Driver fatigue is one among the important factors for accidents, causing loss of precious life and property. Apart from long driving hours, driver fatigue can be due to poor ride quality, cabin noise, high vibration levels and poor ergonomics. In last few years, there has been enough emphasis to improve the noise and vibration comfort of commercial vehicles, which is governed by vibration levels at tactile points such as steering wheel, gear lever, pedal and seat. Steering wheel vibration is an important element which driver uses to express about the vehicle vibration quality. Design of steering system is driven by ergonomics, packaging, durability, safety, vibration & ride and handling requirements.
This paper discusses about methodology of steering assembly development for Noise Vibration and Harshness (NVH) performance of commercial vehicle. It deals with steering wheel targets setting and cascading it to system, sub-system & component level targets and achieving these targets by collaborative Test-CAE approach. Target verification and achievement have been done by using bottom up approach starting from component, sub-system, full vehicle level modal targets for tilt and telescopic steering assembly. Steering wheel vibration levels are evaluated for power train idle and Wide Open Throttle (WOT) condition and the design is further refined to meet the targets. It is also important to validate the Finite element (FE) model, since the critical design changes are based on FE model. Therefore baseline steering wheel and steering assembly is correlated with the experimental results based on modal frequencies and mode shapes.