Experimental and Computational Methods for Investigating Automotive Door Closure Sounds

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Date
Authors
Garro, Giuseppe
Keyword
Acoustics , Acoustic Modeling , Experimental Acoustics , Computational Acoustics , MATLAB , ANSYS , Continuous Wavelet Transform , Continuous Wavelet Analysis , Octave , One-Third Octave Bandwidth , Sound Pressure , Sound Pressure Level , Rigid Body Dynamics , Explicit Dynamics , Transient Structural , Automotive , Door , Automotive Door Closure , Automotive Door Closure System , Impact , Experimental , Computational , Waveform , A-Weighting , Short Time Fourier Transform , ISO , Finite Element Method , FEM , Finite Element Analysis , FEA , Elements Per Wavelength , Microphone
Abstract
The focus of this investigation was to examine the acoustic trends present during operation of an automotive door closure at two impact speeds using experimental and computational methods. The impact speeds were 0.851m/s and 1.179m/s. Transient sound pressure measurements from five different door closure mechanisms were collected in a semi-anechoic chamber using a three-element condenser microphone array. Post-processing methodologies such as Sound Pressure Level versus 1/3 Octave Bandwidth and Continuous Wavelet Transform computations were conducted. These procedures provided an in-depth analysis on the overall generated sound in addition to identifying which frequencies dominate the response at the same time as specific impact events during latch operation. Sound quality metrics such as loudness and sharpness were used to explore how the impulsive sound relates to a consumer’s impression of the sound. It was suggested in past research that individuals prefer sounds that possess a ‘deep’ sound characteristic as opposed to sounds characterized as ‘metallic’. It was revealed that the overall sound quality was mainly influenced by the frequency composition of the sound. The focus of this study was the sound generated by the impact events present during the latch-locking operation. With ANSYS Rigid Body Dynamics and Explicit Dynamics, it was concluded that two impact events within the latch influenced the acoustic response. The impacts occurred between the Striker/Over-Slam Bumper #1 and the Ratchet/Housing. These were labelled as the primary and secondary impact events respectively. Investigation of the experimental sound data revealed that the faster entrance speed (1.179m/s) produced a sound with a larger normalized magnitude. Furthermore, the additional energy allowed frequencies approximately 2.5kHz and below to become more pronounced. The findings suggest that increasing the closing speed could produce a “more preferred” sound based on psychoacoustic principles. A computational acoustic analysis using ANSYS Workbench was performed to complement the experimental analysis. Only the primary impact event was simulated due to the inherent limitations of the workstation used to perform the analysis. Similarities between the computational and experimental data were present. However, it is recommended that an alternate simulation software that is capable of modelling “physical impacts” be used.
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