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Micropillar compression testing is essential for understanding bulk metal plasticity at small scales and has emerged as a key technique for evaluating nanoporous metals like nanoporous gold (NPG). To support experimental design, we present a computational plasticity study on single crystal NPG micropillars, systematically examining four extrinsic factors: pillar height-to-diameter ratio ( 1.5 ≤ h / d ≤ 2.5 ), taper angle ( 0 ≤ θ ≤ 4 ∘ ), friction coefficient ( 0.0 ≤ μ ≤ 0.2 ), and misalignment angle ( 0 ≤ α ≤ 2 ∘ ). The study reveals that NPG exhibits similar trends to its bulk counterpart but is less prone to post-yield buckling in unstable crystal orientations. For optimal NPG pillar stability, an aspect ratio of 1.5 ≤ h / d ≤ 2 is recommended and a moderate taper angle ( θ ≈ 2 ∘ ) to prevent artificial stiffening and yielding. Even minimal friction ( μ ≈ 0.05 ) enhances stability, while buckling is mainly governed by misalignment, requiring α ≤ 1 ∘ to also avoid underestimating the elastic modulus.
Fischer et al. (Fri,) studied this question.