Meso-Simulation Of Compression Breakage And Temperature Rise Ignition Of Heterogeneous Explosives

Heterogeneous explosives are high-energy mixed explosives,which are usually composed of simple explosives and additives,they are widely used in civil,national defense,weapons and aerospace fields.Micro-structural defects(such as cracks and holes)produced in the process of preparation,charging and transportation of heterogeneous explosives not only reduce the impact sensitivity of explosives,but also lead to local energy accumulation and hot spots in explosives,which lead to ignition and pose a great threat to the safe use of explosives.In this paper,the lattice-spring model,which can accurately simulate the impact deformation and crack initiation and propagation of brittle materials,is used as the calculation method to simulate the impact crushing and fracture,particle movement,crack propagation and compression deformation of heterogeneous explosives after being input by external shock waves.The energy generated by friction between lattice points is used as the heat source,with the severe impact deformation and fracture friction of explosives,the heat is accumulated locally in explosives,and finally the thermal decomposition reaction of explosive particles is initiated,and the exothermic process of explosives is described by Arrhenius reaction equation.In this paper,a numerical simulation of the Steven impact test used to evaluate the safety performance of explosives is carried out,and the mechanical response and hot spot formation rules of explosives were obtained,which were similar to the experimental results,and verified the reliability of the calculation model in this paper.The impact tests of round warhead,flat warhead and needle warhead are simulated,the results show that the hot spots of round warhead and needle warhead are similar in distribution,and concentrate in the area below the impact center,while the hot spots of flat head impact are distributed in the area below the edge of warhead.The process of hole collapse and temperature rise of HMX crystal with holes under impact loading is simulated,the shapes of holes in the model are round and triangular.The results show that the size,position and shape of the hole all affect the temperature rise effect during the collapse process.As the radius of the circular hole increases,the temperature rise effect becomes more and more obvious;The farther the hole is from the input position of shock wave,the less likely it is to cause obvious temperature rise.During the collapse of the regular triangle hole,the hot spots are concentrated at each vertex,and the orientation of the regular triangle hole also affects the temperature rise in the simulation.Numerical simulation of shock loading on PBX explosives shows that the existence of holes makes the heterogeneous explosives present an "elastic-plastic" response,and the shock wave is broadened into a double-wave structure of "elastic wave-deformation wave";local high temperature appears in the hole In the area of internal and shear cracks,the porosity increases and the probability of hot spots increases.