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McLarnan, Charles WalterKinematic synthesis of complex linkages /
Doctor of Philosophy, The Ohio State University, 1960, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Links and link-motion;Mechanical engineering;FORTRAN ;Functions of complex variables

Kline, Leo VirgilAnalytical study of the energy-weight and energy-volume characteristics of energy storage systems /
Doctor of Philosophy, The Ohio State University, 1954, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Force and energy;Mechanical engineering

Riggs, Mark R.TIG Welding of Nickel Titanium to 304 Stainless Steel
Master of Science, The Ohio State University, 2014, Mechanical Engineering
Nickel-titanium is a shape memory alloy capable of producing high stresses with an 8% maximum recoverable strain. The rotation of a nickel-titanium (NiTi) torque tube can be controlled by thermally cycling the material through its critical martensite and austenite temperatures. Transforming the phase of NiTi corresponds to a change in its crystalline structure and a macroscopic change in shape. This change in shape, through a controlled thermal input, lends itself well to powering a solid-state actuator. Shape memory alloys can in some cases replace traditional actuators, for instance in harsh aerospace environments where lightweight operation is critical. NiTi is effective as a solid-state actuator, but it is very difficult to machine. The poor machinability of NiTi drives the cost and complexity of system integration to the point where its widespread use is hindered. The general solution is to join NiTi to a structural material and machine the structural material for system integration. Several types of joining methods have been studied such as ultrasonic soldering, adhesives, and laser welding. This study focuses on tungsten inert gas (TIG) welded joints between 304 stainless steel and NiTi tubing. A nickel filler is used in TIG welding of NiTi to 304SS to prevent brittle intermetallics formed by titanium and iron in the weld pool. The thickness of the nickel filler and the current required to create a strong TIG weld in torsion failure is investigated in a Taguchi L9 full factorial test matrix. Based on ultimate failure torque test results and welding observations, a 0.050'' filler thickness with an 85 A starting current was chosen for thermocycling tests with a constant load. The chosen joint parameters produce an average ultimate failure torque of 371 in-lb (41.9 N-m) with a shear strength of 41 ksi (282 MPa). EDS analysis of 0.025'' and 0.075'' filler thickness welds confirm observations from welding and test data with a crack caused by TiFe intermetallics in the 0.025'' filler weld and minimal weld penetration on the 304SS interface with the 0.075'' filler thickness. Results from dye penetrant tests, ultimate failure test data, and sectioned weld analysis were used to gain understanding of TIG welding NiTi to 304SS.

Committee:

Marcelo Dapino, Dr. (Advisor); Mark Walter, Dr. (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

nickel; titanium; nickel-titanium; TIG; tungsten inert gas welding; Mark Riggs; Dapino; Ohio State; Mechanical Engineering; nickel filler; joining; structural material; tungsten inert gas; Marcelo Dapino; torque tube

Li, HaoFatigue Based Structural Design Exploration via Engineering Data Analytics
Master of Science in Engineering (MSEgr), Wright State University, Mechanical Engineering
In manufacturing industry, a successful machine development requires the durability of structure components to meet fatigue life targets. The typical way to obtain fatigue design loads for conceptual design exploration is based on hand calculations or historical data to capture envelopes of expected system responses, which may not guarantee to capture actual damaging loads. In this study, a new approach is developed to extract a fatigue design load set directly from measured load data for a conceptual design exploration. The proposed framework integrates the techniques from data analytics and physics based engineering mechanics to amplify and detect fundamental damaging load patterns. Also, a practical Taguchi optimization method is proposed by using a moving window strategy to minimize the computational cost of design exploration. An industrial scale structural problem, a front linkage structure of a hydraulic excavator, is presented to demonstrate the effectiveness of the proposed methodologies.

Committee:

Ha-Rok Bae, Ph.D. (Advisor); Zifeng Yang, Ph.D. (Committee Member); Sanjiv Kumar Sinha, Ph.D. (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

mechanical engineering

Venkatasubramanian, RajivComposite Nanoparticle Materials for Electromagnetics
MS, University of Cincinnati, 2012, Engineering and Applied Science: Mechanical Engineering
This thesis summarizes the work done toward the fabrication of a novel composite material that is projected as a viable replacement for conventionally used magnetic core materials in various electromagnetic applications. Conventional linear and rotary electric motors, generators and actuators are too bulky to be used in lightweight applications. The major component of weight in electromagnetic devices is the magnetic core, usually made of soft iron. Further, losses due to eddy currents and magnetic remnance occur in soft iron cores. This thesis discusses the different materials suitable that might be to replace soft iron in electromagnetic devices, Methods developed to fabricate different composite cores and their characterization is presented. The composite cores consist of one or more nanoparticle materials consolidated into a polymer or elastomer matrix material. Nanoparticles such as Carbon Nanosphere Chains, Carbon Nano Fibers and Superparamagnetic Iron Oxide nanoparticles were used to fabricate the cores. Superparamagnetic iron oxide nanoparticles were selected as the best among the available materials to achieve optimal core properties needed for electromagnetic applications. As described in this thesis, the ability to control the properties of the cores by varying the types and quantities of the materials used in the process of fabrication is an important advantage over soft iron. A permanent magnet is used to lift the cores to approximately measure the Relative magnetic permeability of the fabricated cores. A Digital Multimeter is used for the measurement of Resistivity of the cores. An Instron Tensile Testing machine is used to determine the strength of the cores. The specific permeability of the superparamagnetic iron oxide powder nanocomposite cores relative to soft iron was measured and the percentage of nanoparticles in the matrix material was increased to increase the magnetic permeability. Superparamagnetic nanoparticles may exhibit higher overall Magnetic Moment compared to paramagnetic materials, and lower core losses compared to ferromagnetic materials, of similar volume fraction. The work documented in this thesis details a process that involves: (i) Nanomaterial Selection, (ii) Matrix Material Selection, (iii) Magnetic Core Fabrication, (iv) Core Material Characterization, and (v) Results Comparison with soft iron. The specific permeability’s of the fabricated nanocomposite material and soft iron were found to be similar when measured using a permanent magnet. The electrical resistivity of the nanocomposite material when compared to soft iron is very high resulting in lower eddy current losses making it suitable for high frequency operations. Future work would consist of testing for superparamagnetic behavior over the entire sample, accurate measurement of the magnetic permeability using a Superconducting Quantum Interference Device (SQUID) or a Vibrating Sample Magnetometer (VSM) and finding ways to improve dispersion of the nanoparticles such as coating the surfaces of individual particles to prevent agglomeration. The nanocomposite core material can then be tested in low and high frequency applications including electric motors, generators, electromagnetic shielding, smart materials, biomedical devices, morphing air foils, switches, sensors and many of the other possibly hundreds of applications that use electromagnetics.

Committee:

Mark Schulz, Ph.D. (Committee Chair); Vesselin Shanov, Ph.D. (Committee Member); David Thompson, Ph.D. (Committee Member)

Subjects:

Engineering

Keywords:

Mechanical Engineering;Nanotechnology;Magnetism;Electromagnetics;Composites;Nanoparticles;

Robie, Bruce HarshawConceptual design by individuals and groups in mechanical engineering
Doctor of Philosophy, Case Western Reserve University, 1991, Mechanical Engineering
The conceptual design skills of sixty-five members of a senior mechanical engineering design class were investigated. The ability of individuals to generate concepts was studied, as was the performance of sixteen sub-groups in both concept generation and concept selection. Individual performance evaluation was based on the number of concepts generated. Group performance was based on the independent evaluation of the faculty member teaching the class. Results were analyzed using factors that identified previous knowledge of design, motivation and personality types. Group operation as determined by questionnaire was also used to analyze group performance. Standardization of the individual performance results based on the number of distinct concepts identified by the sample removed most of the variation due to different tests used. The cumulative percent of concepts generated was logarithmically related to the percent of the subjects identifying those concepts. The cumulative percent of concepts generated was linearly related to the percent of different subjects identifying concepts. This suggests that most concepts were uncommon and that most subjects identified uncommon concepts. A small, significant percentage increase in concepts was found between two different tes t portions where the median number of concepts generated increased from three to six significant factors in individual performance included previous industrial design experience and MBTI (Myers-Briggs Type Indicator) perception type. Intuitive types seem better able to form multiple abstractions of the problem and make connections between those abstractions and previous experience. Training should focus on developing this skill in all individuals. Consensus was positively related to group performance in concept generation along with measures of the group's personality based on LSI (Learning Style Inventory) and the MBTI. Regression equations using these factors described about sixty percent of the variation in the data. Individual leadership and subgroup decision making were inversely related to performance. The concept selection study found that some differences within groups could improve performance while other differences were related to diminished performance. Engineering education should train individuals to function well in groups and the MBTI can be used to construct groups with personality differences.

Committee:

Thomas Kicher (Advisor)

Keywords:

Conceptual design mechanical engineering

Liu, MengxinStudies of Ionic Liquid Hybrids: Characteristics and Their Potential Application to Li-ion Batteries and Li-ion Capacitors
Master of Science in Materials Science and Engineering (MSMSE), Wright State University, 2017, Materials Science and Engineering
Ionic liquids (ILs) have attracted much attention in electrochemical energy storage systems for their advantageous properties over traditional lithium salt/carbonate solvent electrolyte in terms of higher electrochemical potential windows, comparable ionic conductivity, negative vapor pressure and non-flammability. Ionic liquids can be used as the solvent-free electrolyte in electrochemical double layer capacitors (EDLCs) or can act as the important additives to the carbonate electrolyte in lithium ion batteries (LIBs). Recently, lithium ion capacitors (LICs) have emerge as a novel energy storage system to satisfy the demands for higher energy density and higher power density in portable and transportation systems. This Master thesis research is focused on three types of imidazolium based ionic liquids and their hybrids for potential applications to EDLCs, LIBs or LICs. The electrochemical characteristics, including ionic conductivities and stability windows of the three pristine ILs and their hybrids with additions of organic solvent diethyl carbonate (DEC), or common lithium ion electrolyte (LiPF6/EC/DEC) are systematically investigated. The influences of temperature and the volumetric percentage iv of the IL additive on their electrochemical behaviors are discussed. Finally, these ionic liquid hybrids were examined in LIB and LIC devices to assess their impacts on energy storage performances.

Committee:

Hong Huang, Ph.D. (Committee Chair); Henry Daniel Young, Ph.D. (Committee Member); Raghavan Srinivasan, Ph.D. (Committee Member)

Subjects:

Materials Science; Mechanical Engineering

Keywords:

materials science; mechanical engineering

Sridhar, Dheerendra M.Mathematical Modeling of Cable Sag, Kinematics, Statics, and Optimization of a Cable Robot
Master of Science (MS), Ohio University, 2015, Mechanical Engineering (Engineering and Technology)
Cable sag can have significant effects on the cable length computation in a cable robot and this is more pronounced in large scale cable robots, such as the Algae Harvesting Cable Robot System. This requires modeling the cable as a catenary instead of an approximated straight line model. Furthermore, when there is actuation redundancy involved, the modeling and simulation of the system becomes much more complex, requiring optimizing routines to solve the problem. The cable sag compensated or the catenary model was used for the Algae Harvesting Cable Robot System and simulated to solve the Kinematics and Statics problems. This involved optimization of cable tensions and finding the errors involved in the cable length. A relative comparative analysis between the straight line and cable sag model is presented. Finally based on the qualitative and quantitative results obtained, recommendations were made on the choice of model and solution methodologies.

Committee:

Robert Williams, II (Advisor); Hajrudin Pasic (Committee Member); Greg Kremer (Committee Member); Vardges Melkonian (Committee Member)

Subjects:

Applied Mathematics; Engineering; Mechanical Engineering; Robotics

Keywords:

Mechanical Engineering; Robotics; Cable Robot; Cable Sag; Tension; Mathematical Modeling; Optimization; Kinematics; Statics

SUH, JUNWOOTHE DYNAMIC CHARACTERISTICS OF A LIQUID-GAS INTERFACE IN MICROSCALE PORES
MS, University of Cincinnati, 2002, Engineering : Mechanical Engineering
For both Loop Heat Pipes, being developed as a thermal control device for microelectronics in space applications, and the de-watering process in a vibro-separator, the dynamic characteristics of a liquid-gas interface inside micropores greatly affects the efficiency of the entire system. In the pharmaceutical industries, product particles are discharged in the form of a dilute slurry from a reactor to a de-watering device, such as a vibro-separator. For extremely small pores, gravity is insufficient for removing the excess water through the micropore screen. For these cases, it has been suggested that the de-watering process can be initiated by utilizing a vacuum pressure beneath the screen and applying sinusoidal vibration to the screen. To understand the phenomena of de-watering from the product screen of a vibro-separator utilizing vibration and pressure, a single liquid-filled micropore is studied. In past studies [8], the Navier-Stokes and Young-Laplace equations have been used to describe the dynamic motion of the liquid column and liquid-gas interface. A major goal of this study is to experimentally verify this model. In particular, comparison is made between the amplitude and frequency of acceleration required to cause the bubble burst through predicted theoretically and measured experimentally. The Lexan wicks having several pores with a uniform diameter of 50 ìm, 100 ìm, 500ìm and 1 mm are utilized. Depending upon the size of the micropores, two different types of tests were performed. One test utilized no external pressure difference across the wick and other test utilized a pressurized upper chamber.

Committee:

Dr. Frank Gerner (Advisor)

Keywords:

Microsale Pores; Loop Heat Pipes; vibro-separator; mechanical engineering

Donovan, AdamVehicle Level Transient Aircraft Thermal Management Modeling and Simulation
Master of Science in Mechanical Engineering (MSME), Wright State University, 2016, Mechanical Engineering
Many advances in technology are expected to increase the capabilities of next generation aircraft, and these advances will increase the thermal load on the aircraft as well. In order to assess and account for these increased thermal loads, three studies were performed: a fuel pump trade study, a high energy pulsed system (HEPS) implementation study, and a legacy vehicle environmental control system (ECS) study. The fuel pump study addresses the effect of the implementation of a centrifugal fuel pump versus a variable displacement fuel pump. Traditionally, aircraft designers have used a centrifugal fuel pump over a piston based pump based primarily on mass, volume, cost, and reliability. This study considers specific excess power (SEP), fuel burn and thermal margin and shows the piston based pump performing superior mainly because it eliminates fuel recirculation resulting in an increased thermal margin. This investigation demonstrates the benefit of capturing component level models and thermal concerns in the conceptual design process. Both of these issues are vital to the development of future aircraft designs. Additional research needs to be completed to compare both pumps based on the mass and volume of each system. The second study investigates the implementation of a HEPS device at an air vehicle level. HEPS generate excessive amounts of heat during operation, creating challenges in how to integrate them into an aircraft without overwhelming the vehicle’s power and thermal management systems (TMS). In order to evaluate the impact of the HEPS electrical and thermal load on the aircraft's mission, a vehicle level modeling and simulation (M&S) effort must be executed of the power and thermal management systems. To accurately evaluate the total effect on the aircraft, the HEPS must be integrated into a Tip to Tail (T2T) model of the system that includes the aircraft power and thermal management subsystems. With the HEPS system integrated into the T2T model, not only can its mass and volume effects be analyzed, but also the transient power and thermal loads created by the new system can be evaluated for their effect on other aircraft subsystems. Furthermore, the aircraft subsystems can be optimized to vehicle level metrics instead of subsystem level only. This will result in a more effective and balanced overall aircraft design. Using a T2T model to evaluate the integration of a HEPS system on an aircraft will enable assessment of its overall impact to next generation aircraft. Therefore, the significant impact of highly dynamic power and thermal loads on next generation aircraft is addressed. The third study is the implementation of an air cycle based ECS in a legacy (4th generation) air vehicle. Relatively few attempts have been made to define appropriate validation testing constructs for T2T analysis in a transient mode of operation. Current research addresses the process of validation testing using legacy aircraft systems in order to acquire relevant data that will lead to the validation of existing models, and different modeling methods. The model developed in this work will eventually be utilized in these validation efforts at a later date. To this end, an air vehicle system (AVS), turbine engine, generator, and environmental control system (ECS) have been modeled in a T2T model of the actual legacy system. In particular, this study will focus on the creation and integration of the ECS model. The ECS uses an air cycle machine, which utilizes a Brayton refrigeration cycle to cool the air to the cockpit and avionics. The ECS model will be shown to successfully cool these components while subjected to varying bleed rates from the turbine engine.

Committee:

Rory Roberts, Ph.D. (Advisor); Mitch Wolff, Ph.D. (Advisor); Scott Thomas, Ph.D. (Committee Member); Edward Alyanak, Ph.D. (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

mechanical engineering

Zhou, YitongMechanical Characterization of Automotive Electrical Wires and Wire Harnesses
Master of Science, The Ohio State University, 2016, Mechanical Engineering
An automotive wire harness is an organized set of individual electrical wires, terminals and connectors that run throughout the entire vehicle transmitting information and electric power. Wire harnesses may be exposed to tensile, bending and torsion loads during and after being assembled in cars, causing stress and strain in the individual electrical wires without accurate validation from CAE tools. The lack of accurate CAE tools for wire harnesses has been generating extra costs to automotive OEMs for many years due to issues like rattling and interference with other parts. Present CAE software packages are not developed specifically for wire harness simulation and oversimplified models have been used such as elasticity behavior as well as ignoring taping and contact forces. To be able to develop an accurate CAE tool to simulate wire harnesses, the mechanical properties of harnesses and harness components must be fully characterized. However, due to the complexity, flexibility and high variation in wire harnesses and individual electrical wires, their mechanical properties have not been studied systematically and thoroughly in previous studies. In addition, no standards and very few experimental methods for mechanical testing of single electrical wires and wire harnesses have been developed, which led to few empirical data for CAE simulation resulting in inaccurate models. In this study, mechanical experiments have been categorized, developed and conducted on individual electrical wires and wire bundles under different loading conditions to identify key mechanical properties and behaviors. FEA researchers utilized these empirical data to create computational models for electrical wires and wire bundles. The experiments for individual electrical wires were categorized into tensile, bending and torsion tests. From tensile tests, stress-strain curves of three different wires were obtained, and elastic modulus, yield strength, elongation as well as ultimate tensile strength (UTS) were identified. Wires of different types and dimensions showed different properties especially in elongation and UTS. Two bending tests including compression and cantilever bending tests were set up and conducted. In both tests, motion capture was utilized to identify the deflection of wires throughout the whole deformation process. Compression bending tests were conducted under compression load similar to fixed end buckling for four different wires. Results show that there is a large difference in initial force between the samples, which indicates difficulty in FEA simulation. In addition, motion capture plots and pictures showed large differences in deflection orientation but minor out of plane deflection. Cantilever bending test showed more consistency in the load, especially in the initial regime. Torsion tests were conducted based on a force controlled method. The results showed that the rotation angle is highly rate dependent due to creep behavior. Cyclic compression bending tests were conducted on wire bundles with a different and larger setup. Shape deflection was captured by motion capture and force data was collected by load cell. The force data at the first load showed large differences at the beginning for different samples while were very consistent when bent and in other cycles. Plasticity behavior was found in all tests, using which the simulation aspects were able to develop more accurate plastic models for electrical wires and wire bundles under different loading conditions.

Committee:

Marcelo Dapino (Advisor); Soheil Soghrati (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

Mechanical Engineering, Automotive, Electrical

Johnson, Mark BradleyHybrid Particle Image Velocimetry with the Combination of Cross-Correlation and Optical Flow Method
Master of Science in Mechanical Engineering (MSME), Wright State University, 2016, Mechanical Engineering
Particle Image Velocimetry (PIV) has been of relevant discussions lately as the equipment used to obtain temporally and spatially resolved flow fields have advanced rapidly. Despite these advancements, the accuracy of evaluating these images have yet to exceed expectations. Current techniques typically utilize one method, either correlation based (frequently) or optical flow (non-frequently), and both are vulnerable to specific conditions incorporated in the PIV images. Only through the combination of two methods, cross correlation and optical flow, can a technique benefit from the strengths of each method while concealing the flaws each individual method contains. The Hybrid Particle Image Velocimetry method utilizes the fairly unrestricted cross-correlation method, which can process images that contain particles with relatively large displacements, and the high resolution analysis of the Optical Flow method. Susceptible to large displacements, the Optical flow method is restricted to images with particularly small displacements. Combining the two methods requires the constraints set forth on the Optical flow method to be conserved. Meaning that the Cross-correlation results have to be manipulated into a form applicable for the Optical Flow method. Thus steps such as interpolation, shifting the image, and filtering the image are crucial for transitioning cross-correlation results to optical flow analysis. Validating the accuracy of the Hybrid method was conducted through standard PIV images that encompassed various parameters encountered in PIV. Each set of images were analyzed by the hybrid method and three other commonly-used correlation techniques in order to compare the hybrid method’s accuracy with current methods. Results confirmed that the Hybrid method is consistently more accurate than the other methods, especially near the boundaries. Additionally, for cases dealing with large particles or small displacement, the Hybrid method attains more accurate results.

Committee:

Zifeng Yang, Ph.D. (Advisor); Philippe Sucosky, Ph.D. (Committee Member); Rory Roberts, Ph.D. (Committee Member)

Subjects:

Engineering; Mechanical Engineering

Keywords:

mechanical engineering;engineering

Carpenter, Wesley AEngineering Creativity: Toward an Understanding of the Relationship between Perceptions and Performance in Engineering Design
Doctor of Philosophy, University of Akron, 2016, Secondary Education
Few studies have focused on perceptions of creativity in engineering. Previous researchers have tended to focus on perceptions concerning the degree to which creative thinking is emphasized in the classroom, rather than on whether students value creativity as an important part of the engineering design process. Moreover, the relationship between students’ perceptions of the importance of creative thinking in engineering design and their creative performance has not been investigated. Given the value placed on the ability of an engineer to think creatively, it is important to understand how engineering students perceive creativity as it relates to the engineering design process and whether such perceptions have the potential to influence their ability to think creatively during the engineering design process. In this mixed-methods study, perceptions related to four primary themes: students’ perceptions of (a) the definition of creativity with respect to engineering design, (b) the importance of creativity during engineering design, (c) the extent to which creativity was developed throughout the engineering program, and (d) their own creative abilities. Themes were compared among eight engineering students who scored at the extreme ends of the Creative Engineering Design Assessment (CEDA). In addition, perceptions were gathered from 12 mechanical engineering faculty in order to compare their perceptions of creativity in the mechanical engineering program to those of the students. The findings of this study support predictions made by applying the expectancy-value theory, which holds that students who value creativity in engineering design and confidently believe they have the ability to be creative are more likely to be creative in various engineering design scenarios. Further, all students interviewed shared the perception that the mechanical engineering program did little to encourage and develop creative-thinking skills; however, students agreed the program developed the foundational knowledge necessary for creative thought. These findings may be useful for engineering educators as well as for guiding future researchers in the areas of engineering education and engineering creativity.

Committee:

Nidaa Makki, Dr. (Advisor); Susan Kushner Benson, Dr. (Committee Member); Wondimu Ahmed, Dr. (Committee Member); Edward Evans, Dr. (Committee Member); Francis Broadway, Dr. (Committee Member)

Subjects:

Education; Engineering

Keywords:

creativity; engineering education; engineering design; perceptions; expectancy-value theory; mechanical engineering

Mao, ShuoValidation Studies of SC/Tetra Code in 2D and 3D Simulations
Master of Science in Engineering (MSEgr), Wright State University, 2014, Mechanical Engineering
In this thesis, 2D CFD simulations, 3D CFD simulations, and one 2D Fluid-Structure Interaction (FSI) problem were investigated using combined CFD and an FEA (Finite Element Analysis) tool. Discussions focused on turbulence models, mesh sizes, prism layer sizes, under-relaxation-factor, etc. The solution of CFD simulation and FSI simulation was validated using the results of previous CFD solvers and experimental data presented in the literature. The SST model results for the 2D mixing layer, 2D airfoil near-weak, axisymmetric subsonic jet, and 2D convex curvature boundary layer studies agree with previous CFD results within a 1% error. The k-e model with wall function gives better results than the SST model in the natural convection in a square cavity case. The SST model gives accurate results in the study of the drag coefficient of a sphere. The result for the FSI simulation agrees well with previous data.

Committee:

George Huang, Ph.D. (Advisor); Joseph Shang, Ph.D. (Committee Member); Zifeng Yang, Ph.D. (Committee Member); Robert Fyffe, Ph.D. (Other)

Subjects:

Mechanical Engineering

Keywords:

mechanical engineering

Cousineau, Jeffrey ScottEffect of Cooling Rate and Mold Counter Pressure on the Crystallinity and Foaming Control In Microcellular Injection Molded Polypropylene Parts
Master of Science in Engineering (MSEgr), Wright State University, 2012, Mechanical Engineering
Microcellular polymer injection molding is a growing industry technique due to its ability to produce dimensionally stable stress free parts while reducing cycle time, material usage, and energy costs. The process was invented by Dr. Nam P. Suh at the Massachusetts Institute of Technology in the early 1980's. The basic idea is to dissolve a supercritical fluid into the polymer melt which will nucleate and expand within the part core after injection during the cooling stage. Microcellular polymer injection molding is becoming increasingly popular in automotive, semiconductor, and industrial applications. While the technique has been widely successful using amorphous polymers, semi-crystalline polymers present new challenges not encountered during processing with their amorphous counterparts. The polymer chains in a semi-crystalline material develop an organized crystal structure during the cooling stage. Crystal development generates two main issues for microcellular processing. The first being that the excess heat released during the crystal formation affects the expansion of the microcellular bubble causing unpredictable non-uniform growth. The second is that the growth of the crystal structure within the polymer melt expels and displaces the supercritical fluid forcing the foaming to occur out at the edges of the part rather than uniformly through its core. This paper develops and explores strategies to control and overcome these problems. The first strategy is to effectively control the cooling rate. It is well know and has been proven, that increasing the cooling rate during the crystallization process can decrease crystallinity effectively freezing the polymer microstructure in place before the polymer chains can become completely organized. The second strategy is to utilize in mold counter pressure to observe its effect of the development of the foaming and crystallization. In mold counter pressure has been found to be an effective means of controlling bubble size and distribution during amorphous microcellular injection molding therefore it has merit for being an effective method to control foaming with semi-crystalline polymers. These two strategies have been implemented on a set of experiments and the results measured and observed by differential scanning calorimetry and scanning electron microscopy. The results of the experiment indicate the strategies implied are effective methods for improving part quality and also impose confidence in further development.

Committee:

George Huang, PhD (Committee Chair); Shia-Chung Chen, PhD (Committee Co-Chair); Wen Ren Jong, PhD (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

mechanical engineering

Ziebro, Thomas RIn vivo PPy(DBS) sensors to quantify excitability of cells via sodium fluctuations in extracellular solution
Master of Science, The Ohio State University, 2017, Mechanical Engineering
Our current understanding of electrophysiological phenomena is limited by our ability to measure particular processes. There are a number of electrophysiological intracellular and extracellular measuring techniques which currently exist; however, they are not without limitations. These techniques, such as patch-clamping, involve the careful isolation of a singular cell (which removes the cell from its native environment) and subsequent puncturing or suctioning of the cell membrane (which can damage the cellular structure). This research focuses on the development of conducting polymer sensors for in vivo measurements of electrophysiological phenomena. The goal of this work is to create a system by which ion concentration dynamics can be directly measured and analyzed to quantify metrics of biological processes without harming tissues of the organism. Quasi-potentiostatic amperometric sensors were developed using polypyrrole doped with dodecylbenzenesulfonate (DBS) to form PPy(DBS). By applying a cyclic pulse voltage input to the conducting polymer measurement system, and measuring the resulting current response, system parameters can be correlated to deviations from an equilibrium concentration as a function of time. This research will lay the foundation for more complex measurement techniques, both in electrophysiology, as well as in energy storage technology.

Committee:

Vishnu Baba Sundaresan (Committee Member); Daniel Gallego-Perez (Committee Member)

Subjects:

Biomedical Engineering; Cellular Biology; Engineering; Mechanical Engineering; Neurobiology; Neurology; Neurosciences

Keywords:

conducting polymers; PPy; DBS; electrochemistry; bioengineering; biomedical engineering; mechanical engineering; chemistry; neuron; electrophysiology; electrochemistry; system dynamics; sensor design; smart material; tissue nanotransfection;

Rinehart, Aidan WalkerA Characterization of Seal Whisker Morphology and the Effects of Angle of Incidence on Wake Structure
Master of Science in Mechanical Engineering, Cleveland State University, 2016, Washkewicz College of Engineering
Seal whiskers have been found to produce unique wake flow structures that minimize self-induced vibration and reduce drag. The cause of these wake features are due to the peculiar three-dimensional morphology of the whisker surface. The whisker morphology can be described as an elliptical cross section with variation of diameter in the major and minor axis along the length and, angle of incidence, rotation of the elliptical plane with respect to the whisker axis, α at the peak and β at the trough. This research provided a more complete morphology characterization accomplished through CT scanning and analysis of 27 harbor and elephant seal whisker samples. The results of this study confirmed previously reported values and added a characterization of the angle of incidence finding that the majority of angles observed fall within ±5° and exhibit a random variation in magnitude and direction along the whisker length. While the wake effects of several parameters of the whisker morphology have been studied, the effect of the angle of incidence has not been well understood. This research examined the influence of the angle of incidence on the wake flow structure through series of water channel studies. Four models of whisker-like geometries based on the morphology study were tested which isolate the angle of incidence as the only variation between models. The model variations in angle of incidence selected provided a baseline case (α = β = 0°), captured the range of angles observed in nature (α = β = -5°, and α = β = -15°), and investigated the influence of direction of angle of incidence (α = -5°, β = -5°). The wake structure for each seal whisker model was measured through particle image velocimetry (PIV). Angle of incidence was found to influence the wake structure through reorganization of velocity field patterns, reduction of recovery length and modification of magnitude of Tu. The results of this research helped provide a more complete understanding of the seal whisker morphology relationship to wake structure and can provide insight into design practices for application of whisker-like geometry to various engineering problems.

Committee:

Wei Zhang, PhD (Advisor); Ibrahim Mounir, PhD (Committee Member); Shyam Vikram, PhD (Committee Member)

Subjects:

Aerospace Engineering; Aquatic Sciences; Engineering; Fluid Dynamics; Mechanical Engineering

Keywords:

seal; whisker; PIV; biomimicry; fluid dynamics; particle image velocimetry; bio-engineering; engineering; mechanical engineering; aerospace engineering; experimental fluid dynamics;

Hammer, Jeremiah ThomasPlastic Deformation and Ductile Fracture of Ti-6Al-4V under Various Loading Conditions
Master of Science, The Ohio State University, 2012, Mechanical Engineering

Plastic deformation and ductile fracture of Ti-6Al-4V plate stock is investigated under multiple loading conditions. The objective of this study is to generate experimental data that can be used for the development and calibration of constitutive and failure models for numerical simulations of dynamic events. Plastic deformation is investigated at various strain rates, orientations, temperatures, and stocks. The stress state dependence of ductile fracture is also investigated.

Uniaxial tension, compression, and pure shear experiments are conducted at strain rates ranging from 1.0E-4 1/s to 8000 1/s. Specimens are fabricated from several sheet and plate stocks with thicknesses of 2.29mm, 3.56mm, 6.35mm, and 12.7mm. Compression and tension tests are conducted with specimens oriented in several different directions. These data show significant strain rate sensitivity in tension, compression and shear. Both plates exhibit anisotropic plastic deformation behavior in tension and compression. The response of each of the plates are significantly different for yield stress, flow stress, hardening, failure, and anisotropic effects.

Ductile fracture testing is conducted at various stress states, which are achieved with mechanical tests on various sample geometries subjected to various loading conditions. Tension tests are conducted on thin flat specimens, wide flat specimens and axisymmetric specimens with varying notch radii. Thin walled tube specimens are subjected to combined axial-torsional loading for additional states of stress. The results show that the stress triaxiality alone is unable to properly capture the failure characteristics of material. Digital image correlation is used to measure surface strains of the specimens. Parallel LS-DYNA simulations are used to determine the stress states and fracture strains. A fracture locus for Ti-6Al-4V is created in the stress triaxiality and Lode parameter stress space giving a more accurate description of the material fracture.

An experimental technique is introduced to measure full field strains using three dimensional digital image correlation at temperatures up to 800C. This test setup has been designed to be a straight forward, repeatable, and accurate method for measuring strains at high temperatures. Design hurdles included thermal gradients of air, speckle pattern adhesion, viewing window image distortion, camera calibration, and infrared light pollution of the camera sensor. For validation, the coefficient of thermal expansion for Ti-6Al-4V up to 800C is measured using the technique and compared to published values. Tests on Ti-6Al-4V were conducted in tension, compression, and torsion (shear). Experimentally measured coefficient of thermal expansion values correlate well with handbook values. The system performs well for each of the tests conducted here and gives substantially more data than standard methods.

Committee:

Amos Gilat (Advisor); Mark Walter (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

Titanium; Hopkinson bar; Kolsky bar; digital image correlation; high temperature; ti-6al-4v; plasticity; anisotropic; mechanical engineering

Chen, Yen-PinA Study of the Aerodynamic Behavior of a NREL Phase VI Wind Turbine Using the CFD Methodology
Master of Science in Engineering (MSEgr), Wright State University, 2011, Mechanical Engineering

Wind energy is an abundant natural resource that people have been trying to tap in recent decades. More and more wind turbines are being built to solve the world's energy shortage problem. For a wind turbine, power extracted from the wind by the rotor and the torque applied to the wind turbine blades are important issues in the design process. Thus there is a need to predict the performance of wind turbine blades using computer modeling. This work shows the results of a computational fluid dynamic simulation developed to predict the air flow field and associated aerodynamic quantities around the moving blades of a wind turbine.

The commercial software package SolidWorks was used to construct the geometrical model. Two commercial CFD codes, SC/Tetra and FLUENT, were used to do the fluid simulations. This work was performed in two phases. First a two-dimensional airfoil simulation was modeled to investigate the aerodynamic coefficients Cl, Cd, and Cm for the S809 airfoil. Validation of the CFD model was also examined. The second phase of this modeling work was a three-dimensional model of the flow around the NREL (National Renewable Energy Laboratory) Phase VI wind turbine rotor, which is a horizontal axis wind turbine with two blades using an S809 airfoil. In the three-dimensional model, both rotating blades were simulated. Power extracted from the wind by the rotor, torque on the blades due to the wind, pressure distributions on the blades, and air flow velocity distributions around the blades are the results presented in this work. Comparisons between results obtained from numerical computations and those from the experimental investigation and previous computational investigations are in a good agreement.

Subsequently, using FLUENT codes a detailed study of the effect of yaw angle on power extraction and blade torque was performed. Results are presented for yaw angles of 0°, 10°, 20°, 30°, and 60° and wind speeds of 7m/s, 10m/s, 13m/s, 15m/s, 20m/s, and 25m/s. These results show that yaw angles up to 20° do not cause more than a 2% reduction in power extraction, indicating that wind turbines do not have to be perfectly aligned with the wind for good operation. This is beneficial in practice because it may be difficult to align the wind turbine with the wind direction under the condition of rapidly changing wind directions.

Committee:

James Menart, PhD (Advisor); George Huang, PhD (Committee Member); Joseph Shang, PhD (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

mechanical engineering; aerodynamic behavior; wind turbine

Doak, Heather NEFFECT OF PROCESS VARIABLES ON SUB-MELT THERMAL BEHAVIOR AND SOLID-STATE PHASE TRANSFORMATIONS IN BEAM-BASED ADDITIVE MANUFACTURING OF TI-6AL-4V
Master of Science in Engineering (MSEgr), Wright State University, 2013, Mechanical Engineering
The success of laser and electron beam-based fabrication processes for additive manufacture and repair applications requires the ability to control melt pool geometry while maintaining a consistent and desirable microstructure. Previous work has employed a process map approach to link melt pool geometry to solidification microstructure (grain-size and morphology) in beam-based fabrication of Ti-6Al-4V. The current work extends the approach to investigate the effects of process variables on solid-state phase transformations below the solidification temperature through Finite Element Modeling, the 3-D Rosenthal Solution, and experimentation. Process maps for solid-state microstructure could be used to help maintain consistent and reliable mechanical properties during deposition of complex features. The characterization of seventeen Ti-6Al-4V samples was completed through Electron Backscatter Diffraction, X-ray Diffraction, Vickers Hardness tests. The solid-state transformation of Ti-6Al-4V was investigated to find trends in beta grain size, alpha lath thickness, and types of alpha microstructures. Thermal conditions and melt pool areas were verified with Finite Element Analysis and the fitted Rosenthal solution. Results suggest the solid-state alpha morphology is uniform because of constant melt pool area, constant grain area, and constant Vickers Hardness tests.

Committee:

Nathan Klingbeil, Ph.D. (Advisor); Raghavan Srinivasan, P.E., Ph.D. (Committee Member); Jaimie Tiley, P.E., Ph.D. (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

mechanical engineering

Sinko, Robert ArnoldCharacterization, Modeling, and Applications of Novel Magneto-Rheological Elastomers
Bachelor of Science, Miami University, 2012, School of Engineering and Applied Science - Mechanical Engineering

Magnetorheological elastomers (MREs) are an emerging branch within the smart materials field that consists of hard or soft magnetic particles embedded in a rubber compound. Current applications and research have been focused on changing the stiffness of these materials by applying an external magnetic field. Components of vibration absorbers and base isolation systems that employ this material have shown the capability of offering improved performance over conventional solutions. These particular applications use soft magnetic material; however, MRE materials containing hard magnetic filler materials (those that remain permanently magnetized) were the primary focus of this project and are referred to as H-MREs. When a magnetic field is applied perpendicularly to these particles, the filler particles generate a net torque and these samples can be used as a controlled actuator. Preliminary work has been conducted to characterize these H-MREs (since their properties are significantly different than “soft” MREs) and this work has shown their usefulness in engineering applications. However, unlike comparable smart materials such as piezoelectrics and electroactive polymers (EAP), additional modeling and experimentation needs to be conducted in order to develop usable models and better understand their behavior. The first portion of this paper focuses on developing experimental models to predict the behavior of H-MRE materials as cantilevered beam actuators for use in future applications.

Two additional, newer applications for which H-MREs could be useful are energy harvesting and sensing. Sensors are utilized almost everywhere today as they are used to monitor the performance of a system (whether it is fluid flow, vibration measurements, etc.). Piezoelectric materials, those that respond to electric stimuli, and Galfenol, an engineered material similar to MREs, have been studied extensively for their application as self-sensing actuators. It is hypothesized that H-MREs could be used in a similar capacity by developing a way to monitor the displacement of the material using a magnetic circuit. Based on a similar principle, energy harvesting involves the conversion of one form of energy (kinetic, solar, etc.) into a more storable form. Previous research has been conducted using other smart materials in this capacity and it is also hypothesized that H-MREs could be used in a similar capacity by capturing energy from mechanical vibrations and storing it in the form of electrical energy/power using a specialized circuit and the same principles discussed above. The primary goal of the second portion of this project will be to determine the feasibility of using H-MREs in the capacity of energy harvesting and sensing technologies. This feasibility study includes the development of experiments to assess these capabilities and the implementation of the experiments for verification of the predicted behavior. Finally, much consideration is given to work that will need to be done in the future in order to fully understand the behavior of these materials and allow them to be implemented in future relevant applications.

Committee:

Jeong-Hoi Koo, PhD (Advisor); Amit Shukla, PhD (Committee Member); Kumar Singh, PhD (Committee Member)

Subjects:

Materials Science; Mechanical Engineering

Keywords:

Mechanical Engineering; Smart Materials; Actuation; Magnetorheological; Elastomers; Sensing; Energy Harvesting; Material Characterization; Blocking Force; Beam Bending

Buettner, Robert W.Dynamic Modeling and Simulation of a Variable Cycle Turbofan Engine with Controls
Master of Science in Mechanical Engineering (MSME), Wright State University, 2017, Mechanical Engineering
Next generation aircraft (especially combat aircraft) will include more technology and capability than ever before. This increase in technology comes at the price of higher electrical power requirements and increased waste heat that must be removed from components to avoid overheating induced shutdowns. To help combat the resulting power and thermal management problem, a vehicle level power and thermal management design and optimization toolset was developed in MATLAB®/Simulink®. A dynamic model of a three-stream variable cycle engine was desired to add to the capabilities of the power and thermal management toolset. As an intermediate step to this goal, the dynamic mixed-flow turbofan engine model previously developed for the toolset was modified with an afterburner, a variable geometry nozzle, and a new controller to automatically control the new components. The new afterburning turbofan engine model was tested for a notional mission profile both with and without power take-off. This testing showed that the afterburning turbofan engine model and controller were successful enough to justify moving on to the development of the three-stream variable cycle engine model. The variable cycle engine model was developed using the components of the afterburning turbofan model. The compressor and turbine components were modified to use maps that incorporate the effects of variable inlet guide vane angles. The new engine model and components were sized by attempting to match data from a Numerical Propulsion System Simulation model with similar architecture. A previously developed heat exchanger model was added to the third stream duct of the new engine model. Finally, a new simplified controller was developed for the variable cycle engine model based on the controller developed for the afterburning turbofan model. The new variable cycle engine model was tested for a notional mission profile for five cases. The first case operated the engine model without power take-off and with the third stream heat exchanger removed. The second case added shaft power take-off. The third and fourth cases did away with the power take-off and added the heat exchanger to the engine model with two different hot-side mass flow rate conditions. The fifth case tested the engine with both power take-off and the third stream heat exchanger. The results were promising, showing that the variable cycle engine model had variable cycle tendencies even with a minimum of controlled variable geometry features. The controller was found to be effective, though in need of upgrades to take advantage of the benefits offered by a variable cycle engine. Additionally, it was found that both power take-off and heat rejection to the third stream impact the entire engine cycle.

Committee:

Rory Roberts, Ph.D. (Advisor); Mitch Wolff, Ph.D. (Committee Member); Rolf Sondergaard, Ph.D. (Committee Member); Robert Fyffe, Ph.D. (Other)

Subjects:

Aerospace Engineering; Mechanical Engineering

Keywords:

mechanical engineering; aerospace engineering

Lin, Kevin ChristopherAn Analysis of Naturalistic Driver Data in Evaluating Vehicle Longitudinal Control Systems
Master of Science, The Ohio State University, 2017, Mechanical Engineering
As vehicles with advanced driver assistance systems such as adaptive cruise control (ACC) become more common on the roads, many people have begun to raise concerns about their safety and control. The National Highway Traffic Safety Administration (NHTSA) is actively pursuing research in the performance and safety of different types of these systems in an effort to guide their development and to ensure that they are safe to the public. One fundamental aspect of this pursuit is gaining an understanding of human driver behaviors under normal driving conditions. This document presents an analysis of naturalistic driver data as a means to gage the performance and guide development of vehicle longitudinal control systems such as ACC. First, an analysis of the steady-state behavior is discussed, using a frequency content based approach and method to study and extract significant amounts of data. Next, a method is proposed that uses this extracted data to stochastically replicate these behaviors over indefinitely long periods of time. A second analysis of the same set of naturalistic data is also performed to guide the development of a simplified model of an ACC system based on a second-order single degree-of-freedom (SDOF) mass-spring-damper model. The study of the relationship between the behavior of the leading vehicle and the subsequent behavior of the following vehicle is of particular interest as it is used to gage the performance of the aforementioned ACC model under a series of three different inputs.

Committee:

Dennis Guenther (Advisor); Gary Heydinger (Advisor)

Subjects:

Mechanical Engineering

Keywords:

Naturalistic Driver Data; Evaluating; Vehicle Longitudinal Control Systems; mechanical engineering

Yacinthe, SamuelSystem Safety Development of a Performance PHEV Through a Model-Based Systems Engineering Approach
Master of Science, The Ohio State University, 2016, Mechanical Engineering
The Ohio State University is participating in EcoCAR 3, which is a four-year long competition amongst 16 North American university teams to redesign the 2016 Chevrolet Camaro to reduce its environmental impact, while maintaining the muscle and performance expected from the iconic American car. To effectively assess and increase overall product quality and readiness of Ohio State’s vehicle, this work defines and deploys a state of the art Model-Based Systems Engineering (MBSE) approach for managing engineering complexity as it relates to requirements management, traceability, and fulfillment. To demonstrate the effectiveness of the implemented approach, this work presents system safety development activities that have been conducted during the first two years of the competition. As EcoCAR 3 transitions into year-three, this work has already contributed to over a dozen awards by increasing overall documentation, traceability and workflow management as part of the overall engineering development process.

Committee:

Shawm Midlam-Mohler (Advisor); Giorgio Rizzoni (Committee Member)

Subjects:

Automotive Engineering; Mechanical Engineering

Keywords:

Model-Based Systems Engineering, Automotive, Mechanical Engineering

Neal, Michael TDevelopment, Evaluation, and Impact of a Hands-on Introductory Course in Mechanical Engineering
Master of Science, The Ohio State University, 2013, Mechanical Engineering
When The Ohio State University transitioned from quarters to semesters in August 2012, the Department of Mechanical and Aerospace Engineering introduced a new course, titled “Introduction to Design in Mechanical Engineering” (ME 2900). Sophomores generally take ME 2900 during their first semester in the mechanical engineering program. The course uses a hands-on approach to introduce students to the field of mechanical engineering through the fabrication, programming, and analysis of a radial six-cylinder compressed air motor. Half of the semester is devoted to formal machining instruction, and the other half is spent working with the Arduino microcontroller to learn practical electronics skills. During the first year of ME 2900, the air motor became a popular project among the students, and it also served as a useful teaching platform for illustrating diverse concepts within the field of mechanical engineering. ME 2900 has made an impact by helping students excel in future courses, attain and succeed at internships and co-ops, and led many students to discover new research interests and career paths. Future studies will continue to investigate ME 2900’s ongoing effect on the undergraduate mechanical engineering curriculum.

Committee:

Blaine Lilly (Advisor); Daniel Mendelsohn (Committee Member)

Subjects:

Education; Mechanical Engineering

Keywords:

mechanical engineering curriculum; experiential education; hands-on learning

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