Browsing by Author "Andersson, Mirja"

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    Digital twins in a process engineering education environment
    (2020-12-14) Virtanen, Maiju; Andersson, Mirja; Insinööritieteiden korkeakoulu; Otto, Kevin
    Digital twins are growing more popular in the manufacturing industry and across disciplines. The term typically refers to a digital up-to-date representation of a physical system or entity. The use of real time data provided by sensors in the processes enables the user of processing equipment to react fast and accurately to issues that arise and to otherwise make well-informed decisions relevant to the process. The development in machine-to-operator communications is one of the key enablers of Digital Twins and is considered a core feature. This thesis focuses on establishing what a Digital Twin can be in a process related practical learning environment. Since Covid-19 pandemic has had an effect on working methods not only in industrial working environments but also in education and academia, the use of simulation and remote working practices are discussed. Different subcategories of Digital twins are discussed as well as their applicability to the chosen case of a Process Engineering Educational Environment of Arcada University of Applied Sciences. A user research is conducted as lead user interviews as well as surveys for two sets of stakeholders, the teaching staff and students. Based on these, the needs for the development case are identified and presented. Possible applications of digital twin technologies in the predetermined space are presented and their applicability is discussed. The actual implementation of the solutions is left outside the scope of this thesis.
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    On the Short-Term Creep and Recovery Behaviors of Injection Molded and Additive-Manufactured Tough Polylactic Acid Polymer
    (Springer, 2023-11) Gebrehiwot, Silas Z.; Espinosa-Leal, Leonardo; Andersson, Mirja; Remes, Heikki; Department of Mechanical Engineering; Marine and Arctic Technology; Arcada University of Applied Sciences
    The creep and recovery behaviors of a tough polylactic acid polymer are investigated experimentally and theoretically. We studied the influence of manufacturing methods and parameters on the viscoelastic responses. Experimental comparisons were carried out on 13 different samples manufactured using fused deposition modeling (FDM) and injection molding methods. The sample variations in the FDM were based on four infill densities (70-100%) and 3 infill directions (0 ∘, 45 ∘, 90 ∘) . Theoretically, the Burgers and Weibull’s models are used to predict the creep and recovery responses of the samples. Our experimental findings suggest that the injection-molded samples perform better in creep for most of the cases. However, at higher stress loadings, the 90 and 100% infill density samples showed excellent creep resistance behaviors at the 90 ∘ infill direction. On the other hand, the theoretical creep and recovery predictions were based on the nonlinear least-squares regression method. The Burgers model predicted the creep responses with reasonable accuracies. A maximum of 5.83 % mean absolute percentage error (MAPE) was found for the 0° infill direction and 80% infill density sample. On the contrary, the model lacks accuracy in recovery strain predictions, showing an average of 173.15% MAPE for all studied samples. Introducing Weibull’s distribution improved the accuracies showing a 3.44% average MAPE for all samples.