Mechanical Engineering Commons^™

Model Reference Robust Control For Marine Propulsion Systems With Model Uncertainty Caused By Hull Deformation, Zhixiong Li, Xinping Yan, Li Qin, Chengqing Yuan, Zhongxiao Peng

Journal of Marine Science and Technology–Taiwan

A marine propulsion system can be strongly coupled with the hull deformation in a large-scale ship. The interaction of this coupling dynamics increases the nonlinearity and complexity of the control model. Traditional control method based on the empirical PID (proportion-integration-differentiation) parameters has difficulty in dealing with the model uncertainty caused by the hull deflection. However, up to date, limited work has been done to address the model uncertainty problem of the marine propulsion system. It is therefore imperative to develop feasible and effective control systems that take the model uncertainty into account. In this study, a new method based on …

Additive Manufacturing Laser Deposition Of Ti‐6al‐4v For Aerospace Repair Applications, Nanda Kumar Dey, Frank W. Liou, C. Nedic

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Parts or products from high performance metal are very expensive, partly due to the processing complexities during manufacturing. The purpose of this project is to use additive laser deposition and machining processes to repair titanium parts, thus extending the service life of these parts. The study broadly included preparing the defects, laser deposition, machining, sample preparation and mechanical tests. Comparative study of mechanical properties (UTS, YS, percentage elongation) of the repaired samples to the ideal conditions was undertaken. The research throws up interesting facts where the data from the test sample shows enhancement of properties of the repaired part.

Experimental Investigation Of Different Cellular Lattice Structures Manufactured By Fused Deposition Modeling, Osman Iyibilgin, Cemil Yigit, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Experimental tests were conducted to evaluate the compressive properties (yield strength and compressive modulus) and build time for five different cellular lattice structures fabricated by the Fused Deposition Modeling (FDM) process. The lattice structures had repeating unit cells, and the shapes of the unit cell under study included honeycomb, square, diamond, triangle, and circle. Test specimens were manufactured by a Stratasys Fortus 400mc machine using ABS (Acrylonitrile Butadiene Styrene) as the part material. The five different lattice structures were compared with each other and also with the sparse and sparse-double dense build styles that are directly available from the Fortus …

Probabilistic Simulation Of Solidification Microstructure Evolution During Laser-Based Metal Deposition, Jingwei Zhang, Frank W. Liou, William Seufzer, Joseph William Newkirk, Zhiqiang Fan, Heng Liu, Todd E. Sparks

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A predictive model, based on a Cellular Automaton (CA) - Finite Element (FE) method, has been developed to simulate microstructure evolution during metal solidification for a laser based additive manufacturing process. The macroscopic FE calculation was designed to update the temperature field and simulate a high cooling rate. In the microscopic CA model, heterogeneous nucleation sites, preferential growth orientation and dendritic grain growth kinetics were simulated. The CA model was able to show the entrapment of neighboring cells and the relationship between undercooling and the grain growth rate. The model predicted the dendritic grain size, structure, and morphological evolution during …

Development Of Freeze-Form Extrusion Fabrication With Use Of Sacrificial Material, Ming-Chuan Leu, Diego A. Garcia

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The development of Freeze-form Extrusion Fabrication (FEF) process to fabricate three-dimensional (3D) ceramic parts with use of sacrificial material to build support sections during the fabrication process is presented in this paper. FEF is an environmentally friendly, additive manufacturing process that builds 3D parts in a freezing environment layer-by-layer by computer controlled extrusion and deposition of aqueous colloidal pastes based on computer-aided design (CAD) models. Methyl cellulose was identified as the support material, and alumina was used as the main material in this study. After characterizing the dynamics of extruding alumina and methyl cellulose pastes, a general tracking controller was …

Vision-Based Process Monitoring For Laser Metal Deposition Processes, Sreekar Karnati, Niroop Matta, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser Metal deposition is a process with immense scope and promise for becoming a robust manufacturing technology in the near future. Monitoring process variables is very instrumental in process planning and output monitoring. The current work deals with realizing the effect of power modulation on size of the high temperature region during deposition with varying powder feed. A thermal camera was used to visualize and analyze the deposition process. The area of the high temperature region through the deposition was identified and compared to realize the effect of each variable parameter during deposition. The power modulation was fruitful in modulating …

Numerical Analysis Of Thermal Stress And Deformation In Multi-Layer Laser Metal Deposition Processes, Heng Liu, Todd E. Sparks, Frank W. Liou, David M. Dietrich

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct metal deposition (DMD) has gained increasing attention in the area of rapid manucooling rate, resulting in residual stresses and distortion. This paper presents a 3D sequentially coupled thermo-mechanical finite element model to predict residual stresses and deformations. The temperature distribution, thermal stress field and geometry deformation across domain are illustrated. The effect of deposition parameters on residual stress and deflections are also explored. A set of validation experiments for mechanical effects were conducted using laser displacement sensor. The comparisons between the simulated and experimental results show good agreement

Effect Of Architecture And Porosity On Mechanical Properties Of Borate Glass Scaffolds Made By Selective Laser Sintering, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Taylor Comte

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The porosity and architecture of bone scaffolds, intended for use in bone repair or replacement, are two of the most important parameters in the field of bone tissue engineering. The two parameters not only affect the mechanical properties of the scaffolds but also aid in determining the amount of bone regeneration after implantation. Scaffolds with five different architectures and four porosity levels were fabricated using borate bioactive glass (13-93B3) using the selective laser sintering (SLS) process. The pore size of the scaffolds varied from 400 to 1300 μm. The compressive strength of the scaffolds varied from 1.7 to 15.5 MPa …

Analysis Of Intervertebral Disc Degeneration Testing Method, David Williams, Dr. Anton Bowden

Journal of Undergraduate Research

This ORCA research project has focused on the determination of the effects of the order of the mechanical tests on the response of an intervertebral disc. We hypothesized that the order of the mechanical tests may influence the rate of diffusion of the Trypsin throughout the disc, affecting the biomechanical response. We have planned to determine the magnitude of this influence by using statistical techniques to analyze the data acquired. Virtually all of us (80 to 90 percent) will experience back pain in our lives. Low back pain is the leading cause of missed work days. The estimated economic impact …

Influence Of Airway Liquid Hydration And Properties On Human Vocal Fold Vibration, Preston Murray, Dr. Scott Thomson

Journal of Undergraduate Research

The purpose of this research project was to identify a fluid that has similar properties as the airway surface liquid (ASL) that covers vocal folds, and then apply it to a vibrating synthetic vocal fold model to measure its effects.

Parametric Optimization Of Wind Turbine Blades, Brycee Mcewen, Dr. Steven Gorrell

Journal of Undergraduate Research

With ever increasing concerns about the production of greenhouse gases from burning fossil fuels, more and more emphasis is being placed on researching and developing alternative and renewable energy resources. One renewable energy source that has the potential to compete with conventional fossil fuels, is wind energy. In order for wind energy to be competitive, it is necessary to make improvements in both aerodynamic and structural properties of wind turbines.

Piezoresistivity In Nickel Nanostrand Composite Materials As Studied By Three-Dimensional Reconstruction On Focused Ion Beam Serial-Sections, Oliver Johnson, Dr. David Fullwood

Journal of Undergraduate Research

The development of a large-strain sensor technology will open doors for improved engineering design and scientific research in many fields. Such a technology would allow for advances in biomechanical engineering, e.g., prosthetic limb and artificial organ design. Additionally this kind of sensor technology could be used for tactile robotics and even structural health monitoring, such as in wind turbines or architectural structures. Our research group has developed a unique Silicone/Nickel Nanostrand/Nickel Coated Carbon Fiber (Si/NiNs/NCCF) nanocomposite that can measure strains of up to 50% elongation. The purpose of this project was to investigate how the nano-scale structure of this material …

Autonomous Soaring Using Real-Time Wind Estimation, Mark J. Cutler, Dr. Timothy Mclain

Journal of Undergraduate Research

Small unmanned aerial vehicles (UAVs) are obtaining increasing utilization in many applications. Their small size (0.5-4m wingspan) allows them to fly close to the ground, providing useful observation and tracking data. This small size, however, comes at the expense of flight time. As UAV size decreases, the amount of stored energy (electrical or chemical) the UAV is able to carry also decreases. If long flight times are to be obtained with a small UAV, other energy sources must be exploited. Naturally occurring atmospheric phenomena provide one such potential energy source.

Dynamic Loading On Horizontal Axis Wind Turbine Blades, Christopher Brinkerhoff, Julie Vanderhoff

Journal of Undergraduate Research

Currently, there is much interest involving technologies dealing with clean and renewable energy sources. The current goal in the United States is to produce 20% of its electrical needs by wind power by the year 2030. Wind energy is seen as a viable option for further research because of its low carbon footprint and virtually limitless supply of wind, but in order for it to be economically viable, there are certain aspects of wind technology that need improvement.

Economic And Environmental Justification Of A Thermoelectric Waste Heat Recovery System, John Christiansen, Dr. Matthew Jones

Journal of Undergraduate Research

In recent years, the concepts of energy, energy production, effects of energy consumption on the environment, and sustainable development have become increasingly significant as members of society become more aware of their level of energy consumption. However, in energy production for home, commercial, or industrial use, up to 60 percent of the chemical energy potential (in the form of fossil or other fuels) is lost in the form of waste heat. In other words, when fossil or other fuels are burned, only 30 to 40 percent of the potential chemical energy is actually harnessed and converted into useful electricity! This …

Vision-Based Guidance For Air-To-Air Tracking And Rendezvous Of Unmanned Aircraft Systems, Joseph Walter Nichols

Theses and Dissertations

This dissertation develops the visual pursuit method for air-to-air tracking and rendezvous of unmanned aircraft systems. It also shows the development of vector-field and proportional-integral methods for controlling UAS flight in formation with other aircraft. The visual pursuit method is a nonlinear guidance method that uses vision-based line of sight angles as inputs to the algorithm that produces pitch rate, bank angle and airspeed commands for the autopilot to use in aircraft control. The method is shown to be convergent about the center of the camera image frame and to be stable in the sense of Lyapunov. In the lateral …

Development/Ballistics Testing Of Lightweight Sandwich-Composite Body Armor, Brian Spencer, Dr. Anton Bowden

Journal of Undergraduate Research

Body armor is one of the most important tools used in the protection of soldiers and other armed forces around the world. Although the current style of armor, using Kevlar fiber and ceramic inserts, is generally effective, it is bulky and heavy and can cause overheating and lack of mobility. Our research attempts to remedy these issues by using shear-thickening fluid (STF) impregnated Kevlar XP combined with corrugated plastic to create and test lighter, more effective body armor.

Critical Component Selection For Implementing Barriers To Reverse Engineering, Shane K. Curtis, Dr. Christopher Mattson

Journal of Undergraduate Research

Reverse engineering is a prominent design strategy in industry, employed by many to uncover the enabling technologies of innovative products. Unfortunately, there is little motivation for original designers to create new products if competitors can reverse engineer these products and reproduce them at a lower development cost. One solution to this problem involves the incorporation of barriers to reverse engineering into products during the design process. These barriers not only increase the cost of reverse engineering but can also improve product performance with only a small increase in manufacturing or development time.

Low Volume Dispensing With High Speed Dispensers, Sunny Agarwal

Graduate Dissertations and Theses

With the high pace of innovation in the semiconductor manufacturing industry, there has been an increasing demand for more energy efficient and environmental friendly products. This research relates to a complex process of fluid dispensing at low volumes on a printed circuit board. Currently, a more refined non-contact dispensing terminology named “Streaming” is widely used to stream out material at low volumes for various applications. The key solution is to frame a dispensing method that lends itself most closely to the requirements of a specific production process.

This study represents a detailed approach of dispensing low volumes of materials in …

Geometric And Pattern Recognition Combined Algorithms Applied To Digital Image Processing In Aerial Search And Rescue Applications, Jamil Efren Anaguano Correa

Doctoral Dissertations and Master's Theses

The difficult task of generating an automated target detection system from aerial imagery can be achieved through different approaches. However, the robustness of any machine vision system lays on the implementation of vision algorithms. By combining geometric and pattern recognition algorithms, a more effective machine vision scheme is developed. Three modules-Color Identification (CIM), Color Matching (CMM), and Pattern Recognition (PRM)- work as main filters to process images and predict the location of targets based on a set templates. Multiple target detection is also accomplished by implementing a hide and seek method where all matching objects are scanned individually and isolated …