基于性能退化数据的航天产品小子样可靠性评估方法研究

Reliability assessment of aerospace products with traditional theory usually meets challenges. The reason is that the traditional theory is built on the basis of failure data analysis, but adequate failure life data for aerospace products are hardly obtained through life test and accelerated life test, sometimes very few failure data and even with zero failue data appear. This is caused by aerospace product characteristics of high system complexity, enormous/escalating cost, high reliability and long life. However, as an alternative important life information source, performance degradation data could be utilized in these cases to assess the reliablity of aerospace products..In this background, this project is to systematically investigate the small sample reliability assessment method based on the performance degradation process of aerospace products, with basic theory of small sample reliability, stochastic process, performance degradation and accelerated life test analysis. The study will cover three levels, which are respectively single-state performance degradation process reliability analysis, multi-state performance degradation process reliability analysis, experimental verification and engineering application. Firstly, the deterministic and stochastic law of performance degradation data is to be analyzed, single-state performance degradation process is to be modeled and reliability analysis is to be conducted, then based on which multi-state performance curve integral estimate is to be carried out, finally the proposed method be validated by experimental study and engineering examples. The results of this project are expected to provide new support for small sample reliability assessment of aerospace products on both basic theory and applicable techniques.

航天产品具有系统复杂、造价昂贵、可靠性高、寿命长等特点，很难通过寿命试验和加速寿命试验获得足够的失效寿命数据，有时还会出现极少甚至零失效的现象，这对于以失效寿命数据为分析对象的传统可靠性理论是一个巨大挑战，而此时性能退化数据可作为航天产品可靠性评估的重要信息源，为航天产品可靠性评估提供了可行途径。.本项目以当前航天产品可靠性评估为背景，以小子样可靠性、随机过程、性能退化及加速寿命试验分析等理论为基础，对基于性能退化过程的航天产品小子样可靠性评估方法进行系统研究，内容涵盖单状态性能退化过程可靠性分析、多状态性能退化曲线整体测试、试验验证和工程实例分析三个层面，具体包括：性能退化数据确定性和随机性规律分析，单状态性能退化过程建模及可靠性分析，多状态性能曲线整体估计，结合试验研究和实例分析验证和完善项目研究成果，预期为航天产品小子样可靠性评估提供新的基础理论和技术支撑。

我国航天产品通常一次使用，具有系统复杂、造价昂贵、可靠性高、寿命长等特点，很难通过寿命试验和加速寿命试验获得足够的失效寿命数据，有时还会出现极少甚至零失效的现象，这对于以失效寿命数据为分析对象的传统可靠性理论是一个巨大挑战。同时，航天产品的性能曲线测试往往面临小子样的问题。在这样的背景下，本项目基于性能退化数据开展航天产品小子样可靠性分析和评估的研究工作，主要内容如下。.（1）基于独立增量随机过程的航天产品性能退化建模。通过航天产品性能退化机理及影响因素分析，得到了退化过程趋势项和方差项的变化规律，建立了具有时变趋势和方差的非平稳独立增量过程模型，既有效利用了退化数据间的相关性信息，又兼具独立误差项处理简单的优势。.（2）航天产品性能退化过程小子样可靠性分析方法。在退化建模基础上，结合产品性能退化与发生失效通过给定的失效阈值进行判断的实际情况，给出了模型参数的整体估计方法，推导了退化寿命分布模型，并建立了工程中关心的可靠寿命和可靠度点估计及单侧置信下限估计方法，通过不同时刻性能退化数据间纵向信息的有效利用，实现了小子样退化过程的可靠性分析和评估。.（3）航天产品多状态性能退化过程小子样可靠性分析方法。小子样问题在加速退化可靠性评估中尤为突出，本项目综合考虑性能退化模型和加速模型，基于多元随机过程理论，建立了能够兼顾物理模型和随机因素的加速退化模型，给出了各种状态下可靠寿命和可靠度点估计及单侧置信限估计方法，通过各状态性能退化数据的整体统计推断实现了航天产品多状态性能退化曲线小子样测试及可靠性评估。. 在此基础上，完成了卫星离子推力器的退化试验研究和实例示范。结果表明，本项目方法通过充分利用不同试样和不同时刻退化数据间的横纵向信息，能够在相同样本量下有效提高分析精度，在相同精度下减少样本量，为航天产品小子样退化建模和可靠性分析提供重要支撑。.此外，本项目方法对工程常见的复杂产品、大型工业系统具有广阔的应用前景，目前已成功应用于某10N推力器及改进型号部组件、某型离子推力器以及密封橡胶材料的性能分析和小子样可靠性评估，取得了良好的效果。