Molecular-level Simulations of Shock Generation and Propagation in Polyurea
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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A non-equilibrium molecular dynamics method is employed in order to study various phenomena accompanying the generation and propagation of shock waves in polyurea a micro-phase segregated elastomer. Several recent studies reported in the literature suggested that polyurea has a relatively high potential for mitigation of the effects associated with blast and ballistic impact. This behavior of polyurea is believed to be closely related to its micro-phase segregated microstructure consisting of the so-called hard domains and a soft matrix and to different phenomenaprocesses e.g. inelastic-deformation and energy-dissipation taking place at, or in the vicinity of, the shock front. The findings obtained in the present analysis are used to help elucidate the molecular-level character of these phenomenaprocesses. In addition, the analysis yielded the shock Hugoniot i.e. a set of axial stress vs. densityspecific-volume vs. internal energy vs. particle velocity vs. temperature vs. shock speed material states obtained in polyurea after the passage of a shock wave. The availability of a shock Hugoniot is critical for construction of a high deformation-rate, large-strain, high pressure material models which can be used within a continuum-level computational analysis to capture the response of a polyurea-based macroscopic structure e.g. blast-protection helmet suspension pads to blastballistic impact loading.
- Atomic and Molecular Physics and Spectroscopy