Effect Of Corrosion on Noise-Vibration-Harshness Characteristics and Performance of a Cold End Exhaust System

Corrosion resistance is important for long term durability and reliability of exhaust systems. For cold end, the key concern has been corrosion due to salt solution from outside and acidic condensate from inside. Meeting traditional durability and performance criteria have long been the goal for engineers responsible for exhaust system design and development. As a result, NVH characteristics of vehicles are considered in durability and performance design standards but the impact of corrosion is not. Automotive industry is innovating in areas of vehicle design to maximize fuel efficiency. To realize this goal, automakers are working towards light weight designs that consist of thinner material for exhaust components. In this paper, attempt has been made to explain impact of corrosion that should be taken into consideration while designing exhaust systems with thinner materials. This work focuses on corrosion testing, muffler internal components, that are exposed to acidic condensate from inside. The exhaust system components were evaluated, for determining NVH before and after corrosion testing, using bench and vehicle level testing. The corrosion tested parts were evaluated to determine pitting corrosion resistance of the internal components. The evaluation results indicate effect of corrosion on NVH characteristics and performance of an exhaust system.