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Computer based analytical design techniques are transforming the engine design process. Analytical tools allow faster and more accurate design optimization. The design process is also shortened because the electronic transfer of files permits the design to be worked concurrently by engineers working with different analysis packages or on various parts of the design. Prototype parts and tooling can be made directly from the Computer-Aided Design (CAD) by various rapid prototyping methods. The analytical design techniques can also permit a highly optimized design with less possibility of corrections being necessary in the development stages. This paper reviews these new design techniques and examines how they can be used to improve the design technique. The following design tools are discussed.

Life prediction and reliability analysis of a cam roller system were investigated. From the tribological analysis, the cam roller system was found to operate under low film parameter conditions and components were subjected to the risk of contact fatigue. Surface analysis performed on the failed rollers indicated that the surface distress was the primary cause for failure. Then, numerical analyses were performed to evaluate the cam roller life and its related reliability. The adopted approach combined a contact fatigue crack growth calculations with a probabilistic model for controlling the design uncertainty. The computation-efficient Fast Probabilistic Integration (FPI™) code was used to solve the problem. With appropriate descriptions for uncertainty distributions, the surface fatigue life of the specified cam roller system can be predicted along with a confident reliability level.

Design of the pressure pumping mechanism in a distributor fuel injection rotary pump becomes an uneasy task due to the restless demands for raising injection pressure. This paper presents a numerical simulation model developed to analyze the design appropriateness of the cam ring, roller, and shoe components in the pumping mechanism based on their tribological performance. The developed model solves the lubrication of cam/roller and roller/shoe interfaces simultaneously. Lubrication of the cam roller interface is modeled with a mixed lubrication concept to include the surface asperity contact effects. The load-carrying capacity of the surface is characterized by using a contact mechanics model with the measured surface profiles. Assuming the shoe body is rigid, the roller shoe interfacial lubrication is treated as a partial hydrodynamic bearing including the effect at roller slippage.