NAOE Midshipmen Honors Senior Thesis, EN503H and EN504H
Midshipmen interested in pursuing research related to their degree have the opportunity senior year. The range of topics vary based on the requirements and funding of outside sources, as well as the research interests of faculty and midshipmen. The following midshipmen conducted research as part of an Honors Senior Thesis course, EN503H and EN504H, with Professor Dave Fredriksson, Professor Sarah Mouring, CDR Andy Gish, CDR
Jeff Woertz, and Associate Professor Paul Miller.
Midshipman First-Class Chelsea Pixa designed and implemented an experimental plan to examine flow rates and volume exchange of water in Biddeford Pool, a shallow, tidal flat basin in southern Maine. By knowing the flow exchange, mass balance of pollutants can be performed. The coastal oceanographic data sets produced may assist in the management of the natural resources of the area and validate future circulation models. As of 2016, Biddeford Pool has conditionally approved or restricted harvesting of shellfish due to pollution and algal blooms, specifically impacting the clam industry.
In June 2016, field data was collected in collaboration with the University of New England Marine Science Center and advised by Professor Dave Fredriksson. The pressure measurements provided tidal harmonics, flow rates and volume of water exchanged during the dominant semi-diurnal tides. A tide-corrected bathymetric data set was also obtained that can be used as input in a circulation model and to estimate residual volume. Lastly the tidal prism volume was used to determine the maximum mass balance of nitrogen entering Biddeford Pool from a sewer outfall at the entrance.
Picture: Midshipman Pixa paddles kayak to collect data
Midshipman Second-Class Sara Jenkins investigated the use of bamboo as reinforcement in concrete beams. Especially applicable for coastal regions of Asia where bamboo is abundant, population is dense, and concrete is a favored building material, this research is intended to provide a possible alternative to expensive steel rebar and a solution to concrete structures that lack reinforcement altogether.
Bamboo’s impressive strength-to-weight ratio makes it an ideal material to prevent concrete beams from undergoing catastrophic failure. To evaluate bamboo rebar’s feasibility, specimens of various species, age, and cross-section were tested in an Instron Universal Testing Machine with a tensile load applied until failure. The most successful species, Phyllostachys nigra commonly known as black bamboo, was selected from these results. Reinforced beams with varying cross-sections of black bamboo were tested under four-point bending loading conditions and results were compared. This research was inspired and advised by Professor Dave Kriebel, Professor Sarah Mouring, and Ms. Louis Wallendorf.
Pictures: Bamboo failure; Midshipman Jenkins placing concrete into beam form; Concrete beam in testing
Midshipman First-Class Hannah Hughes investigated inductive recharging for a small, commercial autonomous underwater vehicle (AUV), specifically OceanServer’s Iver3 Ecomapper. The design uses a primary coil of wire on a docking station and a secondary coil of wire on the AUV to recharge the batteries. This type of power transfer uses alternating currents running through the primary coil to produce fluctuating magnetic fields that transfer the power to the secondary coil. Different coil configurations were designed and constructed for use on the Iver3’s hull, including coils tangent to the hull and around the hull. Advised by CDR Andy Gish, testing at Naval Surface Warfare Center (NSWC) in Carderock, MD helped determine the efficiency of power transfer for varied coil design, mediums (air and water), and separation distances.
Pictures: Coil loops; Inductive power system
Midshipman First-Class Danny Vegel is combining his knowledge of Naval Architecture and Chinese to examine shipbuilding industries from around the world and undergo a case study of a foreign ship using open source information. This analysis attempts to identify what organizational, cultural, and design elements have spurred leading shipbuilding manufacturers to success and how the United States can potentially apply these ideas to its own industry. By applying principles of Naval Architecture and running model tests, this study also examines the technical capabilities and performance of foreign ships to determine what long-term strategic challenges the U.S. Navy may one day face. Support is provided by Associate Professor Paul Miller, Associate Professor Wenze Hu, David Majerowicz, Bill Beaver, John Zseleczky, Navatek, and the Naval War College.
Pictures: Computer modeling; Hydro Lab model testing; Midshipman Vegel conducting research at Navatek
Midshipman Joseph Halpin characterized corrosion fatigue for a stainless steel alloy (HG10MNN) and investigated substitute materials of nickel-aluminum-bronze (NAB) for naval applications. HG10MNN is designed for improved resistance to mechanical and thermal fatigue, particularly at high temperatures. This material’s increased elastic modulus and excellent castability make it a potential candidate to replace NAB, currently used in many naval propulsion systems. However, insufficient test or operational data exists regarding the durability of HG10MNN while under fatigue in a saltwater environment.
Rotating-beam-fatigue (RBF) evaluations for ambient air and saltwater corrosion were conducted for HG10MNN, along with electron microscopy of the fracture surface. Test results for HG10MNN and open source RBF data for NAB materials are compared for fatigue curves, both in air and saltwater. Both HG10MNN and NAB exhibit asymptotic behavior at approximately 1 billion cycles, at a stress levels of approximately 20 ksi and 35 ksi, respectively. Electron microscopy allowed analysis of the nature of corrosion, indicating the similarities between HG10MNN and common stainless steels. The material’s resistance to fatigue is compromised by its susceptibility to corrosion while under fatigue, thus HG10MNN is not a suitable replacement or substitute for NAB in marine propulsion. This research is advised by CDR Jeff Woertz.
Pictures: Rotating beam fatigue; Electron microscopy results of corrosion; Midshipman Halpin investigating corrosion