Five polymer bonded explosives(PBXs)with the base explosive epsilon-CL-20(hexanitrohexaazaisowurtzi-tane),the most important high energy density compound(HEDC),and five polymer binders(Estane 5703,GAP,HTPB,PEG,and F_(...Five polymer bonded explosives(PBXs)with the base explosive epsilon-CL-20(hexanitrohexaazaisowurtzi-tane),the most important high energy density compound(HEDC),and five polymer binders(Estane 5703,GAP,HTPB,PEG,and F_(2314))were constructed.Molecular dynamics(MD)method was employed to investigate their binding energies(E_(bind))< compatibility,safety,mechanical properties,and energetic properties.The information and rules were reported for choosing better binders and guiding formulation design of high energy density material(HEDM).According to the calculated binding energies,the ordering of compatibility and stability of the five PBXs was predicted as epsilon-CL-20/PEG < epsilon-CL-20/ Estane5703 ≈ epsilon-CL-20/GAP < epsilon-CL-20/HTPB < epsilon-CL-20/F_(2314).By pair correlation function g(r)analyses,hydrogen bonds and vdw are found to be the main interactions between the two components.The elasticity and isotropy of PBXs based epsilon-CL-20 can be obviously improved more than pure epsilon-CL-20 crystal.It is not by changing the molecular structures of epsilon-CL-20 for each binder to affect the sensitivity.The safety and energetic properties of these PBXs are mainly influenced by the thermal capability(C_p^(deg))and density(p)of binders,respectively.展开更多
In this paper,a primary model is established for MD(molecular dynamics) simulation for the PBXs(polymer-bonded explosives) with RDX(cyclotrimethylene trinitramine) as base explosive and PS as polymer binder.A series o...In this paper,a primary model is established for MD(molecular dynamics) simulation for the PBXs(polymer-bonded explosives) with RDX(cyclotrimethylene trinitramine) as base explosive and PS as polymer binder.A series of results from the MD simulation are compared between two PBX models,which are represented by PBX1 and PBX2,respectively,including one PS molecular chain having 46 repeating units and two PS molecular chains with each having 23 repeating units.It has been found that their structural,interaction energy and mechanical properties are basically consistent between the two models.A systematic MD study for the PBX2 is performed under NPT conditions at five different temperatures,i.e.,195 K,245 K,295 K,345 K,and 395 K.We have found that with the temperature increase,the maximum bond length(L max) of RDX N N trigger bond increases,and the interaction energy(E N-N) between two N atoms of the N-N trigger bond and the cohesive energy density(CED) decrease.These phenomena agree with the experimental fact that the PBX becomes more sensitive as the temperature increases.Therefore,we propose to use the maximum bond length L max of the trigger bond of the easily decomposed and exploded component and the interaction energy E N-N of the two relevant atoms as theoretical criteria to judge or predict the relative degree of heat and impact sensitivity for the energetic composites such as PBXs and solid propellants.展开更多
The mesoscopic structures of β-HMX （octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine）- based PBXs （polymer bonded explosives） at room temperature were investigated using dissipative particle dynamics method. The ...The mesoscopic structures of β-HMX （octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine）- based PBXs （polymer bonded explosives） at room temperature were investigated using dissipative particle dynamics method. The parameters and repulsive parameters of dif- ferent polymers and β-HMX, the mesoscopic structures of β-HMX-based polymer-bonded explosives at different temperatures have been studied. The results showed that the compat-ibility between β-HMX and vinylidenedifluoride （VDF）,β-HMX and chlorotrifluoroethylene （CTFE）, VDF and CTFE increased with increasing temperature. The temperature and mo-lar ratio of the polymers played an important role in wrapped process. And there exists the optimum temperature and molar ratio.展开更多
A thorough understanding of drop-weight impacted responses for polymer-bonded explosives(PBXs)is significant to evaluate their impact sensitivity.The characteristics of the drop-weight impacted pressed PBXs including ...A thorough understanding of drop-weight impacted responses for polymer-bonded explosives(PBXs)is significant to evaluate their impact sensitivity.The characteristics of the drop-weight impacted pressed PBXs including deforming,fracturing,forming a local high-temperature region and igniting,were simulated using a coupled mechanical-thermo-chemical model integrating micro-defects evolution.A novel evaluation method for impact sensitivity is established using the relation between the input kinetic energy and the output energy due to deformation,crushing energy,local hot spot energy and ignition.The effects of impact velocity on sensitivity were analyzed and the critical local ignition impact velocity is determined as 4.0-4.5 m/s.The simulated results show that shear-crack friction heating is the dominant ignition mechanism.The region along the boundary of PBXs sample is the most hazardous regions where ignition first occur.The propagation of stress wave in PBXs causes shear-crack hotspot and bulk temperature exhibiting an approximate 45°direction evolution path,which is the main reason that dominated damage-ignition region transits from the boundary to the central of sample.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 10176012)the Important Foundation of China Academy of Engineering Physics (CAEP, 2004Z0503) and 973 Program of China
文摘Five polymer bonded explosives(PBXs)with the base explosive epsilon-CL-20(hexanitrohexaazaisowurtzi-tane),the most important high energy density compound(HEDC),and five polymer binders(Estane 5703,GAP,HTPB,PEG,and F_(2314))were constructed.Molecular dynamics(MD)method was employed to investigate their binding energies(E_(bind))< compatibility,safety,mechanical properties,and energetic properties.The information and rules were reported for choosing better binders and guiding formulation design of high energy density material(HEDM).According to the calculated binding energies,the ordering of compatibility and stability of the five PBXs was predicted as epsilon-CL-20/PEG < epsilon-CL-20/ Estane5703 ≈ epsilon-CL-20/GAP < epsilon-CL-20/HTPB < epsilon-CL-20/F_(2314).By pair correlation function g(r)analyses,hydrogen bonds and vdw are found to be the main interactions between the two components.The elasticity and isotropy of PBXs based epsilon-CL-20 can be obviously improved more than pure epsilon-CL-20 crystal.It is not by changing the molecular structures of epsilon-CL-20 for each binder to affect the sensitivity.The safety and energetic properties of these PBXs are mainly influenced by the thermal capability(C_p^(deg))and density(p)of binders,respectively.
基金supported by the National Key Laboratory of Shock Wave and Detonation Physics,Institute of Fluid Physics,China Academy of Engineering Physics(076100-1197F)the Defence Industrial Technology Development Program(B1520110002)the State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology(KFJJ09-5)
文摘In this paper,a primary model is established for MD(molecular dynamics) simulation for the PBXs(polymer-bonded explosives) with RDX(cyclotrimethylene trinitramine) as base explosive and PS as polymer binder.A series of results from the MD simulation are compared between two PBX models,which are represented by PBX1 and PBX2,respectively,including one PS molecular chain having 46 repeating units and two PS molecular chains with each having 23 repeating units.It has been found that their structural,interaction energy and mechanical properties are basically consistent between the two models.A systematic MD study for the PBX2 is performed under NPT conditions at five different temperatures,i.e.,195 K,245 K,295 K,345 K,and 395 K.We have found that with the temperature increase,the maximum bond length(L max) of RDX N N trigger bond increases,and the interaction energy(E N-N) between two N atoms of the N-N trigger bond and the cohesive energy density(CED) decrease.These phenomena agree with the experimental fact that the PBX becomes more sensitive as the temperature increases.Therefore,we propose to use the maximum bond length L max of the trigger bond of the easily decomposed and exploded component and the interaction energy E N-N of the two relevant atoms as theoretical criteria to judge or predict the relative degree of heat and impact sensitivity for the energetic composites such as PBXs and solid propellants.
文摘The mesoscopic structures of β-HMX （octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine）- based PBXs （polymer bonded explosives） at room temperature were investigated using dissipative particle dynamics method. The parameters and repulsive parameters of dif- ferent polymers and β-HMX, the mesoscopic structures of β-HMX-based polymer-bonded explosives at different temperatures have been studied. The results showed that the compat-ibility between β-HMX and vinylidenedifluoride （VDF）,β-HMX and chlorotrifluoroethylene （CTFE）, VDF and CTFE increased with increasing temperature. The temperature and mo-lar ratio of the polymers played an important role in wrapped process. And there exists the optimum temperature and molar ratio.
基金China National Nature Science Foundation(Grant No.11872119)Foundation Strengthening Project(Grant No.2020-JCJQ-GFJQ2126-007)+1 种基金Pre-research Program of Armament(Grant No.6142A03202002)China Postdoctoral Science Foundation(Grant No.BX20200046)for supporting this project。
文摘A thorough understanding of drop-weight impacted responses for polymer-bonded explosives(PBXs)is significant to evaluate their impact sensitivity.The characteristics of the drop-weight impacted pressed PBXs including deforming,fracturing,forming a local high-temperature region and igniting,were simulated using a coupled mechanical-thermo-chemical model integrating micro-defects evolution.A novel evaluation method for impact sensitivity is established using the relation between the input kinetic energy and the output energy due to deformation,crushing energy,local hot spot energy and ignition.The effects of impact velocity on sensitivity were analyzed and the critical local ignition impact velocity is determined as 4.0-4.5 m/s.The simulated results show that shear-crack friction heating is the dominant ignition mechanism.The region along the boundary of PBXs sample is the most hazardous regions where ignition first occur.The propagation of stress wave in PBXs causes shear-crack hotspot and bulk temperature exhibiting an approximate 45°direction evolution path,which is the main reason that dominated damage-ignition region transits from the boundary to the central of sample.
