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Effect of microstructure on short pulse duration shock Initiation of TATB and initial response mechanism

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Defence Technology（防务技术） 2020年第2期16卷 374-380页

作者： Jun Wang Wei Cao Xiang-li Guo Bi-bo Cheng Lu-lu Zhao Rui-rui Liu Xiao-wei Chen School of Mechatronical Engineering Beijing Institute of TechnologyBeijing100081China Institute of Chemical Materials China Academy of Engineering PhysicsNo.64Mianshan RoadMianyang CityChina

Micro-TATB particles with different sizes and 3D nanoporous TATB architectures with different specific surface areas were prepared through recrystallization to study short pulse duration shock Initiation properties by electric gun technology.For micro-TATB,the Initiation threshold significantly decreases with TATB average size ranging from 79.7μm to 0.5μm.For 3D nanoporous TATB architecture,the Initiation threshold decreases and then increases with specific surface areas increased from 9.6 m^2/g to36.2 m^2/g.The lowest Initiation thresholds are obtained for the micro-TATB with average sizes of 1.3μm and 0.5μm,and 3D nanoporous TATB architecture with specific surface area of 22.4 m^2/g.The shock Initiation thresholds of micro-TATB and 3D nanoporous TATB architectures show significantly decreases with the porosity increased.The decomposition reaction and thermal conductivity properties were further investigated to understand the initial response mechanism.High porosity provides more collapse sites to generate high temperature for formation of hot spots.The low thermal conductivity and decomposition temperature could enhance the formation and ignition of the hot spots,and initial decomposition reaction of TATB.The effect of the decomposition temperature is higher than that of the thermal conductivity on the shock Initiation properties.The enhanced decomposition reaction could pro mote energy release and transfer process from the ignition to the combustio n.This work offe rs a new insight to understand the effects of microstructure on the shock Initiation properties and the initial response mechanism of TATB.

关键词： Short pulse duration shock Initiation Microstructure TATB architecture Chemical reaction Initial response mechanism

Crystal lattice free volume in a study of Initiation reactivity of nitramines:Friction sensitivity

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Defence Technology（防务技术） 2018年第2期14卷 132-136页

作者： Svatopluk Zeman Ning Liu Marcela Jungová Ahmed K.Hussein Qi-long Yan Institute of Energetic Materials Faculty of Chemical TechnologyUniversity of PardubiceCZ-532 10PardubiceCzech Republic Xi'an Modern Chemistry Research Institute Xi'anShaanxi710065China School of Astronautics Northwestern Polytechnical UniversityXi'an 710072ShaanxiChina

The relationship between friction sensitivity(FS) and the crystal lattice free space per molecule, △V. of thirteen nitramines is described by a linear equation, divided into a number of the partial relationships with strong limitations by their molecular structure characteristics. Increasing FS due to raising of the △V values is not clearly confirmed. The influence of the △V values on friction sensitivity of nitramines is similar to that of their aza atoms which influence the mutual orientations of nitro groups in neighboring molecules. The dipole-dipole interaction of the oxygen and nitrogen atoms of nitro groups in neighboring nitramine molecules has a major effect on their own FS. In accordance with this interaction, a directly proportional relationship was derived between FS and the intrinsic gas phase molecular volume, V_(int), of the nitramines mentioned, which is divided also into several straight lines according to relatively tight molecular structure similarity. The relationships found again confirm a level of disorder in the distribution of the forces in the crystal lattice of the "common" quality of ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, in comparison with its reduced sensitivity(RS) or chemically pure analogue.

关键词： Crystal lattice Friction Initiation reactivity Nitramines

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Influence of grain size on the small fatigue crack Initiation and propagation behaviors of a nickel-based superalloy at 650℃

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Journal of Materials Science & Technology 2019年第8期35卷 1607-1617页

作者： Xumin Zhu Congyang Gong Yun-Fei Jia Runzi Wang Chengcheng Zhang Yao Fu Shan-Tung Tu Xian-Cheng Zhang Key Laboratory of Pressure Systems and Safety Ministry of Education School of Mechanical and Power Engineering East China University of Science and Technology Shanghai 200237 China AECC Commercial Aircraft Engine Co. LTD Shanghai Engineering Research Center for Commercial Aircraft Engine Shanghai 201108 China

GH4169 at 650℃ in atmosphere was investigated by using single edge notch tensile specimens. The number of main cracks and crack Initiation mechanisms at the notch surface strongly depended on the grain size. The crack Initiation life accounted for more percentages of the total fatigue life for the alloy with smaller grain size. The fatigue life generally increased with increasing crack Initiation life. The small crack transited to long crack when its length reached 10 times the grain size.

关键词： Fatigue crack Initiation Small crack Crack growth rate Grain size effect High temperature

A review——Pitting corrosion Initiation investigated by TEM

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Journal of Materials Science & Technology 2019年第7期35卷 1455-1465页

作者： B.Zhang X.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

Passive metals have superior resistance to general corrosion but are susceptible to pitting attack in certain aggressive media, leading to material failure with pronounced adverse economic and safety consequences. Over the past decades, the mechanism of pitting corrosion has attracted corrosion community striving to study. However, the mechanism at the pitting Initiation stage is still controversy, due to the difficulty encountered in obtaining precise experimental information with enough spatial resolution.Tracking the accurate sites where initial dissolution occurs as well as the propagation of the dissolution by means of multi-scale characterization is key to deciphering the link between microstructure and corrosion at the atomic scale and clarifying the pitting Initiation mechanism. Here, we review our recent progresses in this issue by summarizing the results in three representative materials of 316F, and Super 304H stainless steel as well as 2024-Al alloy, using in situ ex-environmental TEM technique.

关键词： Pitting Initiation Dissolution TEM Inclusion Second phase

Effect of Initiation manners on the scattering characteristics of semi-preformed fragment warhead

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Defence Technology（防务技术） 2018年第5期14卷 578-584页

作者： Xu-yang Wang Xiang-shao Kong Cheng Zheng Wei-guo Wu Key Laboratory of High Performance Ship Technology (Wuhan University of Technology) Ministry of Education Departments of Naval Architecture Ocean and Structural Engineering School of Transportation Wuhan University of Technology

The lethality of a semi-preformed fragment warhead is closely related to the expand velocity and spatial distribution of the fragments from ruptured metal casing. The topic of how to improve the utilization of charge of have been drawing great attention from researchers and designer in this filed. In present paper,in order to investigate the influence of charge Initiation manners on the scattering characteristics of semi-preformed fragment warhead, the numerical simulations and experimental test are conducted.Firstly, the influence of grid density on numerical results is investigated, and a proper numerical model with relatively high accuracy and effectiveness is determined. Then. numerical simulations of three kinds of different Initiation position of a semi-preformed fragment warhead are carried out. An experimental test of the explosion of a semi-preformed fragment warhead is carried out. By comparing and analyzing the numerical results and experimental data, it is found that the Initiation manners have great influence on scattering characteristics of semi-preformed fragment warhead. The researcher work of this paper would provide an effective alternative method to optimize the design of warhead.

关键词： Initiation manners Semi-preformed fragment warhead Deformation pattern

Damage Initiation and Propagation in Composites Subjected to Low-Velocity Impact:Experimental Results,3D Dynamic Damage Model,and FEM Simulations

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第3期36卷 488-499页

作者： JIA Wenbin WEN Weidong FANG Lei Jiangsu Province Key Laboratory of Aerospace Power System College of Energy and Power EngineeringNanjing University of Aeronautics and Astronautics

A three-dimensional dynamic damage model that fits both small and large damage sizes is developed to predict impact damage Initiation and propagation for each lamina of T300-carbon/epoxy laminations.First,13 specimens of the same lamination sequence are subjected to three different impact energies(10 J,15 J,and 20 J).After the impact,the laminates are inspected by the naked eye to observe the damage in the outer layers,and subsequently X-rayed to detect the inner damage.Next,the stress analysis of laminates subjected to impact loading is presented,based on the Hertz contact law and virtual displacement principle.Based on the analysis results,a three-dimensional dynamic damage model is proposed,including the Hou failure criteria and Camanho stiffness degradation model,to predict the impact damage shape and area.The numerical predictions of the damage shape and area show a relatively reasonable agreement with the experiments.Finally,the impact damage Initiation and propagation for each lamina are investigated using this damage model,and the results improve the understanding of the impact process.

关键词： composites impact three-dimensional dynamic damage model impact damage Initiation and propagation

Association between timing of peritoneal dialysis Initiation and mortality in end-stage renal disease

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Chronic Diseases and Translational Medicine 2019年第1期5卷 37-43页

作者： Yuan Peng Xiao Yang Wei Chen Xue-Qing Yu Department of Nephrology The First Affiliated Hospital Sun Yat-sen University Guangzhou Guangdong 510080 China Key Laboratory of Nephrology National Health Commission and Guangdong Province Guangzhou Guangdong 510080 China

Despite the widespread use of chronic dialysis for end-stage renal disease (ESRD), there is no consensus on the optimal timing of initiating renal replacement therapy. Over the past decade, a worldwide trend toward increasing glomerular filtration rate at the Initiation of dialysis has been noted. However, available data indicate that early dialysis has no survival benefit or is harmful. Peritoneal dialysis (PD) is one alternative for ESRD and has potential survival factors different from those of hemodialysis. The association between the timing of PD Initiation and survival is unclear. This review examines the effect of the timing of dialysis on clinical outcomes in PD patients.

关键词： Peritoneal dialysis (PD) Initiation Mortality Glomerular filtration rate (GFR)

The fragmentation of D-shaped casing filled with explosive under eccentric Initiation

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Defence Technology（防务技术） 2018年第5期14卷 417-421页

作者： Zhi-wei Guo Guang-yan Huang Wei Zhu Shun-shan Feng State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology

With the technical development of new warhead designs and improvised explosive device protection,irregular casing filled with explosive has been paid more attention recently. In this paper, we studied the fragmentation of a type of D-shaped casing, which is a common asymmetric casing in the field of warhead design. Based on the radiograph technique, static explosive experiments were conducted with D-shaped casings under four different eccentric Initiation ratios to explore their fragmentation. A numerical model was then established to simulate the dynamic response of D-shaped casing filled with explosive. The results of numerical simulation were found to agree well with the experimental data.According to the results of numerical simulation and experimental data, the dynamic responses of Dshaped casing were analyzed. The results of the current work pave way for the innovative design of new warhead and for further studying the dynamic response of asymmetric casing.

关键词： D-shaped casing Eccentric Initiation X-ray radiograph technique Fragmentation Numerical simulation

Fatigue crack Initiation of magnesium alloys under elastic stress amplitudes:A review

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Frontiers of Mechanical Engineering 2019年第1期14卷 113-127页

作者： B.J.WANG D.K.XU S.D.WANG E.H.HAN School of Environmental and Chemical Engineering Shenyang Ligong UniversityShenyang 110159China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The most advantageous property of magnesium(Mg)alloys is their density,which is lower compared with traditional metallic materials.Mg alloys,considered the lightest metallic structural material among others,have great potential for applications as secondary load components in the transportation and aerospace industries.The fatigue evaluation of Mg alloys under elastic stress amplitudes is very important in ensuring their service safety and reliability.Given their hexagonal close packed structure,the fatigue crack Initiation of Mg and its alloys is closely related to the deformation mechanisms of twiuning and basal slips.However,for Mg alloys with shrinkage porosities and inclusions,fatigue cracks will preferentially initiate at these defects,remarkably reducing the fatigue lifetime.In this paper,some fundamental aspects about the fatigue crack Initiation mechanisms of Mg alloys are reviewed,in cluding the 3 followings:1)Fatigue crack Initiation of as-cast Mg alloys,2)influence of microstructure on fatigue crack Initiation of wrought Mg alloys,and 3)the effect of heat treatment on fatigue Initiation mechanisms.Moreover,some unresolved issues and future target on the fatigue crack Initiation mechanism of Mg alloys are also described.

关键词： Mg alloys fatigue behavior microstructure crack Initiation deformation mechanism