Study On Explosive Dynamics Of Energetic Materials Based On Finite Volume Method

The study of explosive dynamics is an important foundation of military science and is of great significance to the development of military field.Due to the complexity of explosive dynamics,it is difficult to carry out theoretical and experimental research.With the rapid development of computer,numerical simulation technology has become an important means to study explosive dynamics.Therefore,the study of numerical simulation method for explosive dynamics of energetic materials is of great significance for the study of computational explosive dynamics and the safety analysis of energetic materials.Firstly,based on the basic theory of the finite volume method,the basic principle of the application of finite volume method in solid mechanics is studied.The control equation of the finite volume method is analyzed and the discrete equation of the control equation is obtained.The coupling calculation process of energy conservation equation and state equation is analyzed,the updating algorithm of energy and stress is given.The computer program flow chart of finite volume method is drawn,By solving the structural dynamics problem,the results of finite volume method and finite element method are compared,the accuracy of finite volume method is verified.Secondly,the constitutive model of energetic materials is studied.The basic theory of the generalized viscoelastic statistical crack model is analyzed,the application scope and advantages of the model are discussed,and the basic solving process of the generalized viscoelastic statistical crack constitutive model is explored.Based on the finite volume method and the generalized viscoelastic statistical crack model,a computer program is developed to solve the dynamic response of energetic materials,the computer program flow chart is drawn.Based on generalized viscoelastic statistical crack model,combined with JWL equation of state,the change rule of internal stress and temperature of PBX9501 explosive under simulated bottom pressure is studied,and the time history curves of internal temperature and stress are drawn.When other conditions remain unchanged,the pressure load applied on the bottom of the explosive increases continuously,the variations of temperature and pressure at the bottom of the explosive model are analyzed,the ignition condition of the explosive is discussed,the critical pressure load of the ignition of the explosive is determined,the ignition temperature of the explosive model is analyzed,and the ignition temperature of PBX9501 explosive under this loading condition is preliminarily estimated.Based on the above research,the combustion process of explosive is studied.The mixed criteria of equation of state in combustion and equation of state in combustion are given.The whole process of decomposition reaction,ignition reaction and combustion reaction of explosive model under load is studied,the computer program is programmed and the flow chart of the computer program is drawn.The combustion reaction process of PBX9501 explosive under low amplitude and wide pulse loading is calculated,the variation of temperature and stress of the explosive is obtained in the combustion stage,the time-history curves of temperature and stress of the explosive are drawn,the temperature and stress nephogram of the explosive at different time are output.At the same time,the combustion reaction process of PBX9501 explosive under low amplitude and narrow pulse loading is calculated,the variation of internal temperature and stress of explosive during combustion is discussed.Considering that the air in the bottom gap may cause the chamber explosion or early explosion because of the existence of the bottom gap in the launching environment,the influence of the air compression in the bottom gap on the internal temperature and stress of the explosive is analyzed.The influence of different initial temperature on the internal temperature and stress of PBX9501 explosive is discussed.Based on the theory of adiabatic compression of air,the proportional relationship between the amount of air compression in the bottom gap and the temperature rise in the bottom of the explosive model is analyzed quantitatively,and the minimum amount of bottom gap compression that causes the ignition of the explosive is estimated.