Mechanical Engineering Commons^™

Scanning Laser Registration And Structural Energy Density Based Active Structural Acoustic Control, Daniel Alan Manwill

Theses and Dissertations

To simplify the measurement of energy-based structural metrics, a general registration process for the scanning laser doppler vibrometer (SLDV) has been developed. Existing registration techniques, also known as pose estimation or position registration, suffer from mathematical complexity, instrument specificity, and the need for correct optimization initialization. These difficulties have been addressed through development of a general linear laser model and hybrid registration algorithm. These are applicable to any SLDV and allow the registration problem to be solved using straightforward mathematics. Additionally, the hybrid registration algorithm eliminates the need for correct optimization initialization by separating the optimization process from solution selection. …

Improved Measurement And Separation Techniques For Interior Near-Field Acoustical Holography, Zachary A. Collins

Theses and Dissertations

Recent advances in near-field acoustical holography (NAH) have expanded the theory to interior spaces where multiple sources and/or reflections are present. In 1990, Tamura presented the spatial Fourier transform separation method to measure the reflection coefficient at oblique angles using two measurement planes in the wave number domain. This paper adapts the spatial Fourier transform separation method for application in interior NAH. A practical exploration of important experimental parameters is performed, which include the relative amplitudes of primary and disturbing sources, the measurement plane separation distance, and an acceptable noise floor. This technique is successfully applied in a reverberant environment …

Elastic And Magnetic Properties Of Tb6fe(Sb,Bi)2 Using Resonant Ultrasound Spectroscopy., David Michael Mccarthy

Masters Theses

Tb6FeSb2 and Tb6FeBi2 are novel rare earth compounds with little prior research. These compounds show high and variable curie temperatures for rare-earth compounds. This has lead to a literature review which includes the discussion of: elasticity, resonance, and magnetism. This review is used to discuss the theory and methodology which can relate these various properties to each other. Furthermore, synthesis, x-ray analysis, and RUS sample preparation of Tb6FeSb2 and Tb6FeBi2 were completed.

Resonant Ultrasound Spectroscopy (RUS) elastic studies were taken for Tb6FeSb2 and Tb6FeBi2 as a function temperature from 5-300K, in various magnetic fields ranging from 0-9T. Tb6FeSb2’s and Tb6FeBi2’s …

A Prediction Of The Acoustical Output Of A Golf Driver Head Using Finite Elements, Roger Sharpe

Master's Theses

A simulation was created using LS-DYNA® to determine the acoustical properties of a golf ball and golf driver head impact. LS-DYNA® has a coupled finite element analysis (FEA) and boundary element method (BEM) solver that uses the integral form of Helmholtz’s acoustic wave equation to deliver predicted sound pressure levels at predetermined acoustic points. Validation of the modeling was done on a simple plate donated by Titleist Golf. The plate was modeled and meshed using TrueGrid and impacted by a three layer golf ball model derived from “Tanka’s” paper on multilayered golf balls. The final converging model consisted of 10,900 …