Croatian Digital Thesis Repository
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The connection between implant and abutment in dental prosthetics
No full textU modernoj dentalnoj implantološkoj protetici postoji trend korištenja unutarnjih koničnih konekcija. S obzirom da različiti proizvođači nude različite kutove konusa, najčešće od 1,5° do 45°, postavlja se pitanje biomehaničke uspješnosti pojedinih konekcija pa tako i implantoloških sustava. Veza između nadogradnje i implantata ostvaruje se putem predopterećenja vijka, a otpuštanje tog vijka uslijed cikličkog opterećenja predstavlja najveći mehanički problem ovakvog sustava. U ovom radu, predstavljen je analitički model izračuna sile predopterećenja vijka i momenta otpuštanja sustava te je numeričkim modelom ispitan utjecaj pojedine konekcije na okolnu kost.In modern dental implant prosthetics, there is a trend of using internal conical connections. Given that different manufacturers offer different taper angles, usually from 1.5° to 45°, the question of the biomechanical success of individual connections and thus of implantology systems arises. The connection between the abutment and the implant is realized by screw preload, and loosening of the screw due to cyclic loading represents the biggest mechanical problem for this type of systems. In this thesis, an analytical model for the calculation of screw preload force and the loosening moment of the system is presented. The influence of a few connections on the surrounding bone is examined with a numerical model
Designing the production process using the principles of Lean management
No full textU sklopu rada sam predstavio povijesti otkako se proizveo prvi električni automobil i
koje su njegove primjene. Nakon čega sam analizirao koje su se sve promjene dogodile od tada
do danas kako bi koncept električnog automobila relativno zaživio.
Rad je koncipiran na principu da razvoj predaje koncept proizvoda kojeg je potrebno
proizvesti u određenim količinama i vremenskom intervalu, odnosno industrijalizirati proizvod,
koji će pretrpjeti određene promjene u dizajnu kako bi se način njegove proizvodnje
pojednostavio i investicijski što više rasteretio.
Tako se na proizvodu metodama Lean menadžmenta napravila analiza u kojoj su
utvrđeni nedostatci koji bi zahtijevali dodatne napore i investicije da se proizvod proizvede, s
toga se napravilo nekoliko promjena u dizajnu koje su omogućile jednostavniji način
proizvodnje od prethodnog. Posljedica utvrđenih nedostataka je nemogućnost proizvodnje i
veliki investicijski troškovi.
Na osnovu teorijske podloge Lean menadžmenta i njegovih koncepata proizvodnje,
izabrao sam nekoliko alata i principa koji su se pokazali kao vrlo učinkoviti u postavljanju
novog koncepta proizvodnje i njegovom primjenom u automobilskoj industriji.As part of this master thesis, I presented the history since the first electric car was
produced and what its applications are. After which I analyzed all the changes that took place
between then and now for the electric car concept to come to life relatively.
This master thesis is conceived on the principle that development presents the concept
of a product that needs to be produced in certain quantities and time interval, that is, to
industrialize the product, which will undergo certain changes in design in order to simplify the
way of its production and reduce the investment burden as much as possible.
An analysis was made on the product using the DFMA method, in which defects were
identified that would require additional efforts and investments to produce the product, and
several changes were made in the design that enabled a simpler way of production than the
previous one. The consequence of the identified deficiencies is the impossibility of production
and high investment costs.
Based on the theoretical basis of Lean management and its production concepts, I have
chosen several tools and principles that have proven to be very effective in setting up a new
production concept and its application in the automotive industry
Statistical analysis of data in retail
No full textFokus rada je analiza maloprodajnih podataka online platformi kako bi se utvrdila opća kretanja i korelacije zavisne varijable, predvidjela buduća potražnja te predložila optimalna lokacija skladišta tvrtke. Korišteni su stvarni podaci poslovanja maloprodajne platforme Plac.hr, ali i komplementarne baze podataka za koronavirus (Hrvatski zavod za javno zdravstvo), demografiju stanovništva (Državni zavod za statistiku, GeoPortal Zagrebačke infrastrukture prostornih podataka i dr.) i poslovanje pravnih subjekata (Financijska agencija i Poslovna Hrvatska). Podaci su u obliku vremenskih nizova (eng. time series) od 2020. do 2023. godine, a metodologija uključuje korištenje alata Google Colab za analizu i vizualizaciju podataka u programskom jeziku Python. Cilj rada je pružiti dubinsku analizu vremenskih nizova maloprodajne tvrtke, identificirati trendove, sezonalnosti i korelacije, te primijeniti modele za poboljšanje operativne učinkovitosti e-trgovine. Poseban je osvrt dan utjecaju pandemije COVID-19 na potrošačke navike.The focus of the work is the analysis of retail data from online platforms to determine general trends and correlations of the dependent variable, predict future demand, and propose the optimal location of a company's warehouse. The main dataset relied on real-life business data of the retail platform Plac.hr, as well as complimentary databases on the coronavirus pandemic (Croatian Institute of Public Health), population demography (State Statistical Office, GeoPortal of the Zagreb Spatial Data Infrastructure, etc.), business operations of legal entities (Financial Agency and Poslovna Hrvatska). The data are in the form of time series from 2020 to 2023, and the methodology includes the use of Google Colab for data analysis and visualization in the Python programming language. The work aims to provide an in-depth analysis of time series data of a retail company, identify trends, seasonality and correlations, and apply models to improve the operational efficiency of e-commerce. A special review is given to the impact of the COVID-19 pandemic on consumer habits
Removal of anthropogenic pollutants
No full textUklanjanje antropogenih onečišćujućih tvari iz okoliša ključno je za očuvanje bioraznolikosti, kvalitete zraka, vode i tla te zaštite zdravlja ljudi. Prisutnost tih tvari, kao rezultat ljudske djelatnosti, može uzrokovati ozbiljne ekološke i zdravstvene probleme. Uzroci prisutnosti antropogenih tvari leže u neodgovornim ljudskim aktivnostima, poput nepravilnog odlaganja otpada i upotrebe štetnih kemikalija. U okviru ovog rada prikazani su procesi obrade otpadne vode onečišćene antropogenim tvarima. Rješavanje navedenog problema nužno je za stvaranje održivijeg okoliša i dugoročnu dobrobit ljudi i planeta.The removal of anthropogenic pollutants from the environment is essential for the preservation of biodiversity, air, water and soil quality and the protection of human health. The presence of these substances as a result of human activities can lead to serious environmental and health problems. The causes of the presence of anthropogenic substances lie in irresponsible human activities such as the improper disposal of waste and the use of harmful chemicals. This paper presents the processes of wastewater treatment that are contaminated by anthropogenic substances. Solving this problem is necessary for the creation of a more sustainable environment and the long-term well-being of people and the planet
Preparation of Proof of Measures and a Bill of Cost : Master's Thesis
No full textU ovom završnom radu bilo je potrebno na osnovu projektne dokumentacije izraditi dokaznicu mjera i troškovnik s kojim su obuhvaćeni grubi i završni građevinski radovi.In this final paper, it was necessary to draw up a proof of measure and a bill of cost based on the project documentation which includes rough and finished construction works
Simulation of collinear fatigue crack growth in thin plates
No full textU ovom su radu predstavljene neke od uobičajenih metoda analize napredovanja zamornih pukotina bazirane na principima mehanike loma prilikom cikličkog opterećenja. Također je i dan općeniti pregled mehanike loma, kao i njena primjena na propagaciju pukotina. Iz literature su dani eksperimentalni rezultati rasta zamornih pukotina za uzorak ploče sa središnjom pukotinom i tri pukotine u nizu. Primjenjujući postupak numeričke integracije Parisove jednadžbe, simuliran je životni vijek središnje te triju kolinearnih zamornih pukotina u nizu za promatrani uzorak tanke ploče, pri čemu je uzeta u obzir njihova međusobna interakcija. Procedura je provedena uz pomoć numeričkog programa MATLAB. Koeficijenti intenzivnosti naprezanja su izračunati primjenom metode konačnih elemenata, gdje se područje oko vrha pukotine modelira mrežom singularnim konačnim elementima. Dobivene rezultate naposljetku uspoređujemo s eksperimentalnim podacima rasta središnje i kolinearnih pukotina u pločama opterećenim cikličkim vlačnim naprezanjima preuzetim iz literature. Dodatno je prikazana ovisnost između vrijednosti koeficijenata naprezanja u odnosu na duljine pukotina.In this work some of the common methods that are used for fatigue crack propagation analysis based on fracture mechanics principles are introduced. Also, an overview of fracture mechanics, same as its application on crack propagation is given. For a plate specimen containing one central crack, and also an array of three cracks, experimental results of fatigue crack grow are given from the literature. By applying the procedure of numerical integration of Paris equation, fatigue life for a central crack and for three collinear cracks in a thin plate specimen simulated for thin-plate specimen, where the interaction of multiple propagating crack tips is taken into account. Procedure is implemented by means of MATLAB package. Stress intensity factors are calculated by usage of finite element method, where the crack tip region was meshed by using singular elements. Eventually, simulatin results are compared with experimental results taken from the literature. In addition, dependence between stress intensity factor values with respect to various crack lengths are also presented
Commissioning of flexible robotic cell
No full textU sklopu diplomskog rada prikazana je izrada programske podrške za fleksibilnu robotsku ćeliju kakva se može vidjeti u današnjim proizvodnim postrojenjima. Ćelija sadrži tri robotske ruke proizvođača Stäubli te joj je zadatak sklapanje tri različita predmeta u sklop. Dijelovi od kojih se sastoji sklop su kućište sklopa, PTC senzor i klin. Programibilni logički kontroler (PLC) sinkronizira rad pojedinih elemenata ćelije. Zadaci pojedinih robotskih ruku prikazani su dijagramima toka i opisani su tipovi robotskih ruku. Robotski kontroler CS9 i PLC komuniciraju koristeći Profinet komunikacijski protokol. Fokus ovog rada je izrada programske podrške za tri robotske ruke koja je izrađena u programskom paketu Stäubli Robotics Suite.A flexible robotic cell that can be seen in a modern production facility is presented in this paper. The cell contains three robotic arms manufactured by Stäubli, whose task is to assemble three different objects into an assembly. The assembly is comprised of a housing, PTC sensor and a wedge. A Programmible Logical Controller (PLC) syncronises the movements of specific elements of the cell. The tasks of individual robotic arms are shown in flowcharts and the types of robotic arms are described, The CS9 controller and the PLC communicate using the Profinet communication protocol. The focus of this paper is the creation of software support for three robotic arms, which was created using Stäubli Robotics Suite software package
Optimisation of moulding design for minimisation of warpage
No full textU ovom diplomskom radu predstavljena je problematika vitoperenja polimernih otpresaka nakon izbacivanja iz kalupne šupljine, te je postupak kontra-konturiranja geometrije otpresaka predložen kao jedno od potencijalnih rješenja i detaljnije opisan.
Na početku rada dan je kratki opis svojstava polimera te je objašnjen postupak injekcijskog prešanja. Navedene su vrste ubrizgavalica koje je moguće koristiti za injekcijsko prešanje, te je pobliže opisan kalup za injekcijsko prešanje polimera i njegovi glavni podsustavi. Objašnjeno je ponašanje polimerne taljevine prilikom različitih faza procesa na molekularnoj razini, te je pružen uvid u utjecaj parametara poput temperature taljevine i tlaka ubrizgavanja na cjelokupni proces te proizvedeni otpresak. Prikazane su najčešće greške do kojih dolazi prilikom injekcijskog prešanja, razdvojene na vidljive i nevidljive, te su predložena potencijalna rješenja. Poseban je fokus stavljen na vitoperenje, čije je uklanjanje fokus ovog diplomskog rada.
Opisane su mogućnosti računalnih simulacija injekcijskog prešanja te je prikazan postupak postavljanja analize u programskom paketu Autodesk Moldflow 2010. Proces kontra-kontruiranja geometrije otpreska prikazan je na primjeru optimiranja konstrukcije komponente automobilskog konektora koju proizvodi tvrtka Yazaki Europe Limited. Rezultati računalne simulacije, odnosno deformirani oblik otpreska izveden iz programskog paketa Autodesk Moldflow 2010, korišteni su kako bi se optimirala konstrukcija otpreska. Zaključci o optimalnom obliku konstrukcije otpreska doneseni su na temelju poravnavanja nominalne i deformirane geometrije koristeći programski paket za mjeriteljstvo GOM Inspect 2019. Na kraju rada prikazano je smanjenje sile potrebno za montažu komponentne postignuto kontra-konturiranjem, te je donesen zaključak.This Master’s thesis considers the problem of polymer part warpage upon ejection from the mold cavity, and presents the process of reverse engineering of warpage as one of the potential solutions to the problem.
The beginning of the thesis gives a short description of polymer properties and explains the process of injection molding. An overview of injection molding machines as well as the mold itself and its subsystems is given. The behavior of polymer melts during the injection molding process is explained at a molecular level, and an insight into how parameters such as melt temperature and injection pressure impact the process and the produced part is given. The most common errors which occur during injection molding are shown, split systematically into visible and invisible errors, and potential fixes to these errors are presented. Particular attention is given to warpage, whose elimination is the focus of this Master’s thesis.
The capabilities of software for numerical simulation of the injection molding process are described, and the process of setting up such an analysis in Autodesk Moldflow 2010 is shown. The process of reverse engineering of warpage is shown on the example of optimization of molding design of an automotive connector component produced by Yazaki Europe Limited. The results of the numerical simulation, i.e. the deformed shape of the part exported from Autodesk Moldflow 2010, are used to optimize the mold design. Conclusions about the optimal mold design are drawn based on the alignment of nominal and warped geometry of the part using the GOM Inspect 2019 metrology software. The end of the thesis presents the reduction in force necessary to mount the produced part onto its assembly, which is achieved by reverse engineering of warpage, and a conclusion is made
Permeability control of die-cast aluminium alloy castings
No full textTlačno lijevani odljevci nemaju sasvim homogenu strukturu. Legure u rastaljenom stanju sadrže plinove i oksidne uključke koji mogu izazivati mikropukotine te poroznost kod gotovih odljevaka. Ako se od neke komponente očekuje sposobnost zadržavanja nekog medija (vode, zraka, ulja i sl.), zahtijeva se kontrola propusnosti medija kroz stijenke. Za kontrolu propusnosti tlačno lijevanih odljevaka izrađuju se posebni namjenski uređaji.
U okviru rada opisan je proces tlačnog lijevanja i konstrukcija kalupa za tlačno lijevanje aluminijevih legura. Opisano je kako parametri lijevanja utječu na pojavu propusnosti i koje se još greške na odljevcima mogu pojaviti. Navedene su metode pomoću kojih se ispituje poroznost odljevaka, a na kraju je dan osvrt na ukupne troškove proizvodnje. Teorijska analiza potkrijepljena je primjerom iz industrije.
U zaključku je ukratko objašnjeno koje teme su se obradile u radu i dodani su prijedlozi kako se optimizirao promatrani postupak lijevanja.Die castings do not have a completely homogeneous structure. Alloys, while in a molten state, contain gas bubbles and inclusions that can cause microcracks and porosity in finished castings. If a component is expected to retain a medium (like water, air, oil, etc.) its leak tightness control through the walls is required. Special devices are built to control the leak tightness of die castings.
The thesis describes the process of die casting and the design of molds for die casting of aluminium alloys. It was described how the casting parametres affect the leak tightness and which other defects can occur in castings. The methods used to analyze the porosity of castings were listed and at the end, an overview of the total production costs was given. Theoretical analysis was supported by an example from industry.
In the conclusion, it is briefly explained which topics were covered in the paper and suggestions were added to optimize the observed casting process
Analysis of the optimal product variant using the DMADV method
No full textDMADV metoda je jedna od komponenti 6-sigma metodologije te jedna od češće korištenih metoda u procesu razvoja novih proizvoda. Upotreba DMADV metode u razvoju novih proizvoda može doprinijeti stvaranju proizvoda i usluga koji zadovoljavaju potrebe kupaca, smanjuje vrijeme i troškove razvoja proizvoda, usklađuje proizvod ili uslugu sa strateškim ciljevima organizacije, te povećava konkurentnost isporučujući visokokvalitetne i jedinstvene proizvode. Metoda se sastoji od pet faza, svaka s određenim ciljevima i alatima. Početak čini faza definiranja, koja se usredotočuje na identifikaciju zahtjeva kupaca, odnosno obuhvat projekta i poslovne ciljeve. U fazi mjerenja se potom prikupljaju i analiziraju podatci o trenutnom tržištu, potrebama kupaca i potencijalnim rizicima. Nakon toga, u fazi analize generiraju se i vrednuju alternativna rješenja putem tehnika poput "brainstorminga", "benchmarkinga" i sl. Zatim u fazi dizajniranja odabire se najbolje rješenje i stvara se detaljan plan dizajna za testiranje i validaciju. Na kraju, u faza verifikacije testira se i validira dizajn s pomoću metoda poput simulacija ili FMEA analize.
Fokus rada je na testiranju različitih koncepata, odnosno varijanti proizvoda koji se očituje u različitim arhitekturama pogonskog sklopa električnog vozila. Rezultate dobivene simulacijskim modelima potrebno je usporediti primjenom adekvatnih metoda, te konačno dati prijedlog optimalnog proizvoda uzimajući u obzir kriterije kako eksploatacijskih performansi tako i troškova proizvodnje odabrane varijante.The DMADV method is one of the components of the 6-sigma methodology and one of the more frequently used methods in the process of developing new products. The use of the DMADV method in the development of new products can contribute to the creation of products and services that meet the needs of customers, reduce the time and costs of product development, align the product or service with the strategic goals of the organization, and increase competitiveness by delivering high quality and unique products. The method consists of five phases, each with specific goals and tools. The beginning is the definition phase, which focuses on the identification of customer requirements, that is, the scope of the project and business goals. In the measurement phase, data on the current market, customer needs and potential risks are collected and analyzed. After that, in the analysis phase, valuable alternative solutions are generated using techniques such as "brainstorming", "benchmarking", etc. Then, in the design phase, the best solution is selected and a detailed design plan is created for testing and validation. Namely, in the verification phase, the design is tested and validated using methods such as simulation or FMEA analysis.
The focus of the work is on testing different concepts, i.e., product variants, which are manifested in different architectures of the powertrain of an electric vehicle. It is necessary to compare the results obtained by simulation models using adequate methods, and finally give a proposal for the optimal product, taking into account both the exploitation performance and the production costs of the selected variant