Shape Adjustment of Flexible Rib for Large Deployable Reflector

Abstract

The surface of large deployable reflectors has to be carefully adjusted to achieve the required accuracy, which is an effective way to compensate for manufacturing and assembly errors or other imperfections. An accurate mechanical model is essential for all shape-adjustment methods. The shape adjustment of large deployable reflectors based on the reconstruction, finite, genetic, and tension (RFGT) method is addressed in the assembly phase. The RFGT method includes reverse reconstruction, finite element method, genetic algorithm, and tension adjustment. Combined with the method of subarea photography and splicing, a digital photogrammetry system is used to test the reflector surface. Interpolation is used for curve fitting, and the flexible rib is accurately modeled through reverse reconstruction. The finite element method is used to analyze the deformation regularity of the rib under the stress load of each rope. The relationship between the node shape accuracy for the rib lower edge and the rope stress loads is established. The optimal combination of rope stress loads is obtained using a genetic algorithm. The ropes apply extra tension loads to adjust the shape of the rib based on the original tension. The surface test data show that the rib lower edge is optimized after multiple adjustments in the assembly phase.