| The accuracy error caused by thermal deformation has always existed in many aerospace structures.The main purpose of this paper is to design the tailorable thermal expansion metamaterials which can be used in aerospace and other fields.Based on the idea of structural functional integration,metamaterials can not only meet the design requirements of zero/negative thermal expansion,but also gain good mechanical properties.The main contents of this paper include the design,analysis and performance evaluation of the tailorable thermal expansion structure.In view of the existing research on zero/negative thermal expansion structures,the main stress forms that affect the thermal deformation effect in the structure and the analysis method of thermal stress are obtained,which provides guidance for the design of tailorable thermal expansion structure.In order to design the three-dimensional negative thermal expansion structure,based on the bending dominated negative thermal expansion plane lattice,a three-dimensional lattice design method with negative thermal expansion effect is proposed by introducing local compression-torsion structure.The design of triprism and tetragonal prism lattice is proposed,and the stiffness and thermal deformation theory of three-dimensional negative thermal expansion structure is deduced systematically.The simulation results of tetragonal prism lattice and triprism lattice show that this kind of structure can achieve notable negative thermal expansion.The common problem in the past design of zero/negative thermal expansion structure is that the thermal stress level in the structure is too high.By analyzing the method of avoiding thermal stress,the design of "C" type bimaterial composite rod is put forward,which can realize low thermal expansion and negative thermal expansion.A geometric design criterion based on this kind of composite bar is proposed,and a cell with periodic array is constructed.In other researches of negative thermal expansion superstructures,only the thermal deformation of the structure under the condition of uniform temperature field was concerned.In this paper,the stability of thermal expansion coefficient of this kind of composite rod design under the condition of non-uniform temperature field is proved.By transforming the truss structure into zero expansion composite rod,the thermal deformation isolation platform of the satellite is designed,and the thermal stability of the platform is proved by simulation,which provides a reference for the later engineering application. |
