Microstructure effects on shock response of Cu nanofoams

FP Zhao and HA Wu and SN Luo, JOURNAL OF APPLIED PHYSICS, 114, 073501 (2013).

DOI: 10.1063/1.4818487

Microstructure effects on shock response of Cu nanofoams are investigated with molecular dynamics simulations, including elastic- plastic deformation, Hugoniot states, void collapse, nanojetting, and vaporization. The microstructure features examined include pore shape, arrangement and size, as well as grain boundaries. The elastic-plastic transition, void collapse, and jetting including vaporization, are dependent on the microstructure, although to different extents. The void arrangement and aspect ratio play an important role. The effects of grain boundaries and void size are less pronounced. Considering the measurement scatter inherent for porous materials, the high pressure Hugoniot states are not sensitive to microstructure. Jetting during void collapse is due to tensorial velocity gradients (direction and amplitude), and a combined result of forward, divergent, and convergent flows with varying contributions; this mechanism and related processes are common for different microstructures. Free surface jetting involves necking and cavitation. Elliptical voids with large aspect ratios, and with their centers aligned linearly with the shock direction, are particularly efficient in inducing high speed jetting and vaporization. (C) 2013 AIP Publishing LLC.

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