Study On The Accelerated Aging And Failure Mechanism Of A Compound Explosive

Compound explosives are widely used in the national defense weapon system because of their excellent comprehensive performance.However,during the long-terrm storage process,the aging problems such as performance degradation or failure will occur when affected by environmental factors.Therefore,the study of the aging of such explosives is of great reference value for the research on the safe storage life of the weapon system.Based on the safety storage life of compound explosives,molecular dynamics(MD)simulation and experimental analysis were used to study their performance changing rule and failure mechanism during accelerated aging.The main contents of the paper are as follows:First of all,canonicalensemble ensemble(NVT)and COMPASS force field method were used at different temperatures(245 K?445 K)to simulate the performance of RDX based composite system.The influence of temperatures on the mechanical properties of N-NO2 and cohesive energy density(CED)and binding energy were analyzed.The result showed that with the increase of temperature,toughness of the system decreased,the sensitivity increased,and the thermal stability decreased gradually.Secondly,taking a compound explosive as the research object,the accelerated aging test under the conditions of different storage temperature and time was carried out.The changing law of its performance in quality,volume,mechanical properties and mechanic sensitivity etc.were simultaneously analyzed.The result showed that with the increase of time and temperature,the grain quality decreased gradually,the volume gradually expanded at first and then contracted,but the change rate both less than 1%;Besides,the explosive strength improved in varying degrees after aging,but toughness of charge decreased;It was also noticed that the impact sensitivity decreased,so did the overall friction sensitivity,but little rebound occurred at 80 ?,it's different from the result of MD,because MD didn't considered the effect of wax on composite system.Basing on mastering the changes of explosive performance,Thermal Infrared Spectroscopy(TG),Fourier Transform Infrared Spectroscopy(FTIR)and X-ray Photoelectron Spectroscopy(XPS)were used to study the failure mechanism of modern analytical technology of explosives.The results showed that in the accelerated aging process the failure mechanism was mainly caused by the heat loss of wax,volatilization of water along with low molecular weight components in BR,and the weight loss rate was more than 1%of the MIL-STD-1751;What's more,BR oxidative cross-linking led to BR hard brittle,resulting in explosive increase,rigid viscoelastic variation and the failure of broken charged after aging;Besides,oxidative cross-linking of BR and softing of wax were insensitive to mechanic sensitivity,but during the later stage of aging at 80 ? the increase of wax heat loss and BR hardness after aging make the friction between particles went up,resulting in the increase of friction sensitivity.Then failure of explosives occurred due to the reduction of safety performance.Finally,taking the weightlessness rate of the column as a failure criterion,the Arrhenius model was chosen to predict the safe storage life of the compound explosive.The storage life of the explosive at room temperature of 20 degrees was calculated to be 15.3 years,which provided a certain reference value for the research of aging and storage life of weapons and ammunition.