Mechanical Engineering Commons^™

Estimation Of The Fatigue Life Of Additively Manufactured Metallic Components Using Modified Strain Life Parameters Based On Surface Roughness, Peter Grohs

Masters Theses

In this study, a method is developed to estimate the effects of surface roughness on the fatigue life of additively manufactured titanium Ti6Al4V, aluminum 7075–T6, and steel 4340 alloys through modified strain life parameters using finite element analysis (FEA). This method is highly beneficial to the fatigue analysis of as-built additively manufactured metal components, which possess rough surfaces that reduce fatigue life significantly but are challenging to analyze directly using finite element simulation because of complex geometries, i.e., modeling an exact surface profile is arduous.

An effective stress concentration factor, incorporating roughness data, is defined to quantify their effects on …

Determination Of Chemical Notch, KChem On Aluminum And Steel When Subjected Under Slow Strain Rate Test In Corrosive Environment, Joshua Teo Lee Kuok

Masters Theses

When designing for any mechanical components or system, the question would arise as to how the material would react to the loads subjected on it? Would the component survive its service load? How would it react to environmental corrosion? To answer these questions, the technique used in this thesis paper is the Slow Strain Rate Test (SSRT) method. Aluminum and steel were chosen as the material to be tested in this paper. Al 7075-T651, and Al 6061-T651 was chosen due to its wide range of application, high strength to weight ratio and ease of machinability. It is highly used in …

Model Predictive Power Management Of A Hybrid Electric Propulsion System For Aircraft, Tyler J. Wall

Masters Theses

This work presents the switched optimal power flow control for an aircraft with a hybrid electric propulsion system. The propulsion system is a switched system that operates in either of two modes: (i) battery discharging and electric motor propelling and (ii) battery charging and electric motor generating. The aircraft model and components that form the hybrid propulsion system are modeled as either an algebraic power source/sink or as a dynamic model with appropriate power and state interconnections. With the system model defined, a model predictive control power management strategy is set fourth which minimizes a performance index that includes altitude …

Atmospheric Microbial Community Sampling System For Varying Altitude Collection, Kenneth David Domingue

Masters Theses

The study of airborne microbial communities in the vertical atmosphere is an area of research in which very little data has been collected and analyzed. Developing a vehicle to house biological sampling equipment that collects, and mitigates contamination is required by a team of biology researchers to perform sampling of atmospheric microbial communities. This study uses a sampler box that is attached to aerostatic vehicles: zero pressure balloons and tethered balloon/kite structures. Zero pressure balloons are used for sampling at altitudes above 150 m above sea level, and tethered balloon/kite structures are used for sampling at 30 m and 150 …

Development Of Empirical And Virtual Tools For The Study Of Bicycle Safety, Brent Kostich

Masters Theses

Bicycles have been used as a form of non-motorized transportation for several hundred years. Recently, their use in the transportation realm has been reinvigorated because of growing population densities and efforts to improve environmental sustainability. However, a large deterrent for public use of the bicycle is concern over its level of safety in the transportation environment. The goal of this thesis is to develop two complementary research tools that advance the study of bicycle safety factors.

First, an instrumented probe bicycle (IPB) is constructed from the ground up. The bicycle is outfitted with an array of sensors that are integrated …

Experimental Characterization And Simulation Of Carbon Nanotube Strain Sensing Films, Nagendra Krishna Chaitanya Tummalapalli

Masters Theses

Carbon Nanotubes (CNTs) have excellent mechanical, electrical and electromechanical properties. These properties led to a lot of novel applications. Due to change in electrical properties under mechanical loading, these composites have potential applications in strain sensors, when these are fabricated as films. CNT-based films are commonly fabricated using different physical and chemical techniques based on the property requirements governing those applications. In this work, CNT films were prepared using wet chemical based methods and chemical vapor deposition techniques.

Plasma chemical vapor deposition using microwave power is used in the first method to deposit films on silicon substrates, using Nickel film …

A Genetic Algorithm Incorporating Design Choice For The Preliminary Design Of Unmanned Aerial Vehicles, Kenneth Michael Mull

Masters Theses

Unmanned Aerial Vehicles (UAVs) are currently at the forefront of aerospace technologies. The design of these aircraft is complex and often performance characteristics are coupled to multiple design attributes. At the early design phase both discrete and continuous design choices are present limiting the feasibility of traditional derivative based optimization techniques. In place of these methods, the design space can be explored using a genetic algorithm that mimics the process of natural selection, providing a capable and reliable base airframe constructed from the required performance metrics. By incorporating a genetic multidisciplinary optimization algorithm early in the conceptual design phase, aircraft …

Modeling, Optimizing And Testing Thermoelectric Generators For Liquid-To-Liquid Low Grade Waste Heat Recovery, Ali Eyddan Hamil

Masters Theses

The use of thermoelectric generators (TEGs) for producing electricity from low grade waste heat is thought to be a great solution in the future to reduce the power generation cost because of their advantages of reliability and environmental friendliness. Therefore, the current project aims to study thermoelectric generators for low grade waste heat recovery. In this work, a single unit cell of liquid to liquid thermoelectric generator attached with heat exchangers (heat sinks) is modeled using an internal flow. Its optimum design is obtained based on heat sink optimization and the optimal design method. An analytical model of four unit …

Development Of An Analytical Model For Beams With Two Dimples In Opposing Directions, Mofareh H. Ghazwani

Masters Theses

Structures such as beams and steel plates can produce potentially high levels of unwanted vibrations and noises in the environment. A method of improving the vibration and acoustic characteristics of beams based on introducing dimples on its surfaces will be presented in this study. This method focuses on creating two dimples in the same and opposite direction on beam’s surface where the effect of dimples on the change in beam’s natural frequencies is the problems of interest.

A boundary value model (BVM) is developed for a beam with two dimples and subjected to various boundary conditions using Hamilton’s Variational Principle. …

Optimal Design Of Automotive Exhaust Thermoelectric Generator (Aeteg), Hassan Fagehi

Masters Theses

A consumption of energy continues to increase at an exponential rate, especially in terms of automotive spark ignitions vehicles. About 40% of the applied fuel into a vehicle is lost as waste exhaust to the environment. The desire for improved fuel efficiency by recovering the exhaust waste heat in automobiles has become an important subject. The thermoelectric generator (TEG) has the potential to convert exhaust waste heat into electricity as long as it is improving fuel economy. The remarkable amount of research being conducted on TEGs indicates that this technology will have a bright future in terms of power generation. …

Analytical Modeling And Numerical Simulation Of A Thermoelectric Generator Including Contact Resistances, Shripad Dhoopagunta

Masters Theses

With increasing demand for energy harvesting systems, research has been conducted in different areas in which Thermoelectric Generators (TEG) find their way into the top of many available resources. Out of many energy harvesting systems available, TEGs are comparatively easier to study, to manufacture and also to comprehend while producing enough energy for applications they find use in. They are solid state devices, meaning; they do not have any moving parts and hence makes them durable. Most of the energy that goes out of the automobile as exhaust is reused to power the TEGs. In most of the works that’s …

Analytical Study Of Miniature Thermoelectric Device, Mohammed Dhannoon

Masters Theses

Miniature thermoelectric devices (TE) have been regarded as hopeful devices to attain efficient cooling in microprocessors and other small-scale devices. To recognize the performances of miniature thermoelectric coolers, a thermoelectric cooling module is theoretically analyzed. Particular attention is paid to the impact of the thermoelectric element length effect and the substrate material type influence on the cooling performance. The electrical contact resistance and thermal contact are taken into account.

Furthermore, miniature thermoelectric is compared with large thermoelectric, and effective material properties of miniature thermoelectric are studied. The obtained results also demonstrate power density (cooling/heating power per unit area of the …

Optimization Methodology For Cvt Ratio Scheduling With Consideration Of Both Engine And Cvt Efficiency, Steven Beuerle

Masters Theses

A transmission ratio schedule is developed to optimize the fuel consumption for an automotive continuously variable transmission (CVT) connected to an internal combustion engine (ICE). Although the optimal operating line (OOL) generated from an engine brake specific fuel consumption (BSFC) map can be used to generate a CVT ratio schedule that yields maximum engine efficiency, it was found that OOL-based CVT ratio scheduling does not necessarily offer the best fuel economy because optimal CVT efficiency does not always correspond to OOL tracking. To develop a CVT ratio schedule that can offer the best fuel economy, a novel ratio-scheduling methodology is …

The Decomposition Of Hydroxylammonium Nitrate Under Vacuum Conditions, Gregory A. Neff

Masters Theses

This research investigates the decomposition of the ionic liquid: hydroxylammonium nitrate (HAN), under vacuum conditions. All research was conducted at the Aerospace Laboratory for Plasma Experiments (ALPE) at Western Michigan University. Hydroxylammonium nitrate solution 24% wt. in H2O was used consistently throughout this research. A variety of temperatures and pressures ranging from 23°C to 645°C and 6E-3 Torr to 4 Torr, respectively, were used to decompose HAN. The primary gaseous species resulting from these decomposition conditions are N2O, NO, and trace amounts of NO2. The formation of H2O, and N2 is conditional on the experimental conditions, and the formation of …

Implementing A Linear Quadratic Spacecraft Attitude Control System, Daniel Kolosa

Masters Theses

This thesis implements a linear quadratic attitude control system for a low-thrust spacecraft. The goal is to maintain spacecraft alignment with a time-varying thrust vector needed for trajectory change maneuvers. A linear quadratic attitude control approach is used to maintain spacecraft pointing throughout flight. This attitude control strategy uses the thrust-acceleration input obtained from a linear quadratic optimal trajectory control model that simulates the trajectory of a spacecraft in orbit maneuvers. This attitude model simulates a CubeSat, a small satellite that is equipped with a low-thrust propulsion and attitude control system. An orbit raising and a plane change scenario is …

Broncoblade: An Open Source Wind Turbine Blade Analysis Tool, Alex R. Quinlan

Masters Theses

This thesis reports the development and validation of BroncoBlade, a horizontal axis wind turbine analysis tool. BroncoBlade prepares finite element models and integrates them with an aeroelastic simulator. Analysis results for the SNL100-00 baseline blade are evaluated against reference results published by Sandia National Laboratories. Variations on the SNL100-00 blade incorporating carbon fiber are compared to the baseline blade.

Development Of Cfd Models For The Purposes Of Exploring Free Surface Wave Phenomena, Leonard P. Stoehr

Masters Theses

With the push for finding alternative, green energy sources, the harnessing of energy from ocean and lake waves is becoming a more researched field. To fully understand the behavior of wave interactions and optimize designs to extract this energy, it is necessary to develop computer models that can accurately replicate this behavior. A case is presented in which previous work done using the wave tank found in the Western Michigan University fluids lab is examined. The case involves harnessing the energy generated by ocean waves through the usage of plates of different shapes resting horizontally on the water’s surface. The …

Investigation Of Knock In Gaseous Fuels In The Presence Of Diluents, Roshan Ashok Rodrigues

Masters Theses

Recent energy security and environmental concerns have prompted growing interest into utilization of alternative fuels such as, natural gas and landfill gas. These gaseous fuels contain significant amount of diluents in the fuel composition, such as carbon dioxide, nitrogen, water vapor and other trace gases, which vary by geographical location. Successful engine operation is limited by a phenomenon called "knock", which occurs due to auto-ignition of the end gas ahead of the flame front, and therefore, needs to be investigated with the utilization of these gaseous fuels.

The present contribution discusses the experimental set-up, procedure and results of the investigation …

Selection Of Attractor Sounds For An Audio-Based Navigation System For The Visually Impaired, Brad Salisbury

Masters Theses

Research in to human hearing has been very ‘laboratory’ oriented in the sense that the test environments do not replicate most ‘real world’ situations [J.C. Middlebrooks and D.M. Green, Ann. Rev. of Psychology, 42, 135-159 (1991)]. While very useful information is gained from these types of tests, it is difficult to see how ‘real world’ situations affect sound source localization, recognition, and navigation (walking/way finding) performance. Such information is especially important to people who are visually impaired and dependent on prior knowledge of the environment or audio cues for travel. The research reported here was conducted during the development of …

Subcooled Pool Boiling Heat Transfer Using R113 On Flat Surface, Kamleshkumar J. Suthar

Masters Theses

Pool boiling experiment was conducted to investigate the effect of subcooling on boiling of R-113 using 25mm effective dia. flat surface copper heater. Pool boiling heat transfer measurements were taken for wide temperature range of 5 - 39^o C subcooling and investigated thoroughly. Variation in value of wall superheat of incipience boiling, from 27 to 34^o C and 7 to 11^o C temperature excursion observed. Noticeable effect of subcooling on boiling heat transfer is observed. Degree of subcooling was maintained constant by regulating pressure and keeping constant fluid temperature for each test run. Tests were conducted by …

Using The Boundary Element Method For Prediction Of Sound Radiated From An Arbitrarily Shaped Vibrating Body, Mark J. Christensen

Masters Theses

The Boundary Element Method can be used to predict sound pressure levels radiated from an arbitrarily shaped vibrating body. Using the Direct, Indirect and Approximation formulation one can solve such an ‘exterior’ acoustic problem. In this work, the Direct formulation was chosen. The two major methods employed for implementation of this formulation are the Combined Helmholtz Integral Equation Formulation (CHIEF) and the Burton–Miller Method. Since the CHIEF method was easier to program and adapt to changes, it was decided that the CHIEF method would be the focus of this research. Using the CHIEF method as a guide, a computer simulation …

Development Of An Integrated Sensor For The Measurement Of The Acoustic Local Volume Displacement Of Vibrating Beams, Randall Rozema

Masters Theses

Currently, the methods used for sensing the volume displacement of a vibrating structure entail the use of a polyvinylidene fluoride sensor that spans the entire length of the structure. However, this work shows that the surface behavior related to volume displacement can be measured through the use of a polyvinylidene fluoride sensor that spans only the area of interest. In this application it was shown that two-point sensors are required in addition to the distributed, polyvinylidene fluoride sensor to achieve an accurate measurement. As a result, a set of four beams with different end conditions were constructed so that the …

Experimental Investigation Of Water Spray Cooling Characteristics Of A Solid Heated Surface, Rainer F. Ponzel

Masters Theses

Water spray cooling characteristics of a solid heated surface were investigated to better understand the physical phenomenon of nucleate boiling heat transfer for full cone sprays. An experimental test loop was developed to conduct the spray cooling experiments. A uniform heat flux condition was assumed, and the liquid flow rate and nozzle orifice diameter were selected as the main variables. Two water temperatures were chosen to perform the study. Saturated water spray was utilized to measure the wall superheat temperature. Subcooled water spray was applied to investigate the effect of water spray in the single-phase regime.

Experiments conducted using the …

Flow Due To A Moving Pressure Distribution Over Free-Surface With Finite-Depth Bottom, Noriaki Okita

Masters Theses

Two-dimensional, steady-state and time-dependent analysis of wave making phenomenon due to a moving pressure distribution in sub-critical Froude number was performed. The domain is consisted of undisturbed free-surface at y=0, flat bottom at y=-h, and it is unbounded in horizontal direction. The pressure distribution was treated as an ideal model of an air-cushioned-vehicle (ACV). Ideal flow theory and linearized boundary conditions were used. Numerical integration algorithm was developed to evaluate the analytical solution. The surface elevation, bottom pressure profiles, and wave resistance were analyzed as functions of speed and depth.

The steady-state wave resistance calculated from the surface elevation profile …

Dynamic Pulse Buckling Of Columns With Viscous Damping, Murli Kadandale

Masters Theses

This is a study of dynamic pulse buckling of columns with viscous damping. The differential equations of motion were obtained using the Bemoulli-Navier hypothesis. The effects of axial and rotary inertia were included in the analysis. The Voigt-Kelvin model for a viscoelastic material is used. The Finite Difference Method was employed to solve the differential equations of motion. First columns without geometrical imperfections were studied, and a correlation between the damping modulus and the more familiar damping ratio was obtained. Then beams with initial geometrical imperfection were studied. A suitable dynamic buckling criterion was defined. It was observed that viscous …

An Investigation And Improvement Of Electrorheological (Er) Fluid Technology, Adil F. Dalal

Masters Theses

The purpose of this research was to investigate and overcome the limitations of Electrorheological (ER) fluids and to introduce this advanced technology at WMU. Electrorheological (ER) Fluids are a special class of fluids, which exhibit a reversible, infinitely variable phase transition from a liquid to a solid/semi-plastic state, in the presence of an electric field.

ER fluids can provide a unique solution to the problems of vibration isolation of systems. The applications are currently limited due to the high voltage requirements, electric power related heating and limited research into wear/abrasive characteristics of ER fluids.

A specially designed and constructed "electro-viscosimeter" …

Primary Coolant Flow Characteristics As It Exits The Palisades Reactor, Gregory Alan Baustian

Masters Theses

During fuel cycles 9 and 10 at the Palisades Nuclear Power Plant, new phenomena have been observed using the resistance temperature devices installed in the reactor coolant piping. Oscillations in the temperature readings have been observed leading to the assumptions that there is temperature stratification of the coolant in the reactor hot-legs and that the coolant rotates as it leaves the reactor. In addition, oscillations in the bulk coolant flow within the two hot legs have been postulated. This report outlines work performed using computational fluid dynamics modelling which predict the observed and assumed flow characteristics of the Palisades reactor …

Analysis Of Sandwich Plates Subjected To Blast Loading, Vijay Prasad Bulla

Masters Theses

A dynamic analysis is presented for the bending response of square sandwich plates with isotropic core and facings under blast type pressure. The maximum central deflections of simply supported plates under static and dynamic loadings are compared for various thicknesses and elastic moduli. The deviation of the thick sandwich plate results from the pure-bending theory results is presented for various core properties. Small deflection dynamic iso-response plots are shown for different core rigidities. To study the limits of small deformation linearity for various sandwich plates, non-linear results for deformations under high pressure loads are compared with the linear results. The …