Mechanical Engineering Commons^™

Evaluation Of Skin-Core Adhesion Bond And Low-Velocity Impact Behavior Of Honeycomb Sandwich Structures, Ramanjaneya R. Butukuri

Masters Theses

"Composite sandwich structures offer several advantages over conventional structural materials such as lightweight, high bending and torsional stiffness, superior thermal insulation and excellent acoustic damping. Some of the failure mechanisms in a composite sandwich structure are de-bonding of the composite facesheets from the core structure and damage due to low-velocity impact. In the first part of this work, adhesive fillet formation and adhesive mechanical strength are evaluated as a function of several different sandwich construction design variables. The effect of film adhesive thickness is studied. A process for reticulation of the adhesive is applied and studied. Optimized combinations of core …

Development Of Lower Cost Imaging Systems For Laser Metal Deposition Process, Shyam Barua

Masters Theses

"Laser Metal Deposition (LMD) has been used as an additive manufacturing process in industries such as aerospace and die castings. LMD is especially useful in repair applications involving die repair. However, it is still not used widely in industry due to variations in the quality of parts. There are multiple interactions between various factors which influence the quality of deposit.

There exists a need for defect detection systems to detect any changes in the deposition quality during deposition. On demand detection enables adjustment in process parameters and minimization of rework cost.

Vision systems have been used extensively in the industry …

A Neural Network Based Approach For Path Planning On Costmap, Songjie Chen

Masters Theses

"In this thesis, a path planning method using a three-level hierarchical system model is proposed. In the top level of the hierarchy, the given location points to visit are taken as waypoints. The waypoint navigation process is formulated as a traveling salesman problem (TSP). The Lin-Kernighan algorithm is used to solve the TSP and transfer the solution to the lower level of the hierarchy. In the middle level, the path is represented by a grid-based costmap. A novel modified Grossberg neural network is designed to solve the point-to-point path planning. The bottom level of the hierarchy smoothens the path with …

Analysis And Modeling Of Depth-Of-Cut During End Milling Of Deposited Material, Haythem Gaja

Masters Theses

"This study addresses depth-of-cut detection and tool-workpiece engagement using an acoustic emission monitoring system during milling machining for a deposited material. Online detection of depth-of-cut presents many technical difficulties. Researchers have used various types of sensors and methods to assess the depth-of-cut and surface errors. Due to the strong correlation between acoustic emission and cutting depth during the depth end milling process, it is useful to forecast the depth-of-cut from the acoustic emission signal. This work used regression analysis to model and detect the depth-of-cut. The experiments were carried out on a Fadal vertical 5-Axis computer numerical control machine using …

Quasi-Steady Capillarity-Driven Flows In Slender Containers With Interior Edges, Mark M. Weislogel, J. Alex Baker, Ryan M. Jenson

Mechanical and Materials Engineering Faculty Publications and Presentations

In the absence of significant body forces the passive manipulation of fluid interfacial flows is naturally achieved by control of the specific geometry and wetting properties of the system. Numerous 'microfluidic' systems on Earth and 'macrofluidic' systems aboard spacecraft routinely exploit such methods and the term ‘capillary fluidics’ is used to describe both length-scale limits. In this work a collection of analytic solutions is offered for passive and weakly forced flows where a bulk capillary liquid is slowly drained or supplied by a faster capillary flow along at least one interior edge of the container. The solutions are enabled by …

Combustion Of Lunar Regolith Mixed With Energetic Additives: Thermodynamic Calculations And Experimental Studies, Francisco Alvarez

Open Access Theses & Dissertations

The future of space exploration will require longer missions in order to better understand the conditions of near-Earth celestial objects, like the Moon or Mars. Future space missions will require the development of goods, such as propulsion fuel and structural materials, produced using the extraterrestrial resources available. The area that develops these technologies is called In-Situ Resource Utilization (ISRU). ISRU allows reducing the payload, and as a consequence reduces the energy consumption and cost of space travel. The production of structural materials on the Moon can be accomplished using Self-Propagating High-Temperature Synthesis (SHS). This work describes the combination of ISRU …

Design And Cfd Optimization Of Methane Regenerative Cooled Rocket Nozzles, Christopher Linn Bradford

Open Access Theses & Dissertations

Liquid rocket engines benefit in life cycle from the active regenerative cooling method which passes the fuel as the coolant through channels surrounding the combustion chamber. These channels are designed and optimized using structural considerations as well as heat transfer theory, then CFD simulations with the software FLUENT are performed for the final analysis. The difficulty in using methane as the fuel/coolant is addressed, and requires the use of the ideal gas numerical model in preliminary CFD simulations. Comparison to real gas numerical models is made, and results also given for one channel design. The techniques utilized herein allow the …

Experimental And Numerical Investigation Of The Effect Of Fuel Composition On Flame Stability On A Gas Turbine Combustor, Gilberto Corona

Open Access Theses & Dissertations

Gas turbines are used for power generation and aviation all over the world. Fossil fuels remain the main source of energy for the operation of gas turbines but the recent increase in environmental awareness has influenced government agencies to impose stringent limits on pollutant emissions from power generation plants. Pollutant emissions control is one of the major challenges for gas turbine designers. In this study, experimental methods and computational fluid dynamics (CFD) technologies are used to study the problems that arise when coal derived fuels are used in Gas Turbine Combustors.

Gas turbine designers need both experimental data and combustion …

Evaluation Methods For Health Monitoring Of Aerospace Structure Rotary Joints, Sergio Armando Navarro

Open Access Theses & Dissertations

In September 2007, the excessive vibrations played a significant role in the station operation since one of the rotary joints, which provides the station electrical energy, presented an anomaly. The replacement of its bearing components and re-lubrication were necessary to reduce the problem. To avoid a new anomaly, the inspection of the rotary joints performance continues by using the accelerometers data. This thesis presents three new approaches to monitor the vibrations at the International Space Station based on Root-Mean-Square, kurtosis, and Approximate Entropy (ApEn). MATLAB functions and codes were necessary to implement the three monitoring techniques results from the provided …

Synthesis, Microstructure And Thermal Analysis Of Gd2o3 - Hfo2 Coatings, Chandan Kumar Roy

Open Access Theses & Dissertations

Thermal barrier coatings (TBCs) are critical for future gas turbines of advanced coal based power generation systems. The TBCs are protective layers of low thermal conductivity ceramic materials, which prevent the damage of components that are exposed to very high temperature of the hot gases. Due to increasing demand to improve the efficiency, it is necessary to find alternate TBC materials which can withstand higher temperature for longer period than state-of-art TBCs. The present study focuses on the Gd2O3 stabilized HfO2 (GSH) as a potential candidate for TBC. GSH materials were synthesized in bulk and coatings form. The Gd2O3 content …

Performance Of Four Near Zero Energy Homes: Lessons Learned, Florida Solar Energy Center, Carlos Colon

FSEC Energy Research Center®

While the idea of a zero or near zero energy home is well understood, the actual performance of the structure can be different than expected. High performance homes necessitate increasingly complex envelope, HVAC, water heating, and appliance systems, and successful designs rely on proper function and feedback from those systems to achieve low-energy goals. This paper presents measured data on four near zero energy homes located in Florida that are a part of the U.S. DOE Building America program. The monitored data are compared to both a benchmark model and the prototype computer simulations. By examining the submetered energy data, …

Florida Weatherization Training - Quarterly Report (October 2010-December 2010), Florida Solar Energy Center, Neil Moyer

FSEC Energy Research Center®

The weatherization training for the State of Florida Dept of Community Affairs continues at the Florida Solar Energy Center's Training Facility. Progress for the sixth three months of the contract included a five day classroom training on October 18-22 (17 students) and in-field evaluations (16 students).

2010 Fall Engr333 Project Final Report, 2010 Fall Engr333

ENGR 333

Calvin College dorms have a chronic issue with wasting energy. The dorms have little insulation, high infiltration rates, and are heated by low efficiency boilers. These existing characteristics combine for a larger required heating load and increased energy usage. The excess heat, due to poor temperature control, is often vented out through the windows whenever students deem necessary. This project will attempt to reduce wasted energy and efficiently distribute heat as needed.

The Thermal Systems Design class of 2010 was challenged with retrofitting the Bolt-Heyns-Timmer (BHT) dorm to decrease energy consumption and improve efficiency. The class was presented with the …

Active Noise Control Of A Two-Fan Exhaust-Mounted Array Using Near-Field Control Sources And Error Sensors, Ryan Leonard Rust

Theses and Dissertations

Multiple fans are sometimes used in an array configuration to cool various types of electronic equipment. In addition to adding another noise source, using two fans with closely spaced blade passage frequencies (BPF) can create an annoying beat frequency. A two fan array with each fan having a different BPF was considered. The fans were theoretically modeled at the BPF and first harmonics. Each fan has two acoustic paths to the far field. Thus, each fan was modeled as a two source array. The first control configuration consisted of one control filter using six control sources and six error sensors …

Scanning Laser Registration And Structural Energy Density Based Active Structural Acoustic Control, Daniel Alan Manwill

Theses and Dissertations

To simplify the measurement of energy-based structural metrics, a general registration process for the scanning laser doppler vibrometer (SLDV) has been developed. Existing registration techniques, also known as pose estimation or position registration, suffer from mathematical complexity, instrument specificity, and the need for correct optimization initialization. These difficulties have been addressed through development of a general linear laser model and hybrid registration algorithm. These are applicable to any SLDV and allow the registration problem to be solved using straightforward mathematics. Additionally, the hybrid registration algorithm eliminates the need for correct optimization initialization by separating the optimization process from solution selection. …

Effective Ionic Conductivity Of A Novel Intermediate-Temperature Mixed Oxide-Ion And Carbonate-Ion Conductor, Xue Li, Guoliang Xiao, Kevin Huang

Faculty Publications

A systematic investigation on the effective ionic conductivity (σ_m) of a novel intermediate-temperature mixed oxide-ion and carbonate-ion conductor MOCC consisting of a ceria phase and a carbonate phase is reported. The study explicitly shows that the observed remarkable temperature-dependent σ_m is primarily the result of softening/melting of the carbonate phase as the physical state of the carbonate phase transforms from solid, softened to molten. Differential scanning calorimetry analysis complements the understanding of the observed electrical behavior by revealing temperatures of melting and solidification in agreement with the onset temperatures of σ_m. In addition, the …

A Comparative Verification Of Forecasts From Two Operational Solar Wind Models, Donald C. Norquist, Warner C. Meeks

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The solar wind (SW) and interplanetary magnetic field (IMF) have a significant influence on the near‐Earth space environment. In this study we evaluate and compare forecasts from two models that predict SW and IMF conditions: the Hakamada‐Akasofu‐Fry (HAF) version 2, operational at the Air Force Weather Agency, and Wang‐Sheeley‐Arge (WSA) version 1.6, executed routinely at the Space Weather Prediction Center. SW speed (V_sw) and IMF polarity (Bpol) forecasts at L1 were compared with Wind and Advanced Composition Explorer satellite observations. Verification statistics were computed by study year and forecast day. Results revealed that both models’ mean Vsw are …

Joining Polycrystalline Cubic Boron Nitride And Tungsten Carbide By Partial Transient Liquid Phase Bonding, Grant O. Cook Iii

Theses and Dissertations

Friction stir welding (FSW) of steel is often performed with an insert made of polycrystalline cubic boron nitride (PCBN). Specifically, MS80 is a grade of PCBN made by Smith MegaDiamond that has been optimized for the FSW process. The PCBN insert is attached to a tungsten carbide (WC) shank by a compression fitting. However, FSW tools manufactured by this method inevitably fail by fracture in the PCBN. Permanently bonding PCBN to WC would likely solve the fracturing problem and increase the life of PCBN FSW tools to be economically viable. Partial transient liquid phase (PTLP) bonding, a process used to …

Modeling And Testing Of Dna Motion For Nanoinjection, Regis Agenor David

Theses and Dissertations

A new technique, called nanoinjection, is being developed to insert foreign DNA into a living cell. Such DNA transfection is commonly used to create transgenic organisms vital to the study of genetics, immunology, and many other biological sciences. In nanoinjection, DNA, which has a net negative charge, is electrically attracted to a micromachined lance. The lance then pierces the cell membranes, and the voltage on the lance is reversed, repelling the DNA into the cell. It is shown that DNA motion is strongly correlated to ion transport through a process called electrophoresis. Gel electrophoresis is used to move DNA using …

Optimization Strategy For Resonant Mass Sensor Design In The Presence Of Squeeze Film Damping, Chengzhang Li, Michele H. Miller

Michigan Tech Publications, Part 1

This paper investigates the design optimization of an electrostatically actuated microcantilever resonator that operates in air. The nonlinear effects of electrostatic actuation and air damping make the structural dynamics modeling more complex. There is a need for an efficient way to simulate the system behavior so that the design can be more readily optimized. This paper describes an efficient analytical approach for determining the optimum design for a microcantilever resonant mass sensor. One simple case is described. The sensor design is a square plate that is coated with a functional polymer and attached to the substrate with folded leg springs. …