The Engine Pistons Reliability Research Based On Data Analysis

As one of the main sources of power in modern society, engines are widely used in automobile, ship and engineering machinery and other fields. As a widely used machinery in our real life, its performance and reliability seriously affect our life. Therefore, how to improve the reliability of the engine becomes a target for numerous scholars and experts pursued. And as one of the main parts of engine, the piston’s reliability plays an important role in engine’s performance and reliability.For the analysis of the force on the piston, the finite element simulation is carried out in this paper, the piston is calculated. First AVL_EXCITE software is used to calculate the maximum explosion pressure of gas in cylinder and the average working temperature as well as the lateral force and so on, combined with the measurements of the engine, semi-empirical formula and empirical formula to determine the boundary conditions of the piston temperature field and stress field calculation, using ABAQUS software to calculate the stress and strain of the piston in the condition of heat load, mechanical load and thermal-mechanical coupling conditions. Calculation results show that in thermal load conditions the maximum stress occurred in the second slot, the maximum deformation occurred in the top. Under mechanical load conditions of piston the maximum deformation appears in the lower end of the piston skirt, maximum stress appears in the piston pin internal upper. For thermal-mechanical coupling conditions the maximum stress appears in the piston pin internal upper too, the maximum deformation appears at the top. The article also calculates the cylinder liner’s strain under the thermal-mechanical coupling conditions.To study the relationship between the life of the piston and its working condition, this paper discusses the relationship between the piston life and stress under the conditions of heat load conditions, mechanical load conditions and thermal-mechanical coupling conditions. The results show that in different heat load, mechanical load and thermal-mechanical coupling conditions, the relationship between the life and stress were subject to Arrhenius model, inverse power law model and generalized eyring model. The wear of the piston under different working conditions are analyzed. Put forward using the trend of the piston and cylinder liner deformation amount of overlap method to represent the piston wear, and the results are analyzed. Got the transformation of the piston wear regularity by the working conditions.Based on the Weibull distribution, this article analyzes the field data of the piston, discusses the process and methods to solve of reliability of piston with the least squares method. Due to small sample size, it will not be able to use conventional method to calculate the reliability characteristics quantity. This paper introduces a method to calculate the reliability characteristics quantity by using of Bayes theory of small sample. By contrast, found that the reliability characteristics are similar by using the method of the bayes and by least square method. Show the feasibility of bayesian small sample method.Finally, summarize the full text, points out the shortcomings of the article and the follow-up work is prospected.