In this study, single hole blasts in jointed and unjointed rock plates were simulated using the distinct element code 3DEC. The key of the simulations was to capture the features of brittle failure. To this end, fictitious joints were integrated into two 3DEC rock blasting models. The Coulomb slip model with a newly defined stiffness was applied to the fictitious joints. Additionally, the concept of equivalent cavity was used to prevent element distortions due to high explosion pressure. The verification of the numerical models was done by comparison with small-scale physical model tests. The simulation results revealed clear evidences of brittle failure of the rock plates, without any element distortion.

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The combustion completeness of Al agglomerates affects the performance of solid rocket motor, reducing the agglomerate sizes is effective to enhance the performance. In this study, agglomeration and combustion characteristics of Al particles near the burning surface of ammonium perchlorate (AP) composite propellants were observed using a pulsed laser system. Moreover, to suppress the agglomerate diameter and use the micro-explosion characteristics of Mg-Al particles, Al was partially replaced with magnesium-aluminum (Mg-Al) alloy Moreover, the relation between the proportion of Mg-Al particles and agglomeration diameter of Al particles was investigated. Measurement results showed that a small amount of Mg-Al mixture successfully reduced the agglomerated Al particle size. Furthermore, the agglomeration process that accumulates on AP particles was observed in the aluminized propellant through burning surface observation. Thus, the addition of Mg-Al particles was confirmed to be effective in suppressing the agglomeration process.

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Energetic salts are promising materials in the field of energetic materials, and numerous azole derivative salts have been explored over the past two decades. In this study, we synthesized and analyzed five 5-methyl-1H-tetrazole (MTZ) salts: perchlorate, nitrate, chloride, guanidinium (GN), and potassium dihydrate. These salts were characterized using single-crystal X-ray diffraction, Fourier-transform infrared spectroscopy, and Raman spectroscopy. Among the five salts, the perchlorate salt exhibited the highest calculated density. We also characterized the salts, along with a previously reported sodium salt for comparison, using sealed-cell differential scanning calorimetry and thermogravimetry-differential thermal analysis. Their corresponding exothermic calorific values were ordered as follows: MTZClO₄ ＞ MTZNO₃ ＞ MTZ ＞ MTZCl＞ MTZK･2H₂O ＞ MTZNa･2H₂O ＞ MTZGN. The mass losses of MTZClO₄ and MTZGN commenced at higher temperatures compared to that of MTZ, whereas those of MTZNO₃ and MTZCl occurred at lower temperatures than that of MTZ.

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