Моделювання пошкодження шатуна при надходженні рідини в циліндр ДВЗ

Abstract

Problem. The patterns of a conrod stem deformation during compression of air with a liquid in the internal combustion engine cylinder are considered, and the stem deformation when liquid enters the cylinder (hydrolock) is calculated. It is noted that despite the well-known nature of this damage, no quantitative data are available, which often makes it difficult to determine the damage causes in the practice of ICE operation. Goal of the work is to study the connecting rod deformation mechanism during the loss of stem stability due to hydrolock in the cylinder to obtain quantitative characteristics of this phenomenon, suitable for use in practice to determine the failure causes. Methodology includes simulation of the compression process with a liquid, as well as simulation of the deformation and the buckling of the conrod stem under axial compression. A numerical integration of a system of differential equations describing the change in pressure and air temperature with a liquid in a cylinder by the crankshaft rotation angle is carried out with the initial conditions that were obtained using the standard ICE cycle calculation program. Then the dependence of maximum pressure in the cylinder and the conrod buckling from the combustion chamber filling ratio was determined. Results. For the found strains, the axial deformation of the conrod stem was simulated using the finite element method, the buckling shape of the stem and the stress were determined, and the dependence of the longitudinal bending on the axial deformation of the stem was determined. The simulation results were compared with experimental data on the conrods damages in the ICE operation, as well as with the results of stress calculations using classical methods. Originality. For the first time, a quantitative link was determined between the liquid amount that fell into the internal combustion engine cylinder during hydrolock, the shape of the conrod stem, its axial deformation, and longitudinal bending in case of loss of stability. Practical value. The results can be used in practice when searching for the causes of the internal combustion engines faults, including simulation the ICE damages, in order to clarify the symptoms and causes of the faults associated with hydrolock. Based on the results of the study, the feasibility of the practical application of the damage simulation in studying the fault causes is substantiated. Keywords: internal combustion engine, connecting rod, hydrolock, buckling, simulation.