A Multiscale Approach to Predict the Mechanical Properties of Copper Nanofoams
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.56
A Multiscale Approach to Predict the Mechanical Properties of Copper Nanofoams Hang Ke, Andres Garcia Jimenez, Ioannis Mastorakos Department of Mechanical and Aeronautical Engineering, Clarkson University, Potsdam, NY 13699, US
ABSTRACT
Pure metallic nanofoams in the form of interconnected networks have shown strong potentials over the past few years in areas such as catalysts, batteries and plasmonics. However, they are often fragile and difficult to integrate in engineering applications. In order to better understand their deformation mechanisms, a multiscale approach is required to simulate the mechanical behavior of the nanofoams, although these materials will operate at the macroscale, they will still be maintaining an atomistic ordering. Hence, in this work we combine molecular dynamics (MD) and finite element analysis (FEA) to study the mechanical behavior of copper (Cu) nanofoams. Molecular dynamics simulations were performed to study the yield surface of a representative cell structure. The nanofoam structure has been generated by spinodal decomposition of binary alloy using an atomistic approach. Then, the information obtained from the molecular dynamics simulations in the form of yield function is transferred to the finite element model to study the macroscopic behavior of the Cu nanofoams. The simulated mechanical behavior of Cu nanofoams is in good agreement of the real experiment results.
INTRODUCTION Metallic nanofoams made of materials such as copper (Cu), nickel (Ni), gold (Au) and platinum (Pt) have the potential to present clear advantages in a broad spectrum of low-density and high surface area applications. Their excellent surface to volume ratios make them great choice for catalysts [1], sensors [2], actuators [3], fuel cells [4] and plasmonics [5]. Despite such advantages, metallic nanofoams exhibit brittle behavior macroscopically due to plastic deformation in individual ligaments. In pure metallic nanofoams, the ligament strength does approach the theoretical strength, but there is almost no ability to strain harden, and hence local geometry fluctuations leads to premature macroscopic failure. This lack of macroscopic strength is one of the limiting factors in broadly applying metallic nanofoams. Overall, the mechanical behavior of a metallic
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nanofoam is determined by the relationship between the behavior of the ligaments of which this material is formed and the geometry of the ligaments. For the past few years, large amounts of effort have been devoted to study the mechanical properties of metallic nanofoams. The Gibson and Ashby model [6] has been widely used for theoretical studies of nanofoams to estimate the yield strength, the elastic modulus and ultimate tensile strength.
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