Research On Optimized Design Of Large-diameter Mirrors And Support Structures

Ground-based telescopes are a type of astronomical telescope that plays an important role in human exploration of the mysteries of the universe.In order to pursue deeper and farther detection targets,the telescope mirrors have increasingly larger diameters,and the mirror surface type is increasingly influenced by gravity.Therefore,the support design of the mirror has important research value.The main mirror is a key component of the main optical system of the ground-based telescope.The optimization of the main mirror and its supporting structure is of vital importance to the main mirror and the telescope as a whole.In this paper,a large-caliber ground-based telescope of 1.4m is used to analyze and design the telescope mirror,support structure and support plate.SiC has the advantages of large specific stiffness,good thermal conductivity and mirror polishing,so SiC is the main mirror material.According to the design requirements of the main mirror of the telescope,the main mirror is designed to be lightweight.To ensure that the mirror meets the requirements of the surface shape,it has a better distribution of quality and structure to achieve lightweight processing.By comparing each light-weighted form,the local open style of the back of the reflector is selected as the light-weighted form of the reflector,and the triangle is selected as the light-weight hole structure of the reflector.Combined with theoretical analysis and finite element optimization design methods,the deformation of the mirror is taken as the objective function,and the position of the mirror support point is optimized.The supporting structure of the reflector in this paper is designed with three parts: axial support,radial support and support plate.By reading a large number of documents and comparing the advantages and disadvantages of various supporting methods,the basic principle of large-aperture primary mirror support design is summarized.Freedom analysis and calculation of the structural design of this paper.It is determined that the mirror support in this paper is a combination of axial support and radial support.The axial support is an 18-point whiffle-tree structure and the radial support is a tangential A+ rod.Different from the previous equal force floating whiffle-tree structure,the whiffle-tree structure of this paper is determined by the position of the support point with the objective of optimizing the mirror surface type.Therefore,it is the unequal floating support structure and the specific dimensions are limited.Meta optimization.Through the traditional experience design,finite element modeling,size optimization and topology optimization methods,reference sensitivity analysis results,detailed design support structure.The design structure was verified by finite element analysis.After the design of the mirror and support structure was completed,the structure was analyzed by finite element simulation.Static analysis results show that: under the 1g axial gravity,1g radial gravity,2°C temperature change and 1g axial gravity + 2°C temperature rise,1g radial gravity + 2°C temperature rise,the displacements of the mirror and support components in the axial and radial directions all meet the design requirements.The maximum PV value of the face value is 444.34803 nm and the maximum RMS value is 8.013596 nm.In the dynamic analysis,modal analysis and random vibration analysis also satisfy the strength and stiffness requirements,and the dynamic performance is good.The mirror and support structure are designed.