| In some high temperature,low temperature and rapidly changing environment,the thermal deformation caused by temperature change will affect the original function of the structure,and even cause the thermal fatigue damage of the structure.Therefore,in order to solve the problems caused by thermal deformation and thermal stress,it is urgent to design materials and structures that can accurately control the coefficient of thermal expansion and have excellent mechanical properties and lightweight.In this paper,the tension dominated lattice composites are systematically studied,aiming at using common metal alloy materials to design space support structure which can meet the requirements of zero expansion and certain stiffness.In this paper,the formulas for calculating the coefficient of thermal expansion of hinged and rigid joints of bimaterial triangular cells are derived and verified by finite element method.The elastic modulus and thermal expansion coefficient of metal alloy materials commonly used in engineering are counted.According to the characteristics of triangular cell,the materials are divided into three categories.Based on the stiffness of different material systems and the half vertex angle of cell,the material systems suitable for zero expansion structure design are sorted out.Based on the triangular cell,three kinds of zero expansion support structures are designed,and the design ideas of each structure are introduced.The thermal expansion analysis and stiffness analysis of each structure and its assembly platform are carried out,and the advantages and disadvantages of the three structures are summarized.The discrete design of different material components and the assembly design of the whole zero expansion structure are carried out for the type Ⅱ and type Ⅲ structures.The sensitivity analysis of three kinds of zero expansion structures is carried out.The influence of characteristic parameters such as different half vertex angle,different coefficient of thermal expansion and different elastic modulus E on the coefficient of thermal expansion and stiffness K along the axis direction of the structure is analyzed.The rationality of zero expansion structure design is discussed.Finally,the structure of type Ⅱ and type Ⅲ of discrete assembly design is made by3 D printing technology,and the heating test is carried out.The high-speed camera is used to photograph the experimental process.Finally,the thermal expansion coefficient of the structure in the height direction is calculated,and compared with the results of theoretical analysis and simulation. |
