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Articles 1 - 15 of 15
Full-Text Articles in Mechanical Engineering
A New Approach To Evaluate Fracture Strength Of Uv-Liga Fabricated Nickel Specimens, Catherine Oropeza
A New Approach To Evaluate Fracture Strength Of Uv-Liga Fabricated Nickel Specimens, Catherine Oropeza
LSU Master's Theses
One of the major difficulties faced by MEMS researchers today is the lack of data regarding properties of electroplated metals or alloys at micro-levels as those produced by the LIGA and LIGA related process. These mechanical properties are not well known and they cannot be extrapolated from macro-scale data without experimental verification. This lack of technical information about microscale physical properties has affected the consistency and reliability of batch-fabricated components and leads to very low rates of successful fabrication. Therefore, this material issue is of vital importance to the development of LIGA technology and to its industrial applications. This thesis …
Tribological Behavior Of Nanostructured Nickel, Dean Joseph Guidry
Tribological Behavior Of Nanostructured Nickel, Dean Joseph Guidry
LSU Master's Theses
The present study reports the effects of electroplating parameters on the microstructure, and thus the mechanical and tribological properties, of nanostructured nickel. Electroplating was conducted in a Watt's type bath with a pH of 3.0 carried out using direct current in galvanostatic mode at current densities of 30 mA/cm2 and 15 mA/cm2 in electroplating bath temperatures of 30°C and 50°C. Grain size and distributions were determined from TEM (Transmission Electron Microscope) and SEM (Scanning Electron Microscope) micrographs. Tribological tests were carried out on a pin-on-disc type tribometer. The same tests were conducted on Ni-200 for the purpose of …
Parametric And Sensitivity Analysis Of A Vibratory Automobile Model, Kanika Nicole Vessel
Parametric And Sensitivity Analysis Of A Vibratory Automobile Model, Kanika Nicole Vessel
LSU Master's Theses
Vibration response is an important aspect of any engineering problem. This thesis deals with developing a method to obtain the vibration, parametric and sensitivity of an automobile analyzed as a 2-DOF rigid body system with damping. The focus of the vibration analysis is to obtain the poles, eigenvectors, and natural frequencies of the system. The parametric analysis gave information on how the natural frequency is affected when one of the parameters is perturbed. Information about how much the system is affected by the change in one parameter is what is obtained from the sensitivity analysis. The theoretical solution contained in …
Design And Microfabrication Of A Molded Polycarbonate Continuous Flow Polymerase Chain Reaction Device, Michael Mitchell
Design And Microfabrication Of A Molded Polycarbonate Continuous Flow Polymerase Chain Reaction Device, Michael Mitchell
LSU Master's Theses
The polymerase chain reaction (PCR) is an amplification technique that is used with deoxyribonucleic acid (DNA) and can produce millions of copies of the starting material, even from single molecules. Since its discovery by Kary Mullis in the mid-1980s, PCR has been one of the most important techniques in the arsenal of tools used for genetic analyses. For this research a continuous flow polymerase chain reaction (CFPCR) system was designed, microfabricated from molded polycarbonate, and tested. Finite element modeling was used to model thermal and microfluidic response of the system. X-ray LIGA was used to fabricate mold inserts for the …
A Model Of Heat And Mass Transfer In An Idealized Micro Heat Pipe, Jin Zhang
A Model Of Heat And Mass Transfer In An Idealized Micro Heat Pipe, Jin Zhang
LSU Master's Theses
Micro heat pipes have been used to cool computer chips, but their heat transfer coefficients are low compared with that of conventional heat pipes. To understand this deficiency, an idealized micro heat pipe is proposed that has simplified interfacial geometry but retains the essential physics. It is a long and narrow cavity of rectangular cross section with the bottom made of a wetting material and the top a non-wetting material. A wetting liquid fills the bottom half of the cavity, and its vapor fills the rest. This configuration ensures that the liquid-vapor interface is pinned at the contact line. Since …
Prediction Of Heat Transfer & Flow In Rotating Two-Pass Channels Connected By Holes., Achintya Kumar Pramanick
Prediction Of Heat Transfer & Flow In Rotating Two-Pass Channels Connected By Holes., Achintya Kumar Pramanick
LSU Master's Theses
A computational study of the effect of rotation on the velocity and thermal field for a two-pass channel connected by rows of holes on the divider wall has been conducted. Detailed velocity and Nusselt number distributions are presented inside the rotating two-pass coolant channel. The enhanced cooling in this passage design is achieved by a combination of impingement and crossflow-induced swirl. The cross flow is generated from one coolant passage to the adjoining coolant passage through a series holes placed along the dividing wall. The holes deliver the flow from one passage to another typically achieved in a conventional design …
Liga Mold Insert Fabrication Using Su-8 Photoresist, Jian Zhang
Liga Mold Insert Fabrication Using Su-8 Photoresist, Jian Zhang
LSU Master's Theses
The LIGA process potentially enables economic mass-production of devices with high aspect ratio geometry. Central to the LIGA process is the fabrication of high quality LIGA molds. But in the traditional LIGA mold insert fabrication process, the x-ray photoresist poly-methyl-methacrylate (PMMA) is not highly sensitive to x-rays and a thick piece of PMMA sheet (>1mm) needs too much time to get exposed (bottom dose: 3500J/cm3), which results in excessive cost/ fabrication difficulty of the mold insert. Thus, in this thesis a negative photoresist SU-8 was tested as an x-ray photoresist in the LIGA fabrication process. SU-8 is much more …
Development Of A Micro Power Relay With Static Electrical Actuator, Ren Yang
Development Of A Micro Power Relay With Static Electrical Actuator, Ren Yang
LSU Master's Theses
In this thesis, a research about design and fabrication of a micro power relay is presented. Compared with the traditional electromagnetic relay and solid-state relay, MEMS micro power relay is introduced. After introducing the advantage and other people's research about the MEMS relay, some design and simulation about a new prototype micro power relay are done. Based on the design, UV-LIGA is used as the fabrication method. The bottom part and top part of the micro power relay are fabricated separately. After assembly the top part on the bottom part, some simple tests about the micro power relay are done. …
Transient Thermomechanical Interactions Of Shaft-Bushing Pair In Bearings - A Finite Element Study, Rajesh Krithivasan
Transient Thermomechanical Interactions Of Shaft-Bushing Pair In Bearings - A Finite Element Study, Rajesh Krithivasan
LSU Master's Theses
This thesis presents a finite element parametric study of the transient thermomechanical interactions of shaft-bushing pairs in bearings to gain insight into the nature of two categories of failures encountered in practice. The first type of failure deals with occurrence of the so-called thermally induced seizure (TIS) during the start-up period followed by an investigation of TIS due to a transient flow-disturbance. The second part deals with the thermomechanical interactions of pin-bushing assembly under heavy oscillating loads where the failure is by TIS and/or thermal galling. An extensive set of parametric simulations covering a wide range of loads, speeds, operating …
Tapered Liga Mold Insert, Ryan Anthony Turner
Tapered Liga Mold Insert, Ryan Anthony Turner
LSU Master's Theses
The applications of microstructures produced by the LIGA process are useful in a broad range of fields including: microfluidics, heat transfer, and mechanics. The Microsystems Engineering Team at Louisiana State University has used the LIGA process as a foundation for the team’s productivity in these areas. Many advances in the processes involved in producing these microstructures have been made in the past increasing the efficiency of the entire process. A modified exposure technique in the lithography stage of the LIGA process is being developed to produce microstructures with a draft angle as opposed to the standard straight walled structures. Electroformed …
Buckling Analysis Of Grid Stiffened Composite Structures, Samuel Kidane
Buckling Analysis Of Grid Stiffened Composite Structures, Samuel Kidane
LSU Master's Theses
Buckling of a stiffened composite cylinder is a very complex phenomenon that involves complex interactions between the skin and the stiffeners. Depending on different configurations of the skin and stiffener, different buckling failure modes and failure loads are observed in stiffened cylinders. In this work failure modes and buckling loads of stiffened composite cylinders under uniaxial loading condition is investigated by using analytical and experimental approaches. In the first Chapter an improved smeared method is developed to model the buckling problem of an isogird stiffened composite cylinder. In this model the stiffness contributions of the stiffeners is computed by analyzing …
Effect Of Tip Geometry On Blade Tip Flow And Heat Transfer, David Michael Kontrovitz
Effect Of Tip Geometry On Blade Tip Flow And Heat Transfer, David Michael Kontrovitz
LSU Master's Theses
In an attempt to increase thrust to weight ratio and efficiency of modern gas turbines, engine designers are always interested in increasing turbine operating temperatures. The benefits are attributed to the fact that higher temperature gases yield a higher energy potential. However, the detrimental effects on the components along the hot gas path can offset the benefits of increasing the operating temperature. The High Pressure Turbine (HPT) first stage blade is one component that is extremely vulnerable to the hot gas. The present study explores the effects of gap height and tip geometry on heat transfer distribution. This investigation differs …
Comparison Of Numerical And Experimental Results Of Four Liquid Spray Combustors, Dong Hu
Comparison Of Numerical And Experimental Results Of Four Liquid Spray Combustors, Dong Hu
LSU Master's Theses
Validation of CFD predictions for liquid spray combustion application is a challenging task due to difficulties in both modeling and experimental measurements. Validation is considered to be a key step for successful CFD predictions of combustion systems. The goals of this thesis are threefold: (1) validation of models used for spray combustion predictions, (2) using the validated predictions to explain steady flow and combustion physics, and (3) using the validated procedure to simulate conditions where unstable combustion behavior is observed experimentally, and to explore if such unstable behavior can be predicted correctly. The model validation is done with respect to …
Application Of Duhamel's Theorem To Problems Involving Oscillating Heat Source, Haribabu Krishnamurthy
Application Of Duhamel's Theorem To Problems Involving Oscillating Heat Source, Haribabu Krishnamurthy
LSU Master's Theses
This thesis deals with a systematic development of a method for predicting the temperature field in various domains subjected to oscillating heat sources on its boundaries using the Duhamel’s method. First a method is devised for single domain problems in both Cartesian and cylindrical coordinates for oscillating heat sources and also for unidirectional rotation of shafts in cylindrical coordinates. The analytically computed results for the problems in Cartesian coordinates compared favorably with the results from Finite Element Method, attesting to the validity of this novel approach. Later, the method is extended to predict the maximum temperature in oscillating Pin-Bushing mechanism, …
Hard Surface Coating Experimental Evaluation And Thermomechanical Analysis Of A Seal With Micro Heat Exchanger, Yifan Qiu
LSU Master's Theses
Mechanical face seals are important components of many rotating machinery. Minimizing the friction between seal faces and efficiently removing the heat generated between seal surfaces are two crucial considerations in the design of mechanical seal. Thin film coating and MEMS technology hold great promise for improving the performance of mechanical seals from the viewpoint of reducing friction and heat at the interface in these two aspects. To reveal what effect the coating and MEMS technology can have on tribological properties of seals, friction and wear characteristics of Ti-C:H coatings on seal-like rings and heat transfer performances of a seal prototype …