Shock Initiation Experiment and Modelling of a HMX‐Based Insensitive Pressed Explosive

ABSTRACT To investigate the shock initiation characteristics of an insensitive pressed explosive, a one‐dimensional Lagrangian shock initiation experiment was conducted. The pressure histories of the cyclotetramethylenetetranitramine‐based insensitive explosive JOL‐3 under different loading pressures were obtained. The parameters of the shock initiation reactive flow models for JOL‐3 were calibrated, including the equations of state for the unreacted explosive and detonation products, as well as the reaction rate models. The accuracy of the calibrated Lee‐Tarver and Scaled Unified Reactive Front (SURF) reaction rate model parameters was verified. Effects of the loading pressure amplitude and pulse duration on the shock initiation behavior of JOL‐3 were systematically analyzed. The results show that the calculated run distances to detonation, as well as the shock arrival times at various Lagrangian positions, are in good agreement with the experimental measurements, validating the accuracy of the calibrated reaction rate model parameters. With increasing loading pressure, the detonation growth rate within the explosive is accelerated. Meanwhile, the accumulation of hotspot‐driven chemical reactions behind the shock front further enhances both the shock front propagation velocity and the chemical reaction rate. In addition, the developed SURF reaction rate model is capable of effectively describing the shock initiation processes induced by flyer plates of different thicknesses. Under identical incident pressures, increasing the loading pulse duration leads to significant reductions in both the run distance to detonation and the time to detonation. These findings provide valuable insights for understanding the shock initiation mechanisms of pressed explosives under a range of loading conditions.