Mathematics Masters Theses

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Browsing Mathematics Masters Theses by browse.metadata.department "Mechanical Engineering"

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    Application of image based finite element analysis for mechanical characterization of materials processed by direct energy deposition technology
    (North Dakota State University, 2024) Smith, David
    The main focus of this study is to analyze the elastic properties of two different additively manufactured materials. To this end, a cobalt chromium (CoCr) metal alloy sample and a tungsten carbide-17% cobalt (WC-17Co) cermet specimen were both fabricated by the direct energy deposition (DED) process and were examined in this study. A comparative study between the results obtained from the application of numerical and analytical techniques versus the experimental results could show the accuracy of these techniques for estimation of elastic properties of the samples. A conventionally manufactured CoCr alloy and WC-17Co samples with similar composition was subjected to the same analysis for the purpose of validation of the results. The object oriented finite element analysis (OOF) technique provided acceptable results for the DED processed CoCr sample, but was unsuccessful in the estimation of the elastic behavior of WC-Co DED sample due to its inhomogeneous microstructure.
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    Fluid-structure interaction of steady and pulsating flow through a collapsible thin-walled vessel
    (North Dakota State University, 2024) Chowdhury, Sifat Karim
    An experimental study has been conducted to investigate complex fluid-structure interactions in collapsible tubes under steady and pulsatile flow conditions, which holds significant implications for many physiological fluid transport phenomena. Quantitative analysis of structural deformation and flow field analysis were conducted utilizing Particle Image Velocimetry (PIV) and optical image analysis. The results suggest that the tube wall deformation followed Shapiro’s tube law under static and low-Re steady flow conditions. An increase in flow magnitude triggered self-excited oscillation under a critical range of negative transmural pressure. PIV results revealed periodic asymmetric jet downstream alongside velocity fluctuations during self-excited oscillation. Pulsatile flow induced cyclic symmetrical buckling under positive and neutral transmural pressures, while created traveling wave patterns under negative transmural pressures. Under highly negative transmural pressures, tube collapsed during diastole, limiting the mean flow rate. Brief self-excited oscillation was observed under such conditions, amplifying the peak flow rate within a pulsatile cycle.