Organization:
Mechanical Engineering (ME)

Description

The mission of the Mechanical and Aerospace Engineering department is to provide defense-relevant, advanced education and research programs to meet Naval unique needs, and increase the warfighting effectiveness of the U.S. Naval Forces, DoD and allied armed forces.

Website of the organization

https://nps.edu/web/mae

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Publication Search Results

Now showing 1 - 10 of 49

Pseudo Wigner-Ville Distribution, Computer program and its Applications to Time-Frequency Domain Problems
(Monterey, California. Naval Postgraduate School, 1993-03-01) Shin, Y. S.; Jeon, Jae-Jin; Mechanical Engineering (ME); Mechanical Engineering
Machinery operating in non-stationary mode generates a signature which at each instant of time has a distinct frequency. A time-frequency domain representation is needed to characterize such signature. Pseudo Wigner-Ville distribution is ideally suited for portraying non-stationary signal in the time- frequency domain and carried out by adapting the fast Fourier transform algorithm. The important parameters affecting the pseudo Wigner-Ville distribution are discussed and sensitivity analyses are also performed. Practical examples of an actual transient signal are used to illustrate its dynamic features jointly in time and frequency.
Prototype line of sight and target acquisition software for high resolution databases
(Monterey, California. Naval Postgraduate School, 1995-12) Driels, Morris R.; Lind, Judith H.; Mechanical Engineering (ME); Mechanical Engineering
Wavelet transform for time-frequency analysis of vibrational signature and its application
(Monterey, California. Naval Postgraduate School, 1993-08-17) Shin, Y. S.; Jeon, Jae-Jin; Mechanical Engineering (ME); Mechanical Engineering
Wavelet transform is applied to the analysis of vibration signatures in order to verify the ability of the detection of abnormal condition. It can well describe the dynamics of the signal's spectral composition of a non- stationary and stationary signal to be measured and presented in the form of 3-D time-frequency map. Although wavelet has been developed over about ten years in the mathematics and physics, its engineering applications is a first stage. The objective of this report outlines the definition of the wavelet transform and is to discuss the properties of the wavelet transform as new tool for the vibration analysis, and then demonstrates how it may be applied to the machinery condition monitoring.
A Graphic User Interface (GUI) for generating NPS Autonomous Underwater Vehicle (AUV) execution script files
(Monterey, California. Naval Postgraduate School, 1999-08) Doleac, Joel.; Mechanical Engineering (ME); Mechanical Engineering
Ship shock trial modeling and simulation of USS Winston S. Churchill (DDG 81)
(Monterey, California. Naval Postgraduate School, 2003) Schneider, Nathan A.; Shin, Young S.; Mechanical Engineering (ME); Naval Sea Systems Command; Mechanical Engineering
During World War II many surface combatants were damaged or severely crippled by close-proximity underwater explosions from ordnance that had actually missed their target. Since this time all new classes of combatants have been required to conduct shock trial tests on the lead ship of the class in order to test the survivability of mission essential equipment in a severe shock environment. While these tests are extremely important in determining the vulnerabilities of a surface ship, they require an extensive amount of preparation, manhours, and money. Furthermore, these tests present an obvious danger to the crew on board, the ship itself, and any marine life in the vicinity. Creating a virtual shock environment by use of a computer to model the ship structure and the surrounding fluid presents a valuable design tool and an attractive alternative to these tests. The research summarized in this report investigated the accuracy of shock simulation using the shock trials conducted on USS WINSTON S. CHURCHILL (DDG 81) in 2001. All three explosions DDG 81 was subjected to are simulated and the resulting predictions compared with actual shock trial data. The effects of fluid volume size, mesh density, mesh quality, and shot location are investigated.
Stress analysis of thermowells
(Monterey, California : Naval Postgraduate School, 1974-11-11) Brock, John E.; Mechanical Engineering (ME); Mechanical Engineering
This monograph examineB the mechanical-structural integrity of thermowells to sustain pressurization and excitaticn:s due to fluid flow. Suggested design criteria, which ~re shown to be conservative, are more inclusive than currently employed criteria, and in one tmportant aspect, namely with respect to pressurization, are more liberal.
Sensors for the detection of land-based munitions
(Monterey, California. Naval Postgraduate School, Department of Mechanical Engineering, 1995-09) Healey, Anthony J.; Webber, William T.; Mechanical Engineering (ME); Mechanical Engineering
Damping modeling strategy for naval ship system
(Monterey, California. Naval Postgraduate School, 2003) Shin, Y. S.; Ham, Ilbae; Mechanical Engineering (ME); Naval Surface Warfare Center (U.S.); Naval Surface Warfare Center (U.S.), Carderock Division ; Mechanical Engineering
The damping modeling strategy for naval ship system is presented for ship shock transient time-domain analysis. The Complex Exponential Method is used for extraction of modal parameters in time-domain. Inverse Fourier Transform of Mobility form for general viscous damping model is used to verify the calculated modal parameters. Rayleigh damping parameters are calculated using modal frequency and modal damping ratios. The statistical characteristics of Rayleigh damping parameters are quantified and evaluated in each categorized area: keel, bulkhead and deck. Then the Rayleigh damping parameters are recommended for ship shock response prediction. The damping studies were conducted using 2000 ms data based on DDG 53 Ship Shock Trial.
Nonlinear Response of Cylindrical Shells to Underwater Explosion: Testings and Numerical Prediction Using USA/DYNA3D / June 1, 1991 - March 1, 1992
(Monterey, California: Naval Postgraduate School., 1992-03) Fox, P. K.; Kwon, Y. W.; Shin, Y. S.; Mechanical Engineering (ME); Mechanical Engineering
Nonlinear 3-D Dynamic Analysis Code (VEC/DYNA3D) has been interfaced with Underwater Shock Analysis Code (USA) and capabilities were developed to perform numerical analysis of submerged and semi-submerged marine structures subjected to underwater explosion. A series of numerical analysis were performed to determine the elastic and elasto-plastic responses of cylindrica shell type structures. The results were favorably compared with those of underwater explosion testings. The coupled code USA/DYNA3D makes possible to predict shock-induced damage response of naval structure. In addition, numerical sensitivity analyses were undertaken to determine the importance of various physical and numerical modeling factors. This study showed clearly three types of response modes of cylinder subjected to a side-on explosion: accordion mode, breathing mode and whipping mode.
The Surface Warfare Test Ship
(Monterey, California. Naval Postgraduate School, 2000-01) Calvano, Charles Natale; Harney, Robert C.; Wickersham, David; Farsaris, Ioannis; Malone, Philip; Ruley, David; York, Nathan; Mechanical Engineering (ME); Mechanical Engineering; Physics
A systems engineering approach to the design of a ship conversion to satisfy the requirements for a Surface Warfare Test Ship (SWTS) to be employed by the Port Hueneme Division of the Naval Surface Warfare Center is presented. The ship described would meet test needs for future weapons and sensor systems and provide limited test capability for future hull, mechanical and electrical systems. The current Self Defense Test Ship is over 45 years old, approaching the end of its useful life. A conversion of a decommissioned SPRUANCE (DD 963) class ship is the basis for the replacement Surface Warfare Test Ship. The study proceeds from mission needs and operational requirements through a functional analysis and study of threat weapons to be employed against the SWTS. After summarizing the characteristics of a SPRUANCE Class ship, the study reports an analysis of four alternative conversion schemes. The alternatives are described, with the rationale for choosing that considered best. The chosen alternative is then described and analyzed in several important areas of concern including combat systems functionality, signature characteristics, engineering plant and habitability for test personnel. The fitness of the proposed design for several special evolutions is also described, and alternatives for further enhancing performance are presented.