一种具备可调热膨胀系数的可展开结构的力学特性研究

Control of thermal expansion coefficients (TECs) is critical for structural systems in specialized fields such as aerospace, where extreme temperature variation environments necessitate high thermal stability. Meanwhile, such systems also require efficient space deployment capabilities to address the challenges posed by limited working spaces. Lattice composite structures with tunable properties are gradually being applied in the engineering field. In this study, we propose a triangular combined deployable structure that incorporates space deployment, adjustable thermal expansion, and lightweight properties through an origami-based design utilizing bi-material triangles. By introducing panels with non-zero thickness and strategically adjusting the hinge positions, the idealized origami model is transformed into a three-dimensional load-bearing configuration when tensile forces are applied to both sides of the structure, allowing it to support loads effectively. The TEC of the structure can be engineered to exhibit either positive or negative values by strategically adjusting the geometrical parameters and material combinations, which also allows tuning of structural stiffness. The results show that increasing the angle (the angle between the symmetry axis and the hypotenuse of the triangle) and reducing the thickness ratio (the ratio of material thicknesses with low and high TECs) can effectively lower the TEC of the structure and simultaneously diminish its elastic modulus. Elevating the cell ratio, which is the ratio of the number of cells on the supporting surface to those on the base surface, decreases the TEC and enhances the elastic modulus of the structure. However, it also introduces more deformable connection regions within the structure, leading to a decrease in yield strength. Additionally, the results indicate that greater improvements in lightweight properties can be achieved by reducing the angle and thickness ratio, as well as increasing the cell ratio. The theoretical values of the equivalent TEC in the load-bearing direction of the structure align well with the results from finite element simulations.