Showing papers by "Sang-Kwon Lee published in 2019"

Prediction and Sound Quality Analysis of Tire Pattern Noise Based on System Identification by Utilizing an Optimal Adaptive Filter

Abstract: Identifying the cause of vehicle noise is a basic requirement for the development of low-noise vehicles. The tire pattern noise depends on the tire itself and causes complex and unpredictable sounds. In pneumatic tire pattern design, the prediction technology of the tire pattern noise according to pattern shape design is important. The conventional method of predicting tire pattern noise is to simply scan the pattern shape of tire and to analyze its spectrum. However, this method has limitations because it does not consider the transfer function and precise mechanism of tire pattern noise. In this study, adaptive filter theory was applied to identify the transfer function between the grooves of patterns and measured acoustic data. To predict the waveform of an actual pattern noise in the time domain, the impulse response of this transfer function was convolved by the scanned pattern input of tires. The predicted waveform of pattern noise was validated with the waveforms of measured noise data. Finally, a sound quality index (SQI) of tire pattern noise was developed using the measured pattern noises and was applied to estimate the sound quality of pattern noise. Eventually, using the prediction method from this study, we hope to reduce the time and cost spent on tire pattern design and verification.

Effect of the Fiber Lamination Angle of a Carbon-Fiber, Laminated Composite Plate Roof on the Car Interior Noise

Abstract: The paper presents the change of the interior noise according to the lamination angles of the carbon fiber in the carbon-fiber reinforced plastic (CFRP) laminated composite plate. In the previous paper, the charateristics of the sound radiated from a CFRP plate was studied in the free field condition. In this paper, vibro-acoustic interaction for the CFRP plate with various lamination angles was studed considering the application of the CFRP plate to car roof. In order to study the vibro-acoustic interaction, a certain enclosure with flexible wall was required and then the closed rectangular box was prepared. The one flexible wall of the rectangular box consisted of CFRP plate. Three CFRP plates with fiber lamination angles of [-15/15/15/-15]s, [-30/30/30/-30]s, and [-75/75/75/-75]s were fabricated and used as one flexible wall of the closed box. These plates were excited by an impact force, and the interior sound pressure within the closed box was calculated both theoretically and experimentally. Then, the identified vibro-acoustic characteristics were used to apply the CFRP plate to the roof of a car, thereby shifting the resonance frequency of the interior noise.

Effect of laminated angle of carbon fiber on interior noise on an enclosure under center point excitation

Abstract: This paper presents a novel method to control passively the interior noise of an enclosure such as car cabin by using the movement of the peak level and peak frequency according to the laminated an...