Numerical Simulation And Safety Assessment Of Mixing And Curing Process Of Cast-cured PBX Explosives

Mixing and curing of materials are important steps in the process of Cast-cured PBX explosive charge.The homogeneity of mixing and curing of materials have important influence on the product quality and safety performance of PBX charge.Uneven thermal stress distribution in the curing process will have a negative impact on the curing process safety and charge quality.It is difficult to obtain the safety threshold rule through experiments.Therefore,it is feasible and important to study the safety and charge quality of material mixing and curing process by numerical simulation.In this paper,the blending of PBX slurry was studied by using POLYFLOW software and transient method,aiming to evaluate the uniformity and safety of PBX slurry in the mixing and stirring process by simulation method.Then,based on finite element method,ABAQUS software was used to study the curing process and safety of PBX slurry.Firstly,starting from the five independent parameters of solid and hollow OARS,the parametric modeling of the two OARS was carried out by using the phase Pro/E software.Then,the solid and hollow paddles and mixing kettle in kneading machine were divided into grids by using grid overlapping technology,and the transient simulation of mixed flow field was carried out by the fluid software POLYFLOW.The simulation results show that the temperature,shear rate and pressure are maximized in the meshing part between blade and blade and the part between blade and inner wall.Secondly,the influence of different parameters on the rheological parameters in the mixing process of PBX slurry was studied,including the rotor speed,blade temperature and the temperature of the inner wall of the mixing kettle.The simulation results show that the slurry temperature,pressure and shear rate increase with the increasing of blade speed.By changing the blade temperature or the inner wall temperature of the mixing kettle,the slurry temperature will increase continuously,but the change of the inner wall temperature of the mixing kettle has little effect on the slurry temperature.Thirdly,the influence of blade-blade clearance,blade-wall clearance and blade-bottom clearance on the mixing efficiency of PBX slurry was studied.The results show that the mixing efficiency of PBX slurry is best when the gap between hollow propeller and solid pulp is consistent with the gap between hollow propeller and wall surface and the gap between blade and bottom.Finally,the samples of HMX base PBX explosive with solid content of 88% were prepared.The temperature change during the solidification of PBX explosive was monitored by thermocouple method,and the temperature change curve was obtained.The solidification kinetic parameters of hmx-based PBX explosive were obtained based on the non-uniform temperature difference scanning calorimetry.ABAQUS software was used to simulate the curing process of PBX explosives.Considering the heat release of the curing reaction of PBX explosives,the simulated temperature curve was compared with the measured temperature curve to correct the curing kinetic parameters of hmx-based PBX explosives.The model of the projectile body size was established in ABAQUS software,and the safety and charging quality of the projectile body charging during solidification process were simulated and analyzed by considering the model size of different projectile body and different holding time.The results show that: according to the temperature field and stress field analysis of the projectile body under different holding time,the holding time is 6 days for PBX curing degree and the best safety;With the increase of the size of the projectile body,the temperature difference between the center of the mould and the edge of the mould gradually increases,which will affect the safety and quality of the projectile body during the charging curing process.When the ambient temperature is 40 ℃,50 ℃ and 70 ℃,the time required for full solidification of explosive casting is 12 days,8 days and 4 days respectively.Considering safety factors,the ambient temperature should be 60-70 ℃.