Reliability Evaluation For Product Performance Degradation With Shock

With the development of science and technology,the role of reliability is increasingly important.The traditional method to study the reliability of products is based on the products' failure life data.Due to most products possess characteristics of the long life and high reliability,the failure life data is missing or absent.Therefore,it has practical significance to evaluate product reliability by using product performance degradation.On the one hand,product failure is affected by degradation of the product itself and on the other hand,it is affected by external shocks.These two aspects affect each other.For the complexity of the product use environment,different shocks have different effects on product degradation.Some shocks have no effect on the product,some shocks accelerate the product's degradation process,and some impacts cause the product to fail suddenly.This thesis systematically studies the reliability of product performance degradation under different shocks.The main research contents include the following aspects:(1)Reliability evaluation of shock loads products base on Quantile Regression.Firstly,on the basis of the performance degradation data,a suitable degenerate path model is established,Quantile Regression method is used to estimate the model parameters,and the degenerate paths equation is obtained.Secondly,the sudden increase in natural degradation of the product through shocks,the cumulative degradation of the product is obtained,and the reliability of the product is evaluated.Finally,the reliability evaluation results of the degradation of a certain metal material verify the effectiveness of the method.(2)Product reliability evaluation based on dependent competing failure processes.Random shocks are divided into small shocks(harmless shocks),medium shocks(harmful shocks)and large shocks(fatal shocks)according to the impact of different shock sizes on product degradation.The failure of product performance due to the total degradation of the product reaching its threshold is called the soft failure process;the sudden failure of the product due to random impact is called the hard failure process.This section studies the hard failure process of combining extreme shock and ? shock.It is studied that the product performance degradation is caused by the competition between hard failure process and soft failure process,the analysis and research are performed to obtain the product's reliability expression and failure rate expression.Numerical examples are given to verify the accuracy of the proposed method,and the sensitivity of key parameters to product reliability is analyzed.(3)Reliability evaluation based on competitive failure of products under variable failure threshold.The reliability of product under the degradation-shock interaction is studied.This mutual effect is reflected that the shock has a sudden increase in the overall degradation of the product.And when the degradation reaches a certain value,the failure threshold of the hard failure will change.The reliability of the product under the competition of hard failure and soft failure is studied.Hard failure process is a combination of extreme shock and ? shock.The reliability expression of the product is obtained,and the image of product reliability is obtained by MATLAB simulation.