透镜式缠绕肋压扁缠绕过程数值模拟分析

利用ABAQUS首先以各向同性材料透镜式缠绕肋的肋片压扁进行了数值模拟分析,比较了三种壳单元（S4、S4R、SC8R）和三种体单元（C3D8、C3D8R、C3D8I）模拟分析效率,并给出受力特征;进而以S4R和C3D8I进行了碳纤维复合材料肋片压扁模拟分析,并得到受力特征;最后,建立了完整的缠绕肋整体非线性有限元模型,实现了缠绕过程模拟分析,得到缠绕肋缠绕过程应力、应变及变化特征,以及缠绕弯矩。本文对缠绕肋设计及系统样机研制具有指导和参考价值。
     

Temperature effect on buckling properties of ultra-thin-walled lenticular collapsible composite tube subjected to axial compression

This paper seeks to outline the temperature effect on the buckling properties of ultra-thin-walled lenticular collapsible composite tube(LCCT) subjected to axial compression.The buckling tests of the LCCT specimens subjected to axial compression were carried out on INSTRON-500 N servo-hydraulic machine in dry state and at the temperatures of 25 C, 100 C and 80 C. The load–displacement curves and buckling initiation loads were measured and the buckling initiation mechanism was discussed from experimental observations. Experiments show that the buckling initiation load, on average, is only about 2.2% greater at the low temperature of 80 C than at the room temperature of 25 C due to the material hardening, demonstrating an insignificant increase in the buckling initiation load, whereas it is about 19.5% lower at the high temperature of 100 C than at the room temperature owing to the material softening, implying a significant decrease in the buckling initiation load. The failure mode of the LCCT in axial compression tests at three different temperatures can be reckoned to be characteristic of the buckling initiation and propagation around the central region until rupture. The finite element(FE) model is presented to simulate the buckling initiation mechanism based on the eigenvalue-based methodology. Good correlation between experimental and numerical results is achieved.     

透镜式薄壁CFRP管空间伸展臂轴压屈曲分析及试验

对透镜式截面四层铺设薄壁碳纤维增强塑料(CFRP)管空间伸展臂进行轴压载荷试验,得到轴压临界屈曲载荷及屈曲特性。利用有限元模型进行线性特征值屈曲分析,并引入屈曲模态形式作为初始几何缺陷进行非线性屈曲分析,得到轴压下屈曲临界载荷及非线性屈曲特性,并与试验结果进行对比分析。结果表明初始几何缺陷对CFRP管轴压临界载荷影响较大,给CFRP管加入适当的几何缺陷可更有效模拟实际非完善体的屈曲载荷。进而对其材料厚度、层数和铺设角度进行参数分析,得到各参数对轴压临界载荷的影响程度及敏感性,本文对透镜式薄壁CFRP管空间伸展臂的设计和深入研究具有重要参考价值。     

空间豆荚杆机构收展过程的并行仿真计算

针对空间豆荚杆展开机构的设计,利用显式动态算法和高性能计算资源,对豆荚杆盘卷收拢和展开过程进行了非线性准静态仿真。为满足计算调试和多组工况带来的大规模计算需求,通过计算耗时、应力曲线和能量曲线的对比分析,确立了以提高加载速率为主的显式计算并行加速合理策略。计算过程和结果分析表明,动态仿真方法完全可以用来对豆荚杆机构的功能设计、结构改型和参数调整进行预知仿真,并为试验提供指导和参考。     

可折叠铍青铜弹性豆荚杆焊接成型工艺

可折叠铍青铜豆荚杆的焊接成型是该类豆荚杆研制的难点之一,本文对铍青铜豆荚杆的储能点焊工艺进行了研究,分析了工艺参数及热处理对焊接接头名义剪切强度的影响,给出了优选的工艺参数为焊接电压180 V、保压7 s。在最佳工艺条件下成型并经过340℃/2 h时效处理后,焊接接头的名义剪切强度由52 MPa提高到68 MPa。铍青铜焊接接头的名义剪切断口随着焊接电压的增大,从焊接接头区域向热影响区转移。