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Title A scaled physical model for underwater sound radiation from a partially submerged cylindrical shell under impact
Publication Date
Date Accessioned
Degree MS
Discipline/Department Mechanical Engineering
Degree Level masters
University/Publisher Georgia Tech
Abstract The motivation for this study is to create a scaled laboratory model of a steel construction pile being driven by an impact hammer, which can provide controlled data to aid understanding and development of a structural acoustics numerical model simulating full-scale impact pile driving. The scaled model is approximately thirty times shorter than a typical 30-meter long Cast-in-Shell-Steel (CISS) pile. The relationship between the impact force, structural vibrations, and radiated sound field is analyzed. The time-domain acoustic intensity in the radial direction is found to be predominately negative immediately following excitation by the impact force. Analysis of the radial intensity shows that during the hammer strike, there is a net flow of energy from the structure into the water; however, because the structure and water are acoustically coupled a significant portion of the energy immediately flows back into the cylinder following hammer impact. This fluid-structure interaction results in a highly damped acoustic pulse in the water that propagates to the far field. In addition, the frequency spectra of the impact force, model pile wall acceleration in the radial direction in air and water, and underwater acoustic pressure are analyzed to find transfer functions between these variables. The transfer function between impact force and sound pressure is of particular interest because it can be used to calculate the system response for any other applied hammer force. This transfer function analysis has potential applications in mitigating noise generated by impact pile driving.
Subjects/Keywords Sound radiation; Structural acoustics; Pile driving; Underwater acoustics; Models and modelmaking; Underwater acoustics; Vibration; Piling (Civil engineering); Noise control; Structural dynamics
Contributors Hastings, Mardi (Committee Chair); Ferri, Aldo (Committee Member); Ryherd, Erica (Committee Member)
Country of Publication us
Record ID handle:1853/44874
Repository gatech
Date Indexed 2018-01-11
Issued Date 2012-07-06 00:00:00
Note [degree] MS; [advisor] Committee Chair: Hastings, Mardi; Committee Member: Ferri, Aldo; Committee Member: Ryherd, Erica;

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