Study On Fracture Characteristics Of Explosive Bolts Based On Finite Element Method

Since the beginning of the new century,as the rapid development of space exploration technology,the strategic position of satellite increased gradually for each country focusing on space technology.Satellite separation from the rocket technology is one of the key technologies which is directly related to the successful launch of the rocket,the normal entry of the satellite and has an important impact on the overall performance of the satellite and the completion of the space mission.Explosive bolt is commonly used for initiating explosive separation device.It has a lot of advantages,such as light weight,reliable separation,etc.,but the impact of explosive generated by the spacecraft will have an impact on the structure,which may result in the failure of space missions.Therefore,researches about reducing the effect of the initiating explosive separation device on the structure of the spacecraft,increasing the reliability of satellite separation from the rocket,accurately predicting the impact load caused by the bolt explosion process,simulating the environment of the spacecraft and evaluating the separation and unlocking device reliably by adjusting the structure and material characteristics of typical bolts have far-reaching significance for the satellite launch mission.In this paper,the fracture characteristics of explosive bolts are mainly studied.Firstly,this paper introduces the basic equations and numerical methods of large deformation dynamics in detail and explains the classical propagation theory of detonation wave and the state equation describing the detonation product described in the calculation process of the explosive bolt model,which lay the foundation for the model analysis of explosive bolt.Secondly,the detonation performance of explosives and the dynamic mechanical properties of each material were obtained experimentally.And then,the JWL equation was used to determine the state equation of the explosive and the constitutive relation of the material is described by the elastic-plastic model.In addition,the ANSYS / LS-DYNA is used to simulate the explosion process of typical non-polluting bolts,which provides references for finite element modeling in other explicit nonlinear dynamic environments.Thirdly,the software LS-PREPOST is used to analyze the fracture direction,the strength of the "V-shaped" cut of the explosive bolt as well as the load characteristics of the explosion unit and the overall response of the bolt.The obtained equivalent stress,equivalent plastic strain at the cut,the pressure of the explosive unit and the speed as well as acceleration of the bolt housing meet a criterion within the aerospace field.Finally,through independently designing different angles and depth of the incision structure,the explosion impact characteristics of bolt body under various circumstances is analyzed.The optimal fracture structure of the explosive bolt body is obtained by comparing with the explosive impact force and the explosive impulse of the original bolt.The incision angle is 90 ° and the depth of the incision is 0.08 cm.