Research On The Temperature, Fluctuation And Damage Evolution Of Polymer Bonded Explosives In Launching And Penetrating Environments

PBX explosive is a kind of viscoelastic material with damage.The damage will further expand under the action of external loads in complex and severe environment,which will destroy the structure of explosive and lead to the early initiation of explosive.At present,the safety assessment of the PBX explosives and the design of advanced weapons in the future urgently require us to clarify the damage evolution process and hot spot formation mechanism of the PBX explosives under external loads.In view of the rugged environment in which the polymer-bonded explosive experience in the whole process of projectile launching,flight and penetration,the crack evolution,stress wave propagation and transient response of temperature change of the polymer-bonded explosive in the whole process are studied in this paper.The specific reserch contents and conclusions of this paper are as follows:(1)A method for calculating the transient response of the PBX explosive in the whole process including launch,flight and penetration is presented.Considering the nonlinearity and damage effects of materials,the deformation and inertia fields are discretized by three-dimensional non-linear finite element.The damage evolution of viscoelastic materials with damage is described by Visco-SCRAM model,and the temperature varition is described by macro-temperature volume heating model and micro-friction hot spot model.(2)The correctness of the present model is verified by simulating uniaxial compression test and explosive impact test.The correctness of the hot spot temperature rise model is verified by calculating the temperature rise response of the PBX explosive under given load.The damage response of the PBX explosive under triaxial compression is studied.It is found that the crack radius at both ends of the grain is higher than those of the other parts,and the crack propagation velocity is lower than the stress wave speed.(3)Based on the method presented in this paper,the dynamic response of PBX explosive during the shell motion in bore is studied.The results show that the axial compression of the explosive column occurs during the launching process,and the variation trend of compression deformation is consistent with those of the bottom pressure;under the same conditions,the rifled gun is more likely to cause crack propagation in the PBX explosive than the smoothbore cannon;in this process,the macro volume temperature rise of the PBX explosive and the friction temperature rise of micro-crack surface are very small,and the ignition will not occur.(4)The dynamic response of the PBX explosive in the penetration process of projectile against target plate is analyzed.The results show that rotation of shell can not improve its penetration ability;in this process,the PBX explosive column will undergo axial compression,the compression at the center of the two ends of the column is large,and the axial compression deformation exhibits repeated oscillation;the stress wave propagates faster in the steel shell than the PBX explosive;the shock wave generated by the penetration is the cause of crack propagation,and the crack propagation start attenuating after the projectile penetrates through the target plate;the macro temperature rise of the PBX explosive is affected by strain rate;in this process,the macro temperature rise and friction heat generation are larger than those in the case of prosses of launch,which will not cause the ignition of explosive.