Ride Comfort Analysis of Motor Vehicles using Analytical and Experimental Procedures

Abstract

The occupants of an automobile are subjected to varying levels of vibration, which may not affect them consciously, but passively these are found to contribute to lower back pain, dizziness and discomfort amongst other health hazards when exposed for a chronic period. The primary source of these vibrations apart from the ones originating from the engine, are transmitted from the road during tire road interaction. The effect of this is felt by the occupants via the seat, foot rest, back rest and steering wheel of a four wheeler and the handlebar, footrest and seat in case of a two wheeler. The international standards such as ISO 2631-1:1997 for whole body are followed by vehicle manufacturers for ensuring ride comfort in terms of vibration transmissibility to the occupants. The ride comfort of a vehicle is influenced by the natural and force transfer characteristics of the tire wheel assembly and the suspension system. The objective of the current work is to use analytical models for finding natural frequencies of sprung and unsprung mass and henceforth determining the trend of vibration amplitude influenced by parameters like damping, mass and stiffness values through a forced response analysis. Subsequently, experiments are conducted to measure the real time vibration levels at aforementioned human interaction points. This helps to correlate the analytical study with the experimental outcomes.