Search Results

The purpose of this paper is to experimentally analyze structural-borne contributions of noise, vibration and harshness during tire rolling, also called Road NVH, in a passenger vehicle using energy transfer path analysis method (TPA), applied in a case study. During the investigation, the influences of the accelerations and forces through the A-arm front suspension bushings are highlighted due their contribution to the estimated overall interior noise, which is correlated to measured overall interior noise. The structural contribution begins as a direct result of tire vibration from surface interactions. These mechanical vibrations, mainly below 450 Hz, are transmitted to all chassis and body subsystems, resulting into noise and vibration perceived by the passengers in the cabin interior. This study is motivated by improvements in Powertrain NVH and Wind Noise, which unbalance Road NVH on various conditions.

It is presented a theoretical and experimental study about noise attenuation device in hydraulic power steering systems. Due to the noise reduction from other vehicle sources, as engine, hydraulic system noise contribution has become more relevant. The hydraulic power steering system major noise source is the pump, contributing with its own operating noise, and also by pressure pulsation in pipeline, which in turns excite another sources. The operating principle of attenuation system is the destructive superposition of pressure waves, and for the phenomenon occurrence, the waves must be 180° out of phase. Delay between the waves is obtained through system parameter settings, geometric and physic. So it was performed system modeling, focusing in the pipeline in order to characterize the system components, and also the model validation was done through comparison between model and test data obtained with commercial system.