Numerical and experimental investigation of vibration and response optimization of a car chassis with effect of changing driving speed

Abstract

Vibration of automobile vehicles is the important issue in the entire vehicle design process as it affects the comfort level and the overall image of a vehicle, an experimental evaluation and prediction of vibration level of the vehicle in stationary and driving conditions are often necessary. This paper delves in to a numerical and experimental investigation of vibration and response optimization of a car chassis with peak acceleration and peak amplitude level of vibration as a response parameter in vertical motion. These response parameters were obtained numerically by developing a mathematical model of car and equation of motion. Newmark Beta method used to solve the equation of motion to get the values of response parameters in MATLAB software. For the experimental investigation of the response parameters a car with monocoque chassis, three cylinder engine, Macpherson front suspension and twist beam rear suspension with coil spring considered and FFT analyzer used for the data collection of the response parameters, FFT analyzer works on the fast Fourier transform algorithm. Comparative analysis between the numerical and experimental investigated values of response parameters shows the minimum error of 0.6035% and average error of 2.81% at various points on chassis; it shows the precision of the mathematical model and practical car model. To optimize the performance index of response parameters Fractional factorial design of experiment (DOE) method applied with six factors and two levels. The main effect analysis, analysis of contribution, analysis of variance and backward elimination method were applied in fractional factorial design. Regression equation for the response parameters were obtained with two level six factor fractional factorial design for the vibration level prediction. The comparative analysis of the response parameter levels before and after the optimization shows the reduction of 65.61% in peak acceleration level and reduction of 17.70% in the peak amplitude level of a car chassis with respect to change in the driving speed. The design and optimization method proposed in this study has a significant effect on the vibration reduction of the car chassis which provides a reference for the optimization of the vibration level to improve the performance of car suspension.