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Vibro-Acoustic Analysis Of Car Body Structure

Yiow, Chong Iyat (2001) Vibro-Acoustic Analysis Of Car Body Structure. Masters thesis, Universiti Teknologi Malaysia, Faculty of Mechanical Engineering.

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Abstract

Deflection in structural and dynamic components causes a major portion of objectionable noise perceived in car cabin. To minimise this occurrence, a component can either be stiffened, structural damping increased, or in some cases made lighter to impose less force, thereby reducing noise. In this dissertation, studies were carried out to establish the relationship between response of the car body structure vibration and its corresponding effects to the noise level in the car cavity. In the preliminary work a simple box structure was used such that modelling and computational methods could be established and verified against actual physical measurements. A real car body structure was then selected for computational analysis. In addition to the computational analysis, physical experimental works were undertaken on the simple box structure and Proton Wira underbody-in-white. Normal modes of both test structures were quantified experimentally. Sound pressure levels were also obtained for the cavity involving the simple box structure. Structural and damping modifications on the structures were carried out to enable investigations into influence on the acoustical characteristics of the test structures corresponding to structural modifications. The natural frequencies as identified by the computational method matched closely with the experimental results. Sound pressure level predicted differed moderately from the experimental values with maximum differences of 10%. The studies also showed that sound pressure level in the Proton Wira car cavity could be reduced but only to a certain extent (up to 10%) through structural and additional structural damping coefficient. The accuracy of the sound pressure level measurement could be further improved if the test was conducted in a more controlled environment, such as an anechoic chamber, to minimise the effect of reverberation and extraneous noise.

Item Type:Thesis (Masters)
Subjects:T Technology > TJ Mechanical engineering and machinery
Divisions:Mechanical Engineering
ID Code:6934
Deposited By: Mr Mohd Shukri Ramli
Deposited On:27 Nov 2008 12:39
Last Modified:23 Jan 2011 12:32

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