Shock-induced spall in solid and liquid Cu at extreme strain rates
2009; American Institute of Physics; Volume: 106; Issue: 1 Linguagem: Inglês
10.1063/1.3158062
ISSN1520-8850
AutoresSheng‐Nian Luo, Qi An, Timothy C. Germann, Li-Bo Han,
Tópico(s)Energetic Materials and Combustion
ResumoWe investigate spallation in solid and liquid Cu at high strain rates induced by planar shock loading with classical molecular dynamics. Shock simulations are performed at different initial temperatures and shock stresses but similar strain rates (ε̇∼1010–1011s−1). The anisotropy in spall strength (σsp) is explored for five crystallographic orientations, ⟨100⟩, ⟨110⟩, ⟨111⟩, ⟨114⟩, and ⟨123⟩. For liquid, we examine shock- and release-induced melts as well as premelted Cu. The acoustic method for deducing σsp and ε̇ is a reasonable first-order approximation. The anisotropy in σsp is pronounced for weak shocks and decreases for stronger shocks. Voids are nucleated at defective sites in a solid. For weak solid shocks, spallation occurs without tensile melting; for stronger shocks or if the temperature right before spallation (Tsp) is sufficiently high, spallation may be accompanied or preceded by partial melting. Tsp appears to have a dominant effect on spallation for the narrow range of ε̇ studied here. σsp decreases with increasing Tsp for both solids and liquids, and σsp(Tsp) follows an inverse power law for liquids. The simulated σsp for solid Cu at low Tsp is consistent with the prediction of the power-law relation σsp(ε̇) based on low strain rate experiments.
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