A Continuum Design Sensitivity Analysis of Vehicle Aggregates for Refined NVH Performance

Transmission of vibration and noise to the occupants and especially driver contributes significantly to the quality perception of the motor vehicle and eventually, it affects the overall ride comfort. These forces mainly reach to customer through tactile locations, i.e. floor, gearshift lever, steering wheel and seat. Showroom/Parking customer drive pattern of a vehicle evinces the steering system and driver’s seat rail vibration as strikingly linked aspect to evaluate human comfort [1]. This paper deals with the study of vibration at steering wheel and seat affecting human comfort at engine idle rpm with AC ON and OFF condition for passenger vehicles. The transmissibility of engine and radiator induced vibrations has been investigated with respect to modal alignment of steering and seat system. It has been observed that engine (dominant order or firing order) and radiator fan (1st order) excitation frequencies in proximity to system natural frequency drivesresonance and amplifies the vibration level perceivable to customer. Moreover, due to the upper tolerance limit of power train mount stiffness, rigid body mode of power train is close to the engine excitation frequency. This paper also deals with the fuel pump noise intrusion inside the cabin in showroom/parking drive pattern of a vehicle. Disparate system’s such as steering wheel, seat, radiator fan and fuel pump NVH performance has cascaded down from vehicle to subsystem and component level using the functionally designed and developed test rigs to interpret the root cause and securing the well modal separation of system from engine and radiator fan excitation frequencies. The whole work aims at the target setting and achieving the same at commencement of project and thus reducing development time and cost throughout the project duration of full vehicle NVH refinements.