In situ 3D characterization of impact-extruded ignition and reaction growth behavior of a ductile energetic material

In this study, the modified split Hopkinson pressure bar (SHPB) system, complemented by synchronized high-speed holography and direct shooting imaging techniques, was employed to investigate the impact-induced mechanical, ignition and reaction growth behavior of high-ductility composite energetic materials (CEMs). The experiments were performed over a large range of strain rate conditions of 3,000–6,000 s⁻¹ for samples containing different components of solid explosive granules. The strain-stress relationships, onset of ignition and reaction growth in impact-induced debris clouds were quantitatively studied. The results show that ignition was a result of compression and deformation, triggered significantly by the effects of shear extrusion friction. The critical strain rate of ignition was approximately 4,000–5,000 s⁻¹. The average particle size inside the debris before and after ignition ranges from 41.3 to 49.5 μm. The particle quantity and size produced by the impact of the CEM increase as the strain rate increases. The sustainability of the ignition, or its rapid quenching, was tightly correlated with the size and density of the impact-induced debris cloud. For high-strain rate impacts, denser debris clouds were produced, which effectively favors the sustaining and propagation of the initial ignition core. The results provide valuable insights for establishing the criteria of the impact induced reaction growth and enhancing the safety and reliability of high-ductility energetic materials used in aerospace and national defense applications.