Maximum peak pressure evaluation of an automotive common rail diesel piston engine head

This paper introduces a method to linearize a FE (Finite Element) nonlinear problem. This method reduces calculation time by several orders of magnitude. Therefore, head geometry is optimized without supercomputers. In this paper the method is applied to a very critical component: the aluminum alloy piston head of a modern Common Rail Direct Injection Diesel (CRDID) [1-2]. The method consists in the subdivision of the head, in several volumes, that have approximately a uniform temperature. Each volume has an ad-hoc material model that takes into account of temperature, pressure and pressure derivative. Therefore, material behavior depends on average volume temperature, stress magnitude and stress gradient. This assumption is valid since temperatures vary slowly when compared to pressure (stress). In this paper, a known head is analyzed and validated with this method. The head comes from an engine that has run at full load for a known period (60h). It was therefore possible to evaluate true temperatures on head from residual Rockwell B hardness (HRB). This procedure can be considered a reverse engineering approach to evaluate the evaluate the temperature on the engine head. The test was aimed to evaluate the maximum peak pressure possible for the cylinder head. This relatively easy procedure outputted a reasonable maximum value for the engine. In general, experimental tests have confirmed the cost-effectiveness of this approach. This method can be successfully used in many other applications. From the design to the optimization of new or existing critical engine components.