Shock Compression Deformations Studies Across Interface Using Time Resolved Raman Spectroscopy

In applications requiring high velocity interactions of energetic materials, the shock response of the crystal-binder interface is of great importance. We demonstrate a technique for capturing the high localized deformation of the crystal-binder interface using time resolved Raman spectroscopy at nanosecond intervals. A bi-crystal interface of hydroxyl-terminated polybutadiene (HTPB) sandwiched between crystals is used in the method, with the sample as a whole put on a glass surface and impacted from the opposite end. Aluminum cylindrical flyers with thicknesses of 25um and diameters of 1 mm were accelerated utilizing the laser induced projectile impact test (LIPIT) to create high velocity shock compression loads. The velocity of the projectile was determined using heterodyne photon doppler velocimetry (het-PDV) and ranged from 0.5 to 1.5 km/s. Full field measurements of the 532nm Raman spectroscopic response were acquired using an in-house designed laser array configuration with 27 discrete laser subsets. The pressure and temperature distributions over the interface were calculated using the pre-calibrated peak shifts of the crystals. The highly localized deformation generated by pressure and temperature rise as the shock front travels across the interface was measured in-situ by the time resolved Raman spectroscopic response. The results showed a close correlation of the pressure and temperature rise with the shock-induced deformation.