Mechanical Engineering Commons^™

Fatigue Based Structural Design Exploration Via Engineering Data Analytics, Hao Li

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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 …

Validation Studies Of Sc/Tetra Code In 2d And 3d Simulations, Shuo Mao

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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 …

Computational Investigation Of Rotary Engine Homogeneous Charge Compression Ignition Feasibility, Michael Irvin Resor

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The Air Force Research Laboratory (AFRL) has been investigating the heavy fuel conversion of small scale Unmanned Aerial Vehicles (UAV). One particular platform is the Army Shadow 200, powered by a UEL Wankel rotary engine. The rotary engine historically is a proven multi-fuel capable engine when operating on spark ignition however, little research into advanced more efficient compression concepts have been investigated. A computational fluid dynamics model has been created to investigate the feasibility of a Homogeneous Charge Compression Ignition (HCCI) rotary engine. This research evaluates the effects, rotor radius to crankshaft eccentricity ratio, known as K factor, equivalence ratio, …

The Collapsible Trailer: Design And Manufacture, Robert Hobson

Biomedical Engineering

No abstract provided.

Pvcrov : An Experimental Platform For Multi-Robot Control Systems, Nicholas Prince, Gregory Roos, Jennifer Semones, Chase Traficanti

Mechanical Engineering Senior Theses

As the field of multi-robot control systems grows, the demand for flexible, robust and precise multi-robot testbeds increases. Up to this point, the testbeds that do exist for testing multi-robot controllers are often expensive, hard to deploy, and typically constrained to a single plane of motion. These constraints limit the capacity to conduct research which is why team Autonomously Controlled Electromechanical Systems (ACES) has created the PVCROV system. PVCROV is a low cost, underwater platform for testing multi-robot control systems. By utilizing an underwater environment, ACES created a testbed that is not constrained to a single plane of motion. Additionally, …

Formula Electric : Powertrain, Mark Allison, Bryan Bidwell, Stuart Hopson, Jackson Smith, Carlos Streegan, Dominic Villa

Interdisciplinary Design Senior Theses

The Santa Clara Formula Electric team designed, and manufactured a powertrain for an electric racecar according to the rules prescribed by the SAE International Formula Electric competition. The powertrain is divided into subsystems: the battery pack, battery pack cooling system, motor controller, and the motor. The battery pack was constructed, but full electrical connection of all cells were not made. The pack was not integrated with the motor and motor controller. In addition, due to time constraints, extensive testing could not be completed.

Project Omoverhi : Low-Cost, Neonatal Incubator, Richard Fong, Guillermo Gallardo, William Jeffery, Danny Maeda, Gabriel Romero

Interdisciplinary Design Senior Theses

Project Omoverhi, since its beginning in 2010-2011, has been focused on creating an incubator that has the capability of operating completely off grid. This year the project has been focused on redesigning the original system to reduce the cost to approximately $1000. In addition to this we have designed and implemented a control system that enables the user to set a desired temperature which can be maintained to within 1 degree Celsius. Before the project is able to be completed further work must be done. The thermal storage system that was initially proposed by the original team still needs to …

Anisotropic Compositional Expansion And Chemical Potential For Amorphous Lithiated Silicon Under Stress Tensor, Valery I. Levitas, Hamed Attariani

Mechanical and Materials Engineering Faculty Publications

Si is a promising anode material for Li-ion batteries, since it absorbs large amounts of Li. However, insertion of Li leads to 334% of volumetric expansion, huge stresses, and fracture; it can be suppressed by utilizing nanoscale anode structures. Continuum approaches to stress relaxation in Li_xSi, based on plasticity theory, are unrealistic, because the yield strength of Li_xSi is much higher than the generated stresses. Here, we suggest that stress relaxation is due to anisotropic (tensorial) compositional straining that occurs during insertion-extraction at any deviatoric stresses. Developed theory describes known experimental and atomistic simulation …

Effect Of Process Variables On Sub-Melt Thermal Behavior And Solid-State Phase Transformations In Beam-Based Additive Manufacturing Of Ti-6al-4v, Heather N. Doak

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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 …

Effect Of Cooling Rate And Mold Counter Pressure On The Crystallinity And Foaming Control In Microcellular Injection Molded Polypropylene Parts, Jeffrey Scott Cousineau

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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, …

A Novel Approach To The Part Orientation Problem For Robotic Assembly Applications, Brian James Slaboch

Master's Theses (2009 -)

SCARA (Selective Compliant Assembly Robot Arm) type robots are the most common type of assembly robots. These robots have four degrees of freedom (three rotational and one translational). Typically these robots are used for assembly tasks that take place along a vertical axis. Many times, however, assembly tasks take place along a non-vertical axis. To account for non- vertical axis assembly, parts must be fed in a proper orientation to allow for correct assembly. Parts feeders and specialized end-effectors are typically used to feed parts in their proper orientation. This thesis investigates a novel end-effector that can be used to …

Sr2Fe1.5Mo0.5O6 As Cathodes For Intermediate-Temperature Solid Oxide Fuel Cells With La0.8Sr0.2Ga0.87Mg0.13O3 Electrolyte, Guoliang Xiao, Qiang Liu, Fei Zhao, Lei Zhang, Changrong Xia, Fanglin Chen

Faculty Publications

The performance of Sr₂Fe_1.5Mo_0.5O₆ (SFMO) as a cathode material has been investigated in this study. The oxygen ionic conductivityof SFMO reaches 0.13 S cm^-1 at 800°C in air. The chemical diffusion coefficient (D_chem) and surface exchange constant (k_ex) of SFMO at 750°C are 5.0 x 10^-6 cm² s^-1 and 2.8 x 10^-5 cm s^-1, respectively, suggesting that SFMO may have good electrochemicalactivity for oxygen reduction. SFMO shows a thermal expansion coefficient (TEC) of 14.5 x 10^-6 K^-1 the …

A Study Of The Aerodynamic Behavior Of A Nrel Phase Vi Wind Turbine Using The Cfd Methodology, Yen-Pin Chen

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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 …

Experimental Studies Of Turbulent Boundary Layers Over A Rough Forward-Facing Step And Its Coarse Scale Resolution Approximations, Huiying Ren

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High spatial resolution PIV experiments are performed in the x-y plane at two different spanwise positions to compare the turbulent boundary layers over smooth and rough forward-facing-steps as well as the rough step's two coarse scale-resolution approximations. The Reynolds number based on the step's mean height, Re_h, is 3450 and the ratio of the boundary layer thickness to the step's height is δ/h = 8. The roughness topography on the top surface of the rough step is replicated from a realistic turbine blade and is intrinsically three-dimensional and highly irregular. The surface topographies of the coarse scale-resolution …

A Novel Far-Field Nanoscopic Velocimetry For Nanofluidics, C. Kuang, Guiren Wang

Faculty Publications

For the first time we have been able to measure the flow velocity profile for nanofluidics with a spatial resolution better than 70 nm. Due to the diffraction resolution barrier, traditional optical methods have so far failed in measuring the velocity profile in a nanocapillary or a closed nanochannel without an opened sidewall. A novel optical point measurement method is presented which applies stimulated emission depletion (STED) microscopy to laser induced fluorescence photobleaching anemometer (LIFPA) techniques to measure flow velocity. Herein we demonstrate this far-field nanoscopic velocimetry method by measuring the velocity profile in a nanocapillary with an inner diameter …

La0.85Sr0.15Mno3− Infiltrated Y0.5Bi1.5O3 Cathodes For Intermediate-Temperature Solid Oxide Fuel Cells, Jiang Zhiyi, Changrong Xia, Fei Zhao, Fanglin Chen

Faculty Publications

Porous yttria-stabilized bismuth oxides (YSB) were investigated as the backbones for (LSM) infiltrated cathodes in intermediate-temperature solid oxide fuel cells. The cathodes were evaluated using anode-supported single cells with scandia-stabilized zirconia as the electrolytes. With humidified as the fuel, the cell showed peak power density of 0.33, 0.52, and at 650, 700, and , respectively. At , the cell polarization resistance was only , of the lowest value previously reported, indicating that YSB is a promising backbone for the LSM infiltrated cathode.

Development Of A Velocity Metric For Rigid-Body Planar Motion, Luis Ernesto Criales Escobar

Master's Theses (2009 -)

Two motions of motion quality have been developed for planar motion. They are the "best motion measure" and the "velocity metric". The "best motion measure" identifies the best motion for a given displacement. The "velocity metric" quantifies the discrepancy between two planar motions for the same rigid body.

The best motion measure compares the motion of each particle on the body to an "ideal", but usually unobtainable, motion. This ideal motion moves each particle from its current position to its desired position on a straight-line path. Although the ideal motion is not a valid rigid body motion, this does not …

Hardware Dispenser Project, John D. Raff, Dave Owen, Paul Sheppard

Service-Learning Program

The purpose of this design project was to develop a system that will allow employees of the ARC to be able to work on a greater variety of projects and to improve their productivity. The hardware dispenser group developed a design for a tray that would help the ARC employees work quicker and more efficiently. The tray has bins to hold hardware which the supervisor loads onto the tray. The employee slides a bag over the tip of the funnel and into the clip which holds the bag in place. The worker then chooses which parts need to be in …

Laser Induced Fluorescence Photobleaching Anemometer For Microfluidic Devices, Guiren Wang

Faculty Publications

We have developed a novel, non-intrusive fluid velocity measurement method based on photobleaching of a fluorescent dye for microfluidic devices. The residence time of thefluorescent dye in a laser beam depends on the flow velocity and approximately corresponds to the decaying time of the photobleaching of the dye in the laser beam. The residence time is inversely proportional to the flow velocity. The fluorescence intensity increases with the flow velocity due to the decrease of the residence time. A calibration curve between fluorescence intensity and known flow velocity should be obtained first. The calibration relationship is then used to calculate …

Noble Metal Nanostructures Synthesized Inside Mesoporous Nanotemplate Pores, J. Arbiol, E. Rossinyol, A. Cabot, F. Peiro, A. Cornet, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Noble metal impregnation has resulted in the inclusion of metal nanostructures within the SBA-15 mesoporous silica hexagonal pores (from nanoclusters to nanowires). A bright-field transmission electron microscopy three-dimensional reconstruction is proposed to analyze the localization of nanostructures within the pores of mesoporous nanotemplates. The method allows corroboration whether the nanostructures are synthesized inside the pores or they are synthesized alternatively on the nanotemplate aggregates exterior surface.

Synthesis Of Tin Oxide Nanostructures With Controlled Particle Size Using Mesoporous Frameworks, A. Cabot, J. Arbiol, E. Rossinyol, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Tin oxide nanostructures with controlled narrow particle size distribution were synthesized inside silica mesoporous templates. In this way, particle growth was blocked by physically corseting the tin compound inside the silica frameworks, the pore diameter of which determines the final tin oxide crystallite size distribution. Template structures were subsequently eliminated by chemical methods to collect the unsupported semiconductor nanoparticles. Thus obtained tin oxed nanopowders, with particle sizes in the range between 6 and 10 nm, were structurally, chemically, and electically characterized. The results are compared with those obtained from the characterization of larger crystallite materials.

Surface States In Template Synthesized Tin Oxide Nanoparticles, A. Cabot, J. Arbiol, R. Ferre, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Tin–oxide nanoparticles with controlled narrow size distributions are synthesized while physically encapsulated inside silica mesoporous templates. By means of ultraviolet-visible spectroscopy, a redshift of the optical absorbance edge is observed. Photoluminescence measurements corroborate the existence of an optical transition at 3.2 eV. The associated band of states in the semiconductor gap is present even on template-synthesized nanopowders calcined at 800 °C, which contrasts with the evolution of the gap states measured on materials obtained by other methods. The gap states are thus considered to be surface localized, disappearing with surface faceting or being hidden by the surface-to-bulk ratio decrease.

Distributions Of Noble Metal Pd And Pt In Mesoporous Silica, J. Arbiol, A. Cabot, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Mesoporous silica nanostructures have been synthesized and loaded with Pd and Pt catalytic noble metals. It is found that Pd forms small nanoclusters (3–5 nm) on the surface of the mesoporous structure whereas Pt impregnation results in the inclusion of Pt nanostructures within the silica hexagonal pores (from nanoclusters to nanowires). It is observed that these materials have high catalytic properties for CO–CH4 combustion, even in a thick film form. In particular, results indicate that the Pt and Pd dispersed in mesoporous silica are catalytically active as a selective filter for gas sensors.

Effect Of Residual Thermal Stresses On Fracture Behavior And Mechanical Properties Of Al Sub 2 O Sub 3/Ni Cermets, Guo Jin Li, Da Ming Chen, Xiao Xian Huang, Jing Kun Guo

Faculty Publications

Effect of residual thermal stresses on fracture behavior and mechanical properties of Al₂O₃/Ni cermets was qualitatively explained by using theory on residual thermal stresses. When Ni particles are located within Al₂O₃ grains or Ni content is relatively low, tensile stresses are exerted at Al₂O₃-Al₂O₃ grain boundary. While fracturing, intergranular fracture is easily produced. When Ni particles are dispersed at Al₂O₃ grain boundary or Ni content is relatively high, compressive stresses are exerted at Al₂O₃-Al₂O₃grain boundary. …

Reduced-Temperature Solid Oxide Fuel Cells Fabricated By Screen Printing, Changrong Xia, Fanglin Chen, Meilin Liu

Faculty Publications

Electrolyte films of samaria-doped ceria (SDC, Sm_0.2Ce_0.8O_1.9) are fabricated onto porous NiO-SDC substrates by a screen printing technique. A cathode layer, consisting of Sm_0.5Sr_0.5CoO₃ and 10 wt % SDC, is subsequently screen printed on the electrolyte to form a single cell, which is tested at temperatures from 400 to 600°C. When humidified (3% H₂O) hydrogen or methane is used  as fuel and stationary air as oxidant, the maximum power densities are 188 (or 78) and 397 (or 304) mW/cm² at 500 and 600°C, respectively. Impedance analysis …

Preparation Of Ordered Macroporous Sr0.5sm0.5coo3 As Cathode For Solid Oxide Fuel Cells, Fanglin Chen, Changrong Xia, Meilin Liu

Faculty Publications

Ordered macroporous Sr_0.5Sm_0.5CoO₃ structrures with an average pore size of 140 nm have been prepared using closepacked arrangement of monodispersed polystyrene spheres as templates. A fuel cell using ordered macroporous Sr_0.5Sm_0.5CoO₃ as the cathode, gadolinia-doped ceria (GDC) film as the electrolyte, and GDC–NiO as the anode generated maximum power densities of 150, 196 and 267 mW/cm² at 500, 550 and 600 °C, respectively.

Preparation Of Mesoporous Sno2-Sio2 Composite As Electrodes For Lithium Batteries, Fanglin Chen, Zhong Shi, Meilin Liu

Faculty Publications

Mesoporous SnO₂–SiO₂ composite stable up to 600 °C with a BET surface area of 350 m² g^-1 and an average pore size of 3.4 nm is successfully prepared, which exhibits promising cycling properties as anodes for lithium batteries

Preparation Of Mesoporous Yttria-Stabilized Zirconia (Ysz) And Ysz-Nio Using A Triblock Copolymer As Surfactant, Fanglin Chen, Meilin Liu

Faculty Publications

Mesoporous yttria-stabilized zirconia (YSZ) and YSZ-NiO have been prepared for the first time using Pluronic P103 as a structure-directing agent and inorganic chlorides as precursors in a nonaqueous medium. After being fired at 500°C for 2 h, mesostructured YSZ has a BET surface area of about 146 m² g^-1, with an average pore size of 3.8 nm, while mesostructured YSZ-NiO has a BET surface area of about 108 m² g^-1, with an average pore size of 4.5 nm.

Oxygen Permeation Through Composite Oxide-Ion And Electronic Conductors, Kevin Huang, Michael Schroeder, John B. Goodenough

Faculty Publications

Oxygen permeation through composites consisting of four well-known oxide-ion conductors and a noble metal, Pd or Ag, is reported. The oxides were Zr_0.9Y_0.1O_1.95 (YSZ), (Bi_1.75Y_0.25O₃)_0.95(CeO₂)_0.05 (BYC5), Ce_0.8Sm_0.2O_1.9 (SSC), and La_0.8Sr_0.2Ga_0.83Mg_0.17O_2.815 (LSGM). The results show that (BYC5 + Ag) yields the highest oxygen permeation flux, but the composite deteriorates with time. The composites (SSC + Pd), (LSGM + Pd), and (YSZ + Pd) give stable, but relatively lower oxygen permeation flux …

Preparation Of Mesoporous Tin Oxide For Electrochemical Applications, Fanglin Chen, Meilin Liu

Faculty Publications

Mesoporous tin oxide stable up to 500 °C has been prepared for the first time using both cationic and neutral surfactants.