Federico J. Cavalieri

Numerical and Experimental Stress Analysis of an Internal Combustion Engine Valve During the Closing Event

This paper presents a numerical methodology to predict the stress evolution in an internal-combustion engine valve during the closing event. The problem is studied using a three-dimensional finite element model, showing that the seating process of the valve produces high bending stresses which are not demonstrated by two-dimensional models. The valve stem stress response under impact was registered experimentally using strain gauges and then compared with the finite element method solutions, showing good agreement. The main contribution of this paper is the identification of the factors which generate the development of impact stresses during the closing event in an internal- combustion engine valve and which could result in fatigue failure.

A Mortar Method Combined with an Augmented Lagrangian Approach for Treatment of Mechanical Contact Problems

This work presents a mixed penalty-duality formulation from an augmented Lagrangian approach for treating the contact inequality constraints. The augmented Lagrangian approach allows to regularize the non differentiable contact terms and gives a C\(^1\) differentiable saddle-point functional. The relative displacement of two contacting bodies is described in the framework of the Finite Element Method (FEM) using the mortar method, which gives a smooth representation of the contact forces across the bodies interface. To study the robustness and performance of the proposed algorithm, validation numerical examples with finite deformations and large slip motion are presented.