Studies On Cook-Off Mechanism Of Solid Explosive And 2D Numerical Simulation

The word 'Cook-off' means the premature deflagration or detonation of ammunition caused by the absorption of heat from its environment. The studies of Cook-off event are one of the important aspects in the area of ammunition thermal safety. In the present thesis, the methods of theoretical analysis and numerical simulation are used to study the Cook-off event of energetic materials. The evaluating methods for the thermal safety of weapon or ammunition in complex environment based on numerical simulation of energetic materials are established. The thesis focuses on the Cook-off event of explosives and their parts. The main results of the present study are listed as follows.1) The development in Cook-off researches of energetic materials both at home and aboard is summarized in detail. Cook-off test of energetic materials is one of the important methods to investigate the thermal safety characteristic of energetic materials. In the present, the numerical simulation methods is one of the new focus in the area.2) The 2D numerical simulation model to describe the Cook-off event of the explosives is established. The model is based on Frank-Kamenetskii model, First-Order reaction model and McGuire-Tarver model. The coupling of heat transfer, exothermic reaction and calefaction mechanism of environment is considered in the models. The mathematical basis of the calculation methods is finite element methods (FEM). And generally functions are provided in the FEM program. The data of high temperature ignition experiment is used to validate the models. The result shows that the model and the calculation methods are correct and the calculation result is accorded with the experiment.3) The numerical simulation of RDX Cook-off test is carried out based on the calculation models. Their reaction characteristics, such as the ignition temperature, ignition time and the temperature distributing during the Cook-off test is discussed deeply. Especially, the ignition position inside the explosive part is determined. The factors such as scale of the RDX cylinder, temperature of environment and the heating rate which affect the characteristic of Cook-off event is discussed. The aim at researching into the thermal safety of energetic materials and their parts has been achieved. It is shows that the numerical simulation method to evaluate the thermal safety of energetic materials is practicable.To study the thermal safety of energetic materials and their parts with the method of 2D numerical simulation, characteristics such as the ignition temperature, ignition time and the temperature distributing during the Cook-off test can be obtained more directly. The complex convention of the dimensions of the results is avoided. It is propitious to direct safe manufacture and safe store of energetic materials.