再入过程中的同位素热源可靠性评估

Reliability Evaluation of Radioisotope Heat Unit in Reentry Process

本文综合考虑微观组织不均匀性等材料的内在分散性,以及载荷历程、工作环境等外在分散性的影响,针对放射性同位素热源(RHU)产品结构特点,选用基于随机有限元法的应力-强度干涉模型,采用解析法与蒙特卡罗法相结合的方式,在有限的试验规模下,定量评价了某型RHU在再入过程中经历一系列环境载荷后的可靠性水平。利用本文所述方法计算得到:该型RHU在95%置信度下的可靠度置信下限为0.999989,达到了一般探测器零部件级产品的可靠性评估精度要求,这表明本文所述方法实用、可靠,在RHU的可靠性评估、指导RHU的可靠性设计、降低评估成本方面具有很高的实用价值。

In this paper,the uncertainties of material resistance and applied loading were considered comprehensively.According to the structural characteristics of radioisotope heat unit(RHU),the stress-strength interference model based on stochastic finite element method was selected,and the method of combining analytical method with Monte Carlo method was used to evaluate the reliability level of the RHU which experiences a series of environmental loads in the process of reentry under the condition of limited scale of tests.Through the method described in this paper,it is calculated that the lower confidence limit of reliability of some kind of RHU under 95%confidence is 0.999989,which meets the reliability evaluation accuracy requirements of general detector parts.The above results show that the method described in this paper is practical and reliable,and has a strong practical value in reliability evaluation of RHU,guiding reliability design of RHU and reducing evaluation cost.