Tire-Suspension-Chassis Dynamics in Rolling over Obstacles for Ride and Harshness Analysis

Abstract

Abstract The importance of improving dynamic properties is growing in vehicle development, especially as tire sidewall height is reduced. In particular, accurate prediction of tire and suspension dynamics in rolling over road irregularities is needed for evaluation of ride comfort and impact harshness in realistic driving conditions. Severity of loading from impact against bigger obstacles, such as a speed bump, deep pothole, or curb also helps to assess extreme conditions for tire, suspension, and body joint damage and durability. In this study, a detailed tire-wheel finite element model is combined with the hub and suspension, and attached to a simplified vehicle model with a bicycle-type body and rear half. Transient event simulations of straight rolling over a bump and potholes of various geometries reveal rich dynamics of tire impact deformations and the postimpact tire, hub, and vehicle vibrations. Their relation to the tire resonant modes and rolling-impact load variations is elucidated. Simulations of curb impact and rolling over a long pothole are conducted for conditions similar to a suspension abuse test. In addition to very strong amplification of tire and suspension loads, such events produce severe local tire strains and stresses that indicate tire endurance and performance postimpact effects. An example of oblique bump impact simulation is presented as well.