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    Enhancing Shoulder Joint Biofidelity in the VIVA+ Human Body Model and Evaluating its Response
    (2026) Andersson Fyr, Rasmus; Martinsson, Mollie; Qaddoura, Lilas; Raab, Hannah; Svensson, Karin; Åberg, Elin
    Previous versions of the VIVA+ human body models have demonstrated excessive shoulder stiffness compared to experiments conducted on postmortem human subjects. This study aims to enhance the biofidelity of the shoulder in the VIVA+ model. Data from studies involving postmortem human subject experiments were extracted and applied to two separate models of the acromioclavicular and sternoclavicular joint. Different verification tests were implemented to ensure that the mechanical properties of the joints were implemented correctly. The data from the studies were also used to construct biomechanical response corridors. The model modifications were implemented and evaluated in LS-DYNA, and the corridors were constructed in Python using principal component analysis and Bayesian regression. Initially, a force-deflection corridor was intended, but limitations in the deflection data restricted the final corridor construction to the force-time response. Analysis of the corridors showed that the choice of principal components affected the physical reasonability. The final validation of the updated model involved comparing it with the previous iteration and the response corridors. By implementing the joints in an updated model in LS-DYNA and comparing the simulated VIVA+ response with these corridors, it was possible to assess how closely the updated model was to the experimental human response. The results showed that the updated model was less stiff than the original VIVA+ model, for all model types. The comparison to the corridors showed that the modified model was closer to the corridors at lower impact speed, while the response at higher speeds still differed from the experimental range. This indicates that the updated shoulder joints improved the response of the model, but further development is still needed to fully represent the biomechanical behaviour of the shoulder.
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    Karakterisering av additivt tillverkat martensitiskt rostfritt stål
    (2026) Balaban, Marcus; Forssén, Anton; Popescu, Mihai-Victor; Pütter, David
    Metal Binder Jetting (MBJ) is an additive manufacturing process that enables the production of complex metal components. However, the relationship between the manufacturing process, heat treatment, microstructure and mechanical properties still requires further understanding. In this report, MBJ-manufactured martensitic stainless steel was investigated with the aim of characterizing the microstructure after different heat treatment cycles and relating these changes to the mechanical properties. Four samples that had undergone different heat treatment processes were analyzed. The microstructure was examined using light optical microscopy (LOM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive Xray spectroscopy (EDS). Hardness measurements were performed to evaluate how the different treatments affected the mechanical properties. Grain size, carbide distribution, crystal structure, and chemical composition were studied and compared between the samples. The results show that heat treatment has a clear influence on both microstructure and hardness. Samples that had only been sintered exhibited lower hardness and a more heterogeneous microstructure, whereas normalization contributed to more distinct grain boundaries and a more stable microstructure. The sample that had undergone normalization followed by austenitizing and tempering (process 411) showed the highest hardness, just below 700 HV 1. This could be related to a combination of favorable carbide distribution, relatively controlled grain size and the presence of martensite. The XRD analysis revealed differences in crystal structure between the samples, where the normalized samples showed an increased fraction of BCC-related phases. In contrast, the EDS results showed only minor differences in chemical composition, indicating that the differences in hardness are primarily due to the effect of heat treatment on the microstructure rather than variations in alloy composition. In summary, this report shows that MBJ-manufactured martensitic stainless steel requires a well-adapted heat treatment cycle in order to achieve high hardness and a favorable microstructure. Among the investigated treatments, normalization followed by process 411 appears to be the most promising route for achieving the desired properties. This report is written in Swedish.
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    Towards In-Line Detection of Milk Spoilage Using Nuclear Magnetic Resonance
    (2026) Hildebrand, Olle
    Milk is one of the most important foods in the world, consumed by over 6 billion people annually. Its nutrient rich content makes it a complete food source, however this also leads to that microorganisms can thrive inside the milk. This causes spoilage and the milk can no longer be sold to the consumers. This thesis investigates a new method to detect milk spoilage using NMR. The method would be able to be used as an in-line process and would increase the amount of tested products. Three different microorganisms were studied, Leuconostoc mesenteroides, Exiguobacterium undae, and Pseudomonas chlororaphis. For each microorganism NMR spectroscopy, relaxation times and diffusion were measured by three different instruments and magnetic field strengths, 300 MHz MRI, 60 MHz NMR and 20 MHz TD-NMR. The values were extracted by fitting signal models and the overall trends were observed. Packaging materials effects on the signal-to-noise ratio of the NMR signal and on the relaxation times were also studied at 20 MHz to understand the potential of using low-field NMR in industry. Diffusion experiments showed low potential for industry use due to lacking significant differences for treated and non-treated samples. For T2 clear overall trends could not be observed and microorganisms dependent trends were more clear. T2 showed significantly lower standard deviation than T1 making it interesting for future research. On the other hand, T1 showed the most overall clear trends with an increase over time indicating that the chemical environment is changing due to contamination. The complexity of milk spoilage made it difficult to determine which relaxation time was best indicator for spoilage, but it demonstrated how NMR signals are affected by milk spoilage. More research needs to be done to build on the findings of this thesis, specifically with more replicates and focusing on a specific instrument. Results from packaging material experiments demonstrated how it would not be the hindering factor for an in-line process, it showed that low-field NMR signals could be detectable through materials, even with an aluminium layer. The thesis provided a broader understanding of milk spoilage, its causes and how it affects relaxation times and spectra. All three microorganisms showed similar trends for all instruments suggesting that general spoilage mechanisms can be detected even if the underlying microorganisms differ. The results suggest that low-field NMR could be a viable method for milk spoilage detection.
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    Potential of carbonated industrial by-products in the synthesis of green construction materials
    (2026) Svanberg, Hannah
    Carbonated steel slags have been proposed as a potential precursor in alkali-activated materials, due to their ability to both utilize industrial by-products and store CO2. However, the influence of carbonation on the reactivity and performance of steel slags in alkali-activated systems remains largely unexplored. This thesis investigates the use of carbonated Petrit T (CPT), a by-product from sponge iron production, as a co-binder in alkali-activated materials. Blast furnace slag was used as the primary binder, and was replaced with different mass ratios of CPT. The resulting materials were evaluated with respect to reaction kinetics, phase formation, porosity, microstructure and mechanical performance. The materials were evaluated in terms of setting time, heat evolution during reaction, phase development, molecular structure, surface area, microstructure, elemental composition and compressive strength. The results showed that CPT influenced the reaction behavior of the systems. Low CPT content accelerated the initial setting behavior, while higher replacement levels delayed later reaction stages and reduced mechanical performance. TGA and FTIR analyses confirmed the formation of C–A–S–H gel phases in all alkali-activated samples. They also showed that the carbonate related phases were present after alkali activation and increased with increasing CPT content. BET analysis showed that pore volume and specific surface area increased with increasing CPT content, indicating the formation of a more porous microstructure. SEM/EDS observations revealed the presence of unreacted BFS and CPT particles, suggesting limited participation in gel formation. Overall, the results indicate that carbonated steel slags can be incorporated into AAMs and contribute to CO2 storage through mineral carbonation. However, at the investigated replacement levels, CPT behaved more as an inert filler and negatively impacted the mechanical performance of the materials.