This document describes the advantages of using Mobility transfer function simulations during the development of exhaust systems. The automotive industry demands increasingly stringent levels of acceptable interior noise. The exhaust system is an important contributor to the total vehicle noise and vibration and thus is a target for noise reduction. The use of good vibration isolation systems makes it possible to decrease noise in the vehicle interior compartment. In other words, the vibratory motion in automotive structures results in tactile and acoustic responses. This occurs when the energy coming from the engine (source) is transferred by the Exhaust System (path) and then is transformed into Structural Borne Noise received by the Driver (receiver) through the hanging arrangement of the Exhaust System. In this paper, a procedure to apply the Mobility transfer function to exhaust system design is first described and then an example of correlation results between experimental tests and finite element simulations are shown. These simulations are then used in an optimisation phase to define the proper design to meet the targets.
The most interesting advantage of the application of the Mobility transfer function to exhaust system design is the possibility to change the design of the hangers and/or isolators early in the development process with the support of Computer Aided Engineering (CAE) tools. When using these tools, waiting until the structural and performance validation gates step/process to make changes is avoided and thus much time is saved in the development process.
