Research On The Allocation Method Of A Diesel Engine Reliability Based On The Cost Function

Mechanical system reliability allocation is one of the most important tasks of the design of mechanical system reliability. It assigns the system reliability requirements in the design task book to each subsystem, parts and elements reasonably which is a system to the components of the decomposition process so as to guarantee effectively in the process of design and manufacture.This paper is based on a particular model of diesel engine, which explores the dynamic of the development of domestic and foreign diesel engines, and summarizes the research status and future trends of the reliability allocation methods for mechanical systems. The main content of the paper are summarized as follows:(1) This paper takes FMECA and FTA into the cost function of the diesel engine, and meets the cost functions conditions to raise DM cost function.(2) Quantifies the influence factors with expert grading method and fuzzy prediction according to the criteria of the reliability allocation.(3) Establishes a mathematical model based on DM cost function and completes the reliability allocation of independent assumptions and failure-related mechanical system with genetic algorithm by Matlab.Firstly,this paper finds the influence of parameters on system reliability allocation results in independent assumptions mechanical system, and illustrates the superiority of this method:not only satisfies system reliability requirements, but also costs less compared with the traditional allocation method; Secondly, introduces Copula theory into the mechanical system reliability allocation during considering the failure-related mechanical system reliability allocation, which solves the determination of the relevance and the construction of the computational model. Thirdly, it finds that the results of independent assumptions mechanical system are conservative and the results of the traditional allocation method such as equal distribution method are unreasonable, which illustrates that the failure-related mechanical system reliability allocation based on DM cost function in this paper is more reasonable and credible.(4) Develops mechanical system reliability allocation software by using Matlab and Access database. This software which has10important function modules absorbs the merit of the related softwares and sets FMECA, FTA and independent assumptions mechanical system reliability allocation as a whole. It provides a function with good human-computer interaction which has the superior of simple operation, accurate analysis, intuitive results, and friendly interfaces.