Ding Junhao, Ma Qingping, Li Xinwei, Zhang Lei, Yang Hang, Qu Shuo, Wang Michael Yu, Zhai Wei, Gao Huajian, Song Xu
Department of Mechanical and Automation Engineering, Chinese University of Hong Kong, Sha Tin, Hong Kong, 999077, China.
Faculty of Science, Agriculture, and Engineering, Newcastle University, Singapore, 567739, Singapore.
Adv Sci (Weinh). 2024 Nov;11(41):e2402727. doi: 10.1002/advs.202402727. Epub 2024 Sep 16.
Lattice materials are an emerging family of advanced engineering materials with unique advantages for lightweight applications. However, the mechanical behaviors of lattice materials at ultra-low relative densities are still not well understood, and this severely limits their lightweighting potential. Here, a high-precision micro-laser powder bed fusion technique is dveloped that enables the fabrication of metallic lattices with a relative density range much wider than existing studies. This technique allows to confirm that cubic lattices in compression undergo a yielding-to-buckling failure mode transition at low relative densities, and this transition fundamentally changes the usual strength ranking from plate > shell > truss at high relative densities to shell > plate > truss or shell > truss > plate at low relative densities. More importantly, it is shown that increasing bending energy ratio in the lattice through imperfections such as slightly-corrugated geometries can significantly enhance the stability and strength of lattice materials at ultra-low relative densities. This counterintuitive result suggests a new way for designing ultra-lightweight lattice materials at ultra-low relative densities.
晶格材料是一类新兴的先进工程材料，在轻量化应用方面具有独特优势。然而，超低相对密度下晶格材料的力学行为仍未得到充分理解，这严重限制了它们的轻量化潜力。在此，开发了一种高精度微激光粉末床熔融技术，该技术能够制造出相对密度范围比现有研究宽得多的金属晶格。这项技术能够证实，立方晶格在压缩时，在低相对密度下会经历从屈服到屈曲的失效模式转变，这种转变从根本上改变了通常在高相对密度下的强度排序，即板>壳>桁架，变为在低相对密度下壳>板>桁架或壳>桁架>板。更重要的是，研究表明，通过诸如微波纹几何形状等缺陷来增加晶格中的弯曲能量比，可以显著提高超低相对密度下晶格材料的稳定性和强度。这一违反直觉的结果为设计超低相对密度的超轻晶格材料提供了一种新方法。
