Two elastically equivalent compound truss lattice materials with controllable anisotropic mechanical properties

Compound lattice structures are novel lattice structures with high stiffness and strength and their anisotropy can be easily controlled. In this study, two elastically equivalent compound truss lattice materials, BCS-I and BCS-II, are designed, and their anisotropic elastic properties and strength, such as the initial yield strength and elastic buckling strength, are analyzed and compared. The results show that the anisotropy of the elastic properties and strength as well as the initial deformation mode of the two compound truss lattice materials can be controlled by adjusting the relative thicknesses of their elementary trusses and relative densities. Combined with theoretical analysis, the mechanism of the influence of the relative thickness on the anisotropic mechanical properties of the two truss lattice materials is elucidated. In addition, comparing the mechanical properties of the two compound truss lattice materials reveals that they have the same elastic properties and initial yield strength. And the BCS-I truss lattice material shows better buckling resistance, its elastic buckling strength is never less than that of the BCS-II truss lattice material. By both numerical simulations and experiments, the analytical elastic modulus, initial yield strength, and deformation characteristics are verified. The analysis in this study indicates that by rationally designing and selecting the BCS-I and BCS-II truss lattice materials, the most suitable truss lattice materials can be found according to the loading direction without the need to add more material, which has implications for improving the performance of a wide range of truss systems.