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Non-equilibrium molecular dynamics simulations of spall in single crystal tantalum

2017; American Institute of Physics; Volume: 1793; Linguagem: Inglês

10.1063/1.4971594

1935-0465

Eric N. Hahn, Timothy C. Germann, R. Ravelo, J. E. Hammerberg, Marc A. Meyers,

Metal and Thin Film Mechanics

Ductile tensile failure of tantalum is examined through large scale non-equilibrium molecular dynamics simulations. Several loading schemes including flyer plate impact, decaying shock loading via a frozen piston, and quasi-isentropic (constant strain-rate) expansion are employed to span tensile strain-rates of 108 to 1014 per second. Single crystals of 〈001〉 orientation are specifically evaluated to eliminate grain boundary effects. Heterogeneous void nucleation occurs principally at the intersection of deformation twins in single crystals. At high strain rates, multiple spall events occur throughout the material and voids continue to nucleate until relaxation waves arrive from adjacent events. At ultra-high strain rates, those approaching or exceeding the atomic vibrational frequency, spall strength saturates near the maximum theoretical spall strength.