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As a consequence of the ongoing evolution of engines, where performance is continuously improving and the use of alternative fuels is being adopted by many engine manufacturers, thermal working conditions of the exhaust valves are increasingly critical. In order to better resist the higher temperature levels of the exhaust gases, current development ranges from improvement of the cooling concept for the overall system, new materials for valve set components up to the upgrade of the exhaust manifold material. Change in the design of several valvetrain components due to the increased thermal loads is a logical consequence of this technical evolution process. Hollow exhaust valves filled with Sodium (Na) are a known technology that is widely used in passenger car engines to improve thermal behavior and to avoid the need to change to expensive materials (Ni-base alloys).

In internal combustion engine valves, wear often develops at the interface of the valve seat and the insert as a result of the high pressures produced by the combustion process at the moment of the closing event. An alternative to study the wear is by carrying out experimental tests in specific wear testing machines. The main drawback is that they are time consuming and expensive due to the need to carry out many tests for the usually observed scatter in the results. In the area of numerical methods, the wear simulation has been widely developed in the last years because it can solve complicated time consuming problems with general geometries. The aim of this work is to characterize the wear rate coefficients for bi-metallic pairs commonly used in internal combustion engine valves using experimental results and numerical solutions by using the Finite Element Method. Then, a numerical valve model is provided to demonstrate that the numerical and experimental solutions are in agreement.

Valve engine manufactures have to satisfy the demands of a market that requires to increase the strength of their products and to extend the time between servicing. In a combustion engine valve, the mechanical stresses are generated during the closing event by loads coming mainly from the return spring, the inertia loads of retainer, keeper and stem, closing velocity, valve tilt and the thermal loads from the combustion. The objective of this work is to understand the valve closing process, and to predict numerically the maximum stresses in new valve designs in a shorter time and at lower costs compared with experimental procedures. In this work, the experimental valve stem stress response under impact velocity was registered using strain gauges and then compared by Finite Element Method solutions showing good agreement.