Research On Wear Life Of Cast Iron Cylinder Liner Based On Accelerated Degradation Test

With the development of manufacturing science and technology,the diesel engine is developing towards the enhancement type with high power density and high reliability.As the core part of the diesel engine,the working environment of the cylinder liner is harsher,and the wear tendency is increasing.Therefore,the wear life prediction of cylinder liner is necessary.As a long-lifetime product,cylinder liner cannot get reliability data quickly and waste a lot of financial and material resources if one performs in conventional life test.Aiming at above problems,it is significant to choose the appropriate accelerated test method and lifetime estimation method,which will shorten the test period and save experiment expense,and also can provide scientific basis for the design,use and process improvement of the cylinder liner.In view of this,this study uses a widely used alloy cast iron cylinder liner as the research object,and carry out the research on wear resistance life of cast iron cylinder liner based on accelerated degradation test.The main research contents of this paper are as follows:(1)Theoretical analysis of reliability modeling based on accelerated degradation data of alloy cast iron cylinder liner.The wear mechanism and process of alloy cast iron cylinder liner are analyzed.The performance degradation parameters of alloy cast iron cylinder liner and measurement methods are determined.On that basis,the accelerated degradation model and life distribution model are classified and compared,which lays the foundation for wear life prediction of alloy cast iron cylinder liner.(2)The research on accelerated degradation test of alloy cast iron cylinder liner.Based on the characteristics of working condition of alloy cast iron cylinder liner,the affecting factors of wear are analyzed.We choose load as the accelerated stress,and then the pre-test on reciprocating friction and wear testing machine is implemented.By analyzing the surface morphology of pre-test samples,it can be found that the wear mechanisms of the alloy cast iron cylinder liner under 30MPa,40MPa and 50MPa are the same.Then,based on the theory of accelerated degradation test,the accelerated degradation test scheme is determined.A multiple groups of accelerated degradation tests under different working conditions are conducted,and 75 groups of degradation parameters are obtained.(3)Reliability analysis and wear life prediction of alloy cast iron cylinder liner.Research on the change trend of performance degradation data of alloy cast iron cylinder liner,the performance degradation path models are established,and the statistical analysis of parameters is carried out to predict the pseudo-failure lifetime of alloy cast iron samples when the failure threshold is given.Based on the distribution hypothesis test and failure mechanism consistency test of pseudo-failure lifetime,the life distribution parameters on Weibull are estimated.Finally,through fitting acceleration model,the life characteristics under 20MPa are obtained,including the average life of 14096 hours,the characteristic life of 14400 hours and the median life of 14195 hours.At the same time,the reliability characteristic function curves of alloy cast iron cylinder liners under 20,30,40 and 50MPa are analyzed.In conclusion,the research results of this paper can provide theoretical basis for the research of wear life prediction of alloy cast iron cylinder liner,and the analytic idea and method is universal,and have engineering application value which can provide reference for the research of wear life prediction of other friction pairs of diesel engine.