Multi-optimization for thermal deformation of gravitational wave telescope based on CFRP characteristics

Gravitational wave telescope place extremely high demands on structural thermal deformation, making material selection a critical issue. Carbon fiber reinforced polymer (CFRP) is an ideal choice for the support structure of telescope due to its low coefficient of thermal expansion (CTE) and designable properties. However, current research on the optimization of the CTE of CFRP is scarce, and conventional methods struggle to find layups that meet the requirements. In this paper, an unconventional layup optimization method is proposed to solve this problem. Initially defining the characteristics of the telescope structure and using different layup material for the main and side support rods to minimize thermal deformation. Subsequently, the NSGA-II algorithm is used to optimize the layups which are divided into conventional and unconventional layups. Specimens are then produced from these results and tested to assess the impact of processing errors on practical applications. The results demonstrate that the optimized CFRP meet the CTE requirements and, when applied to the structure, significantly reduces the thermal deformation in the eccentric direction compared to conventional designs. Additionally, a numerical analysis evaluates the effect of ply orientation errors on the performance of unconventional layups, discussing the method's limitations within these contexts.