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In the present automobile market, customers have put demand for smaller cars with better ride and comfort. For small diesel engine cars, where the comfort is known to be inferior to its gasoline siblings, the effect of engine excitation and road inputs has posed the problem of seat back vibrations. Low frequency vibrations are observed at irregular road inputs, which directly get transferred to the human body through the seat back resulting in fatigue and discomfort. This paper describes the use of testing and CAE in reducing the seat back vibrations. First step of the study includes the frequency response functions (FRF) of the seat frame and road data. The CAE model is validated with the test data and the problem areas are identified. The countermeasure design modifications in the seat frame structure are analyzed using CAE (Normal Mode Analysis). The feasible countermeasure action is road tested and clearly shows a reduction in the vibration levels coming on the seat back.

Automotive OEMs quest for vehicle body light weighting, increase in Fuel efficiency along with significant cut in the emissions pose significant challenges. Apart from the effect on vehicle handling, the reduction of vehicle weight also results in additional general requirements for acoustic measures as it is an important aspect that contributes to the comfort and the sound quality image of the vehicle, thus posing a unique challenge to body designers and NVH experts. Due to these conflicting objectives, accurate identification along with knowledge of the transfer paths of vibrations and noise in the vehicle is needed to facilitate measures for booming noise dampening and vehicle structure vibration amplitude. This paper focuses on the application of a unique design and development of vehicle body structure anti-vibration dynamic damper (DD), unique in its aspect in controlling booming noise generated at a specific RPM range.