Influence of Interfacial Dynamics and Multi-Dimensional Coupling from Isolator Brackets on Exhaust Isolation System Performance
Loading...
Date
2016-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
The Ohio State University
Abstract
An automotive exhaust structure is a primary structure-borne noise path by which vibratory forces from the powertrain are transmitted to the vehicle body. The exhaust structure is typically connected to the vehicle body through a system of brackets containing elastomeric isolators, serving as the principal means of vibration isolation. In exhaust isolator system design, the isolator brackets are often modeled as simple springs. This approach neglects the effects of interfacial dynamics and multi-dimensional coupling, which result from distributed mass and stiffness throughout the isolator brackets. Accordingly, the objective of this research is to better understand how the interfacial dynamics and multi-dimensional coupling of the isolator brackets affect the exhaust isolation system performance in the 0-100 Hz range. Therefore, models with a proper representation of these interfacial dynamics and multi-dimensional coupling are created using finite element analysis (FEA) and then parameterized into multi-dimensional lumped parameter models through correlation of static and modal testing on the components and assembled system. The dynamic responses from the models for the exhaust structure and isolator brackets are then combined into a system-level model through a frequency-response-function-based substructuring method. A design study is conducted on the system-level model by systematically changing component parameters and evaluating the effect on the transmitted vertical body forces. The results show that the inclusion of these interfacial dynamics have nominal influence on isolation performance; however, the coupling terms show an observable influence, typically increasing the force transmitted to the vehicle body. In addition, the study identified additional design modifications that could improve isolation performance, such as an increase in isolator material loss factor and an increase in the isolator fore-aft stiffness. Although the results are specific to this isolation system design, the modeling procedure outlined has the potential to be used early in the vehicle design process to identify improvements to other baseline designs.
Description
Keywords
Interfacial Dynamics, Multidimensional Coupling, Exhaust Isolation Performance, Isolator Brackets