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Full-Text Articles in Mechanical Engineering
Characterizing The Acoustic Properties Of The Jet Lab At The National Center For Physical Acoustics, Joshua Anderson Lieblong
Characterizing The Acoustic Properties Of The Jet Lab At The National Center For Physical Acoustics, Joshua Anderson Lieblong
Electronic Theses and Dissertations
Aerodynamic noise has been a problem since the first use of the jet engine for military aircraft in World War II. For further uses of the jet engine to be possible, problems due to jet noise must be researched and addressed. Anechoic chambers were proposed as a testing facility for research in aerodynamic noise because of their supposed free-field characteristics. The international standard ISO 3745-1977 was introduced to determine whether the facilities could be considered anechoic, semi-anechoic, or neither. An experiment was designed to determine at what frequencies the National Center for Physical Acoustics' Jet Lab Facility is non-anechoic, semi-anechoic, …
Smart Nanocoated Structure For Energy Harvesting At Low Frequency Vibration, Sudhanshu Sharma
Smart Nanocoated Structure For Energy Harvesting At Low Frequency Vibration, Sudhanshu Sharma
Electronic Theses and Dissertations
Increasing demands of energy which is cleaner and has an unlimited supply has led development in the field of energy harvesting. Piezoelectric materials can be used as a means of transforming ambient vibrations into electrical energy that can be stored and used to power other devices. With the recent surge of micro scale devices, piezoelectric power generation can provide a convenient alternative to traditional power sources. In this research, a piezoelectric power generator composite prototype was developed to maximize the power output of the system. A lead zirconate titanate (PZT) composite structure was formed and mounted on a cantilever bar …
A Comparative Study Of Segmented Tungsten Rod Penetration Into A Thick Steel Target Plate, Michael Bryant Presnell
A Comparative Study Of Segmented Tungsten Rod Penetration Into A Thick Steel Target Plate, Michael Bryant Presnell
Electronic Theses and Dissertations
This thesis presents results from computational simulations of tungsten alloy segmented rod projectiles (SRP) penetrating an RHA semi-infinite target plate at high velocities. Penetration experimental data show improved penetration efficiency by the segmented projectiles when compared to monolithic (single solid rod) projectiles. For SRP with an aspect ratio (L/D) = 1/8, a loss in penetration efficiency was seen upon successive segment impacts. A numerical simulation impacting tungsten heavy alloy against RHA 4340 steel was performed using the Lagrangian finite element code EPIC 2006. The impact configuration that was modeled consisted of eight successive collinear impacts of discs measured 2mm in …