Mechanical Engineering Commons^™

Synthesis Of Poly(L-Lactic Acid) Scaffolds From Dioxane/Ethanol Using Control Rate Freezing And Study Of Its Microstructural Properties, George Idicula

LSU Master's Theses

Bio-degradable poly (l-lactic acid) (PLLA) scaffolds were prepared by using thermally induced phase separation (TIPS) method. A solution of PLLA-Dioxane was formed by dissolving PLLA in dehydrated 1,4-Dioxane at three wt/vol percentages, specifically 3, 7 and 10%. This PLLA-Dioxane solution was then frozen in borosilicate glass vials (5mL) at three cooling rates (1, 10 and 40 ˚C/min) in a commercially available controlled rate freezer (CRF). The frozen solution was freeze-dried to sublimate the Dioxane. The microstructural properties of the resulting PLLA scaffolds were determined utilizing Scanning Electron Microscopy (SEM) images and uni- axial compressive testing. The relationship between the wt/vol …

Development Of A Laboratory Scale Reactor Facility To Generate Hydrogen Rich Syngas Via Thermochemical Energy Conversion, Mandeep Sharma

LSU Master's Theses

The thesis provides data needed for development of a conical spouted bed (CSB) reactor for the purpose of producing hydrogen rich synthesis gas (syngas). The syngas has potential to utilize energy more efficiently, eliminate pollutant emissions and significantly cut emissions of greenhouse gases. The development of CSB reactor system involves three phases. The first phase investigates the hydrodynamic behavior of a small, laboratory scale, conical spouted bed (CSB) by considering the effect of specific system parameters (stagnated bed height, particle size and inlet diameter) on minimum spouting velocity (ums)o, stable operating pressure drop (∆Pms) and maximum pressure drop (∆PM). Experimental …

Numerical Evaluation And Analysis Of The Adhesion Phenomena In Thermal Barrier Coating Systems Through Bio-Mimicking Plasma Process, Naser Imran Hossain

LSU Master's Theses

Thermal Barrier Coatings or TBCs when abbreviated are an imperative part of the thermal protection system of expensive equipment and machinery in the automobile and aeronautics industry. They provide protection to expensive alloy materials upto a temperature of 2700° C without expensive metallurgical additions. Unfortunately, the problem of coating adhesion has plagued the TBC field for years, leading to catastrophic failures in critical TBC systems. Efforts to chemically improve bond strength has not been entirely successful, so the only other efficient way to do this would be some kind of mechanical interlocking that occurs at micro/nano scales. This research work …

Comparison Of In Vivo Human Knee Joint Kinematics Using Axodes, Jacob Hipps

LSU Master's Theses

The human knee is of particular interest because of its importance in mobility. Pain and stability can be directly related to the motion, or kinematics, of the knee. Many studies have been conducted to quantify human knee kinematics, both in vitro and in vivo. One of the inherent issues with in vivo, skin mounted measurement systems is that they do not account for soft tissue artifact. Compensation for soft tissue artifact has been a difficult challenge for skin mounted tracking systems and has not yet been achieved. Therefore, bone mounted skeletal pins were chosen as the method of gathering kinematic …

Electric Field Influence On The Combustion Of Fuel Droplets, Solomon Benghan

LSU Master's Theses

Improving the combustion efficiency of fuels in combustion devices has become imperative in the face of the diminishing rate of the discovery of new energy sources and an ever increasing demand for energy. While there are other ways of improving combustion efficiency, this study investigated the effect of electric field on the combustion of fuel droplets. In order to model the physics of the problem, a mass transfer evaporation model, heat transfer evaporation model and a simple burning droplet model were considered and their result compared to existing result from literature. A burning rate constant of 1.380mm2/s, 14.910mm2/s and 0.612mm2/s …

Low-Order Modeling Of Micro-Flier Impact With Thin Stationary Energetic Targets, Mark B. Fry

LSU Master's Theses

The impact of high-speed (500-1500 m/s), laser driven micro-fliers with thin energetic targets (10-100 &# 956;m) is being examined to characterize impact-induced heating and combustion of these materials. Aluminum fliers are propelled by a laser into a thin metallic target plate having a layer of energetic material deposited on its backside. Mass spectrometry is performed in vacuo on the energetic side to interrogate the shock-induced chemistry of the energetic material. It is important to ignite and possibly detonate the energetic material without perforation of the target plate avoiding contamination of the vacuum chamber. To guide development of these experiments, a …

Combinatorial Multi-Level Mold Inserts Using Micro Machining And X-Ray Lithography, Oblesh Jinka

LSU Master's Theses

The present technology advancement in biomedical, micro-electro-mechanical systems (MEMS) engineering, bio-MEMS, healthcare, etc. is driving the need to fabricate devices with multi-level, high aspect ratio and complex microstructures, which in turn requires high quality mold inserts with all these features. The present thesis is concentrated in fabricating a multi-level mold insert with complex quasi 3 dimensional micro structures with dimensions down to 10µm and aspect ratios greater than 30 using a process combination of micro milling with X-ray lithography. Therefore, in this study the main focus was to fabricate a high quality mold insert template, which can be electroplated to …

The Effect Of Elevated Water Content On Ethanol Combustion, Baine Bernard Breaux

LSU Master's Theses

Ethanol is currently being considered as a potential alternative to traditional fuels. However, the fuel offers a low return in terms of energy output per dollar invested when compared to fossil fuels. More than 1/3 of the cost associated with bio-ethanol production is devoted to distillation and water removal. This study seeks to validate the use of hydrous ethanol as a practical fuel to be used in lieu of fossil fuels or anhydrous ethanol. Success would reduce the production cost associated with ethanol fuel. Hydrous ethanol was burned in a swirl-stabilized combustor, air is introduced at a constant flow rate …

Flow Distribution And Heat Transfer Coefficients Inside Gas Holes Discharging, Amirhossein Eshtiaghi

LSU Master's Theses

Fluid flow and heat transfer coefficient associated with flow inside short holes (L/D=1) discharging orthogonally into a crossflow was investigated experimentally and numerically for (Re) ̅ ranging from 0.5×105 to 2×105, and blowing ratio ranging from 1.3 to 3.2. The basic configuration studied consists of a feed tube with five orthogonally located gas holes. Four different hole configurations were studied. The transient heat transfer study employs an IR-camera to determine the local heat transfer coefficient inside each hole. Velocity measurements and numerical flow simulation were used to better understand the measured heat transfer distribution inside the hole. The Nusselt number …

Characterizing Impact Induced Hot-Spot Morphology In Granular Solid Explosive, John Gilbert

LSU Master's Theses

Deformation induced ignition of heterogeneous solid explosives is believed to originate at hot-spots within the material which are local regions of elevated temperature resulting from dissipative mechanisms such as plastic deformation and inter-particle friction. Inert meso-scale modeling of these materials can principally account for hot-spot formation enabling the characterization of hot-spot size and temperature distributions which are important for ignition but are di_x000E_cult to experimentally resolve. The focus of this study is to characterize hot-spot morphology, as well as the distribution of hot-spots, behind quasi-steady compaction waves computed from predicted temperature fields resulting from numerical simulations of rigid planar piston …

Towards The Development Of Biotin Carboxylase Driven Robotic Nanoswimmers, Rachel Yates

LSU Master's Theses

The objective of this research is to take the first step towards demonstrating the use of the enzyme biotin carboxylase (BC) as a biomolecular motor. BC is a homodimeric protein involved in fatty biosynthesis in all organisms. The conjecture is that BC can convert chemical energy into useful mechanical work via its conformation change, which acts as a fin or flexible oar producing nonreciprocal motion. To this end, we fabricate a proof-of-concept biomolecular machine driven by BC molecules, viz., a robotic nanoswimmer. This machine consists of a Janus-type nanosize silica particle, where one hemisphere is coated with an intermediate layer …

Programming And Healing Temperature Effects On The Efficiency Of Confined Self-Healing Polymers, Yves Quentin Yougoubare

LSU Master's Theses

Shape memory polymers are smart materials capable of fixing a temporary shape and returning to their initial shape in response to an external stimulus. Since the discovery and acknowledgment of their importance in 1960s, shape memory polymers have been the subject of tremendous and continuous attention. In a previous study conducted on a biomimetic shape memory polymer (SMP), the ability of a self-healing composite to heal, and to repair and restore structural-length scale damage using a close-then-heal (CTH) self-healing mechanism was examined and validated. The present study is purposed with investigation of the effects on healing efficiencies of the variation …

Numerical And Experimental Evaluation Of Preheated Premixed Flames At Lean And Rich Conditions, Joseph Edward Gibson

LSU Master's Theses

Preheating a combustible mixture enhances the laminar burning flux characteristic m_ad with high reaction firing rates. As a result, the flammable zone as defined by inlet conditions of equivalence ratio and temperature is expanded beyond that available at standard ambient conditions; however, fundamental questions in these combustion regimes have not been addressed. In this thesis, preheated lean and rich combustion of methane/air mixtures is studied numerically and experimentally to catalog and confirm expected trends in these regimes. Numerical simulations were completed using both GRI-Mech 3.0 and San Diego mechanisms in the combustion code Cantera. An adiabatic simulation data set …

Modeling Of Dynamics Of Gyroscopic Systems, Siddharth Sharma

LSU Master's Theses

The amplitude of vibrations of a rotating system operating near or at its critical speed grows without bound. This poses a serious problem for the rotating machinery industry from the perspective of design, maintenance, vibration troubleshooting and stability of the rotating equipments.

In this thesis, we wish to develop an exact method of analysis for the system of a mass-less symmetrical shaft rotating in symmetrical bearings (SSSB) with finite displacement at bearing end. The method so developed is expected to be extended to the SSSB model of a shaft having mass. The stability analysis is performed for both the systems. …

Pdms Based Waveguides For Microfluidics And Eocb, Weiping Qiu

LSU Master's Theses

Due to the low cost, fast and ease of molding, PDMS has become one of the most popular materials for microfluidics devices, bioMEMS applications. Meanwhile, the integration of different functional components on to one single chip (or Lab on a Chip) is the dream for many scientists and engineers in the related area. In addition to the necessary mechanical components for accommodating the reactions, such as pumps, valves, mixers and so on, optical components such as waveguides, lens, interferers are all desired to be lumped into such a system.

The waveguide for such a system requires the material to have …

Effect Of Piezoelectric Actuation On Curved Beams And Single Lap Joints, Calicia Johnson

LSU Master's Theses

Piezoelectric materials have seen a significant usage increase over the past decade. They have been found to be effective as either sensors or actuators in smart structure applications, which allows them to act more as an adaptive system rather than a passive system. Piezoelectric materials are very effective transducers which convert mechanical energy into electrical energy, known as the direct piezoelectric effect or they have the ability to convert electrical energy to mechanical energy, known as the converse piezoelectric effect. The absence of additional mechanical parts, its lightweight and high strength to weight ratio is what make piezoelectric materials so …

The Design And Modification Of A Sputter System For Dc Reactive Sputtering Of Alumina And Zirconia Thin Films, Diane Van Ho

LSU Master's Theses

Yttria-stabilized zirconia (7% YSZ) is the most used material for thermal barrier coatings (TBCs) to reduce the conductive heat transfer on turbine blades, but it is not resistant to infrared radiation. In order to reduce radiation heat transfer, alternating materials, such as alumina and zirconia, can be used to fabricate multi-layer coatings in which each layer is optimized to reflect a targeted range of wavelength. This research aims to fabricate these multi-layer coatings by reactive magnetron sputtering. Reactive magnetron sputtering is the sputtering of an elemental target in the presence of a reactive gas that will react with the target …

Two-Stage Biaxial Thermomechanical Cycle Of Shape Memory Polymer Based Syntactic Foam, Abraham Michael King

LSU Master's Theses

A shape memory polymer (SMP) is a polymeric material that exhibits shape memory behavior. It can be “programmed” to take on a desired shape and “recovered” to revert back to its original shape. This ability to remember multiple shapes and switch between them with the application of a stimulus from an outside source is very desirable in certain applications. By dispersing glass microspheres in a SMP matrix, a syntactic foam is created that retains much of the shape memory capabilities but has higher strength and lower density than the pure SMP. These characteristics make this material a good candidate for …

Pool Boiling Enhancement Via Micro Ratchets, Lance Austin Brumfield

LSU Master's Theses

Nucleate boiling is an attractive method for achieving high heat flux at low superheat temperatures. It is frequently used for industrial applications such as heat exchangers and is being considered to cool advanced central processing units (CPU) which produce heat fluxes on the order of 1 MW/m2 and are becoming increasing less efficient to cool via forced conduction of air. The issues with implementing nucleate boiling as a cooling mechanism lies in the difficulty of quantifying the complex and numerous mechanisms which control the process. A comprehensive nucleate boiling model has yet to be formulated and will required in order …

Gas Turbine Blade Tip And Near Tip Heat Transfer With Film Cooling, Gregory Kramer

LSU Master's Theses

Gas turbine blade tips experience very high thermal loads due to high temperature combustion gases and tip leakage flows. This leads to the tip region being very susceptible to experiencing failures. To better understand these effects, experiments were performed in a suction-type low speed wind tunnel cascade to determine heat transfer coefficients and film cooling effectiveness distributions on a highly-loaded 2-D gas turbine blade model in the tip and near-tip regions. The blade shape was generated to match the pressure coefficients of the operating turbine blade design. The model featured multiple tip and pressure side film cooling holes and a …

Design, Fabrication And Characterization Of A New Wind Tunnel Facility – Linear Cascade With A Wake Simulator, Jean-Philippe Junca-Laplace

LSU Master's Theses

A new wind tunnel has been designed and constructed at the LSU Mechanical Engineering Laboratories. The objective was to design a versatile test facility, suitable for a wide range of experimental measurements on turbine blades. The future study will investigate the impact of unsteady inflow conditions on film cooling performance. More specifically, it will study how the unsteady flow due to the upstream passing wakes coming from the front row vane affects the film cooling performances on the turbine blades. The test section consists of a four passage linear cascade composed of three full blades and two shaped wall blades. …

V2o5-Wo3 Composite Films And Surface-Coated Licoo2 For Enhanced Li-Ion Intercalation Properties, Chuan Cai

LSU Master's Theses

We have investigated the enhanced Li-ion intercalation properties of two different materials, which are V2O5-WO3 composite and surface-coated LiCoO2. A simple and novel solution processing method is employed to prepare V2O5-WO3 composite films that demonstrate enhanced Li-ion intercalation properties for applications in Li-ion batteries or electrochromic displays. This solution processing method employs precursors that only contain the elements of V, W, O and H, which avoids impurity elements such as Na that has been commonly used in other solution methods (e.g. using precursors of sodium metavanadate and sodium tungstate solution). The V2O5-WO3 composite films show enhanced Li-ion intercalation properties compared …

Phase Investigation Of Zirconia Fibers And Their Applications On Solid Oxide Fuel Cells (Sofcs), Luping Li

LSU Master's Theses

Pure zirconia nanofibers were fabricated by electrospinning zirconia-polymer precursor and subsequent annealing. Fiber properties such as polymer decomposition, crystallization formation, phase transformation, surface morphologies, etc., were investigated by various techniques, including thermogravimetric analysis (TGA) and differential thermal analysis (DTA), high temperature differential scanning calorimeter (HTDSC), powder X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), etc. It was found the crystallization of as-spun fibers started at 450 °C and the initial crystallized zirconia phase was tetragonal (t), which began transforming to monoclinic (m) phase at 650 °C as evidenced by XRD; HTDSC showed at different thermal circles, the m-to-t transformation …

Degradation Behavior Of Shape Memory Polymer Due To Water And Diesel Fuel, Mohammad Nazmul Hasan Nahid

LSU Master's Theses

Shape memory polymers (SMP) are smart materials, which have the ability to memorize the original or permanent shape. Owing to this characteristic SMP can be used as a sensor, a transplant, as well as structural materials in wide range of applications. Despite its importance, its degradation behavior is still not completely known; and only a limited amount of work has been reported in the literature. In this thesis, the experiments have been carried out to evaluate the degradation behavior of Veriflex- SMP (industry supplied SMP samples) upon exposure to two different types of liquids; water and diesel fuel separately. It …

Characterization Of Composite Piezoelectric Materials For Smart Joint Applications, Hari Prasad Konka

LSU Master's Theses

Piezoelectric materials have the ability to provide desired transformation from mechanical to electrical energy and vice versa. When a mechanical force is applied to the piezoelectric material an electrical voltage is generated and when an electrical voltage is applied to the piezoelectric material it gets strained or deformed. Owing to these characteristics piezoelectric materials can be used as a sensor, an actuator, as well as a power generation unit. The high brittleness property of the original piezoelectric material is one of the major constraints in using them in the engineering applications. In order to overcome this disadvantage the composite piezoelectric …

Design And Fabrication Of Micronozzles For Drug Delivery Applications, Yuxuan Zhou

LSU Master's Theses

Inhaled drug is an important drug delivery route. It is widely used in medications for respiratory disorders. However, it has some significant limitations, for examples, concentration of drug, output, and particles size, are not accurately controlled in most of the available drug delivery systems today. Various new devices and technologies continue to be developed and introduced. Vibrating orifice is one of them. The critical issue of vibrating orifice technology is the fabrication of micro-nozzles. Traditional technique to fabricate these nozzles is to use dry etching method, which tends to be expensive and inconvenient for mass production. Other two optional fabrication …

A Portable Phonatory Feedback Device For Patients With Speech Disorders, Richie Sajan

LSU Master's Theses

Vocal intensity-related speech disorders such as dysarthria and vocal nodules can limit quality of life and reduce the patient’s ability to interact with family, socialize, or pursue employment. Behavioral speech therapies exist to address these issues but have limited effectiveness because they are expensive and clinic-based. The ability to monitor vocal intensity outside of the clinical setting will greatly aid in the treatment of these speech disorders, enabling patients to make quicker progress by reinforcing techniques learned in the clinic. The Voice Volume Monitor (VVM) is a portable and cost-effective therapeutic aid designed for this purpose, providing real-time feedback regarding …

Computational Examination Of Compaction Wave-Boundary Interaction In Granular Explosive, Anirban Mandal

LSU Master's Theses

Interactions between initially planar, piston supported compaction waves in heterogeneous energetic solids and macro-scale rigid boundaries were computationally examined for a wide range of piston impact speeds (20 ≤ U_p ≤ 500 m/s) and initial solid volume fractions of the material (0.73 ≤ ϕ₀ ≤ 0.90). The response of the material was described by a continuum theory that accounts for both elastic and inelastic compaction in a thermodynamically consistent manner. Initial conditions were imposed by interpolating the spatial structure of one-dimensional steady compaction waves onto two-dimensional domains considered in this study. For a planar wedge boundary, the peak …

Enhancement Of Single-Lap Joint Strength Under Tension Using Piezoelectric Actuation, Ryan Michael Meyer

LSU Master's Theses

Composite adhesively bonded joint structures have seen increased use over conventional riveted due to their ease of manufacturing and quality strength-to-weight ratios. However, adhesively bonded joints lack the rigidity and failure strength of riveted assemblies, due to high stress concentrations which develop in the adhesive layer, which makes them prone to undesirable deformation and failure. Piezoelectric materials feature the ability to produce mechanical strain when subjected to an applied voltage and vice-versa. Therefore, it is proposed to use piezoelectric actuators to transmit counterbalancing forces to increase the rigidity and strength of composite joints. Existing studies have been limited in that …

Fatigue Fracture And Microstructural Analysis Of Friction Stir Welded Butt Joints Of Aerospace Aluminum Alloys, Vinay Raghuram

LSU Master's Theses

Friction-Stir-Welding (FSW) has been adopted as a major process for welding Aluminum aerospace structures. Al-2195, which is one of the new-generation Aluminum alloys that has been used on the external tank of the new super lightweight external tank of the space shuttle. The Lockheed Martin Space Systems (LMSS), Michoud Operations in New Orleans is continuously pursuing Friction-Stir-Welding technologies in its efforts to advance fabrication of the external tanks of the space shuttle. The future launch vehicles which will have to be reusable, m, an dates the structure to have good fatigue properties, which prompts an investigation into the fatigue behavior …