Wang Xinglong, Wang Cheng, Zhou Xin, Wang Di, Zhang Mingkang, Gao Yun, Wang Lei, Zhang Peiyu
Science and Technology on Plasma Dynamics Laboratory, Air Force Engineering University, Xi'an 710038, China.
Basic Department, Air Force Engineering University, Xi'an 710051, China.
Materials (Basel). 2020 Oct 27;13(21):4786. doi: 10.3390/ma13214786.
Heat-resistant, load-bearing components are common in aircraft, and they have high requirements for lightweight and mechanical performance. Lattice topology optimization can achieve high mechanical properties and obtain lightweight designs. Appropriate lattice selection is crucial when employing the lattice topology optimization method. The mechanical properties of a structure can be optimized by choosing lattice structures suitable for the specific stress environment being endured by the structural components. Metal lattice structures exhibit excellent unidirectional load-bearing performance and the triply periodic minimal surface (TPMS) porous structure can satisfy multi-scale free designs. Both lattice types can provide unique advantages; therefore, we designed three types of metal lattices (body-centered cubic (BCC), BCC with Z-struts (BCCZ), and honeycomb) and three types of TPMS lattices (gyroid, primitive, and I-Wrapped Package (I-WP)) combined with the solid shell. Each was designed with high level of relative density (40%, 50%, 60%, 70%, and 80%), which can be directly used in engineering practice. All test specimens were manufactured by selective laser melting (SLM) technology using Inconel 718 superalloy as the material and underwent static tensile testing. We found that the honeycomb test specimen exhibits the best strength, toughness, and stiffness properties among all structures evaluated, which is especially suitable for the lattice topology optimization design of heat-resistant, unidirectional load-bearing structures within aircraft. Furthermore, we also found an interesting phenomenon that the toughness of the primitive and honeycomb porous test specimens exhibited sudden increases from 70% to 80% and from 50% to 60% relative density, respectively, due to their structural characteristics. According to the range of the exponent value n and the deformation laws of porous structures, we also concluded that a porous structure would exhibit a stretching-dominated deformation behavior when exponent value n < 0.3, a bending-dominated deformation behavior when n > 0.55, and a stretching-bending-dominated deformation behavior when 0.3 < n < 0.55. This study can provide a design basis for selecting an appropriate lattice in lattice topology optimization design.
耐热承重部件在飞机中很常见，并且它们对轻量化和机械性能有很高的要求。晶格拓扑优化可以实现高机械性能并获得轻量化设计。采用晶格拓扑优化方法时，选择合适的晶格至关重要。通过选择适合结构部件所承受的特定应力环境的晶格结构，可以优化结构的机械性能。金属晶格结构具有出色的单向承重性能，而三重周期极小曲面（TPMS）多孔结构可以满足多尺度自由设计。这两种晶格类型都能提供独特的优势；因此，我们设计了三种类型的金属晶格（体心立方（BCC）、带Z形支柱的BCC（BCCZ）和蜂窝晶格）以及三种类型的TPMS晶格（类金刚石晶格、原始晶格和I型包裹结构（I-WP））并结合实体壳。每种晶格都设计有较高的相对密度水平（40%、50%、60%、70%和80%），可直接用于工程实践。所有测试样本均采用选择性激光熔化（SLM）技术，以Inconel 718高温合金为材料制造，并进行了静态拉伸测试。我们发现，在所有评估的结构中，蜂窝测试样本表现出最佳的强度、韧性和刚度性能，这尤其适用于飞机内耐热单向承重结构的晶格拓扑优化设计。此外，我们还发现了一个有趣的现象，由于其结构特性，原始晶格和蜂窝多孔测试样本的韧性分别在相对密度从70%增加到80%和从50%增加到60%时出现突然增加。根据指数值n的范围和多孔结构的变形规律，我们还得出结论，当指数值n<0.3时，多孔结构将表现出以拉伸为主的变形行为；当n>0.55时，表现出以弯曲为主的变形行为；当0.3<n<0.55时，表现出拉伸-弯曲为主的变形行为。本研究可为晶格拓扑优化设计中选择合适的晶格提供设计依据。
