Effect of Elastomeric Isolator on Dynamic Response of an Exhaust System

Abstract Elastomeric isolators are typically used as connectors between the body-side and exhaust-side hangers to modulate the vibrational excitation input from the exhaust system into the vehicle underbody, Fig. 1. The dynamic response of these isolators must be properly tuned to avoid any interior cavity boom or structural vibration transmission. This paper studies the effect of elastomeric properties of the isolator material on the dynamic response of the exhaust system and the transmitted force response. A simplified geometry for an exhaust system is considered. The solution procedure developed may be used for an arbitrary number of isolators. In order to separate the coupling effect of multiple isolators, the effect of a single isolator is studied in detail. The problem solution is developed for a generic functional form for the dynamic stiffness of the isolator. The resulting system of equations leads to a nonlinear transcendental equation for an eigenvalue problem. Based on the available experimental data for typical isolators a functional form of dynamic stiffness is considered. The resulting solution reveals the influence of the elastomeric isolators on the dynamic characteristics of a typical exhaust system. Further, the frequency response of the force transmitted is also obtained. This procedure may be used to either predict the effect of a particular isolator for varying ambient conditions (temperature, preload, vibration amplitude) and/or may be used to tune the properties of an isolator to best suit a particular application.