Examination of the Mesoscopic Scale Response of Shock Compressed HeterogeneousMaterials Using a Line-Imaging Velocity Interferometer

摘要

In order to provide detailed response data for validation of three dimensionalnumerical simulations of heterogeneous materials subjected to impact loading, an optically recording velocity interferometer system (ORVIS) has been adapted to a lime-imaging instrument capable of generating precise mesoscopic scale measurements of spatially resolved velocity variations during dynamic deformation. While the use of this diagnostic has been demonstrated on several different classes of heterogeneous materials, studies have focused on pressed granular sugar as a stimulant material for the widely used explosive HMX. Tests on this material address mesoscopic scale thermomechanical effects in the absence of complications due to rapid reactions. For low-density (65 percent theoretical maximum density) pressings of sugar, material response has been investigated as a function of both impact velocity and changes in particle size distribution. The amplitude and frequency of observed transverse and longitudinal wave structures are generally consistent with the highly structured mesoscopic response seen in the 3-D simulations. In parallel with instrumental developments, several approaches for detailed analysis of the spatially resolved velocity-time data are being evaluated. The utility of Fast Fourier Transform (ITT) filtering for reduction of certain types of ORVIS image data has been demonstrated.