Investigating the dynamic response of heterogeneous mixtures with variable geometric complexity

The dynamic response of an energetic surrogate mixture of sugar and Polydimethylsiloxane (PDMS), subjected to uniaxial loading, has been investigated. Of particular interest in this investigation were the fluctuations observed at the Hugoniot states of heterogenous mixtures. This research seeks to better understand what portion of these fluctuations can be attributed to the simple mechanical response of the meso-structure of the mixture. The approach was to build samples with increasing complexity, experimentally load them and simulate them, so that direct comparisons can be made. Samples were fabricated with either a single sugar cube embedded within the binder, or two sugar cubes separated by varying distances embedded within the binder material. After samples were built, the 3D geometry was obtained using XCT scans. PDV probes were focused on specified locations within the heterogeneous mixture so that a more direct comparison between experiments and simulations could be obtained. Experiments were performed in a one-dimensional plane strain configuration with shot velocities ranging between 79 m/s and 573 m/s. Numerical simulations were performed utilizing the three-dimensional Eulerian hydrocode (CTH). The results indicate a systematic response signature superimposed on the Hugoniot plateau which is correlated to the geometry. In order to fully realize the particle velocity traces captured by the PDV it was necessary in some instances to include air bubbles.