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In order to have a robust exhaust system design a comprehensive durability analysis is required. This durability analysis should include thermal loads, engine vibration loading, and proving ground road loads. The dynamic performance evaluation in exhaust system development is a valuable tool to identify the best design alternative. The finite element analysis (FEA) applications in the design of automotive exhaust system have become an indispensable tool. Both the cost and cycle of the product development benefit from its usages. This paper presents a robust design procedure for the dynamic performance of exhaust system in a passenger vehicle. For dynamic analyses it is essential that the complete exhaust assembly is modeled, including manifold, a representation of the engine, and a flex decouple model. This is because dynamic excitation is predominantly comprised of unbalanced forces within the engine, which is transmitted to the exhaust system through the flex decoupling element.

Cyclic firing loading conditions coupled with high thermal loads are the main causes for failure of the cylinder head. A complete thermo-mechanical fatigue analysis of a cast aluminum cylinder head should include both high and low cycle fatigue. Reliable nonlinear material behavior, accurate thermo-mechanical stress analysis, and dependable failure criterion are the keys to successful life prediction. The low cycle fatigue is primarily due to thermal stress resulted from repeated start-up and shut-down cycle of the engines. The high cycle fatigue is mainly due to the firing loads, as amplitude stress, accumulated to the mean stress due to the thermal load. In this paper the required CAE simulations for high/low cycle fatigue of cylinder head will be discussed.

The internal combustion (IC) engine has been developed for a century. The fundamental principles and basic structure have not evolved much. However, the demand on engine performance, fuel economy and emissions is contradictorily challenging for automotive industry. Due to higher power output and operating temperature in modern engine design, concerns on long term sealing performance of the interfaces between the various components of engine are addressed throughout IC engine development process. Since improper sealing among engine components could affect engine functionality, performance, efficiency and emissions, the interactions between the gasket and the component under various operating engine conditions must achieve design goals. The gasket has to provide a leak-free sealing guarantee from the moment it is first installed, and maintain its function for the life of the engine. The use of FEA tools in sealing analysis has grown substantially over the past few decades.

Due to the current federal requirements for increasing vehicle fuel economy, more engineering resources are allocated to the up-front analysis with the purpose of increasing vehicle fuel economy. Engine friction is one of the biggest factors influencing the fuel economy. The cylinder bore distortion plays an important role for the friction between the sliding pistons and the cylinder bore. The quality of the cylinder bore distortion has significant impact on the overall engine efficiency and performance. The cylinder bore distortion will result into consequences such as power loss, blow-by, oil consumption, and NVH issues. To meet the cylinder bore distortion requirements, the engineering community turns efforts to the early design stage during product development. The CAE applications in the design of automotive engine have become an essential tool. Both the cost and cycle of the product development benefit from its usages.