Introducing Neutral Polymeric bonding agents(NPBA) into the Nitrate Ester Plasticized Polyether(NEPE)propellant could improve the adhesion between filler/matrix interface, thereby contributing to the development of ne...Introducing Neutral Polymeric bonding agents(NPBA) into the Nitrate Ester Plasticized Polyether(NEPE)propellant could improve the adhesion between filler/matrix interface, thereby contributing to the development of new generations of the NEPE propellant with better mechanical properties. Therefore,understanding the effects of NPBA on the deformation and damage evolution of the NEPE propellant is fundamental to material design and applications. This paper studies the uniaxial tensile and stress relaxation responses of the NEPE propellant with different amounts of NPBA. The damage evolution in terms of interface debonding is further investigated using a cohesive-zone model(CZM). Experimental results show that the initial modulus and strength of the NEPE propellant increase with the increasing amount of NPBA while the elongation decreases. Meanwhile, the relaxation rate slows down and a higher long-term equilibrium modulus is reached. Experimental and numerical analyses indicate that interface debonding and crack propagation along filler-matrix interface are the dominant damage mechanism for the samples with a low amount of NPBA, while damage localization and crack advancement through the matrix are predominant for the ones with a high amount of NPBA. Finally, crosslinking density tests and simulation results also show that the effect of the bonding agent is interfacial rather than due to the overall crosslinking density change of the binder.展开更多
Interface debonding between particle and matrix in composite propellant influences its macroscopic mechanical properties greatly. For this, the laws of interface cohesive damage and failure were analyzed. Then, its mi...Interface debonding between particle and matrix in composite propellant influences its macroscopic mechanical properties greatly. For this, the laws of interface cohesive damage and failure were analyzed. Then, its microscopic computational model was established. The interface mechanical response was modeled by the bilinear cohesive zone model. The effects of interface properties and particle sizes on the macroscopic mechanical behavior were investigated. Numerical simulation of debonding damage evolution of composite propellant under finite deformation was carried out. The debonding damage nucleation, propagation mechanism and non-uniform distribution of microscopic stress-strain fields were discussed. The results show that the finite element simulation method based on microstructure model can effectively predict the trend of macroscopic mechanical behavior and particle/matrix debonding evolution process. It can be used for damage simulation and failure assessment of composite propellants.展开更多
This study is to identify the critical interface in a geosynthetic multilayer liner system by examining the effects of the interface shear strength of liner components, leachate level, leachate buildup cases, and peak...This study is to identify the critical interface in a geosynthetic multilayer liner system by examining the effects of the interface shear strength of liner components, leachate level, leachate buildup cases, and peak and residual interface strengths. According to current landfill design procedures, conducting stability analysis along the same interface at both the back slope and base may result in a non-conservative result. The critical interfaces with the minimum factor of safety are generally found at different locations along the back slope and base. The critical interface for a multilayer liner system cannot simply be assumed during stability analysis. It can shift from one interface to another with changes in the leachate level and with different leachate buildup cases. The factor of safety for an interface with a high friction angle and low apparent cohesion generally drops much more quickly than it does under inverse conditions when the leachate level increases. The failure interface in a liner system under residual conditions is usually different from the failure interface under peak conditions.展开更多
The barrel lifes of three small caliber rifles were tested by using the propellant with nanomaterial and the standard propellant respectively. The test results show that the service life increases observably due to ad...The barrel lifes of three small caliber rifles were tested by using the propellant with nanomaterial and the standard propellant respectively. The test results show that the service life increases observably due to adding nanomaterial to the propellant. Then, the influence of the nanomaterial on the tube was researched by splitting the two barrels tested and detecting their inner surfaces. It was found that the erosion of the barrel bore is reduced observably by using the propellant with nanomaterial. And it makes the volume and the size of the gun chamber change less. Therefore, the barrel life can be prolonged by adding the nanomaterial in the propellant.展开更多
基金National Natural Science Foundation of China(U22B20131)for supporting this project.
文摘Introducing Neutral Polymeric bonding agents(NPBA) into the Nitrate Ester Plasticized Polyether(NEPE)propellant could improve the adhesion between filler/matrix interface, thereby contributing to the development of new generations of the NEPE propellant with better mechanical properties. Therefore,understanding the effects of NPBA on the deformation and damage evolution of the NEPE propellant is fundamental to material design and applications. This paper studies the uniaxial tensile and stress relaxation responses of the NEPE propellant with different amounts of NPBA. The damage evolution in terms of interface debonding is further investigated using a cohesive-zone model(CZM). Experimental results show that the initial modulus and strength of the NEPE propellant increase with the increasing amount of NPBA while the elongation decreases. Meanwhile, the relaxation rate slows down and a higher long-term equilibrium modulus is reached. Experimental and numerical analyses indicate that interface debonding and crack propagation along filler-matrix interface are the dominant damage mechanism for the samples with a low amount of NPBA, while damage localization and crack advancement through the matrix are predominant for the ones with a high amount of NPBA. Finally, crosslinking density tests and simulation results also show that the effect of the bonding agent is interfacial rather than due to the overall crosslinking density change of the binder.
基金Sponsored by the General Armament Department Advanced Research Project (20101019)
文摘Interface debonding between particle and matrix in composite propellant influences its macroscopic mechanical properties greatly. For this, the laws of interface cohesive damage and failure were analyzed. Then, its microscopic computational model was established. The interface mechanical response was modeled by the bilinear cohesive zone model. The effects of interface properties and particle sizes on the macroscopic mechanical behavior were investigated. Numerical simulation of debonding damage evolution of composite propellant under finite deformation was carried out. The debonding damage nucleation, propagation mechanism and non-uniform distribution of microscopic stress-strain fields were discussed. The results show that the finite element simulation method based on microstructure model can effectively predict the trend of macroscopic mechanical behavior and particle/matrix debonding evolution process. It can be used for damage simulation and failure assessment of composite propellants.
文摘This study is to identify the critical interface in a geosynthetic multilayer liner system by examining the effects of the interface shear strength of liner components, leachate level, leachate buildup cases, and peak and residual interface strengths. According to current landfill design procedures, conducting stability analysis along the same interface at both the back slope and base may result in a non-conservative result. The critical interfaces with the minimum factor of safety are generally found at different locations along the back slope and base. The critical interface for a multilayer liner system cannot simply be assumed during stability analysis. It can shift from one interface to another with changes in the leachate level and with different leachate buildup cases. The factor of safety for an interface with a high friction angle and low apparent cohesion generally drops much more quickly than it does under inverse conditions when the leachate level increases. The failure interface in a liner system under residual conditions is usually different from the failure interface under peak conditions.
文摘The barrel lifes of three small caliber rifles were tested by using the propellant with nanomaterial and the standard propellant respectively. The test results show that the service life increases observably due to adding nanomaterial to the propellant. Then, the influence of the nanomaterial on the tube was researched by splitting the two barrels tested and detecting their inner surfaces. It was found that the erosion of the barrel bore is reduced observably by using the propellant with nanomaterial. And it makes the volume and the size of the gun chamber change less. Therefore, the barrel life can be prolonged by adding the nanomaterial in the propellant.
