Research On Maintainability Test Evaluation For Off-road Vehicle

Based on the research status at home and abroad on the vehicle maintainabilitytesting, the problems faced with the domestic off-road vehicle maintainability testingare analyzed, thesis topic and research contents are made clear, that is to carry outresearch centering on "the selection of evaluation index parameters""the simulationfailure sample selection”“the experimental data processing" and "the experimentalverification" of the off-road vehicle maintainability testing, the contents are asfollows:(1) Based on the three considerations on the aspects of the general requirementsof the maintainability, the vehicle test conditions of the automobile test field and themaintainability factors that the users care about, the off-road vehicle maintainabilityevaluation index parameters can be divided into six quantitative parameters and sevenqualitative parameters.The quantitative parameters relate to the parameters of themaintenance time category, the task maintenance category, the maintenanceman-hours category, including the average corrective maintenance time, the averagepreventive maintenance time, the average replacement time for the important parts,the maximum replacement time for the important parts, the thousand-kilometercorrective maintenance man-hours, the thousand-kilometer preventive maintenanceman-hours.The qualitative parameters respectively are the maintenance accessibility,the standardization, the interchangeability, the maintenance security, the convenienceof the detecting and diagnosis, the error proofing measures, as well as theidentification mark, the human factors engineering and the maintenance guaranteefactor.(2) Aiming at the simulated fault samples of the off-road vehicle maintainabilityevaluation test, the selection process of the simulated fault samples is formulated. The process is totally divided into5steps.①According to the structure characteristics ofthe off-road vehicles, the primary maintenance units are layered to get the samples ofdifferent layers.②The primary maintenance units under the same layer are dividedinto sample groups by using the estimation maintenance time parameter to get thesample groups of different estimation maintenance time.③Calculating the failure rateand the relative occurrence probability of the primary maintenance units in eachgroup.④In combination with the demand quantity of the fault samples, calculating thesimulated fault sample quantity for distribution verification of each layer in eachgroup.⑤The sample individuals that need to be conducted the simulated fault repairtesting in each layer and each group are determined by using the method of randomsampling.(3) The data abnormal values inspection, the homogeneity testing and thecalculation flow of the index parameters in the off-road vehicle maintainabilityevaluation test are formulated by using the statistical methods.The unqualified dataare eliminated by conducting the anomalous value checking, the homogeneity test andthe index parameters calculation on the testing data, getting the indicator parameterswhich can be used to assess the off-road vehicle repair performance.(4) The test schemes and test procedures of the off-road vehicle maintainabilityare formulated and the test platform is set up to conduct the off-road vehiclemaintainability evaluation test.The indicator parameters such as the average correctivemaintenance time, the average preventive maintenance time and so on verified by thetest reflect the general requirements for the off-road vehicle maintainabilityindustry;The parameters of the average corrective maintenance time for the importantparts and the maximum repair time for the important parts reflect the contents such asthe maintenance fees, the maintenance time and so on which are cared about by boththe users and the maintenance service stations.The parameters of thethousand-kilometer corrective maintenance man-hours and the thousand-kilometerpreventive maintenance man-hours reflect the maintenance manpower situation,presenting the off-road vehicle repair manpower indicators.The qualitative indexestype parameters reflect the repair persons’ subjective feelings towards the repair work, which can convey characteristics of the product maintainability design aspects. Studyon the experimental verification shows the verifiability of the above-mentionedparameters.