Damage characterizations and simulation of selective laser melting fabricated 3D re-entrant lattices based on in-situ CT testing and geometric reconstruction
Damage characterizations and simulation of selective laser melting fabricated 3D re-entrant lattices based on in-situ CT testing and geometric reconstruction
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DOI：
10.1016/j.ijmecsci.2019.04.054
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发表时间：
2019-07-01
影响因子：
7.3
通讯作者：
Fang, Daining
中科院分区：
文献类型：
--
作者：
Geng, Luchao;Wu, Wenwang;Fang, Daining
近年来，金属增材制造（AM）被广泛应用于工业应用，例如：生物医学，航空航天，汽车，船舶和海上部分。增材制造在制造具有无限任意拓扑布局和复杂内部微结构的先进轻质工业部件方面表现出了上级制造效率和经济优势，并且还用于制造拉胀材料和结构。本文基于原位中断显微CT测试研究了选择性激光熔化（SLM）制备的三维凹型晶格的损伤特征和力学行为，并基于几何重构模型进行了模拟，以探索潜在的失效机制。首先，建立了三维凹形网格刚度、泊松比和强度等力学性能的理论模型;其次，基于三维微CT扫描分析了三维凹形网格的几何误差和加工缺陷，并进行了原位微CT间断压缩试验，研究了三维凹形网格的变形过程和破坏机理。最后，利用三维断层图像建立了三维凹状晶格缺陷的形状、位置和分布的图像有限元模型，并进行了数值模拟，研究了缺陷对SLM增材制造三维凹状晶格结构力学性能的影响。研究表明，重入晶格的破坏行为不仅取决于其拓扑结构，还取决于几何缺陷和表面缺陷。此外，所提出的中断原位micro-CT机械加载实验和图像有限元方法也可以揭示边缘周围的断裂失效和粉末粘附之间的关系。将损伤演化过程与数值模拟结果进行对比，验证了材料的失效模式。
In recent years, metal additive manufacturing (AM) are widely employed for industrial applications, such as: biomedical, aerospace, automotive, marine and offshore sections. AM demonstrated superior manufacturing efficiencies and economic advantages for advanced lightweight industrial components with unlimited arbitrary topological layouts and complex internal microstructures, and are also employed for fabrication of auxetic materials and structures. In this paper, damage characterizations and mechanical behaviors of selective laser melting (SLM) fabricated 3D re-entrant lattices are investigated based on in-situ interrupted micro-CT test, and simulation based on geometric reconstructed models are performed for exploring the underlying failure mechanisms. Firstly, theoretical models for predicting the mechanical properties of 3D re-entrant lattice are developed, such as stiffness, Poisson's ratio and strength, etc. Secondly, the geometrical errors and fabrication defects of 3D reentrant lattices are analyzed based on 3D micro-CT scanning, in-situ micro-CT interrupted compression tests are performed for studying the deformation process and failure mechanisms. Finally, image finite element models with the detailed information of the shape, position and distribution of defects of the 3D reentrant lattices are constructed from 3D tomographic images, and numerical simulations are performed for studying the effects of the defects on the mechanical performances of the SLM additive manufactured 3D re-entrant lattice structures. It is shown that the failure behavior of the reentrant lattice is governed not only by its topology, but also by the geometric defects and surface defects. Moreover, the proposed interrupted in-situ micro-CT mechanical loading experiments and image finite element approaches can also shed lights on the relations between fracture failure around the edge and the powder adhesion. The damage evolution process is compared with the numerical simulation results to verify the materials failure modes.