Examensarbeten för masterexamen


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  • Post
    Influence of laser-based powder bed fusion processing parameters on the microstructure of a metastable HEA
    (2022) Anilkumar, Vishnu; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Chalmers University of Technology / Department of Industrial and Materials Science; Guo , Sheng; Bala , Malladi
    High entropy alloys (HEAs) constitute a novel class of alloys containing multiple principal elements in nearly equiatomic proportions. This compositional complexity increases the configurational entropy and hence stabilizes the formation of solid solutions. The unprecedented compositional complexity has reportedly enabled HEAs to perform better than conventional alloys in various situations. Manufacturing HEAs using additive manufacturing techniques such as laser based powder bed fusion (LB-PBF) helps in preventing the formation of detrimental phases, owing to high solidification rates compared to conventional casting. Rapid melting and solidification during the layer-by-layer printing could also result in martensitic transformations in some metastable HEAs. This work focuses on the development of non-equiatomic metastable HEAs based on the CoCrFeNi grade, aiming to engineer martensitic transformation via tuning the printing parameters. After evaluating the relative densities of the specimens from the parametric development using the design of experiments methodology, two specimens printed with a significant difference in laser power were selected for further analysis. Scanning electron microscopy analyses of as-printed specimens revealed the presence of banded features spanning across the microstructure. Subsequent analyses using transmission Kikuchi diffraction revealed that these bands correspond to the HCP phase, indicating the occurrence of the martensitic transformation during printing. Tensile testing of as-printed specimens with two different processing parameters exhibited a similar yield strength of 560 ± 10 MPa and an engineering strain of 34 %. This could be due to the similar transformation induced plasticity (TRIP) behavior of the two materials during loading.
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    Synthesis and characterisation of TiAl/Al2O3 for high-temperature applications
    (2022) Ranjith, Shravan; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Chalmers University of Technology / Department of Industrial and Materials Science; Hryha, Eduard; Cordova Gonzalez, Laura
    There is an increasing demand for new materials to improve engine efficiency and keep up with the regulations in the aerospace sector. The titanium aluminide (TiAl) has been a material of interest mainly because of the properties such as low density, high stiffness, and high creep resistance. In addition, aluminium oxide (Al2O3) as reinforcement particles allows to improve corrosion resistance and mechanical properties. Metal matrix composites (MMCs) can attain superior mechanical and thermal properties because of the reinforced matrix. These materials could be processed by surface coating on low value parts as well, extending its pool of applications to marine, chemical and other applications. In this master thesis, the synthesis of TiAl/Al2O3, titanium metal matrix composite material from titanium dioxide (TiO2) and aluminium (Al) will be investigated. Ball milling and synthesis at high temperature have been employed to attain the phase transformation to TiAl/Al2O3. During synthesis, the effect and influence of argon (Ar) and hydrogen (H2) atmospheres on the final composite was studied. Oxygen analysis and thermogravimetric analyses were used to follow material synthesis in this study. X-ray diffraction peaks confirmed the phase transformation from TiO2 and Al to TiAl/Al2O3. The final particle morphology was characterised using scanning electron microscopy (SEM) and light optical microscopy (LOM).
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    Applying Generative Design for Development of Optimal Parts
    (2023) Andersson, Lukas; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Chalmers University of Technology / Department of Industrial and Materials Science; Asbjörnsson, Gauti; Asbjörnsson, Gauti; Olsen, Tommy; Bhadani, Kanishk
    In recent years generative design and topology optimisation have been added to CAD. Tools like generative design will generate an optimal design given a model that captures the part intent. Depending on the model criteria, optimal designs may be lighter, stronger and cheaper than parts developed through conventional means. Such benefits are of great interest and companies may want to introduce such tools into their development process. In this project, a diverse selection of Volvo Penta parts is investigated using the generative design tool newly introduced to their CAD system. By reverse engineering the parts and understanding the system and requirements, a model describing the structure and volume of the part was created. Using this model several alternate parts were generated and evaluated using a cost model describing the cost of manufacturing and cost during operation. The parts generated through generative design were shown to be superior compared to the original with the performance indicator used. Drawbacks were also shown mostly relating to implementation and difficulties in defining the models.
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    Tracking for future internal logistics: How to commercialise RTLS technology at Virtual Manufacturing
    (2022) Hallén, Alice; Krajewski, Martyna; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Chalmers University of Technology / Department of Industrial and Materials Science; Örtengren, Roland; Rosengren, Pontus
    Abstract As new technology emerges, the need to innovate to remain competitive increases. Stemming from industry 4.0, the smart factory concept is the heart of the Industrial Internet of Things (IIoT), where real-time tracking is an important part of intelligent manufacturing. Real-time tracking of various objects in production and warehouses are an essential control element that supports the organisation’s decision-making. When deviations and unplanned changes appear, it can supply the necessary information in the right format and at the right time. In collaboration with the consulting company Virtual Manufacturing Sweden AB (VM), this thesis project explores how tracking equipment can be commercialised to improve internal logistics. The result was a case study proving that the computer vision-based tracking system Dragonfly was fitted for indoor localisation of moving vehicles. Functions for visualisation of tracking data such as spaghetti diagrams were developed along with an early-stage standardised work method. Furthermore, the master thesis handles limitations, development areas, and opportunities within the subject of Real-Time Location Systems (RTLS) in manufacturing.
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    Engineering Change management: A study on how to develop an Engineering Change Management framework at Northvolt AB
    (2022) Siva Kumar, Raahul Kumar; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Chalmers University of Technology / Department of Industrial and Materials Science; Bergsjö, Dag; Bergsjö, Dag; Eller, Enrico
    Abstract Northvolt, an explorer in battery manufacturing, has been developing various types of battery cells for different applications. For this, there is a wide range of activities involved in producing batteries successfully. This includes R&D, sourcing the raw materials, getting components from the suppliers, testing the material- part and assembly level, producing battery cells, battery module making, and finally, deliver ing the product. In parallel to these developmental activities, changes emerge, and these can be on a whole termed error correction, performance enhancements, and business-related factors. The changes can vary from a clerical change in a drawing to a supplier change that affects the entire process line. And these changes are largely iterative (plan, test and review) in nature and span for weeks. In a fast-growing organization like Northvolt, a proper system to streamline the workflow in managing these changes is essential. The main objective of this thesis is to study the current system in the company, specifically in the cell design division, and form a working framework that focuses on impact analysis. The process flow evolves with the aid of literature and feedback from the stakeholders- The aim is to use the Engineer ing change management layout on the abstract level and build a customized set-up concurrent to the organization’s requirements.