DEVELOPMENT OF 7 DOF FULL CAR MODEL FOR RIDE-COMFORT ANALYSIS OF COMMERCIAL BUS.

The Automobile industry is striving for improvement in design to provide passenger comfort in Commercial vehicles segment. Ride is considered to be one of the crucial criteria for evaluating the performance of a vehicle. In the Industry, Quarter-car model has been used for years to study the vehicle’s ride dynamics. Generally, Quarter car models are 2 DOF models which focus the analysis over one wheel, hence, due to the lower degree of freedom as well as absence of pitch and roll analysis involved in quarter car, the output may be inaccurate. In this project, we have developed a 7 DOF full-car Model to perform the ride- comfort analysis for Light Duty 4x2 Commercial Bus using MATLAB Simulink which can be used to tune the suspension design to meet the required ride-comfort level. Firstly, experimental data and physical parameters are collected by performing Practical Test on 4x2 Bus on a Class A, B and C road profile. Secondly, a Full Car Mathematical Model with 7 DOF has been developed for a H.D. bus using MATLAB Simulink, ver. R2018a. The model is designed for independent dynamic damping on all 4 wheels along with the independent spring stiffness. Road data is given as an input to the Mathematical Model and the Roll, Pitch and Bounce data is determined as output. The simulated and actual data is correlated and validated using Time domain and Frequency domain analysis. Furthermore, fitment of data in Ride Comfort Index is carried out as per ISO 2631. Therefore, a parametric model to encompass all vehicle architectures ranging from IC engine to electric powertrain under the commercial bus segment is developed for detailed ride and comfort analysis.