Abstract
PURPOSES : The rumble strip installed at the highway near the tollgate has the purpose to reduce the vehicle velocity or prevent sleepiness by awakening people to the danger. These rumble strip has different vibration decibel from the rumble strip shapes, resulting in some fatigue damage to human because a driver suffers from a lot of stress and displeasure. In this connection, the objective of this paper is to analyze the vibration decibel perceived by a driver in the vehicle under some conditions. METHODS : The vibration decibel conveyed from the tire can be analyzed. The frequency analysis methods were used according to DFT (Discrete Fourier Transform) analysis, FFT (Fast Fourier Transform) analysis, CPB (Constant Percentage Bandwidth) analysis. But the frequency analysis method in this paper is the 1/24 OCT(Octave) band analysis because of the convenience of the analysis and the overall vibration amplitude along the frequency. RESULTS : By using the results of the vibration decibel after analyzing the 1/24 OCT band analysis, these results can be compared from some conditions (e.g., rumble strip shape, uniform velocity of a vehicle, road condition, mass of a vehicle). As a result, the numerical values of decibel are not directly proportional to the vehicle velocity. CONCLUSIONS : At the condition that a vehicle is passing by the rumble strip, the value of a vibration decibel at the rumble strip of the cylinder shape is smaller than the rumble strip of rectangular shape regardless of the rumble strip depth and width. At the mass condition, the more a vehicle is massive, the more the vibration decibel increases. At the road condition, the vibration decibel at the wet road is smaller than the value at dry road condition.
