Mathematical modelling of layered contact mechanics of cam-tappet conjunction

The paper briefly introduces a fast converging mathematical model to predict the peculiarities of the non-conforming contact between an infinitely long cylinder and a coated elastic substrate. The proposed method is then integrated into a multi-physics analysis of the valve train system of a racing type internal combustion (IC) engine. Due to relatively high loads and speeds experienced, particularly in the cam–tappet contacts, hard wear resistant coatings are used, which greatly influence the contact mechanics performance. Results indicate that the layer thickness is the determining factor in contact characteristics, which alters during the cam cycle. Therefore, for optimal performance coatings of non-uniform thickness should ideally be applied to the circumference of the cam rather than the usual coating of the tappet surface with a given thickness.

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