Analysis of structure-borne noise in vehicles by modifying the stiffness of joint parts in the suspension system and vehicle body

Abstract

This study aims to change and improve the transmitted force to the vehicle body, the noise transfer function (NTF), and vehicle interior noise by modifying the stiffness of joint parts, which are the local areas of the subframe and body in white (BIW) connected to isolators. We adopted frequency response function (FRF)-based substructuring in order to understand the effects of the stiffness of joint parts for reducing the vibration in the transfer path of a “chassis-isolator vehicle body”. In addition, a process that could be used to predict the vehicle interior noise was developed based on FRF-based substructuring. Using the FRF-based substructuring technique, the transmitted force from the chassis to the vehicle body caused by the increased stiffness of the joint parts in the chassis and vehicle body was calculated. Subsequently, the NTF from the joint parts of a vehicle body to the driver's ear location was calculated. In the chassis, the transmitted force to the vehicle body increased or decreased with increasing stiffness of the joint parts of the chassis, and the vehicle interior noise showed similar tendency of the transmitted force. In the vehicle body, the transmitted force to the vehicle body increased when the stiffness of the joint parts of the BIW was increased. However, as the noise transfer function was reduced beyond the increase in the transmitted force, the vehicle interior noise decreased. The role of the isolator stiffness is dominant for determining change of the transmitted force, which affects the vehicle interior noise. Therefore, in order to reduce the vehicle interior noise, the stiffness of isolator and joint parts should be set in consideration of the transmitted force from the chassis to the vehicle body.