Elastic and plastic Poisson’s ratios of nanoporous gold

Abstract

a b s t r a c tWe explore the elastic and plastic Poisson's ratios, m E and m P , of nanoporous gold, using digital image correlation during compression experiments including load/unload segments. The two coefficients differ significantly, with m E independent of the ligament size, L, and with a trend for m P / L at not too large L. Disorder in the network of ligaments may explain why m E is smaller than predicted by lattice-based models. Finite element simulations, based on the Deshpande-Fleck constitutive law, validate the data analysis. The constitutive law captures work-hardening and transverse flow of nanoporous gold in good agreement with the experiment.

Scaling laws of nanoporous gold under uniaxial compression: Effects of structural disorder on the solid fraction, elastic Poisson's ratio, Young's modulus and yield strength

“…Experiments on nanoporous gold are usually performed on cubic or cylindrical samples with finite dimensions Lührs et al, 2016;Wang et al, 2015;Wang and Weissmüller, 2013). Taking the previous considerations into account, symmetric boundary conditions are seen as the better representation of the macroscopic geometry and are used for further evaluation.…”

“…In the following section, the extended scaling laws will be applied to experimental data presented in (Lührs et al, 2016) and (Huber et al, 2014). This allows a determination of the parameter A and an estimation of the corresponding yield strength.…”

“…Thus, the absolute value of the Young's modulus depends strongly on the selected relevant strain range. In (Lührs et al, 2016) it was shown that the elastic Poisson's ratio is independent of the ligament size and not sensitive to strain changes which makes its experimental determination considerably more reliable. As shown in the present work, the elastic Poisson's ratio is strongly dependent on structural changes (Fig.…”

On the origin of the anomalous compliance of dealloying-derived nanoporous gold

“…Nanoporous metals, and specifically nanoporous gold (NPG), made by dealloying are emerging as model systems for understanding the mechanical behavior of small-scale solids and of nanomaterials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The materials exhibit a uniform microstructure in the form of a network of nanoscale "ligaments", whose size can be adjusted to values between a few and several hundred nanometers [4].…”

“…Macroscopic samples typically exhibit highly reproducible mechanical behavior. Their excellent deformability under compression enables experiments that provide access to strain-rate sensitivity [10], elastic and plastic Poisson's ratios [13,16], as well as the evolution of flow stress and stiffness during the plastic densification of the network [12,14,17,18]. Of particular relevance is the observation of strong variations of strength as well as stiffness with ligament size [1,2,[6][7][8]10,11,14].…”