典型压装与浇注PBX炸药缝隙挤压损伤-点火响应

When polymer-bonded explosives (PBX) charges are rapidly extruded in a crack in the warhead's case, it's required to accurately predict unexpected ignition of cased PBX for safety reasons. Using the combined microcrack and microvoid model (CMM), damage-ignition responses of crack-extruded PBX are investigated in three aspects: (i) interactions between crack and extruded PBX; (ii) mechanical-thermal-chemical responses of PBX at the macroscale; and (iii) underlying mechanisms of damage-ignition at the mesoscale. Meanwhile, the difference between two typical PBXs (pressed PBX-5 and casted GOFL-5) in response to crack-extruded loading is compared. The results show that, under 200 m•s^-1 extruded velocity, pressed PBX-5 exhibits brittle failure (extruded 3 mm at 60 μs) and shows a stress concentration near the crack; microcrack shows a rapid growth along the 45° angle with the extruded surface. In contrast, under the same extruded condition, casted GOFL-5 exhibits a rapid flow rate near the crack; large quantities of material are extruded (extruded 9 mm at 60 μs). Both pressed and casted PBXs show an ignition near the crack. Shear-crack hotspot is the dominated ignition mechanism for PBX-5, while locally plastic dissipation is a possible dominated ignition mechanism for GOFL-5.