Dependence of piston ring parameters determination accuracy on the method of calculation

Mathematical models are commonly used at the stage of piston ring design and during examination of ring collaboration with liner surface. Both analytical and numerical methods are used for development of such models. In the case of models based on analytical methods the range of their application is usually limited only to selected cases while the use of numerical methods allow to widen the range of their applications but their accuracy depends on increment used. The paper presents a procedure of verification of the piston ring mathematical model constructed by the authors using numerical methods. Conformity between the results obtained using this program and the results of analytical calculations concerning the displacement of ring free ends brought about by the acting loads was the aim of the analysis. Exemplary computations were carried out for three compression rings of different geometry. Regarding the conformity of achieved results as satisfactory for practical use probable causes of observed discrepancies were pointed out. Relations between energy accumulated in curved bar and loading force (according to the Castiliano's theorem) were used in a course of calculations. Exemplary calculations were carried out for compression rings of three types engine, i.e. automotive, bulldozer and marine ones. A probable cause of differences between results of calculations carried out according to various analytical methods have been pointed out assuming their accuracy as satisfactory for practical purposes.