Research on Residual Stress Measurement of Magnesium Alloy Cabin Castings

Owing to the nonuniform wall thickness and complex internal structure， the measurement of the residual stress on magnesium alloy cabin castings is complex and difficult extremely， and thus seldom research has focused on the residual stress of magnesium alloy castings. In this paper， the blind-hole method， the X-ray diffraction (XRD) method， and the contour method are used to conduct comprehensive and systematic residual stress tests for a magnesium alloy cabin casting. The results show that the residual stress on the surface of the casting obtained by the blind-hole method is between -20.03 MPa and -71.03 MPa， the residual stress obtained by the XRD method is between -26.01 MPa and -87.11 MPa， while the residual stress obtained by the contour method is between -45.89 MPa and 76.87 MPa. The study can lay a basis for the subsequent research of magnesium alloy cabin castings， and provide a reference for the residual stress test of magnesium alloy castings.     

聚酰亚胺复合膜的泊松比设计

空间薄膜材料的泊松比是张拉中产生膜面褶皱的主要原因之一。为此，需要对薄膜的泊松比进行设计，从而削弱甚至消除薄膜的泊松比效应对膜面精度产生的影响。针对应用于空间结构中的新型正交各向异性纤维增强复合膜，使用正交椭圆孔阵列对复合膜胞元进行泊松比设计，分析其等效的经纬双向泊松比随孔间边界距离和椭圆本身的长短轴之比的变化规律。讨论了打孔后孔间边界距离g,以及椭圆长轴占长短轴之和的比例r，对打孔后薄膜胞元的等效泊松比产生影响的原因。g对等效泊松比的影响主要体现在两个方面：其一是g值影响了胞元的旋转能力，其二是g值决定了材料参数对打孔后的等效泊松比的影响程度。g值越大，等效泊松比越大。r值对等效泊松比的影响主要是胞元的旋转能力，r值越大，旋转能力越大，等效泊松比越小。     

固定翼无人机编队的启发分布式模型预测控制

针对无人机编队飞行控制中队形保持、路径规划、重构、防撞等多重功能需求,采用启发型分布式模型预测控制框架,将需求转化为多目标优化问题中的代价函数与相容性约束求解,实现了对无人机编队飞行的一体化控制.同时,采用分阶段式的轨迹规划算法,融合模型预测轨迹规划与多项式轨迹规划,利用多项式轨迹系数实现高效的邻居轨迹信息交互,从而增大了模型预测控制的预测范围,并降低了规划控制过程中的计算量与通信量.最后,通过9架无人机的协同避障编队仿真,证明了该方法的有效性.