Study On Reliability Evaluation Method And Theory Of Product Competitive Failure Based On Performance Degradation Data

The reliability is a theoretical basis for evaluating the performance and safety of the products.It has always been favored by academics and industry scholars.Traditional reliability evaluation methods are based on probability theory,and modeling and analysis by a large number of failure data.However,with the progress of industrial technology and the use of new materials,it is difficult to collect a large amount of failure data in a short time,zero failure data or less failure data to restrict the reliability evaluation of products.Therefore,in addition to collecting failure data from life test,performance degradation data can reflect the reliability of products to a certain extent.When the performance degradation data is used to reliability modeling,the product failure process is influenced by various random shocks,and the process is accompanied by the sudden failure of various modes at the same time,and the failure of the product is competitive.So,this paper will do some research on the reliability modeling method and engineering application of competitive failure based on performance degradation data.The main research contents are as follows:(1)When performance degradation data are used product reliability modeling,the degree of performance degradation may cause sudden failure of various modes.The relationship between performance degradation failure and sudden failure is analyzed.The reliability evaluation models of products with independent failure and dependent failure are established respectively.The life distribution of products under specific failure modes is also obtained.(2)In order to analyze the effect of degradation degree on sudden failure,Copula theory is introduced and the correlation between performance degradation and sudden failure is described by Copula function.The method of product reliability analysis under the condition of performance degradation failure and sudden failure is given.The example analysis shows that with the increase of the Copula correlation degree,the reliability value of the later stage is smaller.(3)Due to the shock load,the failure of the product is often caused by the stress greater than its strength.The strength of a product is a random variable depending on the material characteristics,structure and manufacturing process.The reliability evaluation of products under constant strength threshold and random strength threshold are analyzed respectively.The reliability evaluation model of products under the condition of failure correlation between shock and performance degradation is established.The reliability expression of products under random shock is obtained.(4)Traditional reliability statistical analysis shows that the strength is constant or a static random variable.However,with the fatigue,erosion,aging and other properties,the strength of products will gradually decrease,the decreasing process is a continuous state.Therefore,the strength threshold degenerate trajectory model is constructed.A competitive failure model with soft failure and hard failure coexistence is established.Failure characteristics of products under ? shock failure are analyzed.The evaluation method of product competitive failure under the condition of soft failure,hard failure and ? shock failure is obtained.The reliability of the product is calculated.The feasibility of the model is analyzed by an example.