Molecular Dynamics Simulation Of Mechanical Properties Of Polymer Bonded Explosive

Along with the rapid development of the modern military technology, the requirements for energy performance and comprehensive performance of energetic materials keep increasing. With the detonation performance of single compound explosive and excellent mechanical properties of novel polymer, polymer bonded explosive(PBX) has been widely used in many fields, such as industry and military. At the same time, as computer science and technology is developing rapidly, using the method of simulation and calculation to study the structure and performance of PBX can provide theoretical guidence for the formulation design of PBX.In this thesis, molecular dynamics simulation was carried out at different temperatures and pressures to study structure and properties of PBX9501 binder, F2311 and F2314. Isothermal compression behavior of the three binder model at 600 K and 700 K were researched, and equations of state being suitable to them were found by fitting pressure-volume-temperature data got from MD simulations. The mechanical properties of the three binders at the temperatures of 295 K and one atmospheric pressure were predicted by using static mechanics method, and compared with each other’s mechanical properties. The effects of temperature and pressure on the mechanical properties of PBX9501 explosive were discussed by using COMPASS force field, and the changes of maximum trigger bond lengths of components were used to analyze the influence of temperature on the sensitivity of the system. The results are as following:1) Using Tait and Sun equations of state to fit the isothermal compression curve of binders, and results show although there are some differences between the two equations of state for different binders, the classical Tait and Sun state equations are suitable for describing isothermal compression behavior of PBX9501 binder, F2311 and F2314.2) The rigidity of PBX9501 binder increases and the elasticity decreases with the increases of pressure. Instead, with the increase in temperature, the rigidity of the material decreases while the flexibility increases. Comparing mechanical properties of the three binders, it can be found that the rigidity of F2314 is the strongest, followed by F2311, and the flexibility and plasticity of PBX9501 binder is the best.3) With the increase of temperature, the rigidity of PBX9501 explosive tends to weaken, while plastic and flexible crescendo. Under external pressure, PBX9501 explosive gradually shows toughness and the toughness is better at high pressure. At the same time, the thermal sensitivity of PBX9501 were studied by using MD method, and it can be found the thermal sensitivity of PBX9501 explosive increases with the increasing of temperature and the maximum trigger bond length increased significantly at 375 K.The results can provide the selection of binder for the formulation design of PBX and the improvement of processing technic of PBX9501 with some theoretical support.