CI engine as a case study of thermomechanical FE analysis of the piston - piston rings - cylinder system

The compression-ignition engine as a case study of a methodology of the numerical modelling and simulation of the piston - piston rings - cylinder system was presented in the paper. Thermomechanical FE analysis, taking into account thermal and mechanical loads, was carried out using the MSC.Marc/Mentat software. The mechanical loads included loads due to inertial and gas forces as well. A three dimensional solid geometrical model of the considered set was developed using AutoCAD software, whereas the finite element mesh was generated using Altair HyperMesh. Kinematic boundary conditions - the vertical displacement and acceleration of the piston - were described by the corresponding curves as a function of time for selected engine speed. Changes in pressure on the piston crown were estimated based on data from the engine manufacturer and the corresponded indicator diagram available in the literature. The results of thermomechanical FE analysis were presented in the form of stress and/or displacement contours. The main aim of the analysis was to determine the deformation of the piston depending of on the piston material. Two types of material were compared - the actual one PA12 aluminum alloy and the new composite material with low hysteresis. The second material was characterized by slight differences of the coefficient of thermal expansion for heating and cooling.