Analisis Kerusakan Engine High Blow-By Pressure Pada Mesin SA6D125E-2 UNIT bulldozer D85ESS-2A

Bulldozer merupakan alat berat yang digunakan untuk mendorong material dan untuk pembukaan jalan. Dalam melakukan pekerjaannya, bulldozer banyak menggunakan tenaga mesin sehingga sering terjadi kerusakan pada komponen mesinnya. Kerusakan high blow-by pressure pada mesin bulldozer merupakan hal yang perlu diperhatikan karena dapat menyebabkan kerusakan pada komponen di dalam mesin dan mengakibatkan menurunnya performa mesin. Penelitian ini dilakukan dengan mengidentifikasi data pada technical analysis report, program analisis pelumas, dan hasil overhaul. Technical analysis report dilakukan dengan cara mengukur blow-by pressure dan engine speed untuk mengetahui performa engine. Program analisis pelumas dilakukan dengan mengambil sampel oli pelumas lalu dianalisis di laboratorium untuk mengetahui keausan dan kontaminan pada oli pelumas engine. Dari hasil penelitian, dapat ditarik kesimpulan bahwa penyebab dari kerusakan high blow-by pressure adalah masuknya kontaminan berupa debu kedalam ruang bakar dan menyebabkan gesekan abnormal pada piston, piston ring, dan cylinder liner. Gesekan abnormal ini mengakibatkan celah antara piston, piston ring, dan cylinder liner semakin besar sehingga tekanan hasil pembakaran bocor menuju crankcase melewati celah tersebut. Dampak yang ditimbulkan dari kerusakan high blow-by pressure adalah penurunan tenaga mesin, sehingga unit bulldozer harus dilakukan perbaikan dengan mengganti komponen yang rusak agar unit dapat bekerja dengan optimal.

Remaining useful life prediction of cylinder liner based on nonlinear degradation model

In order to effectively monitor the wear and predict the life of cylinder liner, a nonlinear degradation model with multi-source uncertainty based on Wiener process is established to evaluate the remaining useful life (RUL) of cylinder liner wear. Due to complex service performance of cylinder liner, the uncertainty of operational environment and working conditions of cylinder liner wear are considered into the model by a random function. The probability density function (PDF) formula of RUL is derived, and the maximum likelihood estimation method is adopted to estimate the unknown parameters of PDF. Considering the evaluated parameters as the initial values, the model parameters are updated adaptively, and an adaptive PDF is obtained. Furthermore, the proposed model is compared with two classical degradation models. The results show that the proposed model has a good performance for predicting the life, and the error is within 5%. The method can provide a reference for condition monitoring of cylinder liner wear.

Tribological evaluation of piston ring/cylinder liner assembly in automotive engines using GNP as a lubricant additive

Friction and wear are the main causes of energy dissipation in automotive engines. To minimize the frictional power losses, it is extremely important to improve the tribological characteristics of ring/liner assembly which accounts for almost 40–50% frictional power losses. The present study attempts to mitigate friction and wear of the ring/liner tribo-pair using GNP/SAE 15W40 nano-lubricant. To simulate the ring/liner interface, the tribological performance of nano-lubricants was assessed using a tribometer based on ASTMG181 standard under various operating conditions. The coefficient of friction (COF) and wear rate lowered using graphene nano-lubricants (GNL). The tribological results showed that friction coefficient, wear rate, and surface roughness of piston ring improved in the range 17.71%–42.33%, 25%–40.62%, and 61%, respectively, under GNL lubricating conditions during the boundary lubrication. Further, the characterization of wear tracks of piston ring and cylinder liner confirmed tribo-film formation on worn surfaces resulting in decreased COF and wear rate.

Calculation of contact pressure and contact zone in slip pairs of marine diesels

Annotation – The durability of marine diesels significantly depends on the operation of friction pairs, such as: piston rings - cylinder liner; crankshaft - bearing shell, plunger - sleeve, and others. This is primarily due to the constant contact interaction of the elements of the friction pairs at different temperatures and load. Therefore, the research of normal pressure and the definition of contact areas in the friction pairs, the studying of the influence of the quality of lubricants on these characteristics are important tasks for predicting the longevity of marine diesels. The solution of these problems is based on the application of mathematical models of processes (numerical simulations) that occur in friction pairs. This considers two main processes that occur during the operation of the friction pairs: the research of contact and tangential stresses that occur in friction pairs in the framework of elastic or elastic-plastic contact models; study of hydrodynamic processes in a thin layer of oil between the elements of the friction pairs. The combination of these processes allows to sufficiently assess the influence of the elastic-mechanical properties of the sliding vapor elements and the viscosity and hydrodynamic characteristics of the oils on the durability of the marine diesel unit. The first process is researched in this work. In particular, for the analysis of contact stresses and contact zones in friction pairs, the method of numerical modeling is used, which is based on the differential equations of the theory of elasticity. With the help of fundamental solutions (influence functions), the problem is reduced to an integra-differential equation with the Gilbert’s kernel. The solution of which is constructed using the method of orthogonal polynomials as well as easy-to-use approximation formulas. Numerical simulations were performed, as a result, the maximum pressure and contact zone parameters for some combinations of friction pairs materials of marine diesel engines were determined. In particular, the influence of the radial gap on the pressure distribution and the size of the contact zone between the elements of the friction pairs of marine diesels is established.

Numerical study of the physical processes of gas leakage in the compression ring in diesel engines

In this research, the construction of a numerical model is proposed for the analysis of the friction processes and the thickness of the lubrication film present in the compression ring of internal combustion engines. The model is built using MATLAB software, and three load conditions are used as reference (2 Nm, 4 Nm, and 6 Nm) with a rotation speed of 3600 rpm, which correspond to a stationary single-cylinder diesel engine. Comparison between model estimates and experimental results show that the development model could predict the actual engine conditions. The deviation between the numerical model and the experimental data was 17%. It was shown that the increase in engine load causes a 16% increase in the friction force of the compression ring, which implies a 50% increase in power loss due to friction processes. In general, the model developed allows the analysis of the friction processes in the compression ring and its effect on the lubrication film, considering the leakage of the combustion gases. In this way, the construction of a more complex mathematical model is achieved, which allows improving the precision in the analyzes related to the interaction between the compression ring and the cylinder liner.