Study on thermal-mechanical coupling performance and failure mechanism of titanium alloy lattice structures in high temperature environment

Abstract

Three types of lattice structure unit cell specimens of kagome, single-stage pyramidal and multistage pyramidal were designed and manufactured by using 3D printing technology, out-of-plane compression tests and numerical simulations in the room temperature environments of 25℃ and high temperature of 350℃ were carried out. The analysis clarified the influence of the three design parameters of cell number, structure form and structure level on the out-of-plane load-bearing capacity of the lattice structure, and revealed the thermal-mechanical coupling performance and failure mechanism of the lattice structures. The results show that the carrying capacity of the kagome lattice increases linearly with the number of cells, which verifies the rationality to use single cells instead of multiple cells to carry out related research. Further analysis showed that the failure mode of three lattice structures was all internal core buckling leading to the overall failure of the structure, and the structural level has the most significant impact on the mechanical properties of the lattice. Due to the addition of the secondary core, the multistage pyramidal lattice structure has a larger heat transfer surface area and load-bearing capacity: under the same weight, the internal core heat transfer surface area increased by 131.9% comparing with the single-stage lattice structure, and at 25℃ and 350℃, the ultimate load of single-stage lattice structure increased by 18.4% and 23% respectively. At the same time, due to the increase in heat transfer surface area, the bearing capacity of the multistage lattice unit cell was slightly affected by high temperature than the kagome and single-stage lattice unit cells.