A Heavy Commercial Vehicle Reliability Evaluation System Research

Vehicles are necessary for people to travel and play an important role in the social development.However,there is still a gap between domestic level and the world advanced level,the vehicle reliability is currently the concern of the auto industry.In order to research further the vehicle reliability,it is necessary to analyze vehicle reliability and propose corresponding improvement measures.Based on the current development status of vehicle reliability,a set of reliability evaluation system is proposed.Taking a heavy commercial vehicle as the object,this paper studies the reliability from three aspects after collecting related test data.First of all,the vehicle reliability level is evaluated.The vehicle reliability test data is collected and regularities of mean time to failure(MTTF)distribution is analyzed.Secondly,MTTF is validated by Kolmogorov-Smirnov test to verify it corresponds with the two-parameter Weibull distribution.Finally,the vehicle reliability index is solved and it includes failure density function,failure distribution function,reliability function,hazard function,Q-percentile life,medium life and mean time to failure.Next,the reliability of vehicle subsystems and failure modes is analyzed by fault tree analysis(FTA)and failure mode effects and criticality analysis(FMECA).After fully understanding the characteristics of the vehicle subsystems,reliability block diagram(RBD)is established.On the one hand,the vehicle failure is determined as the top incident of FTA and the model is constructed from top to bottom.Then,the importance degree of basic events is concluded by quantitative analysis and qualitative analysis and components that need to be improved the reliability are determined.On the other hand,the failure modes and causes are analyzed by FMECA.And then,failure modes that need to be improved are determined by the calculation of criticality.In the end,after the reliability analysis of the vehicle and components,the reliability allocation is carried out to improve the reliability.On the basis of FTA and analytic hierarchy process(AHP),a comprehensive analysis tool is proposed.Compared with FTA,the tool takes into account work environment and criticality,therefore,it's more accurate.Besides,the tool is more clear than AHP because it improves the efficiency of distribution and reduces the influence of subjective factors.Through the vehicle reliability research,the reliability of a heavy commercial vehicle is analyzed systematically.In addition,the graphical user interface(GUI)designed for vehicle reliability index calculation and solution of the weight vector for comprehensive analysis method is established to improve work efficiency.