Sealing reliability modeling of aviation seal based on interval uncertainty method and multidimensional response surface

Many variables affect the sealing performance, and their distribution characteristics are difficult to obtain with probabilistic methods owing to the high cost involved. Numerous problems in engineering are similar due to the appearance of small-sample parameters. In this study, the sealing reliability of an aviation seal was defined as the research object, and an interval uncertainty method and multidimensional response surface were proposed to calculate the sealing reliability.Based on this, we first analyzed the failure mechanism of the aviation seal and established a leakage rate model. Then, based on the non-probabilistic interval model, an interval uncertainty method was proposed to construct the analytical model. With reference to the limit state equation from the structural reliability theory, the multidimensional response surface was used for fast calculation.Then, we chose the single-cylinder gas steering gear used in aircraft as the case study, its sealing reliability in working and non-working statuses were calculated, and the results were verified with the actual maintenance records. By analyzing the sensitivity of some variables, we can improve the sealing reliability of the aviation seal by improving the surface roughness only if the cost allows.Finally, we consider that the method proposed in this study realizes the application of smallsample uncertainty analysis in reliability analysis, and could provide a feasible way to solve the similar problems in engineering with multidimensional and small-sample parameters.     

飞机轮胎溅水鸡尾流特性数值模拟

当飞机起落架的多轮经过涉水跑道时，除侧向溅水之外，在轮胎之间由于两股侧向水流汇聚，会形成类似公鸡尾的溅水形态，称之为鸡尾流。相比于轮胎的侧向溅水，鸡尾流成因复杂，且水量更大，溅水高度更高，可能对飞机安全造成更严重的危害。采用数值分析方法对飞机轮胎溅水产生的鸡尾流现象成型机理开展研究。根据轮胎几何结构特点建立飞机轮胎溅水模型，其中轮胎及跑道采用FEM方法建模，积水模型采用SPH法，给出了鸡尾流的形态和速度分布，通过与侧向溅水形态分布的分析与比较，揭示了鸡尾流溅水的形成机制，并研究了水深、轮胎间距、轮胎速度等因素对于鸡尾流形态以及速度分布的影响规律，初步验证了ESDU工程算法对于无翻边轮胎鸡尾流形态描述的可参考性。     

固体运载火箭抗强电磁脉冲优化设计方法

本文分析了火箭在飞行过程中的强电磁脉冲(EMP)环境，建立了箭上敏感设备受强电磁脉冲干扰的优化设计模型，包括传导干扰及辐射干扰两种设计模型。针对起飞质量对火箭总体参数设计的制约问题，以最小质量增量为目标函数，采用模拟退火(SA)算法，对箭上典型电气系统抗强电磁脉冲防护进行优化设计研究，为箭上敏感设备抗强电磁脉冲指标与质量增量提供了平衡选取方法。优化结果表明,火箭在飞行过程中典型电气系统的抗强电磁脉冲性能指标达到要求的同时，实现了火箭质量增量最小的目标。     

立靶测试系统立靶密集度测量不确定度评定

基于CCD的数字立靶测试系统是一种非接触立靶测试方法，提出了采用视觉标定分析坐标结果的方法，介绍了同步雷达触发、CCD成像，通过图像分析得出立靶测试结果的测试系统。为了完善基于CCD的数字立靶测试系统的测量结果，建立测量模型，根据视觉标定法、系统结构等分析评定各因素带入的不确定度分量。     

China's First Hard X-Ray Astronomical Satellite Formally Put into Service

正A ceremony was held on January30 to announce the Huiyan satellite,China’s first Hard X-ray Modulation Telescope(HXMT)put into service.HXMT was formally delivered and put into service after it completed test tasks covering the satellite platform,payloads and ground application system.     

大型或复杂构形辐射等效热平衡试验方法

对于大型或复杂构形不能参加的不完整状态热平衡试验,提出并证明了使试验等效完整状态的必要条件,即补偿两种状态下参试部位吸收的辐射热流之差。为验证这种等效方法的充分性,利用两种热分析软件对一个构造算例的多种状态进行了数值试验,结果表明方法可行。     

五自由度气浮仿真试验台的动力学建模

五自由度气浮仿真试验台是在地面模拟微小卫星空间运动的一种重要仿真设备。通过分 析试验台的系统结构,定义世界系、轨道系及本体系三个坐标系,建立了其所模拟微小卫星 空间运动的一般情况下轨道动力学和姿态动力学模型,最后根据试验台目前执行机构为冷气 推进装置的实际工作情况导出了试验台状态方程,为下一步试验台模拟微小卫星的自治飞行 提供了理论基础。