基于重要抽样法的热防护系统热可靠性评估方法

Assessment of thermal reliability of thermal protection systems by importance sampling method

热防护系统的可靠性直接影响到高超飞行器的安全性和结构完整性。为提高热防护系统可靠性分析的效率,在之前研究的基础上提出了基于重要抽样(Importance Sampling,IS)的热可靠性评估方法,给出了该方法的具体实施流程和评价方法,有效解决蒙特卡洛法(Monte Carlo method,MC)对于低失效概率问题分析效率过低的问题。以典型的非烧蚀热防护系统为例,在考虑材料、几何尺寸不确定性的情况下进行了热可靠性分析,验证文中方法的有效性。计算结果表明,要得到同等置信度的失效概率结果,重要抽样法所需的抽样次数仅为传统蒙特卡洛法10%,大大提高了可靠性分析的效率。

Safety and structural integrity of hypersonic vehicles are directly influenced by the reliability of their thermal protection system(TPS).To improve the efficiency of reliability analysis of TPS,a new method based on importance sampling was proposed in this paper.The detailed calculation procedure and thermal reliability assessment methods were also introduced.The thermal reliability analysis of a typical non-ablative TPS with uncertainties about material properties and geometries was used as numerical example to verify the effectiveness of the proposed method.The results indicate that to achieve reliability result with the same confidence level,importance sampling method needs only 10%simulation iterations of the conventional Monte Carlo method,which dramatically improves the efficiency of reliability analysis.