Mechanical Engineering & Applied Mechanics Masters Papers

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    Cavitation Inception and Contaminant Effects
    (North Dakota State University, 2014) Jordahl, Jennifer Marie
    Within a liquid, it is possible to lower the pressure to a point in which the nuclei gas bubbles will cause cavitation inception. During this drop in pressure, at constant temperature, the bubble tension will increase to the inception pressure. The difference between vapor pressure and the pressure where inception occurs is the tensile strength of the liquid. Frankel introduced the calculation of the potential tensile strength of a liquid. Studies show a drastic difference in the calculated potential tensile strength of a liquid and the tensile strength obtained through experimentation. Environmental effects or contaminants affect cavitation inception. Studying the mechanics of a bubble will help one to predict if inception, and later cavitation, may occur and to what extent.
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    Device Design for In-Situ EIS Measurements of Organic Coatings Under Accelerated Degradation Via Impingement Flow
    (North Dakota State University, 2020) Yuan, Quan
    This paper demonstrated a holistic approach to the study of corrosion degradation mechanism of organic coatings using impingement flows. A state-of-the-art impingement flow testing device was developed for the experimental investigations of coating degradation behavior under various fluid flow conditions. The testing device employed Electrochemical Impedance Spectroscopy (EIS) to monitor and quantify the coating performance. This study prepares us for a pathway to investigate the degradation mechanism of coatings using both mechanistic and electrochemical approaches. This paper provided a limited amount of experimental data to show the capability of the current experimental setup. A pigmented marine coating was tested under a 90-degree jet impingement flow of a looped 3.5% wt. NaCl solution. The measured impedance results indicated that the coating barrier property decreased for all tested flow rates. It was also found impingement flow can accelerate the coating degradation process comparing with the standard stationary immersion tests.
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    Literature Review of the Aerodynamics of Flapping Flight in Micro Air Vehicle Applications
    (North Dakota State University, 2014) Morman, Joshua
    Biological flapping wing flyers achieve flight maneuverability and efficiency in low speed flight environments that has not been replicated by man-made flyers. Micro Air Vehicle (MAV) design goals are to develop flyers that maintain flight in environments that biological flyers excel in which includes low speeds, hovering, and urban settings. This flight is characterized by flow phenomena that are not well understood such as: flow separation and vortical flow. The goal of this study is to perform a literature review about the aerodynamics of flapping flight and discuss the application to MAV design. The study will evaluate the design initiatives of MAV. Experimental and computational test methods are reviewed. Low Reynolds number aerodynamics are studied. The effects of airfoil aeroelasticity and geometry are discussed. Then, the application of the aerodynamics to flapping motions are reviewed. Finally, operational MAV designs are studied and recommendations are made to further advance the state of the art.
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    Micromechanical Characterization of Brain White Matter with Bi-Directional Orientation of Axonal Fibers
    (North Dakota State University, 2015) Shankar, Saurav
    Axonal injury within the white matter of human brain and spinal cord has led to several diseases in the Central Nervous System (Karami and Shankar, [1]). Diffuse axonal injury, one of the forms of Traumatic Brain Injury is caused due to swelling and elongation of axons in case of explosions, small and severe accidents, falling from heights where the brain gets an impact due to sudden movement of skull or hit by an object. A brain tissue model with bidirectional orientation of axonal fibers within the white matter of human brain has been developed. This brain tissue represents a repeating unit cell (RUC) modeled in ABAQUS (finite element software) [2] which comprises of axons and extracellular matrix (Karami and Shankar, [1]). Hyperelastic material properties of white matter sheet corona radiata of a porcine brain with bidirectional orientation of axonal fibers within the extracellular matrix is considered (Karami and Shankar, [1]).
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    Parametric Investigation of a Dielectric Barrier Dishcarge Plasma Actuator
    (North Dakota State University, 2010) Bejawada, Narender Goud
    The dielectric barrier discharge (DBD) plasma actuator is considered an effective flow control device in various aerospace applications such as drag control, lift control, and stall control. The DBD plasma actuator has many potential benefits in active flow control applications, such as an absence of moving parts and low power draw. Numerous studies have been done to estimate the effect of plasma flow on specific aerospace applications. These studies have revealed that the performance of the plasma actuator depends on a number of parameters, such as operating voltage and currents, materials, and the surrounding air velocity, to name a few. Unique combinations of these parameters are required for optimal performance of the actuator; therefore, robust parametric studies have been undertaken to fully predict the plasma-based flow fields. The present study focuses on evaluating the influence of electrical, geometrical and material parameters on the single DBD plasma actuator flow. The electrical parameters include voltage and frequency, whereas electrode gap orientations and dielectric materials are considered geometrical and materials parameters, respectively. The parametric study was done by estimating the plasma-induced velocity in quiescent media with the Particle Image Velocimetry (PIV) system for various actuator settings and operating conditions. The effects of the above parameters and characteristic behavior on the single DBD plasma actuator are discussed and compared. The obtained maximum velocities for different settings and operating conditions are used as a basis for comparison. Results showed that the operating voltage was the maJor parameter influencing the actuator performance, and the electrode gap orientations (±1 mm) had negligible effect. IV
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    A Review of Biomechanics of Arterial Stent Implants
    (North Dakota State University, 2022) Yurek, Joshua Collin
    This work looks to provide a review of modern stents by evaluating the need for them as well as providing a detailed engineering analysis of the conditions they are subjected to. It is estimated that over two million of these devices are implanted in patients annually. Of those implanted, a majority are used in the treatment of arteriosclerosis. This disease causes arterial walls to thicken and toughen leading to restricted blood flow and in extreme cases, complete loss of circulation. Arteriosclerosis and complications arising from it form a leading cause of death in the developed world. Although there are a variety of treatment options available, stents have been successfully used for several decades. The review of numerous technical reports infers that stents must withstand complex multi-axial loading conditions while being able to withstand an immense number of loading cycles, making the design and implementation of stents a significant feat.
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    A Review of Flow Diagnostic Methods and Applications
    (North Dakota State University, 2023) Dale, Matthewscott
    This work provides an overview of common flow velocimetry and diagnostic techniques, including their working principles and the application of these techniques. Probe velocimetry techniques such as pitot tubes and hot wire anemometry are discussed along with unintrusive techniques such as Laser Doppler Velocimetry and Particle Image Velocimetry. Density, pressure, and temperature diagnostic methods are also examined, in particular shadowgraph/schlieren imaging, pressure/temperature sensitive paints, and infrared thermography. Benefits and drawbacks of each method are examined as well as the applications. The goal of this review is to provide the reader with a basic understanding of the methods discussed, as well as to give insight as to which methods are particularly useful and applicable to engineering measurements.
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    Simulation of a Sudden Expansion Using Axis Symmetric Modeling for Newtonian Blood Flow
    (North Dakota State University, 2014) Schmit, Christopher
    This paper examines the flow of a Newtonian modeled blood through axisymmetric sudden expansion geometry. Reynolds number of 500, 2000, 3500, 5000, and 6500 are examined using laminar, shear stress transport, and base line analysis solvers using ANSYS 14.0. Simulation data sets are then examined against experimental data sets provided by the FDA. Results of the solution sets indicate that the laminar case set (Re = 500) is well predicted by the laminar solution set, while the fully turbulent flow (Re = 6500) is well predicted by the shear stress transport solver. Simulation and comparison of transitional cases lead to moderate discrepancies from the experimental data.
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    Survey of Methods for Achieving Low Gasoline Fuel-Permeation in Rotationally-Molded Articles
    (North Dakota State University, 2018) Nerenz, Brent
    The establishment of governmental regulations on the evaporative emission performance of fuel system components has caused molders and their material suppliers to develop innovative materials and processes by which to meet such requirements. Rotational molding is a common processing choice for fuel containers given its ability to produce complex, hollow geometries with consistent wall thickness. A number of strategies have been devised for meeting fuel permeation requirements in rotationally molded containers, each demonstrating significant benefits and detriments to the processor. Single, homogeneous materials have difficulty in simultaneously providing adequate fuel permeation, durability, and affordability. The ability of rotational molding to create containers having a plied, multi-polymer architecture allows molders to create articles which exhibit exceptional performance in each aspect. Multi-layer processing creates unique challenges for the rotational molder; however, different technologies have been demonstrated which enable multi-layer articles to be produced from a single material introduction, thereby maximizing processing efficiency.