je opisan generalni koncept procesa, koji je podijeljen u dva podprocesa. Prvi se odnosi na interpretaciju testnih zahtjeva u jasne tekstualne korake testa. Drugi se odnosi na generaciju testnih skripti iz jasnih tekstualnih koraka. Prikazana je validacija i analiza rezultata. Na samom kraju dan je zaključak o primjeni modela u realnom industrijskom okruženju i navedena su moguća poboljšanja.This thesis describes the development of a test case design procedure using artificial intelligence methods for testing control units in the Hardware in the Loop (HiL) environment. One of the key steps in the HiL testing process is interpretation of test requirements within a particular software solution. Test requirements are written by various domain experts. Because multiple individuals are involved in the process of writing test requirements, each person has their own writing style, which makes automating this part of the process challenging. The idea is to develop a methodology for test script creation from test requirements using Large Language Models (LLM). First, a general introduction about HiLs and LLMs is given and then a general concept is described. The process is divided into two subprocesses. First one refers to the interpretation of test requirements into clear textual test steps. Second one refers to the generation of test scripts from clear textual test steps. Validation and analysis of the results are presented. At the end of the thesis, a conclusion is given on the application of the methodology in a real industrial environment as well as possible further improvements
Automation of the heat staking process
No full textCilj projekta kojim se bavi ovaj rad je izrada stroja za automatizirano toplo deformiranje. U sklopu ovog rada projektirat će se početna, eksperimentalna stanica za ispitivanje parametara toplog deformiranja te će se dati prijedlog za izgled konačnog stroja.
U prvih nekoliko poglavlja dat će se opći opis i značajke toplog deformiranja, te će se navesti neke od postojećih izvedbi koje pokazuju moguće smjerove projektiranja ovog stroja.
U glavnom dijelu rada opisat će se konstrukcija eksperimentalnog postava koji će služiti za dobivanje parametara koje će koristiti konačni stroj.
Zatim na red dolazi prijedlog okvirnog izgleda konačnog stroja sa opisanim trenutno poznatim zahtjevima .
U zaključku će se dati osvrt na projekt te njegove prednosti i nedostatke.The goal of the project that this paper deals with is the construction of a machine for automated hot staking. In this paper, an initial experimental station will be designed for testing hot staking parameters, and a proposal for the design of the final machine will be given.
In the first few chapters, a general description and features of hot staking will be given, and some of the existing designs will be listed that show possible directions in the design of this machine.
The main part of the paper will describe the construction of the experimental set-up that will serve to obtain the parameters that will be used by the final machine.
Then comes the proposal of the rough design of the final machine with the currently known requirements described.
In the conclusion, an overview of the project with advantages and disadvantages will be given
Analysis of composite hollow insulators in instrument transformers by laboratory tests and finite element method
No full textPotreba za električnom energijom je svakim danom sve veća, a samim time je i potreba za uređajima za distribuciju, pretvorbu i sigurnu uporabu električne energije sve veća. Takvi uređaji su transformatori. Vrsta transformatora koji su zaduženi za upravljanje, nadzor i zaštitu distributivnih mreža su mjerni transformatori. Mjerni transformatori dijele se na strujne, naponske, kombinirane i specijalne i oni pretvaraju prvotno izmjerene struje i napone na vrijednosti koje su prikladne za mjerenje. Zbog svoje specifične, vitke, konstrukcije su mjerni transformatori skloni lomu. Najkritičniji dio transformatora je izolator. Izolator se proizvodi od porculana ili od kompozita, a sve više se teži kompozitnim izolatorima zbog manje mase i nekih boljih mehaničkih svojstava materijala. Kompozitni izolatori se proizvode u izvedbi laminiranog kompozita s različitim tehnologijama namatanja vlakna ojačala u matricu. Končar naručuje izolatore od provjerenih proizvođača, ali je tehnologija proizvodnje poslovna tajna pa točna mehanička svojstva kompozita koja služe za valjanu analizu nisu poznata. U ovom diplomskom radu provedeno je laboratorijsko ispitivanje izolatora u Končarevom Institutu prema normi HRN EN IEC 61462:2023. Tri tipa izolatora proizvedenih različitim tehnologijama su prema normi bili podvrgnuti na savojno opterećenje koje je dominantno kod izolatora. Također je napravljena FEM-analiza u svrhu usporedbe rezultata. Željeni ishod je bio zamijeniti skupo laboratorijsko ispitivanje brzom i jeftinijom analizom konačnih elemenata. FEM-analiza je provedena u Ansysu gdje su postavljeni svi potrebni rubni uvjeti i opterećenja. Rezultati dobiveni s Instituta dosta su se razlikovali od rezultata dobivenih numeričkom metodom konačnih elemenata. Zaključak koji se može donijeti je da FEM-analiza daje zadovoljavajuće rezultate u usporedbi s eksperimentalnim ispitivanjem, ali i da su potrebna poboljšanja. Potrebno je definirati daljnji slijed ispitivanja ili novu metodu ispitivanja gdje bi se uklonili potencijalni čimbenici koji negativno utječu na krajnje rezultate analize i ispitivanja. Predložene promjene su uklanjanje inicijalnog opterećenja, dodavanje više uzoraka prilikom ispitivanja te, ako je moguće, provjera mehaničkih svojstava kompozita dobivena od proizvođača kako bi se unijeli točni podatci i samim time se osigurala točnost FEM-analize.The demand for electrical energy is increasing daily, and consequently, the need for devices for the distribution, conversion, and safe use of electrical energy is also growing. Such devices are called transformers. A type of transformer responsible for the management, monitoring, and protection of distribution networks is the instrument transformer. Instrument transformers are divided into current, voltage, combined, and special transformers. They convert initially measured currents and voltages into values suitable for measurement. Due to their specific, slender construction, instrument transformers are prone to breaking. The most critical part of the transformer is the insulator. Insulators are made of porcelain or composite materials, with a growing preference for composite insulators due to their lower weight and some of their better mechanical properties. Composite insulators are made in the form of laminated composites with different fiber – winding technologies. Končar orders insulators from verified manufacturers, but the manufacturing technology is a trade secret, so the exact mechanical properties of the composites used for a valid analysis are unknown. In this Master’s thesis laboratory testing of insulators was conducted at the Končar's Institute according to the HRN EN IEC 61462:2023 standard. Three types of insulators, manufactured using different technologies, were subjected to bending loads, which are dominant in insulators, according to the standard. A finite element method (FEM) analysis was also conducted for comparison. The desired outcome was to replace expensive laboratory testing with a faster and cheaper finite element analysis. The FEM analysis was performed in Ansys, where all necessary boundary conditions and loads were set. The results obtained from the Institute differed significantly from those obtained by FEM. The conclusion that can be drawn is that the FEM analysis gives satisfactory results compared to the experimental test, but also that improvements are needed. It is necessary to define a further testing sequence or a new testing method to eliminate potential factors that negatively impact the final results of the analysis and testing. The proposed changes include removing initial loading, adding more samples during testing, and, if possible, verifying the mechanical properties of the composite provided by the manufacturer to ensure the accuracy of the FEM analysis
Comparative analysis of Hilumin and aluminium welded joints made with different types of lasers
No full textU ovom diplomskom radu provedena je detaljna usporedba zavarenih spojeva između niskougljičnog čelika prevučenog niklom (Hilumin) i aluminijske legure serije 1050, izvedenih na disk i fiber laseru.
Teorijski dio rada obuhvaća opis principa rada lasera, klasifikaciju i karakteristike različitih tipova lasera, metode ispitivanja laserski zavarenih spojeva te specifičnosti zavarivanja raznorodnih materijala.
U eksperimentalnom dijelu rada provedena je analiza makrostrukture i mikrostrukture te mjerenje mikrotvrdoće HV0,01 u osnovnim materijalima, zoni utjecaja topline i metalu zavara, na zavarenim spojevima s oba tipa lasera. Nakon analize i usporedbe dobivenih rezultata doneseni su zaključci o prednostima i nedostatcima zavarivanja na disk i fiber laseru.In this thesis, a detailed comparison was conducted of welded joints between nickel-coated lowcarbon steel (Hilumin) and aluminum alloy series 1050, performed using disk and fiber lasers, was conducted.
The theoretical part of the thesis includes a description of the principles of laser operation, the classification and characteristics of different laser types, methods for testing laser-welded joints and the specific challenges of welding dissimilar materials.
In the experimental part, an analysis of macrostructure and microstructure was conducted, along with HV0.01 microhardness measurements in the base materials, heat-affected zone and weld metal of the welded joints with both types of lasers. Following the analysis and comparison of the obtained results conclusions were drawn about the advantages and disadvantages of welding with disk and fiber lasers
Investigation of efficiency of different cooling methods for pouch battery cells
No full textU diplomskom radu provedeno je ispitivanje hlađenja vrećastih ćelija na četiri ćelije, pri čemu
je svaka podvrgnuta različitoj vrsti hlađenja. Svaka ćelija opremljena je s 28 temperaturnih
senzora, ravnomjerno raspoređenih po površini, kako bi se osiguralo precizno praćenje
temperature tijekom ispitivanja. Ispitivanje je provedeno prema unaprijed definiranoj ispitnoj
proceduri, a svaki slučaj hlađenja obuhvaćao je nekoliko podslučajeva.
U prvom slučaju analizirano je hlađenje terminala: najprije pozitivnog, zatim negativnog, a
potom oba terminala istovremeno. Drugi slučaj uključivao je hlađenje jedne strane ćelije, a
zatim obje strane. U trećem slučaju ispitano je hlađenje jednog ruba ćelije, kao i oba ruba
istovremeno. Konačno, četvrti slučaj primijenio je kombinirano hlađenje, koje je obuhvatilo
hlađenje terminala i strana ćelije.
Rezultati pokazuju da je četvrti, kombinirani način hlađenja najučinkovitiji. Ovaj pristup
omogućio je postizanje najnižih i najravnomjernijih temperatura tijekom ispitivanja,
osiguravajući optimalne toplinske uvjete za rad ćelije. Zaključci istraživanja ističu važnost
kombiniranog pristupa hlađenju za učinkovito toplinsko upravljanje u vrećastim ćelijama.The Masters’ thesis presents the cooling examination of pouch cells, which was conducted on
four cells, each subjected to a different type of cooling. Each cell was equipped with 28
temperature sensors, evenly distributed across its surface, to ensure precise temperature
monitoring during the tests. The testing was carried out according to a predefined test
procedure, with each cooling scenario comprising several sub-cases.
In the first scenario, terminal cooling was analyzed: first the positive terminal, then the negative
terminal and finally both terminals simultaneously. The second scenario involved cooling one
side of the cell, followed by cooling both sides. In the third scenario, cooling of one edge of the
cell was tested, as well as cooling of both edges simultaneously. Finally, the fourth scenario
implemented combined cooling, which included cooling of the terminals and the sides of the
cell.
The results indicate that the fourth, combined cooling method was the most effective. This
approach achieved the lowest and most uniform temperatures during testing, ensuring optimal
thermal conditions for cell operation. The study’s conclusions highlight the importance of a
combined cooling approach for efficient thermal management in pouch cells
Utjecaj topologije i volumenskog udjela na integritet 3D tiskanih komponenti opterećenih na savijanje
No full textAn introduction to Additive Manufacturing (AM) technologies with a focus on 3D metal printing was given, and a short overview of the theory related to cellular porous structures, in particular, to Triply Periodic Minimal Surface (TPMS) structures was presented. Porous materials offer not only direct benefits such as lighter construction, material savings, and improved physical properties but also indirect advantages stemming from their widespread application in industries like aerospace and automotive, leading to fuel savings and environment protection. In this thesis the effect of specific weight and the type of cellular porous structure on the failure behaviour of a beam specimen subjected to bending was investigated. Three distinct structures (Schoen IWP, Fischer-Koch S, and Schoen F-RD), with five different specific weights, made from AlSi10Mg aluminium alloy using Direct Laser Metal Sintering (DMLS) technology were examined. A three-point bending test was conducted at room temperature using a Zwick/Roell 1456 universal testing machine to assess sample failure.
The bending forces with respect to specimens’ deflection were recorded, and energy absorption and ductility indices were computed in order to investigate the effects of the three different porous structures and their specific weight on the bending strength of the considered specimens. It was observed from the experimental results that specimens with lower specific weight can bear relatively higher load compared to specimens with higher specific weight. Furthermore, in fractured specimens crack extension was influenced by the type of structure, suggesting that future control of crack propagation could be achieved through geometrical arrangements of pores.Dan je uvod u tehnologije aditivne proizvodnje (AM) s fokusom na 3D ispis metala, te je dan kratak pregled teorije vezane uz stanične porozne strukture, posebice strukture trostruko periodične minimalne površine (TPMS). Porozni materijali nude ne samo izravne prednosti kao što su lakša konstrukcija, ušteda materijala i poboljšana fizička svojstva, već i neizravne prednosti koje proizlaze iz njihove široke primjene u industrijama poput zrakoplovne i automobilske, što dovodi do uštede goriva i zaštite okoliša. U ovom diplomskom radu istražen je utjecaj specifične težine i vrste stanične porozne strukture na ponašanje pri slomu savijanja uzorka grede. Ispitane su tri različite strukture (Schoen IWP, Fischer-Koch S i Schoen F-RD), s pet različitih specifičnih težina, izrađene od AlSi10Mg aluminijske legure korištenjem tehnologije izravnog laserskog sinteriranja metala (DMLS). Ispitivanje savijanjem u tri točke provedeno je na sobnoj temperaturi korištenjem Zwick/Roell 1456 univerzalnog ispitnog stroja za procjenu kvara uzorka.
Zabilježene su sile savijanja s obzirom na otklon uzoraka, a izračunati su indeksi apsorpcije energije i duktilnosti kako bi se istražili učinci triju različitih poroznih struktura i njihove specifične težine na čvrstoću savijanja razmatranih uzoraka. Iz rezultata pokusa uočeno je da uzorci manje specifične težine mogu podnijeti relativno veće opterećenje u odnosu na uzorke veće specifične težine. Nadalje, u slomljenim uzorcima na širenje pukotine utjecao je tip strukture, što sugerira da bi se buduća kontrola širenja pukotine mogla postići pomoću geometrijskog rasporeda pora
Electrical properties of battery cells of electric vehicles
No full textSrce svakog električnog vozila je baterija, sastavljena od stotina baterijskih ćelija. Kvaliteta ćelije određuje kvalitetu, svojstva i životni vijek električnog vozila. Mehanička oštećenja ćelija česta su pojava u praksi, no još uvijek nije u potpunosti poznat njihov izravan utjecaj na mikrostrukturu i električna svojstva. U ovom radu ispitivan je utjecaj udubina i ogrebotina na električna svojstva čeličnih i aluminijevih cilindričnih litij-ionskih baterijskih ćelija. Tijekom 39 dana mjerene su unutarnje temperature, napon i otpor baterijskih ćelija. Pokazano je kako promatrana mehanička oštećenja nemaju značajan utjecaj na brzinu pražnjenja baterijskih ćelija, ali da nisu nimalo zanemariva i bezopasna.Battery, the heart of the electric vehicle, is assembled from hundreds of cells. The quality, final properties and life span of electric vehicles are connected to quality of their batteries. It's still not fully discovered how mechanical damages affect the electrical properties and microstructure of battery cells. This master's thesis studies the impact that dents and scratches have on the electrical properties of steel and aluminum cylindrical lithium-ion battery cells. Internal temperature, voltage and resistance were measured during 39 days. Study shows dents and scratches don't affect the discharge rate significantly but they are still harmful and should be avoided if possible
Numerička simulacija udarnih oštećenja kompozitne konstrukcije horizontalnog stabilizatora
No full textThis master's thesis investigates the numerical simulation of impact damage on composite horizontal stabilizer structures caused by bird strikes. The primary objective is to develop and validate a numerical model capable of predicting the damage inflicted by bird strikes on horizontal stabilizers made from carbon fiber reinforced polymer (CFRP). Using advanced computational techniques such as finite element analysis (FEA), the research evaluates the post-impact structural integrity of these components.
The significance of this research lies in the increasing incidence of bird strikes as air traffic grows, posing substantial risks during critical flight phases like takeoff and landing. The thesis underscores the necessity of rigorous analysis and mitigation strategies to ensure flight safety. It also highlights the aviation industry's transition towards composite materials, which, while offering superior strength-to-weight ratios, exhibit complex failure mechanisms under impact that must be understood to enhance resilience.
The research employs Abaqus/Explicit and LS DYNA for simulating bird strikes, detailing the methods and procedures for creating accurate models. Comparing simulation results with experimental data is crucial for validating theoretical models and refining them to better represent real-world phenomena. This process involves meticulous qualitative and quantitative analyses, considering uncertainties and requiring interdisciplinary collaboration. The convergence of simulation and experimental results is vital for innovation and improvement in aerospace engineering.Ovaj diplomski rad istražuje numeričku simulaciju oštećenja na kompozitnim horizontalnim stabilizatorima uzrokovanih udarima ptica. Primarni cilj istraživanja je razviti i potvrditi numerički model sposoban predvidjeti oštećenja nastala udarom ptica na horizontalne stabilizatore izrađene od polimera ojačanog ugljičnim vlaknima (CFRP). Koristeći napredne računalne tehnike poput metode konačnih elemenata (FEA), istraživanje procjenjuje konstrukcijski integritet ovih komponenti nakon udara.
Značaj ovog istraživanja leži u sve većoj učestalosti udara ptica s porastom zračnog prometa, što predstavlja značajne rizike tijekom kritičnih faza leta poput polijetanja i slijetanja. Rad naglašava nužnost rigorozne analize i strategija ublažavanja kako bi se osigurala sigurnost leta. Također ističe prijelaz u zrakoplovnoj industriji prema kompozitnim materijalima koji, iako nude superioran omjer čvrstoće i težine, pokazuju složene mehanizme loma pri udaru koje je potrebno razumjeti za poboljšanu otpornost.
Istraživanje koristi Abaqus/Explicit i LS DYNA za simulaciju udara ptica, detaljno opisujući metode i postupke za stvaranje točnih modela. Usporedba rezultata simulacije s eksperimentalnim podacima ključna je za validaciju teorijskih modela i njihovu prilagodbu kako bi bolje predstavljali stvarne fenomene. Ovaj proces uključuje detaljne kvalitativne i kvantitativne analize, uzimanje u obzir nesigurnosti i zahtijeva interdisciplinarnu suradnju. Konvergencija simulacijskih i eksperimentalnih rezultata ključna je za inovacije i napredak u zrakoplovnom inženjerstvu
Robotically assisted tunnel placement in ACL reconstruction of the knee
No full textU sklopu završnog rada napravljen je konceptualni prijedlog rješenja za robotski potpomognutu rekonstrukciju prednjeg križnog ligament koljena. Identificirani su ključni dijelovi operativnog zahvata te je napravljena detaljna tehnička razrada procesa bušenja tunela pomoću robota na femuru i tibiji. U uvodnom dijelu se opisuje područje medicinske robotike te provodi istraživanje trenutnih medicinskih robotskih sustava koji se koriste u ortopedskim operacijama. Uz detaljno opisivanje anatomije koljena i prednjeg križnog ligamenta (ACL) provedena je analiza trenutnog artroskopskog pristupa prilikom operacije. Opisan je tijek operativnog zahvata u svrhu njihove implementacije na robotskom rješenju. Za metodu predoperativne i intraoperativne lokalizacije korišten je NDI Polaris Spectra sustav koji je danas vodilja u svijetu operacija vođenih pomoću kamere te uz to opisan i postupak krute registracije pacijenta. Proveden je idejni plan operativnog zahvata na anonimiziranoj CT snimci stvarnog pacijenta. U sklopu simulacije cijelog operativnog zahvata ali i potrebne analize mogućih robotskih rješenja napravljena je virtualna operacijska sala unutar programa RoboDK. Provedenim simulacijama napravljena je analiza radnog područja robota s predloženim alatom te je prikazom rezultata simulacije dobivena uspješnost pojedinog robota za ostvarivanje koncipiranih kretnji. U sklopu medicinskog laboratorija u CRTA-i napravljen je fizički postav ispred robota KUKA LBR Med 7 R800 te je u stvarnosti implementiran Polaris Spectra sustav. Sve navedene metode koncipirane su u svrhu uspješnog i preciznog bušenja tunela (engl. tunnel placement) s kojim je cilj nekad u budućnosti ostvariti bolje rezultate u području rekonstrukcije ligamenata koljena.Within the scope of the bachelor thesis, a conceptual proposal for a robot-assisted reconstruction of the anterior cruciate ligament (ACL) of the knee was developed. The key parts of the surgical procedure were identified, and a detailed technical elaboration of the tunnel drilling process using robots on the femur and tibia was conducted. The introductory section describes the field of medical robotics and investigates current medical robotic systems used in orthopedic surgeries. Along with a detailed description of the anatomy of the knee and the anterior cruciate ligament (ACL), an analysis of the current arthroscopic approach during surgery was conducted. The course of the surgical procedure is described for the purpose of its implementation in the robotic solution. The NDI Polaris Spectra system, which is a leader in the world of camera-guided operations today, was used for preoperative and intraoperative localization methods, and the process of rigid patient registration is also described. The conceptual plan of the surgical procedure was carried out on an anonymized CT scan of a real patient. As part of simulating the entire surgical procedure and the necessary analysis of possible robotic solutions, a virtual operating room was created within the RoboDK program. Through the conducted simulations, an analysis of the robot's working area with the proposed tool was made, and the results of the simulation showed the effectiveness of each robot in achieving the conceived movements. Within the medical laboratory at CRTA, a physical setup in front of the KUKA LBR Med 7 R800 robot was created, and the Polaris Spectra system was implemented in reality. All the mentioned methods were conceived for the purpose of achieving successful and precise tunnel placement, with the goal of achieving better outcomes in the field of knee ligament reconstruction in the future