Vibration Analysis of a Bus’s Air Spring Suspension Subjected to Random Road Profile

Abstract

Vehicle dynamics model in type of 1/4 is used for vibration analysis under the effect of random road profile with different grades. The mathematical model to describe the used random road profile is able to change the type of investigated road grades by selecting the corresponding power spectral density parameter of the road grade according to the ISO 8608 standard. Random road profile is ivestigated in the range of frequency domain from 0 to 50 (Hz). The air spring stiffness and the damping coefficience are determined on the basis of reference to the practical vehicle. The variation of relative displacement amplitude of the suspension in the range of investigation domain is small, the air spring stiffness used in the calculation is constant. The obtained results corresponding to different grades of road surface roughness including displacement and acceleration parameters. Relative displacement is a parameter that aims to verify the ability to ensure safe working of the suspension, namely rattle spacing. Acceleration is used to evaluate the vehicle's comfort. Calculation results are analyzed as the basis for evaluating the influence of the air spring stiffness and road surface conditions on the comfort of the vehicle, as the basis for changing the air spring stiffness in accordance with adjusting the pressure of it according to the type of road profile quality.