离子推力器极少数据可靠性评估方法

Reliability evaluation method of ion thruster with very few failure data

针对只有两台离子推力器进行寿命试验,试验结果为极少失效数据的情况,建立了一种离子推力器整机可靠性评估方法.通过引入区间统计量的概念,充分开发从最后一个失效数据继续试验到没有发生产品失效这一重要试验信息,由高斯-马尔科夫定理计算出寿命分布参数的最佳线性无偏估计,并给出离子推力器可靠度和寿命的单侧置信下限.最后,对美国NASA研制的型号为XIPS-13的离子推力器进行可靠性评估,得出了其寿命需求10000h的可靠度单侧置信下限为0.87及给定可靠度为0.9时的寿命单侧置信下限为9 024.6h,该方法精度较高,便于工程应用.

A reliability evaluation method of ion thruster was established under the situ- ation that only two ion thrusters were tested and the results were represented by very few failure data. Meanwhile, the significant test information from the last failure data test to non-occurrence of failure was fully developed by introducing the concept of interval statistic. Best linear unbiased point estimator of the life distribution parameters was calculated by u- sing Gauss-Markov theorem. And then the one-side lower confidence limits of reliability and life were given. At last, while evaluating the reliability of NASA＇s XIPS-13 ion thrusters, the one-side lower confidence limits of the reliability with the demanding lifetime 10000h was 0.87 and the one-side lower confidence limits of the lifetime with a given reliability 0.9 was 9 024. 6 h. It demonstrates that this method has high accuracy and can be easily applied in en-gineering.