科研之友
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摘要
Molecular dynamics simulations are performed to study size effects on the impact response of copper nanobeam targets subjected to impacts by copper nanobeam flyers with different impact velocities. It is found that the Hugoniot response is size-dependent, while the aspect ratio - that is, the ratio of flyer and target nanobeam heights - has a small effect. It is also observed that the propagation speed of a disordering front generated at the impact surface is close to the shock wave speed initially, but decreases as dislocations form. The thermal gradient in the target is mainly due to the quasi-temperature difference (transient spatial localization of kinetic energy) between hexagonal-close-packed atoms and face-centered-cubic atoms. The findings for the impact stress, defect evolution, and quasi-temperature could be useful for better understanding the responses of nanosystems to extreme loading conditions.
