COMPARATIVE ANALYSIS OF THE STRESS-STRAIN STATE OF MODERNIZED PISTONS OF LOW-SPEED MARINE ENGINES WARTSILA RT-FLEX96C AND RTA96C

Abstract

The current tempo of ship engine development dictates the need to create universal methods for studying the thermal and stress state of the main parts of internal combustion engines (ICE), which can reduce the time of their design an d defect. The complexity of the piston design increases markedly with the need to increase the capacity of power equipment. The design of the piston in the three-dimensional problem, with a complete estimate of the actual configuration of the stress-strained state (SSS), is currently a complex problem. The finite element method (FEM) has great possibilities for such calculations. This article is devoted to the analysis of the stress-strained state of the piston in its materials under the influence of operating loads using modern CAD/CAE complexes. It is established that the maximum total stresses according to the von Mises criterion are 178.7 MPa for the RT-flex engine and 198.6 MPa for the RTA engine, which are observed in the contact area of the bearing sur-face of the piston bottom with the skirt. In general, the diagram of stress distribution on the other part of the piston shows a uniform distribution of stresses on the bottom of the piston (on average 90… 120 MPa) and on its side surface (10… 15 MPa). The maximum displacement values are 0.55 mm for the RT-flex engine and 0.357 mm for the RTA engine. The results of the analysis of the displacement diagram’s isosurfaces indicate the localization of the maximum displacements in the central part of the piston crown.