长拉杆-止口连接弯曲刚度损失及对转子系统振动响应影响

航空燃气轮机为了实现高负荷、轻质化的追求，在转子结构设计中，趋向于提高转速和加大长径比。这使得转子系统弯曲模态临界转速降低，转子在工作转速范围内不可避免会产生一定的弯曲变形。转子弯曲变形会影响连接结构界面接触特性的变化，使其连接结构局部弯曲刚度产生损失。因此，对于工作转速靠近弯曲临界的高速转子系统，需要考虑连接结构界面接触状态变化对转子系统振动特性的影响。以高负荷的长拉杆-止口连接转子系统为对象，分析连接界面接触应力分布特性，提出连接结构弯曲刚度损失修正方法，以此为基础建立界面连接转子动力学模型。通过对止口连接三级轴流压气机转子结构动力学特性的仿真和试验研究表明，在靠近弯曲振型临界转速下，转子连接界面接触状态的变化会产生弯曲刚度损失，对转子动力学特性具有显著影响。     

Aerodynamic design of tractor propeller for high-performance distributed electric propulsion aircraft

Aiming to maximize the aerodynamic performance of the Distributed Electric Propulsion (DEP) aircraft, a hybrid design framework which focuses on the aerodynamic performance of the propeller/wing integration has been developed and validated numerically. Variable-fidelity modelling for propeller aerodynamics has been used to achieve computational efficiency with reasonable accuracy. By optimizing the aerodynamic loading distributions on the tractor propeller disk, the induced slipstream is redistributed into a form that is beneficial for the wing downstream, based on which the propeller blade geometry is generated through a rapid inversed design procedure. As compared with the Minimum Induced Loss (MIL) propeller at a specified thrust level, significant improvements of both the lift-to-drag ratio of the wing and the propeller/wing integrated aerodynamic efficiency is achieved, which shows great promise to deliver aerodynamic benefits for the wing within the propeller slipstream without any additional devices.     

面向集中力扩散的回转曲面加筋拓扑优化方法

为了提高航天器回转曲面加筋型连接结构的集中力扩散效率，需要开展回转曲面加筋集中力扩散结构设计。传统放射肋设计方法普遍依赖设计经验、难以满足集中力高效扩散需求。因此，提出一种面向集中力扩散的回转曲面加筋拓扑优化方法。第1步，建立了一种基于各向异性过滤技术的集中力扩散拓扑优化方法，保证拓扑优化结果满足回转曲面加筋制造工艺要求；第2步，提出了一种基于网格变形技术的拓扑优化结果智能重构方法，可高效准确地对回转曲面加筋拓扑优化结果进行模型自动重构。基于所提出方法，以卫星平台对接环这种典型的回转曲面加筋壳为对象开展算例研究，并将优化结果与传统放射肋设计结果进行对比。结果表明，所提出的优化方法可得到加筋构型清晰、满足回转曲面加筋制造工艺要求的优化结果，且具有集中力扩散效率高、网格质量依赖性低、拓扑特征重构高效等优点。     

基于3D Zernike矩的巡检器与空间站的相对导航算法

针对航天器相对导航问题，以空间站表面为"特殊地形"，提出一种基于大型航天器表面巡检的相对导航算法。首先，运用巡检飞行器上的TOF （Time of Flight）相机测量空间站表面局部点云数据，以该点云数据为实时图，以空间站表面先验点云数据为基准图。然后，利用3D Zernike矩与三维地形间的一一对应关系，将三维地形匹配转化为基于3D Zernike矩的特征向量匹配。在此基础上求解实时图与匹配上的基准图间的相对位置、相对姿态，从而确定两航天器间的相对导航参数，并通过实验分析了匹配精度及速度的主要影响因素。最后，将该相对导航参数与惯性系统推算的相对导航参数在扩展卡尔曼滤波器的框架下实现信息融合，估计了巡检飞行器与空间站间的相对位置、相对姿态，实验结果表明，相对位置精度优于0.002 m，相对姿态精度优于0.1°。     

基于双滤波器的高精度目标跟踪估计方法

针对连续推力的合作航天器，采用双重无迹卡尔曼滤波(DUKF)算法估计其状态和加速度。通过状态滤波器和参数滤波器的配合，提升滤波精度，完成运动状态和参数的估计，从而实现合作目标的运动轨迹跟踪。与合作航天器相比，非合作航天器存在大小未知、发生时刻未知的机动，无法获得加速度，且信息获取和运动状态的估计难度大。针对非合作航天器，基于简化的相对运动方程，结合天基平台获得目标的观测信息，采用两个扩展卡尔曼滤波(EKF)及基于半正焦弦的机动检测策略实现多未知脉冲机动的运动状态的估计。仿真结果表明：相比于无迹卡尔曼滤波（UKF），DUKF在对合作航天器的状态和加速度估计方面具有更快的收敛速度和更高的滤波精度；对于存在未知机动的非合作航天器，通过对比验证机动检测策略与滤波器切换策略相结合的方法的有效性，该方法能够检测到多次机动并且减少误判。     

Grinding force and surface quality in creep feed profile grinding of turbine blade root of nickel-based superalloy with microcrystalline alumina abrasive wheels

Creep feed profile grinding of the fir-tree blade root forms of single crystal nickel-based superalloy was conducted using microcrystalline alumina abrasive wheels in the present study. The grinding force and the surface quality in terms of surface topography, subsurface microstructure, microhardness and residual stress obtained under different grinding conditions were evaluated comparatively. Experimental results indicated that the grinding force was influenced significantly by the competing predominance between the grinding parameters and the cross-sectional root workpiece profile. In addition, the root workpiece surface, including the root peak and valley regions, was produced with the large difference in surface quality due to the nonuniform grinding loads along the root workpiece profile in normal section. Detailed results showed that the surface roughness, subsurface plastic deformation and work hardening level of the root valley region were higher by up to 25%, 20% and 7% in average than those obtained in the root peak region, respectively, in the current investigation. Finally, the superior parameters were recommended in the creep feed profile grinding of the fir-tree blade root forms. This study is helpful to provide industry guidance to optimize the machining process for the high-valued parts with complicated profiles.     

Impact of bending dies with different friction forms on forming force and quality of tubes manufactured by free bending technology

In the 3D free bending forming system, the bending die can be designed either in a sliding type or rolling friction type. Bending die-based sliding friction type is often called normal bending dies; however, the bending dies-based rolling friction type includes bending die-based roller type and ball type in structure. In the current study, the impact of three bending dies on the forming force, and the bent tube quality was investigated. The obtained results showed that the tangential stresses and strains of the tubes formed by the bending die-based roller type were the smallest among the three bending dies. Besides, the spherical bearing force P_U was reduced drastically after using the roller type and ball type compared to the sliding friction type. Moreover, the uniformity of the wall thickness distribution of the tubes formed by the roller type and ball type was better than those obtained from the sliding friction type. In addition, the cross-section distortion rate was reduced by 2.8% using the roller type, and 1.8% using ball-type compared to the sliding friction type.     

火星车转移坡道柔顺性优化设计及动力学分析

对一种抽展式火星车转移坡道开展柔顺性优化设计和动力学分析。首先，分析火星车与存在异面角的坡道的挤压几何原理。然后，设计坡道的间隙机构和限位机构，并计算出机构关键设计参数的最优值，以自适应调整两侧坡道的距离，〖JP2〗减小火星车与坡道护栏之间的相互作用力。最后，对坡道下落过程和火星车在坡道上的行驶过程进行动力学仿真，验证坡道柔顺性优化设计的效果。结果表明：优化后的坡道柔顺性大幅提高，坡道可以自适应调整两侧的距离；使用优化后的坡道，可以有效降低火星车与坡道护栏的作用力，实现火星车在坡道上的安全行驶。     

基于测试数据的卡箍非线性等效建模方法

为了快速准确地计算卡箍管路系统的振动响应，提出了基于测试数据的卡箍非线性等效建模方法。对卡箍直管系统进行低幅值激励的模态测试，利用试验数据对有限元模型进行修正，识别卡箍线性刚度、线性阻尼参数。对卡箍直管系统开展不同激励水平下的恒力测试，通过样条插值多项式法将恒力频响函数转换为恒位移、恒速度频响函数，并进一步识别卡箍非线性等效刚度、非线性等效阻尼，建立了考虑卡箍非线性的等效动力学模型。研究表明:该卡箍等效动力学模型的预测频响函数与试验频响函数的最大误差仅为-6.9%，可以有效地反映卡箍实际的刚度、阻尼特性，对解决卡箍管路系统的振动响应分析具有重要的指导意义。      

复杂动态环境下无人飞行器动态避障近似最优轨迹规划

针对复杂动态环境下无人飞行器的动态障碍规避问题，基于合理假设建立了无人飞行器和动态障碍的运动学模型，并综合考虑无人飞行器飞行过程中的终端约束、控制输入约束、安全避障约束等，以能量最少为性能指标构建动态避障问题数学描述。之后，针对终端约束和控制输入约束，依据优化模型预测静态规划算法(OMPSP)生成初始轨迹；针对动态避障问题的不等式约束，引入松弛变量并结合滑模变结构控制方法设计松弛变量动力学，实现对一个、多个或同时多个动态障碍的安全规避；最后，依据有限时间微分动态规划(RHDDP)算法进行轨迹优化，获得满足上述各种约束并能规避动态障碍的近似最优轨迹。