Transfer path analysis and control of vehicle structure-borne noise induced by the powertrain

Because of the higher requirements for vehicle comfort and people’s increasing ecological consciousness, research on the interior noise in a vehicle has received wide concern, among which structure-borne noise is hard to diagnose and control. To solve the problem, the transfer path analysis method of powertrain structure-borne noise has been systematically analysed. By introduction of the powertrain source–path–receiver model, this method enables us to estimate and study the vibro-acoustic transfer functions and their operational forces. Since structure-borne noise is composed of multiple paths, the aim of this paper is to discuss different synthesis methods for this noise. On the basis of previous discussion, the transfer path analysis test of a certain vehicle is carried out, and the transfer function and operational data at idle and second-gear wide-open throttle are obtained. The test data are processed and an acoustic contribution analysis of the target is performed using LMS software. The results of analysis show that the right-hand side mount represents the main contribution path. Then the match principle of the bracket dynamic stiffness of the powertrain isolation system is proposed. On the basis of the transfer path analysis results and the above principle, the bracket on the body side of the right-hand side mount is improved by combination of the experimental transfer path analysis and the finite element method. The test results show that the A-weighted sound pressure level of the interior noise at idle and second-gear wide-open throttle are reduced by 2.9 dB(A) and 4 dB(A) respectively after improvement. Also there is no obvious booming noise at second-gear wide-open throttle. It is expected that this paper can help automotive noise, vibration and harshness engineers to perform trouble shooting and sound design.