Anupam Neogi

Shock induced phase transition of water: Molecular dynamics investigation

Molecular dynamics simulations were carried out using numerous force potentials to investigate the shock induced phenomenon of pure bulk liquid water. Partial phase transition was observed at single shock velocity of 4.0 km/s without requirement of any external nucleators. Change in thermodynamic variables along with radial distribution function plots and spectral analysis revealed for the first time in the literature, within the context of molecular dynamic simulations, the thermodynamic pathway leading to formation of ice VII from liquid water on shock loading. The study also revealed information for the first time in the literature about the statistical time-frame after passage of shock in which ice VII formation can be observed and variations in degree of crystallinity of the sample over the entire simulation time of 100 ns.

On shock response of nano-void closed/open cell copper material: Non-equilibrium molecular dynamic simulations

Non-equilibrium molecular-dynamic simulations were carried out on model three-dimensional nano-void copper material with different idealised pore structure and porosity to highlight differences in response behaviour between them when subjected to various piston velocities simulating planar shock loading of different intensities. This article demonstrates and explains from a mechanistic perspective the differences in response observed with respect to Hugoniot elastic limits, dislocation line and jet formation, void collapse mechanism and hot spot generation, specific volume, partial recrystallisation and temperature evolution in void collapsed regions, shock and particle velocity curves.

Shock compression of polyvinyl chloride

This study presents shock compression simulation of atactic polyvinyl chloride (PVC) using ab-initio and classical molecular dynamics. The manuscript also identifies the limits of applicability of classical molecular dynamics based shock compression simulation for PVC. The mechanism of bond dissociation under shock loading and its progression is demonstrated in this manuscript using the density functional theory based molecular dynamics simulations. The rate of dissociation of different bonds at different shock velocities is also presented in this manuscript.

A metastable phase of shocked bulk single crystal copper: an atomistic simulation study

Structural phase transformation in bulk single crystal Cu in different orientation under shock loading of different intensities has been investigated in this article. Atomistic simulations, such as, classical molecular dynamics using embedded atom method (EAM) interatomic potential and ab-initio based molecular dynamics simulations, have been carried out to demonstrate FCC-to-BCT phase transformation under shock loading of 〈100〉 oriented bulk single crystal copper. Simulated x-ray diffraction patterns have been utilized to confirm the structural phase transformation before shock-induced melting in Cu(100).

Shock-Induced phase transition of single crystal copper

We have carried out a series of multi-million atoms non-equilibrium molecular dynamics simulations to investigate the effect of crystal orientation over the shock induced plasticity and phase transformation in single crystal copper. Crystallographic orientation of [100], [110] and [111] has been studied for various intensity of shock ranging from 1.0 km/s to 3.0 km/s. During shock wave propagation along and , a FCC-to-BCC phase transformation has been observed to occur behind the shock front at higher intensity of shock. Nucleated body centered phase is identified through common neighbor analysis, polyhedral matching template method, radial distribution function and also from the energetic of the particles.