To address the short comings of the Lee-Tarver ignition and growth reaction rate equation, which comprises numerous parameters (15) and is difficult to calibrate, semi-periodic trigonometric functions were introduced to optimize the model. The new reaction rate equation enhances the continuity of the ignition term, restricts the maximum value of the shape factors for the growth and completion terms to 1, mitigates the parameter compensation between the proportional coefficients and the shape factors, eliminates the reaction degree limit of the trinomial structure, reduces the number of parameters in the reaction rate equation to 10, thereby improving parameter calibration efficiency. Based on LS-DYNA, a secondary development was conducted for the improved ignition and growth model. Comparative calculations were performed to assess the shock initiation simulation results from the Lee-Tarver model and the optimized model, revealing highly consistent results for the internal pressure and reaction degree of the explosive, validating the correctness of the model development. Utilizing test data from explosive-driven metal plates, the parameters of the optimized ignition and growth model were calibrated with LS-OPT, and the sensitivity of the rate equation parameters was statistically analyzed to identify key parameters, providing a reference for further improving parameter calibration efficiency. Comparisons between test and simulated results of explosive-driven metal plates showed a simulation error of less than 3%, confirming the engineering validity of the calibrated parameters. Applying the improved ignition and growth model with safety experiments, the impact initiation response characteristics of ammunition under bullet/fragment impact were investigated. Within 66 μs after bullet impact, the peak internal pressure of the explosive reached 14.5 GPa (48.3% of the detonation pressure), indicating no detonation reaction occurred. Under fragment impact conditions, the peak internal pressure of the explosive was only 0.79 GPa, with the reaction degree near the impact point being higher than in other regions, but the maximum reaction degree was merely 0.01, confirming no detonation. The simulation results of the optimized model exhibited good consistency with test results, validating the engineering applicability of the optimized and developed ignition and growth model.

To investigate the effect of boron nitride (BN) content on the explosion performance of on-site mixed emulsion explosives, the microstructure of BN-containing on-site mixed emulsion explosives were characterized by transmission electron microscopy and optical microscopy, and the thermal sensitivity, shock wave parameters, detonation velocity, and brisance of explosives were measured through steel plate tests, air explosion tests, the probe method, and lead cylinder compression tests. Combined with theoretical calculations, the influence of BN content on the microstructure, thermal sensitivity, and explosion performance of explosives was systematically studied. The test results indicate that the addition of BN does not significantly affect the stability of the internal phase droplets. At 240 ℃, the explosion delay time of the explosive samples increased from 114.28 s (blank sample) to 173.95 s (1.2% h-BN). As the mass fraction of BN increased from 0 to 1.6%, the detonation velocity, brisance, peak overpressure and specific impulse exhibited a trend of increase followed by decrease. The detonation velocity increased from 3850.45 m/s to 4724.89 m/s, and then decreased to 3903.20 m/s, with a maximum increase of 22.71%; the brisance first increased from 13.86 mm to 19.87 mm, and then decreased to 17.18 mm, with a maximum increase of 43.36%; the peak overpressure increased from 136.44 kPa to 318.33 kPa, and then decreased to 285.41 kPa, with a maximum increase of 133.31%; the specific impulse increased from 9.23 Pa·s to 33.98 Pa·s, and then decreased to 31.99 Pa·s, with a maximum increase of 268.15%. The study demonstrates that the incorporation of an appropriate amount of BN can significantly enhance the explosion performance of site-mixed emulsion explosives.

Porous ammonium nitrate is frequently used for specific applications due to its porous structure when compared with conventional ammonium nitrate, however, its higher transportation costs increase overall operational expenses. This study investigated the preparation of porous granular modified ammonium nitrate using ionic surfactant PST as an additive via spray granulation. The effects of varying PST concentrations (0−0.4%) on the pore structure, oil absorption capacity, thermal stability, and explosive properties of ammonium nitrate were examined. The research results indicate that increasing PST content gradually transforms dense ammonium nitrate particles into a porous structure with distinct interconnected pores. Thermal stability remains essentially unchanged, and the matrix chemical composition undergoes no fundamental alteration, though its adsorbed water content decreases. The modified samples exhibit enhanced binding capacity with the oil phase. The detonation velocity of the assembled charge increases from “failed to detonate normally” in the unmodified state to 2831.85 m/s. Trace amounts of PST can induce the formation of a porous structure in ammonium nitrate without significantly compromising thermal safety, while markedly improving detonation velocity performance, demonstrating potential for engineering applications.

Micro-jetting and micro-spallation at metal interfaces under intense shock loading play pivotal roles in applications such as inertial confinement fusion (ICF). These phenomena exhibit inherent complexity due to their multi-scale dynamics, strong nonlinearity, and coupled multi-field interactions. Under extreme irradiation conditions, the formation of high-pressure nanoscale helium bubbles significantly alters interface failure mechanisms. Using molecular dynamics methods, we investigate micro-jet growth and damage evolution in helium-containing copper subjected to double supported shock loadings. Helium bubbles demonstrate lower critical activation stress thresholds for expansion compared to void nucleation, with these thresholds being dependent on bubble distribution and number density. Under low-pressure primary shocks, helium-containing metals produce more pronounced micro-jets than pure metals. During secondary shocks, helium bubbles promote jet fragmentation, resulting in higher maximum velocities at micro-jet tips while maintaining comparable velocity distributions in micro-jet bodies. Secondary shocks show negligible effects on bulk helium bubbles that were previously compressed by initial shocks and partially rebounded due to rarefaction waves without complete recovery. Near-surface ruptured bubble walls may reattach to bubble bases after secondary shocks, temporarily re-trapping helium atoms that are subsequently released during unloading-induced re-expansion and rupture. The collapse mechanism of helium bubbles under secondary shock is closely related to the helium bubbles size and the strength of secondary shock. This study establishes fundamental physical understanding and provides a theoretical foundation for future cross-scale investigations of coupled micro-jetting and micro-spallation evolution in irradiated helium-containing metals.

By combining first-principles calculations under the framework of density functional theory (DFT) and the CALYPSO crystal structure prediction method, the structural stability of the inert element helium (He) and alkaline-earth metals under high-pressure conditions has been systematically investigated. The calculations reveal that among the alkaline-earth metals, strontium (Sr) forms compounds with He exhibiting relatively low energy values. Consequently, the crystal structure of Sr₂He at 400 GPa was predicted. Electron localization function (ELF) and density of states (DOS) analyses show no tendency for covalent bond formation between Sr and He atoms. Furthermore, Bader charge analysis reveals ionic bonding between Sr and He atoms, with charge transfer occurring from He to Sr. These results provide key insights into the bonding mechanism of Sr₂He. This study elucidates the crystal structure, bonding nature, and electronic properties of Sr₂He, offering theoretical support for understanding the stability and physical properties of such metastable materials and providing important guidance for their experimental synthesis.