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Access Type

WSU Access

Date of Award

January 2016

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Mechanical Engineering

First Advisor

Sean Wu

Abstract

This dissertation presents the HELS based NAH with laser and use normal surface velocity as input in near-field acoustic holography. The conventional HELS based NAH uses acoustic pressure as input to reconstruct sound field quantities, while this modified HELS based NAH with laser utilizes the normal surface velocities measured by LDV to reconstruct the acoustic quantities at interested positions. Theoretical principles of the HELS based NAH with laser have been fully developed and the method has been verified in theoretical perspective. Two theoretical examples verify that HELS based NAH with laser can obtain exactly the same results as analytic solution. The error analysis shows that the magnitudes of errors are bounded and the HELS based NAH with laser is robust and reliable.

Numerical simulations have been conducted on ideal sound sources. Another numerical study has been conducted on some special cases of a transverse vibration problem of thin plates. The reconstructed acoustic field is compared with the theoretical values, and it testifies that HELS based NAH with laser is also applicable to both ideal sound sources and complex sound sources. Experimental validation was finished by reconstructing acoustic pressure generated by a subwoofer. Through comparing the reconstructed sound pressure at 4 different positions with measured values from microphones, it demonstrates that the HELS based NAH with laser demonstrates succeed in reconstructing sound pressure based on normal surface velocity input.

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