航空学报 > 2019, Vol. 40 Issue (8): 422796-422796   doi: 10.7527/S1000-6893.2019.22796

某航天器输氢管道系统结构完整性评估

胡世威, 梁浩, 徐兵   

  1. 中国工程物理研究院 总体工程研究所, 绵阳 621999
  • 收稿日期:2018-11-19 修回日期:2018-12-29 出版日期:2019-08-15 发布日期:2019-03-01
  • 通讯作者: 梁浩 E-mail:15681625@qq.com
  • 基金资助:
    国家自然科学基金(U630144,11572298);中国工程物理研究院统筹规划项目(TCGH0402)

Assessment procedure for structural integrity of hydrogen pipeline system for spacecraft

HU Shiwei, LIANG Hao, XU Bing   

  1. Institute of Systems Engineering, China Academy of Engineering Physics, Mianyang 621999, China
  • Received:2018-11-19 Revised:2018-12-29 Online:2019-08-15 Published:2019-03-01
  • Supported by:
    National Natural Science Foundatin of China (U630144,11572298); Planning and Co-ordination Project of China Academy of Engineering Physics(TCGH0402)

摘要: 为保障某航天器在服役年限内不发生事故,针对航天器上采用插入焊接技术的精密管道系统进行结构完整性评估。在考虑到系统存在整圈的环形未焊透缺陷基础上,结合工程实践,假设在焊接区域存在更危险的平面缺陷。首先,开展高压气相热充氢试验下的标准拉伸和三点弯试验得到管道系统材料"J-75"在临氢环境下应力应变曲线和断裂韧性。其次,采用有限元程序计算系统在内压、惯性载荷与离面位移作用下的应力分布,考虑到间隙配合中的不确定性,改变模型中的最大间隙多次模拟计算,发现最大应力位置基本不变,以此区域作为假想缺陷的具体萌生区域。最后,采用失效评估图(FAD)方法对存在4种缺陷模式的系统分别进行结构完整性评估。通过引入安全裕度的概念,发现系统在含有初始尺寸(0.15 mm)的4种平面缺陷时,均处于安全状态,并且安全裕度都在2倍以上;通过工程临界分析(ECA)发现随着缺陷尺寸的增大,系统中含有缺陷2(位于管道焊接区域最大应力处的轴对称平面且沿焊深方向扩展的缺陷)时最为危险,且当缺陷深度超过0.61 mm时将断裂失效;考虑到测试数据的弥散性,针对系统最危险的模式,以安全裕度为可靠性指标,将失效评估图方法与可靠性评价相结合,得到系统在含有尺寸为0.15 mm的缺陷2情况下保有足够安全裕度的可靠性下限值超过0.999 5。

关键词: 氢损伤, 间隙配合, 失效评估图, 工程临界分析, 可靠性

Abstract: To ensure no accident will happen within the service life of the system, the sophisticated piping-valve system connected by insert welding technology is adopted as a structural integrity assessment procedure. Based on engineering practices, we assume more dangerous plane defects in the welding area on the basis of the circumferential defects lacking penetration. First, the stress strain curves and fracture toughness of J-75 in the presence of hydrogen are obtained by combining high pressure gas phase thermal hydrogen pre-charging test with the standard tensile and single edge bend test. Then the FE program is used to calculate the stress distribution under the loading of inertia, internal pressure, and off-surface displacement. Considering the uncertainty in clearance fit, the maximum clearance in the model is changed during multiple simulations, and it is found that the maximum stress position is almost unchanged, where the hypothetical defect will be produced. Finally, the Failure Assessment Diagram (FAD) method is used to assess the structural integrity of the system with four defect modes. By introducing the concept of safety margin, we found the system has more than twice of the safety margin when it contains four types of plane defects in initial size. Using the Engineering Critical Analysis (ECA), as the defect size increases, the system becomes the most vulnerable when it contains the defect 2, which is located on a symmetrical plane at the maximum stress area at the weld of the pipe and extending along the direction of welding depth. When the defect depth exceeds 0.61 mm, the fracture failure happens. Targeting at the most dangerous mode of the system, considering the dispersion of the test data of material properties, and taking the safety margin as the reliability index, the FAD method is combined with reliability assessment. The results show that the confidence level of the reliability of the system exceeds 0.999 5 under with the defect 2 condition of 0.15 mm.

Key words: hydrogen damage, clearance fit, failure assessment diagram (FAD), engineering critical analysis (ECA), reliability

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