Impact of Suspension Failures on the Dynamic Response of a Vehicle Multibody Model

Abstract

Irregularities in road profiles generate excitations in the tires of vehicles traveling over them. These excitations are absorbed by the vehicle's suspension, which has the function of minimizing the transfer of these forces to the vehicle’s body, and consequently to the driver and passengers, ensuring both comfort and safety for the individuals, as well as protection for the vehicle’s cargo. This study aims to analyze the dynamic behavior of a vehicle traveling on an irregular road profile to evaluate how a failure in the vehicle’s suspension influences comfort, vehicle safety, and the driver’s health. Initially, a class C road, considered a reference for Brazilian roads according to the ISO 8608:2016 standard, was modeled during a predefined time and speed. Using a seven-degrees-of-freedom multibody model of a full vehicle, plus one degree of freedom for the driver’s seat, a calculation routine was developed using Python programming language for the numerical integration of the dynamic interaction between the vehicle and the road. Vibration modes of the vehicle’s sprung mass and its wheels were obtained for verification with literature results, as well as displacements and accelerations of the various degrees of freedom to assess the Power Spectral Density - PSD associated to comfort and handling parameters of the vehicle. Finally, using the ISO 2631-1:2010 standard, the health guidance zones for a predefined expected daily exposure of the driver were determined. After verifying the calculation routine, several faults were implemented: for instance, one in the right front damper and another simulating irregular tire inflation on the same wheel, in order to evaluate the sensitivity of the vehicle's dynamic behavior and how such failures impact the driver’s health, emphasizing the importance of vehicle maintenance. The results obtained can be extrapolated to other road profiles and speeds, as well as include defects in the driver's suspension.