实验技术与管理

星敏支架系统包括星敏安装板和星敏支架。通过反距离加权法重构的应变场对弯曲、拉压应变与变形场的关系进行求解，建立了星敏安装板的大挠度变形场重构方法；基于最小二乘法重构的应变场，使用曲率迭代法推导了支架变形场；建立了支架与安装板组合体变形的几何关系式，得到支架在产生变形的安装板上的位移表达式。基于变形场重构方法设计了应变测点布置方案，使用FBG光纤传感器建立了星敏支架应变监测系统，根据实验得到的离散应变测点数据，重构了星敏支架系统的应变场与变形场。结果表明，星敏支架系统的变形重构误差不超过3.84%。该方法适用于四边固定的弹性薄板-支架系统变形场的监测，为复杂约束条件下的装配体变形场重构研究提供了依据。

[Objective] Star sensor bracket systems are composed of star sensor mounting plates and star sensor brackets. The bracket system connects the star sensor with the satellite body. Because such sensors must maintain high operational accuracy during operation, their structural characteristics considerably impact the deformation field distribution. In addition, existing deformation reconstruction techniques have high computational complexity and long calculation times. For instance, B-spline interpolation and inverse finite element deformation reconstruction methods have large computational loads when processing large-scale data, and their accuracy is determined by the mesh conditions and initial conditions such as constraint and loading method. To address these issues, a deformation field reconstruction technology based on strain measurements was proposed for the star sensor bracket system. [Methods] For the reconstruction and analysis of deformation fields, the system deformation was decomposed into mounting plate and bracket deformations, as well as the bracket displacement caused by the mounting plate deformation. The strain field was determined by reconstructing the discrete point strain measurement data for the large deflection deformation of the mounting plate using the inverse distance weighting method. The relationship between bending, tensile, and compressive strains, as well as the deformation field in the microelements, was determined, and a discrete digital integration method was used to derive the deformation curves of N parallel lines. These N curves were then fitted to obtain the surface deformation diagram of the mounting plate. The star sensor bracket was simplified as a beam structure, with its deformation mainly manifesting as a small deflection. Bending stress produced the strain that induced the deformation in the structure, with a mid-surface strain of 0. When a beam structure undergoes small bending deformation, it will generate a rotation angle. Multiplying the rotation angle by the radius of curvature gives the chord length. The difference in curvature radius between the upper surface and the neutral plane is known. Therefore, the chord length of the upper surface and the neutral plane is obtained, which leading to the beam surface strain. Based on these findings, the discrete curvature and distance between discrete points were used as inputs for calculation, and the coordinate positions of each point on the curve were determined via point-by-point iterative operation. These positions were fit to obtain the corresponding curve for calculating the deformation. Finally, the geometric relationship of the deformation of the sensor bracket and mounting plate was established, and the displacement expression of the bracket mounted on the deformed mounting plate was derived. [Results] As a result, the deformations of the mounting plate and bracket were superposed. An experimental deformation measurement platform was also developed for the star sensor bracket system. By applying weighted loads, the deformation of the sensor bracket and mounting plate was measured using the FBG strain monitoring system. The reconstruction results were compared with the displacement sensor measurement data, which revealed that the bracket reconstruction error did not exceed 3.84%. The proposed deformation field reconstruction method realized the rapid and accurate reconstruction of the deformation fields based on discrete point strain monitoring data. It thus provided a basis for studies on the deformation field reconstruction of assemblies under complex constraint conditions.