Reaction Evolution Characteristics of Ignited DNAN-Based Explosive Charges with Pre-cracks

To investigate the influence of cracks and gaps on the reaction evolution characteristics of aluminum-containing DNAN-based explosives after the formation of mechanical induced hotspots, explosive charge samples with different initial cracks were fabricated. An explosive impact ignition device based on gun propellant combustion loading was designed. The evolution process following the ignition of explosives was simulated. Pressure changes and post-test morphological features of the explosives were recorded. Numerical simulations were conducted to analyze the stress field and reaction distribution of explosive charges with different initial cracks under the same loading conditions. The results indicate that the crack-free and single-line crack explosive charge with no gap debris remained intact, and pressure dropped rapidly after the peak with no reaction occurred, and the hot spot region was located at the bottom. While for the single-line crack explosive charge with 1mm gap, the explosive charge fractured and exhibited local low-order reactions, with a slow pressure decay process. Among these, the hot spot region of the single-line crack explosive shifted to the side surface, while the cross-line crack explosive formed dual hot spot regions on both the side surface and bottom, further enhancing the reaction intensity. This demonstrates that pre-cracks significantly influence the explosive reaction process by altering stress distribution and expanding hot spot regions.