High-Temperature Life Assessment of Exhaust Components and the Procedure for Accelerated Durability and Reliability Testing 2012-01-2058

Fatigue, creep, oxidation, or their combinations have long been recognized as the principal failure mechanisms in many high-temperature applications such as exhaust manifolds and thermal regeneration units used in commercial vehicle aftertreatment systems. Depending on the specific materials, loading, and temperature levels, the role of each damage mechanism may change significantly, ranging from independent development to competing and combined creep-fatigue, fatigue-oxidation, creep-fatigue-oxidation. Several multiple failure mechanisms based material damage models have been developed, and products to resist these failure mechanisms have been designed and produced. However, one of the key challenges posed to design engineers is to find a way to accelerate the durability and reliability tests of auto exhaust in component and system levels and to validate the product design within development cycle to satisfy customer and market's requirements. In this paper, a dimensional analysis based life assessment model and the corresponding accelerated testing procedure for exhaust components are developed. Their capabilities are demonstrated with a two-stress level pure fatigue test and the V-shape specimen test for creep-fatigue-oxidation durability evaluation. The modeling approach and the accelerated testing procedure developed in this paper can be used for commercial vehicle aftertreatment development as well as for other high-temperature applications.