Theses (Department of Mechanical Engineering)
Állandó link (URI) ehhez a gyűjteményhez
Theses collection of the Department of Mechanical Engineering. The collection was started in 2023.
At the University of Debrecen, in accordance with the 2022 amendment to the 2011 Higher Education Act, student theses are only accessible from devices connected to the University's Eduroam WiFi network or from a university IP address.
“The thesis or diploma work of a student who has successfully passed the final examination shall be stored in full in the academic system of the higher education institution, and a record shall be maintained thereof. The stored theses and diploma works – with the exception of parts classified as confidential in accordance with the relevant legislation – must be made accessible and searchable without restriction through the academic system.” Further info on the National Higher Education Act in Hungarian: Felsőokt. tv. (új) - 2011. évi CCIV. törvény a nemzeti felsőoktatásról - Hatályos Jogszabályok Gyűjteménye.
Böngészés
legfrissebb feltöltések
Megjelenítve 1 - 20 (Összesen 123)
Tétel Korlátozottan hozzáférhető Inverse material model calibration of rubber bumperPromy, Tabassum Tasnim; Huri, Dávid; DE--Műszaki KarThis study explores an inverse calibration process to find the material parameters of the constitutive model that will lead to accurate prediction of the bumper behavior based on an experimental dataset. An axisymmetric model of a rubber bumper and platens were utilized and simulated for compressive load using finite element method. The simulation dataset was used to predict the material model parameter by surrogate model based optimization method. For the simulation and optimization ANSYS was used. The fitted parameters were further validated by comparing stress and strain data to the specimen.Tétel Korlátozottan hozzáférhető INVESTIGATION OF FAILED DQ400 TYPE TRANSMISION CONTROL UNIT AFTER LEAN HEAT TESTMuhammed Abdul, Basith; Huri, Dávid; DE--Műszaki KarSummary of The post-investigation of DQ400 TCU failures in a production line provides a profound overview of the core causes affecting the product reliability and process steadiness. Since the various repeating defects were identified after Lean Heat Test and the End-of-Line procedure, the Min KL30 current-based failure was treated as the most frequent and dangerous failure. This defectiveness was highly reoccurring, providing significant danger for electrical functions and final customer satisfaction. As a result, a profound RCA and Structured CAPA were conducted. The root cause of Min KL30 failure was identified through the comprehensive analysis of defective samples, Process Audits, and cross-sectional imaging. This RCA determined that the Min KL30 defect appears due to contamination and micro-residues related to solder that are placed in the near valve connector and baseplate sections. Solder balls, metallic dust, and flux residues create unintended conductive bridges between them in a harsh thermal environment, as observed during the LHT process. More so, the inaccurate soldering temperature, excessive amount of conveyor speed, and bad post-soldier cleaning performance contribute to leftover solder debris on the PCBA. The lack of proper guidelines in AXI contributed to the fact that the device was unable to discover the micro defects. On these grounds, a set of corrective and preventive measures was developed and proposed to eliminate the root causes. The major improvements include a cleaning brush thickness and density increase to make it more reliable in post-solder efficiency, re-soldering temperature re-optimization to avoid the molten solder instability, and reduction of the conveyor speed to guarantee constant and uniformly distributed wetting and solidification of solder. Additionally, recommending renovating the AXI inspection system to a novel one, furnished with complex and accurate image processing algorithms, and defect recognition based on AI will increase defect sensitivity and accuracy, with items like small metallic particles or the solder balls covered under the component insides can be otherwise imperceptible. The estimated results from enacting these measures are immense. While examining the vital process parameters and replacement of the inspection capability, the overall solder defects rate will be at 80 to 90% reduced levels, directly increasing the First Pass Yield and reducing the numerous leans and reworks. The number of Min KL30 current fires will be reduced, to increase the Mean Time Between Failures, a characteristic of better field reliability, which will boost the test rate reduction, lowering the warranty claim strata. On the production side, the process gauge will have better stability, scarce unanticipated stoppers, and increased Overall Equipment Effectiveness compliance. Economically, these endeavors are seen to result in a Cost of Poor Quality breakdown to a more than tenable limit through more supply of material, enhanced test cycle opportunity, and closely flat resource wastage. Therefore, in the end, this research effectively resolves a significant recurring failure within the production process of the DQ400 TCU. Still, more importantly, it adds to the culture of structured problem solving and data-supported decision-making, which continually strengthens the manufacturing system. The conclusion emphasizes the value of process integration, predictive maintenance, and innovative inspection processes within high-end modern automotive electronic manufacturing. Finally, their successful application consolidates the Production line’s status to successfully address its vision of achieving sustainable quality improvement and associated product reliability and long-term competitiveness standards, as desired by the global automotive industry.Tétel Korlátozottan hozzáférhető DESIGN OF A CHAIN WAXING SYSTEM FOR SOLID FILM LUBRICANTSKupoluyi, Oluwagbemisola Favour; Huri, Dávid; DE--Állam- és Jogtudományi KarThis thesis presents the design of a chain waxing system intended for applying solid film lubricants to bicycle chains. The work begins with a review of existing chain lubrication methods, highlighting the limitations of conventional wet and dry lubricants and the advantages of solid wax coatings. Solid film lubricants commonly used for bicycle maintenance are introduced, with emphasis on their friction-reducing properties, cleanliness, and durability. The structural characteristics, materials, and wear mechanisms of bicycle chains are then analyzed to determine the lubrication requirements and the critical contact zones. Based on these insights, a conceptual chain waxing system is developed, including a heating bath, chain-handling components, and a break-in mechanism designed to ensure uniform wax penetration. The design process incorporates practical constraints, ergonomics, and ease of maintenance. The thesis concludes that the proposed system provides a cleaner, more consistent, and more efficient lubrication method, and it offers a foundation for future optimization and prototype development.Tétel Korlátozottan hozzáférhető Surrogate Model Based Parameter Tuning of Tabu Search Algorithm for the Shape Optimization of Automotive Rubber BumpersHassan, KM Euphe; Huri, Dávid; DE--Műszaki KarThe computational effort and time required to design the best shapes that can sustain a high stress and deformation level is usually computationally hectic and time consuming. To improve efficiency, there is therefore needs to minimize the design time without affecting the quality. This research paper is based on the use of Tabu Search (TS) algorithm in parameter optimization in optimization of shapes of rubber bumpers in air springs of heavy-duty vehicles. TS is a metaheuristic optimization method that is ideal in multidimensional problems that are complex enough, and this makes it a potential choice in the optimization of engineering designs. The algorithm enhances exploration as it allows exploration to avoid moves that revisit solutions that have already been explored in order to overcome local optima and find globally optimal solutions. In addition, TS has the ability to effectively search the vast spaces, enabling a thorough search of the objective functional landscape. Nevertheless, it has a high computational cost, which is seen in the multitude of evaluations that must be carried out, which is a serious problem. To solve this the current research incorporates a surrogate modeling technique alongside TS that gives a learned predictive model to estimate objective measures. The hybrid strategy minimizes the cost of computation and maintains its accuracy in optimization. The ease of the surrogate model in combination with the TS framework allows the efficient exploration of the design space that produces optimal bumper geometries that are much more computationally efficient and produce better design quality.Tétel Korlátozottan hozzáférhető MATLAB-Based Finite Element Solver for 2D Prismatic BeamsHabib, Ahnaf; Mankovits, Tamás; DE--Műszaki KarThe paper presents a finite element solver of 2D prismatic beam based on Timoshenko beam theory written in MATLAB. It corrects the conventional Euler-Bernoulli limitations with the introduction of shear deformation and moment of inertia, which makes it more dependable regarding thick, short or high-frequency beam cases. Many students usually work with black-box commercial tools like Femap or Ansys in classes and thus don’t know how things work under the hood. To tackle this, the entire process here is presented in a stepwise, clear and modular code. In that manner, students can observe each calculation and begin with developing their own engineering mindset and solutions. The solver takes input in the form of a spreadsheet, is user friendly and provides visual results of the undeformed and deformed shapes. It also calculates displacement, bending moments, shear force and stress contours to facilitate exploration with varied geometry, material, loads and boundary conditions and view the effect of each variable on the results. The value of the solver as an instructional tool is demonstrated when the solver results are compared to the commercial software results and experimental data. It is a useful guide for undergraduate classes on mechanics, finite element analysis, as well as computational modelling, and can be built upon as an educational platform in the future.Tétel Korlátozottan hozzáférhető CT-BASED RECONSTRUCTION OF CLOSED-CELL ALUMINUM FOAMSChang'a, Victoria Alexander; Mankovits, Tamás; DE--Műszaki KarClosed-cell aluminum foam is the type of foam where its pores are closed, forming a pocket of air or a bubble. Closed-cell aluminum foam is used in different fields, such as aerospace, structural, railway, shipbuilding, and many others, because of its lightweight, sound and vibration absorption properties, excellent heat insulation, non-combustibility, environmental friendliness, mechanical damping, and many other properties. A closed-cell aluminum foam have a complex internal structure, which makes it challenging to build its 3D and 2D geometric models for further studies. This study aims to conduct a parametric modeling of the closed-cell aluminum foam using CT (computed tomography) images of the foam to reconstruct 3D models with Materialise Mimics V26 software and 3-Matics V18 (its twin). The reconstruction will be conducted by varying different parameters, like segmentation and other mesh-processing parameters, to develop models. The geometric properties of these models will be compared to the actual measured geometric properties to determine which set of parameters gives the accurate model.Tétel Korlátozottan hozzáférhető Optimization of an Automotive Engine Piston System for Weight ReductionHussein, Bassel Ashraf Ibrahim; Huri, Dávid; Menyhárt, József; DE--Műszaki KarThis thesis investigates the structural behavior and optimization potential of an automotive piston–connecting rod assembly using finite element analysis and topology optimization. After establishing the design requirements and modeling a baseline piston system, a detailed FEA was conducted under peak combustion loading to identify stress distribution, deformation, and stiffness characteristics. The results showed that the steel connecting rod and cap had significant weight-reduction potential due to their high safety margins. A density-based topology optimization was then applied with manufacturability constraints, leading to a redesigned component that preserved stiffness while removing low-stress material. The optimized design achieved a substantial 26.6% mass reduction without compromising structural integrity. Overall, the thesis demonstrates a practical and effective workflow for lightweighting reciprocating engine components to improve efficiency and performance.Tétel Korlátozottan hozzáférhető Vehicle Traction Battery ModellingKhounmanyketh, Thidaphone; Menyhárt, József; DE--Műszaki KarIn recent years, the rate of Electric Vehicle (EV) adoption has been gradually increasing. In order for the Battery Management System (BMS) to perform effectively, accurately, and efficiently depends on the accuracy of the battery model of the battery pack. The work performed in this thesis is to model the battery pack, both the electrical model and the thermal model, using the datasheet specification from the automotive manufacturer, “Nissan Leaf.” Starting from laying the theoretical knowledge framework and battery modelling method on the software MATLAB/Simulink from the battery cell level up to the pack level architecture, after modelling the battery pack, the constant current at different C-rates is performed on the model to validate its behaviour against the real physical battery behaviours: cell voltage, pack SOC, and temperature under various current loads. The results of the simulation are aligned with the physical laws of the lithium-ion battery; the higher the C-rate, the more rapid the SOC, the terminal voltage decreases, and the higher the rise in temperature. In conclusion, the battery model of the Nissan Leaf, as presented in this thesis, can accurately describe the behaviour of the physical battery pack.Tétel Korlátozottan hozzáférhető 3D SCANNING ANALYSIS AND MANUFACTURING DESIGN FOR WIRE BENDINGMokaya, Ian Momanyi; Bodzás, Sándor; DE--Műszaki KarA wire bending machine is a piece of apparatus that uses mechanical power to manipulate the shape or size of a wire for gainful use. The goal of this research is to analyze the functioning of the wire bending machine and perform 3D scanning on some elements of the machine with the aim of understanding its working mechanism and developing its manufacturing technology. In this study, we begin by conducting an assembly design analysis on the machine in a CAD software, CATIA, so as to better visualize the different elements that it comprises and their connections. We relate these elements based on an analytical description of the mathematical principles that define the connections in the assembly, especially on the primary elements, the gear pair. We then perform and analyze a 3D Scanning analysis on some of the elements of the machine to determine the complexity of their profiles and identify any deviations in measurement between the modelled parts and the scanned parts. Afterwards, we use this information to develop and analytically describe a manufacturing technology for the machine, providing a template for the analysis of similar machines and development of manufacturing technologies for similar machinery. We also describe a deformational analysis of the wire under bending to describe its behavior under operation.Tétel Korlátozottan hozzáférhető FEM ANALYSIS AND SURFACE ROUGHNESS OF THE WIRE BENDING MACHINEEnnamouss, Ibtissam; Bodzás, Sándor; DE--Műszaki KarThe goal of this thesis is to analyze the function of the wire bending machine, and the measurement of the surface Roughness of the tooth gears within the machine. The study begins with disassemblage of the machine to the maximum possible parts to understand the complexity of the machine. Then each component is measured precisely. The next step was modelling the machine in a CAD software (Catia) for better visualization, and to be ready for future tests. A Surface Roughness measurement is then performed specifically on the teeth of the gear pair to investigate the accuracy of the manufacturing process and the geometric establishment of the profiles. Finally, Finite Element Analysis of connecting spur gear pair as a part of the machine, to describe the deformation of the gears during operation.Tétel Korlátozottan hozzáférhető Implementing lean principles in assembly lines to reduce waste and enhance productivity.Dangwal, Shaurya; Matkó, Andrea Emese; DE--Műszaki KarThis thesis was conducted in Bürkle, Debrecen with a sole aim to showcase how the lean tools were implemented in the shopfloor of the company. Bürkle is responsible for assembly of the machine and selling it to its buyers world-wide. Some of its machines include photovoltaic laminators, plastic card manufacturers, etc. As this was a plant with an ‘unique production’ concept’ it required better and individual planning to meet the quality requirements in every machine being customized according to the customers’ needs. There were many problems identified while initially setting up the company like lack of proper documentation, many safety hazards, lack of skills, knowledge and experience of the workers. Various quality defects which were going unnoticed and all necessary machines and tools were not present but the plant had already started its operation. There were times when the workers would sit idle for hours waiting just because their machine stopped working. W Sometimes the electrical department had to wait for the mechanical department to finish working or sometimes there power outages which led to many processes coming to a complete standstill as the generators were not strong enough to run the whole company There were power cables lying around the floor and sometimes with their copper part outside. The incoming goods had also a problem as it did not have an organized section for it. The goods were unloaded in a different part of the company instead of the warehouse because some of the doors were not of the size of the parts and because of this they had to be moved to the other side of the factory. These factors played a huge role in the overall image of the company. To solve this various measures were taken such as implementing various lean tools such as 5S, Kaizen, 8 wastes etc. There was implementation of ISO 9001 standard which led to continuous quality checks on the various departments as part of the ISO standard implemented and was taken quite seriously. All of these measures led to a greater identification of already existing problems and helped to synchronize the assembly process with various departments of the shopfloor such as mechanical, electrical, quality check. There was the introduction of the ERP system which played a major role in modernizing the shopfloor. Every information was now a few touches away in a digitally stored database. Various training sessions were conducted for the workers which helped raise accountability for their work. This made everything start to work in a streamline motion and helped all the departments to get the necessary information and simultaneously reach their goals on time. All these steps led to a decrease of wastage during the assembly process and increased the efficiency of all the processes to its maximum. Various KPIs and analyses also helped in understanding and reaching the necessary goals of the company.Tétel Korlátozottan hozzáférhető Fatigue Prediction of a Closed Cell Aluminium Foam Using Experimental Approaches and FEM SimulationsRutunga, Erasmus Gozibert; Balogh, Gábor; DE--Műszaki KarClosed cell aluminium foams have been widely used in a range of applications including crash absorptions, impact resistance and in structural applications which involve lightweight materials. However, the fatigue life and behaviour prediction of the closed cell aluminium foam under cyclic loading stands to be challenging given the porous structure, internal defects and stress concentrations of the foam. This investigation gives a comprehensive understanding on the deformation behaviour and fatigue life of a closed cell aluminium foam using combined experimental and numerical approaches. An instron 8800 universal testing machine was used to carry out compression fatigue tests in order to evaluate deformation response and fatigue resistance under cyclic loading. Ansys Workbench R1 2024 was used to perform finite element analysis, assess deformation patterns, compute equivalent stress distributions and estimate fatigue life with appropriate fatigue model and K-a relationships. A 3D voronoi geometry was created by representative volume element (RVE) method using CATIA V5 software. The results from both approaches were compared to validate the numerical model and predict the most realistic fatigue prediction function for the foam. The study provides insights into fatigue mechanisms in a closed cell aluminium foam and illustrates the feasibility of finite element method as an effective tool for predicting fatigue life, performance and supporting improved material design for lightweight structural components.Tétel Korlátozottan hozzáférhető Effects of Printing Parameters on Material Characteristics of SLS Printed TPUTuvshinbat, Orchlon; Huri, Dávid; DE--Műszaki KarThis thesis presents a clear and well-structured investigation into how Selective Laser Sintering (SLS) printing parameters influence the mechanical behaviour of TPU materials. The author provides a thorough literature background, followed by a carefully designed experimental methodology using Box–Behnken design and ISO-standardized compression testing. The analysis is detailed and methodologically sound, with effective use of MATLAB for data processing and interpolation. The results demonstrate clear parameter–property relationships and offer practical insights for optimizing TPU printing on desktop SLS systems. Overall, the thesis contributes valuable knowledge to the field of additive manufacturing, particularly regarding flexible polymer materials.Tétel Korlátozottan hozzáférhető Ensuring Optimal Performance and Longevity For Milling TechnologyDik, Walid Khalid M; Deák, Krisztián; DE--Műszaki KarThis thesis examines the key factors that affect the performance, reliability, and service life of milling machines, emphasizing the importance of proper maintenance in modern manufacturing. It reviews the main types and components of milling machines and identifies common failures such as tool wear, chatter, overheating, and dimensional inaccuracies. The work evaluates several diagnostic and condition-monitoring techniques—including vibration analysis, acoustic emission monitoring, infrared thermography, spindle current sensing, and NDT methods—that enable early detection of faults. Various maintenance strategies, such as preventive, predictive, corrective maintenance, TPM, FMEA, RBM, and AHP, are compared to highlight how data-driven approaches reduce downtime and cost. The thesis also describes essential repair procedures like spindle repair, alignment, calibration, and electrical system troubleshooting. Overall, it concludes that predictive maintenance combined with continuous monitoring offers the most effective path to ensuring sustainable, accurate, and cost-efficient milling operations.Tétel Korlátozottan hozzáférhető Development of an Energy Recovering Eddy Current Braking system for Sustainable Electric VehiclesVimalan, Vinoy; Balogh, Gábor; DE--Műszaki KarThis study explores a new eddy current braking (ECB) system designed to recover part of the energy typically lost as heat during braking. While conventional brakes and traditional ECBs waste kinetic energy and regenerative braking in EVs is less effective at high speeds, the proposed hybrid ECB concept targets this gap by enabling energy harvesting where ECBs perform best. The research analyzes electromagnetic design, material choices, thermal behavior, and simulation methods to identify practical ways to convert braking losses into usable energy. It also reviews current, limited ECB energy-recovery approaches and introduces a design that preserves ECBs’ durability, simplicity, and non-contact operation while enabling realistic energy recapture.2025Tétel Korlátozottan hozzáférhető FINITE ELEMENT ANALYSIS OF AXI-SYMMETRIC RUBBER BUMPER USING FEMAPChoko, Samuel Ogbonna; Mankovits, Tamás; DE--Műszaki KarThis work proposes a finite element analysis and optimization for an axisymmetric rubber bumper to enhance energy absorption and impact resistance capabilities. The objective of this work is to effectively analyze the nonlinear deformation phenomenon for rubbers using the ANSYS Workbench and optimize its geometric configuration to improve its efficiency. For large deformation simulations, the Mooney-Rivlin model has been utilized to describe the behavior of rubbers, and deformation analyses using both triangulation and quadrilateral mesh patterns have also been conducted to understand their respective deformations. Analysis demonstrated that quadrilateral mesh patterns are more accurate for deformation, resulting in faster convergence. The baseline compression simulation was also carried out with a displacement limit of 20 mm, resulting in a corresponding force reaction of 117,040 N and energy absorption of about 745 J. This nonlinear force-displacement response was validated to resemble actual hyperelastic material response subjected to compression constraints. Optimization simulations for design followed modifications to essential geometric variables in the steel structure to within ±10% variations from baseline assumptions. Three optimal solutions emerged using DesignXplorer parametric analysis. The optimized design has shown about 20% improvement in energy absorption capabilities. It can therefore be asserted that controlled variation in structural geometry parameters and surface interaction properties has played a significant role in improving the efficiency of rubber buffer dampers and will continue to contribute to making energy-absorption systems durable, reliable, and maintenance-free.Tétel Korlátozottan hozzáférhető Thermal modelling and simulation of Wire Arc Additive ManufacturingSekar, Pugazhanthi; Balogh, Gábor; DE--Műszaki KarThis thesis details the development and validation of a Finite Element Method (FEM) transient thermal model for the Wire Arc Additive Manufacturing (WAAM) process, focusing on single-layer deposition of Stainless Steel 316L and Ti-6Al-4V alloys. The core objective was to accurately predict the thermal behavior, addressing the challenges of complex thermal history and heat accumulation that govern the final part's microstructure and mechanical properties. The model successfully implemented Goldak's Double Ellipsoidal heat source and temperature-dependent material properties, predicting realistic peak temperatures (up to 2800 ∘C) and melt pool dimensions (e.g., 6.2mm width, 3.4mm depth for SS316L) consistent with established experimental literature. The findings validated the FEM framework for predicting thermal gradients and cooling rates (150−250 ∘C/s at the surface), offering a crucial tool for optimizing WAAM process parameters and guiding future research into residual stress and microstructure modeling.Tétel Korlátozottan hozzáférhető DESIGN OPTIMIZATION OF AXI-SYMMETRIC AUTOMOTIVE RUBBER BUMPER USING ANSYS DESIGN EXPLORERHenry-Chibor, Chukwuemeka Daniel; Mankovits, Tamás; DE--Műszaki KarAutomotive rubber bumpers are energy-absorbing components within the bumper system in automobiles that support the energy absorption and impact mitigation for protection in the event of low-speed collisions. Although existing research examines rubber bumper shape optimization using various algorithms and numerical tools. This thesis aims to detail an end-to-end procedure; from initial model setup to the optimization of the shape of the rubber bumper using Ansys Design Explorer. The optimized model achieved a 19.5% increase in force reaction at the target displacement, meaning that the implemented workflow can serve as an efficient guide for the optimization process of rubber bumper designs toward predefined mechanical performance.The methodology provides a workable framework for future tasks involving hyperelastic components, adaptation of more complex load cases or advanced material models to simulate real world conditions more accurately can be considered for further refinement.Tétel Korlátozottan hozzáférhető IMPACT OF DUST AND SOILING ON SOLAR PANEL EFFICIENCY & MAINTANCE STRATIGESAhmed, Islam Ahmed Fathi; Deák, Krisztián; DE--Műszaki KarIn this thesis the combined technical, environmental and operational problems of dust and soiling on PV were addressed in order to offer a multidisciplinary analysis of how the factors contribute to reduced energy generation, damage to module components, and impact long-term maintenance needs. The work combines empirical observations, environmental simulations and cost-based optimization of maintenance, to provide a coherent model from which to predict sustainable performance and prolong life of PV installations across different climate environmentsTétel Korlátozottan hozzáférhető Manufacturing Process and Technology Design of Vehicle Tooth GearAbdelfattah, Omar Khaled Abdalla; Bodzás, Sándor; DE--Műszaki KarThis thesis looks at how vehicle gears are designed, manufactured, maintained, and improved to ensure reliable performance. Since gears sit at the heart of any transmission, getting their design right has a huge impact on how well a vehicle handles power and how long the system lasts. The work begins by comparing how automatic and manual gearboxes age and what each one needs in terms of preventive maintenance. It then moves on to the design of a helical gear, created using CAD tools. After that, the study builds a detailed model of the gear-manufacturing process with plant simulation software to show how production would run in practice. The final part reviews the results of that simulation to see where the process can be tightened or optimized. Taken together, the study connects design, maintenance, and manufacturing so that the complete gear-production workflow can be better understood and improved.