Multiscale modeling of copper and copper/nickel nanofoams under compression
Multiscale modeling of copper and copper/nickel nanofoams under compression
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DOI：
10.1016/j.commatsci.2019.109290
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发表时间：
2020-02
影响因子：
3.3
通讯作者：
H. Ke;A. G. Jimenez;D. M. D. Silva-D.-M.-D.-Silva-93463720;I. Mastorakos
中科院分区：
文献类型：
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作者：
H. Ke;A. G. Jimenez;D. M. D. Silva-D.-M.-D.-Silva-93463720;I. Mastorakos
在过去的几年里，以相互连接的韧带网络形式存在的纯金属纳米泡沫在催化剂、电池和光学等领域显示出了巨大的潜力。然而，它们往往很脆弱，因此很难集成到工程应用中。基于这些原因，人们提出了一种新的材料，即由韧带表面涂覆一层金属薄层制成的复合金属纳米泡沫材料。这些纳米泡沫塑料的力学性能取决于它们的相对密度和内部几何结构。在这项工作中，我们结合分子动力学和有限元方法，研究了镍包覆铜韧带纳米泡沫材料的压缩行为。我们还研究了这种行为与其微观结构的关系。为此，我们建立了不同类型的代表性单元结构，并进行了多轴压缩试验的原子模拟，以产生屈服面。然后将生成的屈服面曲线拟合到归一化模型中，得到形状参数。最后，引入塑性模型来研究和比较它们在压缩下的力学行为。结果表明，韧带的涂层可以改善纳米泡沫塑料的力学性能。它们还揭示了微观结构几何在加强这些结构方面的重要性和局限性。这些发现可用于设计具有定制机械性能的金属纳米泡沫。
Pure metal nanofoams in the form of interconnected ligament networks have shown strong potential over the last few years in areas such as catalysts, batteries, and optics. However, they are often fragile and therefore difficult to integrate into engineering applications. For these reasons, a new class of materials, composite metallic nanofoams made of ligaments coated with thin metallic layers, have been proposed to solve these issue. The mechanical properties of these nanofoams depend on their relative density and their internal geometrical structure. In this work, we combine molecular dynamics (MD) and finite element method (FEM) to investigate the compressive behavior of nanofoams made of copper ligaments coated with nickel. We also investigate how this behavior relates to their microstructures. For that purpose, we built different types of representative cell structures, and atomistic simulations of multiaxial compression tests were performed to produce yield surfaces. Then the generated yield surfaces were curve fitted into a normalized model to obtain the shape parameters. Last, a plasticity model was introduced to study and compare their mechanical behavior under compression. The results suggest that the coating of the ligaments can improve the mechanical behavior of the nanofoams. They also reveal the importance and the limitations of the microstructural geometry on the strengthening of these structures. These findings can be used for the design of metallic nanofoams with tailored mechanical properties.