Structural design and analysis of the primary mirror cell truss for a next-generation large spectroscopic survey telescope

To meet the stringent requirements of the ESST primary mirror cell truss in terms of weight, stiffness, and thermal stability, this study proposes a three-layer spatial truss structure for the primary mirror support system. A hybrid material strategy is developed to achieve an optimal balance between structural rigidity and cost efficiency. The optimization objectives are defined as maintaining the total structural mass below 16 tonnes while minimizing the displacement at the segment support points. The results show that an all-steel design limits the maximum support deformation to 0.518 mm, with a material cost of 1.92 million CNY. By incorporating 0.89% carbon fiber reinforced polymer (CFRP), the maximum deformation is reduced to 0.49 mm, with a material cost of 2.016 million CNY, thereby satisfying the ESST performance criteria. This study provides a cost-effective structural design solution for the next-generation large spectroscopic survey telescope in China.