Studies On Component Storage Reliability Based On Proportional Hazards Model

For storage component not in operation,we often fail to get its accurate failure time.Only through regular inspection can we determine whether the components are invalid.Therefore,the exact life of the failure component is unknown,and we can only get the failure time interval,but not the exact life.Moreover,during the storage process,the life of component will be influenced by environmental factors,such as temperature and humidity.Therefore,considering the environmental factors to evaluate the reliability of component is very practical.Based on the experimental data that only known the amount of failure components but not known its exact life,conditional median method is used to determine the failure time of components,and a proportional hazards model considering environmental factors is built in this paper to evaluate the reliability of components.The component test data is set as follows.A life test on n components is conducted at the time₀t?28?0and the amount of failure components is only recorded at the timet₁?27?t₂?27??43??27?t_k.That is to say,only the amount of the failure components can be observed in[t ₀,t ₁),[t ₁,t ₂),?43?,[t_k-1,t _k),which is denoted asr₁,r ₂,?43?,r_k respectively.The number of invalid components at the timet_k is denoted asr_k?10?1.For the Weibull component,conditional median method is used to calculate the medium lifetime in[t ₀,t ₁),[t ₁,t ₂),?43?,[t_k-1,t _k),[t _k,?10??)respectively,which is denoted as?₁,?₂,...,?_k,?_k?10?1.For exponential component,the medium lifetime in[t _k,?10??)is improved to?7?t_k+?_k?10?1?8?/2.The equivalent life of the test component is obtained.On this basis,a proportional hazard model,which considering environmental factors,is constructed to estimate the reliability of the components.The mean residual life of the component and the sensitivity of the component to environmental factors are also studied in this paper.The effect of the improved median method proposed in this paper is better compared with the ones in literature.It is more practical to incorporate the environmental factors into the proportional hazard model to evaluate the reliability of the components.