Mechanical Engineering Commons^™

Bio Inspired Lightweight Composite Material Design For 3d Printing, Kaushik Thiyagarajan

Electronic Theses and Dissertations

Lightweight material design is an indispensable subject in product design. The lightweight material design has high strength to weight ratio which becomes a huge attraction and an area of exploration for the researchers as its application is wide and increasing even in every day-to-day product. Lightweight composite material design is achieved by selection of the cellular structure and its optimization. Cellular structure is used as it has wide multifunctional properties in addition to the lightweight characteristics. Applications of light weight cellular structures are wide and is witnessed in all industries from aerospace to automotive, construction to product design. In this …

Assessment Of Varying Model Representations In Cfd Simulations, Caitlin R. Gerdes

Electronic Theses and Dissertations

This thesis investigates the effects of varying model refinement and representation of computational fluid dynamics (CFD) simulations in two case studies. Product and process realization in engineering design requires substantial resources (time and money) in order to test novel designs for effectiveness. In recent decades, engineering has been relying more heavily on simulation-based analysis in the design process with computer models to help reduce the demands for real-life testing. The first case study analyzed in this thesis is a photobioreactor, which is used to grow microalgae for biofuel and require a balance of nutrients, light, and mixing for growth. The …

Simulation Of Magnetically Confined Inductively Coupled Plasma, Sina Javadpour

Electronic Theses and Dissertations

In this work, a new parallel coil design was presented to address the need for high density inductively coupled plasmas with enhanced properties and a more uniform and consistent distribution, suitable for large-area material processing. Fluid model simulations of 3D argon inductively coupled plasma (ICP) were performed in COMSOL for the proposed coil and a conventional single cylindrical coil with the same impedance to be used as reference, to compare and evaluate the performance of this new halftoroidal parallel coil design and study its effects on the main variables of the generated plasma. Through different comparisons of the simulations results, …

Mechanical Property Characterization Of Discontinuous Fiber Reinforced Composites By Computer Modeling, Amrit Bhusal

Electronic Theses and Dissertations

The desire to make high strength, lightweight, less corrosive, high fatigue resistance materials in auto industries, aero industries, biomedical industries have given a chance for in-depth study of composite materials. To get the profound knowledge of composites, different experiments are conducted which often take huge resources, cost and time. Computer modeling and analysis have gained popularity in Finite Element Analysis (FEA) because it can be used to predict the mechanical property of different materials. In this thesis, FEA technique has been used to predict mechanical property of discontinuous fiber reinforced composites (FRC). If we are able to foretell the mechanical …

Assessing The Near-Wall Hemodynamics In The Left Coronary Artery Using Cfd, John Junior Asiruwa

Electronic Theses and Dissertations

The objective of this thesis is to computationally investigate the flow mechanics and the near-wall hemodynamics associated with the different take-off angles in the left coronary artery of the human heart. From this study, we will be able to evaluate if the increase in the take-off angles of the left coronary artery will significantly increases or decrease the likelihood of plaque (atherosclerosis) buildup in the left coronary artery bifurcations. This study quantifies the effects of the varying take-off angles on the branches along the left anterior descending (LAD) of the left coronary artery using computational fluid dynamics (CFD) simulations. The …

Development Of Heterogeneous Catalysts For Upgrading Biomass Pyrolysis Bio-Oils Into Advanced Biofuels, Shouyun Cheng

Electronic Theses and Dissertations

The massive consumption of fossil fuels and associated environmental issues result in an increased interest in alternative resources such as biofuels. The renewable biofuels can be upgraded from bio-oils that are derived from biomass pyrolysis. Catalytic cracking and hydrodeoxygenation (HDO) are two most promising bio-oil upgrading techniques for biofuel production. Heterogeneous catalysts are essential for upgrading bio-oil into hydrocarbon biofuel. Although some progresses have been made, the cost and effectiveness of catalysts still remain challenges. The main objective of this study was to develop efficient heterogeneous catalysts for upgrading bio-oils into advanced hydrocarbon biofuel with low costs. In catalytic cracking, …

Mechanical And Computational Evaluation Of Cementitious Materials With Hollow Glass Microsphere Inclusions, Zachary J. Wallace

Electronic Theses and Dissertations

The effect of volumetric replacement of cementitious materials by an inert filler known as hollow glass microspheres on elastic properties is evaluated in this study through a combined computational and experimental approach. This approach considered the variation in properties of type I Portland cement for 0, 5, 10, and 15% volume fractions of two kind of glass microspheres; one was high density with high crushing strength, and the other with a relative lower density. Using a suite of software called Virtual Cement and Concrete Testing Laboratory (VCCTL), the microstructural details were determined for 80% degree of hydration of the cement …

Effect Of Vibration Of Unconsolidated Sand On The Performance Of Interferometric Vibration Sensors, Cody Berrey

Electronic Theses and Dissertations

Interferometric vibration sensors are widely used for ground vibration measurements where traditional contact sensors are not desired. Laser Doppler vibrometers (LDV) and digital speckle pattern interferometers are studied in this thesis. The working principle of laser Doppler vibrometry and digital shearography is described. The effect of vibration of the unconsolidated sand on the performance of both sensors is experimentally investigated.

The vibration of unconsolidated sand can cause an increase of noise in the laser Doppler vibrometer output and cause speckle decorrelation in digital speckle pattern interferometry (referred to as digital shearography). An experimental investigation of the effect of varying the …

Local Transient Characterization Of Thermofluid Heat Transfer Coefficient At Solid-Liquid Nano-Interfaces, Mehrdad Mehrvand

Electronic Theses and Dissertations

The demands for increasingly smaller, more capable, and higher power density technologies in microelectronics, energy, or aerospace systems have heightened the need for new methods to manage and characterize extreme heat fluxes (EHF). Microscale liquid cooling techniques are viewed as a promising solution for removing heat from high heat flux (HHF) systems. However, there have been challenges in physical understanding and predicting local thermal transport at the interface of micro and nanoscale structures/devices due to ballistic effects and complex coupling of mass, momentum, and energy transport at the solid-liquid-vapor interfaces over multiple time and length scales. Moreover, it's challenging to …

Computational Fluid Dynamics Study Of Thromboembolism As A Function Of Shunt Size And Placement In The Hybrid Norwood Palliative Treatment Of Hypoplastic Left Heart Syndrome, John Seligson

Electronic Theses and Dissertations

The Hybrid Norwood procedure has emerged as a promising alternative palliative first stage treatment for infants with Hypoplastic Left Heart Syndrome (HLHS). The procedure is done to provide necessary blood flow to the pulmonary and systemic regions of the body. The procedure can affect hemodynamic conditions to be pro-thrombotic, and thrombus particles can form and release from the vessel walls and enter the flow. Assuming these particles are formed and released from the shunt surface, a Computational Fluid Dynamics (CFD) model can be used to mimic the patient's vasculature geometry and predict the occurrence of embolization to the carotid or …

Hydrodynamic Measurements Of The Flow Structure Emanating From A Multi-Row Film Cooling Configuration, Michael Voet

Electronic Theses and Dissertations

The demand for more power is rapidly increasing worldwide. Attention is turned to increasing the efficiency of modern methods for power generation. Gas turbines provide 35% of the power demands within the United States. Efficiency of gas turbines is defined in an ideal sense by the thermal efficiency of the Brayton Cycle. The overall efficiency of a gas turbine can be increased while simultaneously maximizing specific work output, by increasing the turbine inlet temperature. However, even with the advancements in modern materials in terms of maximum operating temperature, various components are already subjected to temperatures higher than their melting temperatures. …

Application Of Multiaxial Cyclic Loading For Constitutive Model And Parameter Determination Of Steels, Bassem Felemban

Electronic Theses and Dissertations

For many candidate materials, constitutive models and their parameters are identified using uniaxial test data. Real components, however, generally operate in a multi-axial loading environments. Consequently, constitutive models deployed by uniaxial conditions may carry over to service conditions with inherit limitations. Research is proposed to determine the constitutive model constants for the creep and plasticity responses of a material via multi-axial fatigue testing which may contain ratcheting. It is conjectured that directly regressing data under conditions that favor those of actual service use will lead to more accurate modeling under these conditions, as well as a reduced consumption of model …

Heat Transfer, Friction, And Turbulent Analysis On Single Ribbed-Wall Square Channel, Christopher Vergos

Electronic Theses and Dissertations

An experimental investigation of heat transfer and friction behavior for a fully developed flow in a non-rotating square channel was conducted under a wide range of Reynolds numbers from 6,000 to 180,000. The rig used in this study was a single ribbed wall variant of Ahmed et al.'s [ 1 ] rig from which results of this rig were compared. Ahmed et al.'s rig was a replica of Han et al.'s square channel [ 2 ] used to validate their work, and expand the Reynolds number range for both heat transfer and friction data. The test section was 22 hydraulic …

Investigation Of Heat Transfer Enhancement Within A Concentric Annulus, Alexander Hanhold

Electronic Theses and Dissertations

Effective heat exchange is key for many energy applications including heat exchangers, heat extraction from heat source, and heat rejection to ambient thermal sink. This study focuses on the investigation for a specific heat exchange configuration, namely heat removal within a concentric annular passage using helical turbulators and jet impingement. Numerical testing was used to see how the different geometric parameters affect the heat transfer and pressure drop within the annulus by using helicoil turbulators. A vast range of designs were studied by changing the turbulator shape, pitch, and blockage ratio while maintaining a constant Reynolds number of 25,000. CFD …

Academic Blade Geometries For Baseline Comparisons Of Forced Vibration Response Predictions, James Little

Electronic Theses and Dissertations

Predicting the damping associated with underplatform dampers remains a challenge in turbomachinery blade and friction damper design. Turbomachinery blade forced response analysis methods usually rely on nonlinear codes and reduced order models to predict vibration characteristics of blades. Two academic blade geometries coupled with underplatform dampers are presented here for comparison of these model reduction and forced response simulation techniques. The two blades are representative of free-standing turbine blades and exhibit qualitatively similar behavior as highly-complex industrial blades. This thesis fully describes the proposed academic blade geometries and models; it further analyzes and predicts the blades forced response characteristics using …

A Study On The Plasticity And Fracture Behaviors Of Inconel 718 Under Multiaxial Stress And Extremely Low Cycle Fatigue Loadings, Mohammed Algarni

Electronic Theses and Dissertations

Engineering materials and structures are usually subjected to multiaxial stress states loading due to geometrical effects, residual stresses, or multi-directional loading. Ductile fracture and Extremely Low Cycle Fatigue (ELCF), less than 100 cycles to fail, are two common and co-exist failure modes in many engineering structures. However, the linkage between these two failure modes under multi-axial loading conditions has never been systematically studied. This research summarizes an extensive work of experimental and numerical studies of ductile fracture and ELCF under different stress states for nickel-base superalloy material "IN718" under room temperature. Specially designed specimens and tests were used to achieve …

Continuous Oscillation: Vibrational Effects And Acceptable Frequency Ranges Of Small Bore Piping In Field Applications, Marie Kasprzyk

Electronic Theses and Dissertations

In turbomachinery, a common failure mode is cracking of welds at the equipment and piping connection point. Each incidence of these cracks causes a forced shutdown to perform repairs that cost millions of dollars. This type of failure is predominately seen in small bore piping, which has a nominal diameter of 2 inches and smaller. This thesis addresses the failure prediction analysis of small bore piping, specifically in turbomachinery applications. Performing failure analysis to predict the potential cracking of welds will allow for replacement of the piping during a planned shutdown which in the long term saves money due to …

Statistical Analysis Of Multi-Row Film Cooling Flowfields, Craig Fernandes

Electronic Theses and Dissertations

A huge part of modern day power generation research and development strives to achieve higher thermal efficiencies and specific work outputs for both gas turbine Brayton and combined cycles. Advances in cooling technologies, both internal to turbine blades and external, provide the easiest way to accomplish this by raising the turbine inlet temperature far beyond the super-alloy's allowable temperature. Discrete film cooling injection, an external cooling technique, ensures a cool blanket of compressed air protects the blade surface from the harsh mainstream gas. To optimize the coverage and effectiveness of the film, a thorough understanding of the behavior and flow …

Tensile-Compressive Asymmetry And Anisotropy Of Fused Deposition Modeling Pla Under Monotonic Conditions, Casey Perkowski

Electronic Theses and Dissertations

Additive Manufacturing (AM) continues to gain popularity for its ability to produce complexly-shaped final use components that are impractical to manufacture by traditional methods; however, additive manufactured parts contain complex mesostructures that result in directionally-dependent mechanical properties that have yet to be fully characterized. This effort demonstrates a framework of experimental and analytical methods needed to characterize the uniaxial monotonic behavior of fused deposition modeling PLA using tensile and compressive experiments on specimens printed at various orientations. Based on experimental results, the asymmetry and anisotropy of the tensile and compressive response was analyzed for a candidate material. Specimens from different …

Multi-Axial Thermomechanical Characterization Of Shape Memory Alloys For Improved Stability, Douglas Nicholson

Electronic Theses and Dissertations

Shape recovery in shape memory alloys (SMAs) occurs against external stress by means of a reversible thermoelastic solid state phase transformation typically between so-called austenite, martensite and R-phases. The ability to do work enables their use as high-force actuators in automotive and aerospace applications while superelastic NiTi is of interest in biomedical devices such as stents. Both R-phase and martensite can detwin, reorient and undergo a thermal or stress induced transformation. For these reasons, it is difficult from ordinary macroscopic measurements to decouple elastic and inelastic contributions (from their respective phases) from the overall deformation. In situ neutron diffraction is …

Simulations Of Impinging Jet With A Range Of Configuration, Devansh Singh

Electronic Theses and Dissertations

Impinging jet technique is widely increasing across the globe due to its ability to produce high heat and mass transfer as compared to other traditional methods. Three cases of impinging jets related to cooling technologies for a gas turbine were investigated. The first case involves a single jet impinging on a flat plate. The second case has an array of jets impinging on a curved surface. The third case deals with simulating impinging jet in crossflow. The first case was used for validation and shows the effect of mesh and inlet boundary conditions. After careful observation, it was seen that …

Cfd Analysis Methods For Systems Driven By Natural Convection, Aaron Propst

Electronic Theses and Dissertations

Natural convection driven flows are present in many engineering applications such as HVAC, electronics cooling, and cryogenic systems. Predicting the flow behavior of such systems requires experimentation or numerical simulation through Computational Fluid Dynamics due to the complex interactions of natural convection. Recent advances in computing resources have made CFD increasingly popular for engineering analysis of fluid dynamics and heat transfer. CFD simulation has several advantages over experimentation including: 1) cost, 2) ease of changing design parameters, and 3) time required to obtain results. These advantages lead to an increased likelihood of discovering an optimal design. However, systems with complex …

Statistical Shape Modeling To Quantify Variation In The Proximal Humeral Anatomy, Paul B. Sade Sr.

Electronic Theses and Dissertations

The fit of the humeral prosthesis to the intramedullary canal and the replication of the anatomic humeral head center are important factors in Total Shoulder Arthroplasty (TSA). The objective of this thesis was to develop a Statistical Shape Model (SSM) of the cortical and cancellous bone regions of the proximal humerus, and to assess potential shape differences with gender and ethnicity, with a goal of informing implant design. An SSM was used and Principal Component Analysis (PCA) was applied to data that represented both the cancellous and cortical humeral bone of 63 healthy subjects and cadavers. Anatomical measurements and PC …

Experimental Observation Of The Relationship Between The Pressure Drop And Flow Rate Of Radial Flow Through Porous Media., Matthew William Okruch

Electronic Theses and Dissertations

This research experimentally observed the relationship between pressure drop and flow rate for high velocity, radial flow through porous media. The criterion for what represents high velocity is a function of the Reynold’s number of the flow. Pressure drop – flow rate curves were developed by flowing air and water through the porous carbon block samples. Each sample’s permeability was calculated from on the air test results. Each sample’s porosity was determined through digital microscope image analysis. Darcy’s Law, the Forchheimer equation, and the Ergun equation were converted to the radial flow domain and compared to the experimental data. The …

Microfluidic Platform For Impedance Characterization Of Endothelial Cells Under Fluid Shear Stress., Vanessa Velasco

Electronic Theses and Dissertations

Endothelium dysfunction has been associated with many pathophysiological processes leading to cardiovascular diseases. Studying endothelium behavior is vital to understand the onset, prevention, and treatment of such diseases. Electrical impedance spectroscopy has been shown to provide a real-time in vitro evaluation of cell behavior including cell monolayer permeability. However, the majority of published work has been primarily with static cell culture models or macro-scale models that do not properly represent the physiological sizes, structures, and environmental conditions of human blood vessels. Within this dissertation, the design, fabrication, characterization, and application of a microfluidic impedance platform is presented for the in …

The Effects Of Ball Interactions On The Dynamic Behavior Of A Ball Balancer Rotating At Speeds Above The Translational Resonant Frequency Of The System., Gregory A. Dedow

Electronic Theses and Dissertations

Many applications are inherently rotational in nature. These applications range from industrial products to consumer products. As seen in a traditional frequency response plot, the motion of a rotating imbalance does not approach zero as the forcing frequency is increased. Unlike a traditional forced mass spring oscillator, the motion of the rotating imbalance approaches some non-zero value. To account for this residual motion, some systems utilize a balancing device to reduce this motion. These balancing devices can be passive or active, depending on the design considerations. This paper will focus on the traditional, passive ball-type balancer due to its simplicity …

Effect Of Non-Uniform Air-Side Velocity Distribution On Heat Transfer Model Predictions For Microchannel Condenser., Zachary Chapin

Electronic Theses and Dissertations

This is a study of the effects on heat transfer capacity predictions of microchannel condensers when airflow is maldistributed due to the shape of the condenser. The three shapes investigated in this study are flat, U-shape and roll. Each coil was tested in a water calorimeter and those results were compared to the model prediction. The model prediction was calculated using CoilDesigner™ modeling software with standard correlations. Using the uniform airflow assumption, the model over predicted the heat capacity measured in the calorimeter by 5-11% depending on the coil and inlet conditions. The local airflow velocity was measured using a …

Mechanical Properties And Microstructure Evolution Of 17-4 Ph Stainless Steel Processed By Laser-Powered Bed Fusion., Harish Irrinki

Electronic Theses and Dissertations

Laser powder bed fusion (L-PBF) is a potential manufacturing route for the production of tooling using different steel materials. However, there is a limited understanding of how the mechanical properties and microstructures of the L-PBF produced parts vary with change in powder type and process conditions. The current research studied the influence of L-PBF process parameters on mechanical properties and microstructures of 17-4PH stainless steel using gas and water-atomized powders. The results demonstrate the feasibility of using water-atomized powders as starting raw materials instead of typically used gas-atomized powders to fabricate parts in the L-PBF process at high energy densities.

A Preliminary Study Of The Relationship Between Complexity, Motivation, And Design Quality., Philip John Mountain

Electronic Theses and Dissertations

This collection of work comprises a preliminary study of the relationships between product complexity, design motivation, and design quality. Complexity, as it relates to the design process, is largely undefined and there exists no generally accepted method of measurement. This study applies an independent data set to a complexity measurement technique and develops complexity measurements at the pre and post design stages. Pre design is considered when design ideas are in formation and customer needs are being addressed. Post design is considered when a functional prototype is realized, manufacturing and assembly processes have been considered, and the product design is …

Aging Assessment Of High Voltage Single Component Room Temperature Vulcanized Silicone Rubber (Rtv-1) Subjected To Aqueous Salt, Monika Bleszynski

Electronic Theses and Dissertations

Single component room temperature vulcanized (RTV-1) silicone based caulk used in high voltage insulators and other applications is frequently subjected to environmental pollutants. Aging of RTV-1 silicone rubber is the result of various stressors, including environmental aging conditions such as UV, acid, and salt exposure from ocean mist. Loss of hydrophobicity due to damage of the hydrophobic methyl groups, as well as loss of mechanical strength due to depolymerization via hydrolysis as a result of aqueous salt exposure were the two main factors of material aging assessed in this work. Multiple RTV-1 formulations were initially assessed for resistance to aging …