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

高温环境下钛合金点阵结构热力耦合性能与失效机理研究

¹ School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China
² Aircraft Strength Research Institute of China, Xi′an 710065, China

Received: 8 May 2021

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.

摘要

设计并采用3D打印技术制备了单级Kagome、单级金字塔和多级金字塔3类点阵结构单胞试件, 开展常温(25℃)和高温(350℃)环境下的面外压缩试验测试和数值仿真分析, 阐明了胞元数目、结构形式与结构层级3个设计参数对点阵结构面外承载能力的影响规律, 进而揭示了点阵结构的热力耦合性能和损伤失效机理。研究结果表明, Kagome点阵承载能力随胞元数目增加呈线性递增关系, 验证了采用单胞元代替多胞元开展相关研究的合理性。进一步分析表明, 3种点阵结构失效模式均为内部芯子屈曲导致结构整体失效, 同时结构层级对点阵力学性能影响最为显著。由于加入二级芯子, 多级金字塔点阵单胞具有更大的换热表面积和承载能力: 在同等质量下, 内部芯子换热表面积相对于单级点阵单胞增加131.9%, 在25℃和350℃下的极限载荷相对单级点阵单胞分别增加18.4%和23.0%。同时, 由于增大换热表面积, 多级点阵相对Kagome和单级点阵的承载能力受高温影响更小。