Study of Hugoniot Elastic Limit in Tantalum single crystal using elastic precursor decay at normal and elevated temperature:Molecular Dynamics study

Crystalline solids subjected to extremely high strain rates, as happens in shock wave propagation, is an important branch of material science.Knowledge of HEL is of fundamental importance in shock wave studies.Among BCC metals, Ta has several technological advantages due to its excellent mechanical property and thermodynamic phase stabilty at extreme conditions.This makes it useful in designing high impedence flyers for equation of state studies.

MD simulation of Ta has been performed in an effort to study formation of two-wave structure and its attenuation over distance. This leads to determination of HEL as a function of peak stress and sample thickness in two principle orientations. The work is mainly focused on studying decay of elastic precursor with advancement of shock along sample at normal and elevated temperature.The precursor decay for sub-micron sized sample has been modeled with empirical fitting relation. The fit predicts experimental result and other MD results for above-micron sized sample.This indicates that computationally intensive simulation for longer lengths can be avoided. Also, strong crystal anisotropy effect has been observed in onset of elastic-plastic wave.


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