Study On Fracture Dynamics Of Granular System

The problem of launch safety of propellant charge has become a big puzzle, which was greatly concerned by weapon experts all over the world for many years. Since compression fracture of propellant charge under corresponding charge configuration is the radical reason of bore burst caused by propellant charge, how to exactly describe the fracture rule of propellant charge at projectile base under compression stress, has become the key problem in the research field of launch safety of propellant charge. This paper based on the project of launch safety, tried to study the international puzzle of compression fracture dynamics of propellant charge, establishing the sumilation system for compression fracture dynamics of propellant charge, which could provide theory foundation and testing method for effectively evaluating launch safety of propellant charge. The main contents are as follows:1 The computing efficiency for the dynamics simulation of granular system was improved by using neighbor list searching arithmetics and contact detection methods, which made the simulation for large movement and compression fracture of granulaer system constituting of lots of propellant grains become likelihood. The dynamics of accumulation, contact and collision of granulaer system were simulated for the granular system as propellant charge, which provided theoretical basis for simulating compression fracture dynamics of propellant charge.2 Based on discrete element method, propellant grains were divided into spring-spheres fractutre model, the theoretic expression for spring constants in discrete model of propellant grains were obtained, and the dynamics behavior of fracture of propellant grians impacting rigid boundary with different initial azimuths was simulated. The simulation system for fracture dynamics of granulaer system was established.3 The fracture dynamics for granular system of propellant charge was tested by the physical simulation device, the fracture test and initial dynamic vivacity ratio experiment were taken respectively for nitrocellulose propellant and nitramine propellant, and the surface area of fractured propellant grains was acquired by these steps.4 The compression fracture dynamics behavior of nitrocellulose propellant charge and nitroamince propellant charge were simulated under different conditions. For the application example of the method, the dynamics as packing, collision, large motion and compression fracture of propellant bed in chamber of 100mm smooth-bore gun were simulated, and the increment surface areas of fractured propellant bed were acquired, which provided theoretic foundation for the research of launch safety of propellant charge.