Other Mechanical Engineering Commons^™

Shield Design For Maximum Deformation In Shape-Shifting Surfaces, Daniel Eduardo Perez

USF Tampa Graduate Theses and Dissertations

This research presents the initial studies and results on shield design for Shape-Shifting Surfaces (SSSs) seeking maximum compression and maximum expansion of a unit-cell. Shape-Shifting Surfaces (SSSs) are multilayered surfaces that are able to change shape while maintaining their integrity as physical barriers. SSSs are composed of polygonal unit-cells, which can change side lengths and corner angles. These changes are made possible by each side and corner consisting of at least two different shields, or layers of material. As the layers undergo relative motion, the unit-cell changes shape. In order for the SSS to retain its effectiveness as a barrier, …

Generalizable Methods For Modeling Lumbar Spine Kinematics, Craig Joseph Simons

Electronic Theses and Dissertations

A more complete understanding of lumbar spine kinematics could improve diagnoses and treatment of low back pathologies and may advance the development of biomechanical models. Kinematics describes motion of the five lumbar vertebrae without consideration for the forces that cause the motion. Despite considerable attention from researchers and clinicians, lumbar spine kinematics are not fully understood because the anatomy is not accessible for direct observation and the complex governing biomechanics produce small magnitude, coupled intervertebral movements.

The overall goal of this project was to develop a descriptive model of intervertebral lumbar spine kinematics that is applicable to a generalizable subject …

Review Of Electrochemical And Electrodischarge Machining, Kamlakar P. Rajurkar, M. M. Sundaram, A. P. Malshe

Department of Mechanical and Materials Engineering: Faculty Publications

Electrochemical and electro-discharge machining processes are the two major electro-machining processes with unique capabilities. Electrical Discharge Machining (EDM) and Electrochemical Machining (ECM) offer a better alternative or sometimes the only alternative in generating accurate 3-D complex shaped macro, micro and nano features and components of difficult–to-machine materials. Technological advances reported in electrochemical and electro discharge machining processes, which reflect the state of the art in academic and industrial research and applications, are briefly reviewed in this paper.

Wire Electro-Discharge Machining Of Titanium Alloy, Farnaz Nourbakhsh, Kamlakar P. Rajurkar, Ajay P. Malshe, Jian Cao

Department of Mechanical and Materials Engineering: Faculty Publications

This paper presents an experimental investigation of wire electro-discharge machining (WEDM) of titanium alloy. The objective is to investigate the effect of seven process parameters including pulse width, servo reference voltage, pulse current, and wire tension on process performance parameters (such as cutting speed, wire rupture and surface integrity). A Taguchi L18 design of experiment (DOE) has been applied. All experiments have been conducted using Charmilles WEDM. It was also found that the cutting speed increases with peak current and pulse interval. Surface roughness was found to increase with pulse width and decrease with pulse interval. The Analysis of Variance …

Selective Detection And Automated Counting Of Fluorescently-Labeled Chrysotile Asbestos Using A Dual-Mode High-Throughput Microscopy (Dm-Htm) Method, Myoung-Ock Cho, Hyo Mi Chang, Donghee Lee, Yeon Gyu Yu, Hwataik Han, Jung Kyung Kim

Department of Mechanical and Materials Engineering: Faculty Publications

Phase contrast microscopy (PCM) is a widely used analytical method for airborne asbestos, but it is unable to distinguish asbestos from non-asbestos fibers and requires time-consuming and laborious manual counting of fibers. Previously, we developed a high-throughput microscopy (HTM) method that could greatly reduce human intervention and analysis time through automated image acquisition and counting of fibers. In this study, we designed a dual-mode HTM (DM-HTM) device for the combined reflection and fluorescence imaging of asbestos, and automated a series of built-in image processing commands of ImageJ software to test its capabilities. We used DksA, a chrysotile-adhesive protein, for selective …

Photovoltaic Device, Jinsong Huang, Bin Yang, Yongbo Yuan

Department of Mechanical and Materials Engineering: Faculty Publications

An apparatus includes a substrate; and a photoactive layer disposed on the substrate. The photoactive layer includes an electron acceptor material; an electron donor material; and a material having dipoles.

Solution-Processed Nanoparticle Super-Float-Gated Organic Field-Effect Transistor As Un-Cooled Ultraviolet And Infrared Photon Counter, Yongbo Yuan, Qingfeng Dong, Bin Yang, Fawen Guo, Qi Zhang, Ming Han, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

High sensitivity photodetectors in ultraviolet (UV) and infrared (IR) range have broad civilian and military applications. Here we report on an un-cooled solution-processed UV-IR photon counter based on modified organic field-effect transistors. This type of UV detectors have light absorbing zinc oxide nanoparticles (NPs) sandwiched between two gate dielectric layers as a floating gate. The photon-generated charges on the floating gate cause high resistance regions in the transistor channel and tune the source-drain output current. This ‘‘super-float-gating’’ mechanism enables very high sensitivity photodetectors with a minimum detectable ultraviolet light intensity of 2.6 photons/µm²s at room temperature as well …

Analysis Of Electrically-Forced Vibrations Of Piezoelectric Mesa Resonators, Huijing He, Guo-Quan Nie, Jin-Xi Liu, Jiashi Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We study the electrically forced thickness-shear and thickness-twist vibrations of stepped thickness piezoelectric plate mesa resonators made of polarized ceramics or 6-mm class crystals. A theoretical analysis based on the theory of piezoelectricity is performed, and an analytical solution is obtained using the trigonometric series. The electrical admittance, resonant frequencies, and mode shapes are calculated, and strong energy trapping of the modes is observed. Their dependence on the geometric parameters of the resonator is also examined.

High Performance Low Temperature Solid Oxide Fuel Cells With Novel Electrode Architecture, Yu Chen, Qian Liu, Zhibin Yang, Fanglin Chen, Minfang Han

Faculty Publications

In this study, we have fabricated high performance low temperature solid oxide fuel cells (LT-SOFCs) with both acicular anodes and cathodes with thin Gd-doped ceria (GDC) electrolyte film. The acicular Ni-Gd_0.1Ce_0.9O_2−δ (Ni-GDC) anode was prepared using freeze drying tape casting, while the hierarchically porous cathode with nano-size Sm_0.5Sr_0.5CoO₃ (SSC) particles covering an acicular GDC skeleton was prepared by a combination of freeze drying tape casting and self-rising approaches. The acicular electrodes with 5–200 μm pores/channels enhance mass transport, while SSC particles of about 50 nm in the cathode promote …

Energy Trapping Of Thickness-Shear And Thickness-Twist Modes In A Partially Electroded At-Cut Quartz Resonator, Huijing He, Guoquan Nie, Jinxi Liu, Jiashi Yang

Department of Mechanical and Materials Engineering: Faculty Publications

The thickness-shear and thickness-twist vibrations of a finite and partially electroded AT-cut quartz resonator are investigated. The equations of anisotropic elasticity are used with the omission of the small elastic constant c56 . An analytical solution is obtained using Fourier series from which the free vibration resonant frequencies, mode shapes, and energy trapping are calculated and examined.

Sustainability For Die Manufacturing: Comparative Study Of Wedm And Milling, Matthew S. Kalus

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Sustainability is more important in today's culture due to the increasing demand for a more eco-friendly society. Concentrations in minimizing and reducing environmental impacts, energy and natural resources have been forthcoming in industry. The tool, mold and die industries are the most well known industries that machine harder materials using mills and WEDM. The objective of this thesis was to compare the sustainability differences in both of these machines utilizing the accepted standards for evaluating the manufacturing process performance for sustainability. These standards include the evaluation of the process parameters, raw materials, power, tools and fluids which all contribute to …

A Study Of Hdpe In High Pressure Of Hydrogen Gas: Measurement Of Permeation Parameters And Fracture Criteria, Sompong Prachumchon

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The permeation parameters of hydrogen gas in high density polyethylene (HDPE) system are sought by comparison with a diffusion model. The method of Green’s functions is used to obtain solutions for the diffusion model. Permeation parameters are found from transient experimented data during two processes; pressurization followed by depressurization. The mechanical compression of HDPE during the pressurization process resulted in lower diffusivity coefficient values and higher solubility values. The results show that the diffusivity coefficient value in the pressurization process is 37% of that during the depressurization process. At the start of the depressurization process, a short-duration fast flow rate …

Handitrike - Recumbent Tricycle, Sean Higginson, Kevin Howie, Vinay Patel

Mechanical Engineering

This report covers the design and construction of the recumbent racing tricycle for Mr. Robert T. Kelly, a disabled veteran. Unfortunately Rob’s right leg is five inches shorter than his left one and therefore is unable to properly operate standard cranks. Our team HandiTrike is composed of Sean Higginson, Kevin Howie, and Vinay Patel and our project requires us to come up with a design that is feasible to complete within the given three quarters, as well as allow Rob to gain full use of his tricycle. Currently Rob ‘s trike uses the standard crank set up found on most …

Formula Sae Turbocharger Engine Development, Eric Griess, Kevin Mccutcheon, Matthew Roberts, William Chan

Mechanical Engineering

This project, Formula SAE Turbocharger System Development, was sponsored by the Cal Poly, San Luis Obispo Formula SAE team. The team proposed this project in order to have a powerful yet lightweight engine so they can be extremely competitive at their competition. The baseline output of the single cylinder 450cc engine (2006 Yamaha WR450F) was 46 horsepower and 27 ft-lb of torque. The goal of this project was to increase the output of that engine to 60 horsepower and 35 ft-lb through the use of a turbocharger.

Predicting Vehicle Dynamics For Roadside Safety Using Multibody Systems Simulations, Brett D. Schlueter

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Accurate means for predicting vehicle dynamics is required in the design and testing of roadside safety hardware. Past research has used finite element (FE) modeling to this end, but multibody systems (MBS) modeling may provide a more efficient way to solve these problems. MBS modeling using Adams/Car was investigated by first compiling an introduction to the program, then performing basic vehicle dynamics simulations using a supplied model. Next, a model of a 2270 kg pickup was created and validated against physical test data involving impact with a speed bump. Finally, pickup trajectories in 4H:1V and 6H:1V V-ditches were predicted for …

Atomistic Investigation Of Scratching-Induced Deformation Twinning In Nanocrystalline Cu, Junjie Zhang, Tao Sun, Yoganda Yan, Dong Shen, Xiaodong Li

Faculty Publications

Deformation twinning is an important deformation mode of nanocrystalline metals. In current study, we investigate the scratching-induced deformation twinning in nanocrystallineCu by means of molecular dynamics simulations. The tribological behavior, the deformation mechanisms, the formation mechanism of deformation twins, and the grain size dependence of the propensity of deformation twinning are elucidated. Simulation results demonstrate that deformation twinning plays an important role in the plastic deformation of nanocrystallineCu under nanoscratching, in addition to dislocation activity and grain boundary-associated mechanism. The nucleation of initial twinning partial dislocations originates from the dissociation of lattice partial dislocations that emit from grain boundary triple …

Maximal Force Characteristics Of The Ca2+-Powered Actuator Of Vorticella Convallaria, Sangjin Ryu, Matthew J. Lang, Paul Matsudaira

Department of Mechanical and Materials Engineering: Faculty Publications

The millisecond stalk contraction of the sessile ciliate Vorticella convallaria is powered by energy from Ca²⁺ binding to generate contractile forces of ~10 nN. Its contractile organelle, the spasmoneme, generates higher contractile force under increased stall resistances. By applying viscous drag force to contracting V. convallaria in a microfluidic channel, we observed that the mechanical force and work of the spasmoneme depended on the stalk length, i.e., the maximum tension (150–350 nN) and work linearly depended on the stalk length (~2.5 nN and ~30 fJ per 1 mm of the stalk). This stalk-length dependency suggests that motor units of …

Static Balancing Of The Cal Poly Wind Turbine Rotor, Derek Simon

Master's Theses

The balancing of a wind turbine rotor is a crucial step affecting the machine’s performance, reliability, and safety, as it directly impacts the dynamic loads on the entire structure.

A rotor can be balanced either statically or dynamically. A method of rotor balancing was developed that achieves both the simplicity of static balancing and the accuracy of dynamic balancing. This method is best suited, but not limited, to hollow composite blades of any size. The method starts by quantifying the mass and center of gravity of each blade. A dynamic calculation is performed to determine the theoretical shaking force on …

Shear-Horizontal Vibration Modes Of An Oblate Elliptical Cylinder And Energy Trapping In Contoured Acoustic Wave Resonators, Huijing He, Jiashi Yang, John A. Kosinski

Department of Mechanical and Materials Engineering: Faculty Publications

We study shear-horizontal free vibrations of an elastic cylinder with an oblate elliptical cross section and a traction-free surface. Exact vibration modes and frequencies are obtained. The results show the existence of thickness-shear and thickness-twist modes. The energy-trapping behavior of these modes is examined. Trapped modes are found wherein the vibration energy is largely confined to the central portion of the cross section and little vibration energy is found at the edges. It is also shown that face-shear modes are not allowed in such a cylinder. The results are useful for the understanding of the energy trapping phenomenon in contoured …

Order-Disorder Transition Of Aragonite Nanoparticles In Nacre, Zaiwang Huang, Xiaodong Li

Faculty Publications

Understanding nacre’s bottom-up biomineralization mechanism, particularly, how individual aragonite platelets are formed, has long remained elusive due to its crystallographic peculiarity and structural complexity. Here we report that crystallographic order-disorder transition can be triggered within individual aragonite platelets in pristine nacre by means of heat treatment and/or inelastic deformation, offering a unique opportunity to discriminate mysterious aragonite nanoparticles in transmission electron microscopy. Our findings unambiguously uncover why aragonite nanoparticles in pristine nacre have long been inaccessible under TEM observation, which is attributed to the monocrystal-polycrystal duality of the aragonite platelet. The underlying physical mechanism for why an individual aragonite platelet …