Wenjie Fan

1. Honeycomb sandwich panels usually consist of upper and lower composite facesheets and a lightweight honeycomb core. They offer high specific strength, high specific stiffness, and strong bending...

The scanning drive mechanism of the spaceborne microwave-sounding antenna has two working modes of constant speed and variable speed, and the special structural form and layout of the reflecting surface lead to a large perturbation moment in the constant speed and variable speed scanning modes. The optimized design of the reflecting surface reinforcement structure of the antenna’s scanning drive mechanism is of great significance for the adjustment of the dynamic stiffness and rotational moment of inertia of the system, which helps to reduce the influence of the moment perturbation. In this paper, a design method combining topology optimization and size optimization is adopted to optimize the design of the reflecting surface reinforcement structure of the planar antenna. The topology optimization constrains the volume, and the objective function is the first-order frequency maximum. The topology optimization results show that the reinforcement is arranged along the center in a “palm” shape. The size optimization is based on the objective of minimizing the rotational inertia of the structure, and the constraints are the dynamic stiffness and the RMS of the structural stress values. The dynamic stiffness of the structure is improved after size optimization, the mass of the reinforcing bar is reduced by 26% compared with the original structure, the rotational inertia of the planar antenna is reduced by 39% compared with the original structure, and the perturbation moments are decreased by 52% at uniform speeds and by 39% at variable speeds.

Mechanical interfaces are prevalent in industries like aerospace and maritime, where the normal contact stiffness on these surfaces is a crucial component of the overall stiffness of mechanical structures. From the perspective of structural mechanics, normal contact stiffness significantly affects the dynamic response of mechanical structures and must be considered in mechanical design and simulation analysis. Essentially, the mechanical interface represents a typical type of nonlinear contact, characterized by both its non-uniform distribution and its frequency-dependent properties under external excitations. A plate structure was designed to study the distribution and frequency-dependent characteristics of normal contact stiffness on the mechanical interface. Experiments validated that the normal contact stiffness not only significantly increases the fundamental frequency of the plate but also alters its mode shapes. To replicate the experimental results in simulations, the BUSH elements were used to model the normal contact stiffness within the plate structure, arranging it non-uniformly and setting it to vary with frequency according to the plate’s mode shapes and frequency response. This method accurately replicated the plate’s mode shapes and response curves within the 0–1000 Hz range in simulations.

The normal operation of spaceborne parabolic cylindrical reflector antennas under various operating conditions relies on maintaining the root mean square (RMS) of the reflector surface’s deformation within reasonable limits. In engineering practice, the designing of reinforced ribs is the primary way to control the RMS of the reflector surface. However, the layout and dimensions of reinforced ribs for many existing designs rely on the experience of the designer and lack a theoretical foundation. This leads to suboptimal layouts and dimensions in many designs, deviating from the optimal design. To address these concerns, this study proposes a comprehensive design approach that combines both topology optimization and parametric analysis. Optimization and parametric analysis were conducted for a large-sized spaceborne composite parabolic cylindrical reflector antenna. The layout and dimensions of the reinforced ribs were reconstructed based on the optimization results and parametric analysis. This study also obtained the influence of the height and thickness of the reinforced ribs on the RMS of the reflector surface. Subsequently, utilizing antenna temperature field simulations as thermal excitation inputs, finite element thermal distortion analyses were conducted for the reflector surfaces without reinforced ribs, with the original reinforced ribs designed based on empirical methods, and with optimized reinforced ribs. In comparison to the original design of the reinforced ribs, the optimized design, without an increase in the volume of the reinforced ribs, reduced the RMS of the reflector surface from 0.6025 mm to 0.5561 mm, resulting in an optimization ratio of 7.7%. Moreover, when compared to the reflector surface without reinforced ribs, the optimized design achieved a 17.9% reduction in RMS.

对比分析了不同截面形式管状伸杆的力学性能，发现TRAC截面比STEM和CTM截面具有更大的截面惯性矩与收拢高度之比，但其截面厚度较大，且弯心与形心不重合，导致局部弯扭组合屈曲.提出了一种管状伸杆的新型截面形式XTEM，其具有两个对称轴，弯心与形心重合；设计并建立了四种截面形式的伸杆有限元模型，分析得到了四个截面的截面惯性矩.结果表明，在同样的收拢高度下，XTEM截面伸杆在厚度增加较小的情况下，两个轴向的截面惯性矩比CTM截面分别增加了77%和35%，比STEM截面分别增加了30倍和6.7倍.

以空间应用需求日益广泛的大型平板缝隙天线为研究对象, 介绍了其结构组成. 为减小天线热变形, 对天线外侧4个安装角的连接方式做了改进设计, 并在极高温和极低温两种工况下进行热变形分析, 得到改进前后两个方案的变形结果. 在极高温工况下, 天线阵面Y向热变形均方根值从改进前的0.52 mm减小到0.3 mm; 在极低温工况下, 天线阵面热变形均方根值从改进前的0.35 mm减小到0.1 mm. 结果表明改进后的方案满足设计要求, 从而确保了天线在轨电性能的指标.