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Microcrack-and microvoid-related impact damage and ignition responses for HMX-based polymer-bonded explosives at high temperature

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Defence Technology（防务技术） 2022年第9期18卷 1602-1621页

作者： Hai-jiao Xue yan-qing wu Kun yang Yi wu State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China School of Aerospace Engineering Beijing Institute of TechnologyBeijing100081China

Investigating the damage and ignition behaviors of polymer-bonded explosive(PBX) under a coupled impact and high-temperature loading condition is required for the safe use of charged PBXs. An improved combined microcrack and microvoid model(CMM) was developed for better describing the thermal effects of deformation, damage, and ignition responses of PBXs. The main features of the model under typical dynamic loadings(i.e. uniaxial tension and compression, and lateral confinement) at different initial temperature were first studied. And then the effects of temperature on impact-shear sensitivity of HMX-based PBXs were investigated. The results showed that the ignition threshold velocity of shear-crack hotspots exhibits an increase from 260 to 270 to 315-325 m/s when initial temperature increases from 301 to 348 K;and then the threshold velocity decreases to 290-300 m/s with the initial temperature continually increasing to 378 K. The predicted ignition threshold velocity level of the explosives under coupled impact and high temperature loading conditions were consistent with the experimental data.

关键词： PBX Thermal-mechanical coupling Numerical simulation Impact Sensitivity

Effect of interface behaviour on damage and instability of PBX under combined tension-shear loading

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Defence Technology（防务技术） 2023年第5期23卷 137-151页

作者： Quan-zhi Xia yan-qing wu Feng-lei Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081PR China

To study the effect of interface behaviour on the mechanical properties and damage evolution of PBX under combined tension-shear loading, the present work establishes the numerical model of a PBX three-phase hybrid system, which introduces a nonlinear plastic damage cohesion model to study the mechanical response and damage process. The parameters in the model were fitted and *** the crack growth rate as the feature, the damage state in each stage was determined, and the damage instability criterion was given. The effects of interfacial tensile strength and shear strength on the damage process of PBX were studied. On this basis, serrated and hemispherical structures interface of PBX has been developed, which affects the damage process and instability during the loading *** results indicate that damage state response of PBX experiences the process of stable load bearing,unstable propagation, and complete failure. At the critical moment of instability, the overall equivalent effective strain of material reaches 3024 με and instability loading displacement reaches 0.39 mm. The increase of interfacial tensile strength and shear strength significantly inhibits the damage of PBX. The effect of interfacial shear strength on critical instability of PBX is approximately 1.7 times that of the interfacial tensile strength. Further, interface opening along the normal direction is the main damage form at the interface. Serrated and hemispherical rough interfaces can significantly inhibit propagation of cracks, and the load bearing capacity is improved by 22% and 9.7%, respectively. Appropriate improvement of the roughness of the interface structure can effectively improve the mechanical properties. It is significantly important to have a better understanding of deformation, damage and failure mechanisms of PBX and to improve our predictive ability.

关键词： PBX explosives Interface behaviour Damage Instability Crack propagation

Numerical simulation of drop weight impact sensitivity evaluation criteria for pressed PBXs

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Defence Technology（防务技术） 2023年第1期19卷 76-90页

作者： Hong-zheng Duan yan-qing wu Kun yang Feng-lei Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081PR China

A thorough understanding of drop-weight impacted responses for polymer-bonded explosives(PBXs)is significant to evaluate their impact *** 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 *** effects of impact velocity on sensitivity were analyzed and the critical local ignition impact velocity is determined as 4.0-4.5 m/*** simulated results show that shear-crack friction heating is the dominant ignition *** region along the boundary of PBXs sample is the most hazardous regions where ignition first *** 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.

关键词： Polymer-bonded explosives(PBXs) Drop weight impact Numerical simulation Sensitivity evaluation criterion Hotspot mechanism

Damage-ignition mechanism studies on modified propellant with different crosslinking density under dynamic loading

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Defence Technology（防务技术） 2023年第10期28卷 155-164页

作者： Hong-zheng Duan yan-qing wu Xiao Hou Kun yang Feng-lei Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081PR China School of Aerospace Engineering Beijing Institute of TechnologyBeijing100081PR China The Fourth Institute of China Aerospace Science and Technology Corporation Xi'an710025PR China

The study of high-energy and low-vulnerability propellants is important for the power performance and safety of solid propellant rocket *** modified split Hopkinson pressure bar(SHPB)tests are performed on two kinds of propellant with different crosslinking density to study the dynamic mechanical responses and damage-ignition *** apparatus is equipped with a highperformance infrared camera and high-speed camera to capture the deformation,damage-ignition feature and temperature evolution images in the impact *** results suggested that the mechanical responses and damage-ignition mechanism of the propellants were affected by the strain rates and crosslinking *** damage-ignition degree is more intense and the reaction occurs earlier with the increase of strain *** propellant 1 with higher crosslinking density,the critical ignition strain rate is 4500 s^(-1).Two kinds of propellants show different ignition mechanism,*** generation,propagation and final fracture for propellant 1 while viscous shear flow for propellant ***,the SEM images also reveal the difference of damage-ignition mechanism of the two kinds of ***,the ignition mechanism under different strain rates and critical ignition strain rate of propellants are further explained by the theoretical calculation of temperature variations.

关键词： The modified propellants Dynamic loading Mechanical property Damage-ignition mechanism Experimental and theoretical calculation

Shock response of cyclotetramethylene tetranitramine(HMX)single crystal at elevated temperatures

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Defence Technology（防务技术） 2023年第3期21卷 147-163页

作者： Kai Ding Xin-Jie Wang Zhuo-Ping Duan yan-qing wu Feng-Lei Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081PR China

To investigate the shock response of cyclotetramethylene tetranitramine(HMX)single crystals at elevated temperatures(below the phase transition point),plate impact experiments at elevated temperatures were designed and *** HMX/window interface particle velocities at temperatures of 300 K,373 K,and 423 K were measured by the velocity interferometry system for any reflector(VISAR)*** further analyze the related mesoscale deformation mechanisms,a nonlinear thermoelastic-viscoplastic model was developed,which considers thermal activation and phonon drag dislocation slip *** proposed model could well reproduce the measured thermal hardening behavior of Hugoniot elastic limit(HEL)of HMX single *** elevated temperatures,the reduced dislocation mobility was observed,which stems from both phonon scattering and radiative damping *** speaking,radiative damping contributes less than phonon scattering to thermal hardening *** calibrated model was further used to predict shock response of HMX single crystals with different thicknesses at different initial *** the stress relaxation and elastic precursor decrease with thickness are mainly due to the rapid dislocation *** insights shed light on the interplay between dislocation motion and dislocation generation in thermal hardening behavior,stress relaxation,and elastic precursor decay,which serves to reveal the mesoscale deformation mechanisms at elevated temperatures.

关键词： deformation elevated dislocation

Configuring single-layer MXene nanosheet onto natural wood fiber via C-Ti-C covalent bonds for high-stability Li-S batteries

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Journal of Energy Chemistry 2024年第8期95卷 701-711,I0016页

作者： yangyang Chen Yu Liao Ying wu Lei Li Zhen Zhang Sha Luo Yiqiang wu yan qing College of Materials Science and Technology Central South University of Forestry and TechnologyChangsha 410004HunanChina

Lithium-sulfur batteries(LSBs)are considered promising candidates for next-generation battery technologies owing to their outstanding theoretical energy density and ***,the low conductivity and polysulfide shuttling effect of S cathodes severely hamper the practical performance of ***,in situ-generated single layer MXene nanosheet/hierarchical porous carbonized wood fiber(MX/PCWF)composites are prepared via a nonhazardous eutectic activation strategy coupled with pyrolysis-induced gas *** unique architecture,wherein single layer MXene nanosheets are constructed on carbonized wood fiber walls,ensures rapid polysulfide conversion and continuous electron transfer for redox *** C-Ti-C bonds formed between MXene and PCWF can considerably expedite the conversion of polysulfides,effectively suppressing the shuttle *** impressive capacity of 1301.1 m A h g^(-1)at 0.5 C accompanied by remarkable stability is attained with the MX/PCWF host,as evidenced by the capacity maintenance of 722.6 m A h g^(-1)after 500 ***,the MX/PCWF/S cathode can still deliver a high capacity of 886.8 m A h g^(-1)at a high S loading of 5.6 mg cm^(-2).The construction of two-dimensional MXenes on natural wood fiber walls offers a competitive edge over S-based cathode materials and demonstrates a novel strategy for developing high-performance batteries.

关键词： Lithium-sulfur batteries S cathodes MXene nanosheets Wood fiber C-Ti-C bonds

Anabolic-androgenic steroids and cardiovascular risk

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Chinese Medical Journal 2019年第18期132卷 2229-2236页

作者： Jian-Di Liu yan-qing wu Department of Cardiology The Second Affiliated Hospital of Nanchang University Nanchang Jiangxi 330006 China

Objective:Anabolic-androgenic steroids (AAS) represents a group of synthetic testosterone derivatives that play an important role in clinical *** drugs are widely abused among the general public to increase lean weight and improve athletic *** has been reported that AAS use can produce many adverse effects,especially the occurrence of cardiovascular *** there are many related studies,there has been no consensus on AAS use and cardiovascular *** present study was to review the effect of AAS on the cardiovascular *** sources:The data in this review were obtained from articles included in PubMed and the National Center for Biotechnology Information *** selection:Original articles,case reports,and systematic reviews about AAS were selected for the ***:The use/abuse of AAS is correlated with higher cardiovascular risks,and many AAS users/abusers had cardiovascular ***,there are many confounding factors in the studies that explored the causality between AAS intake and disease development,and additional studies are required to determine AAS ***:AAS produces toxic effects on the cardiovascular system,and it is necessary to ensure that more people know this about AAS,including medical personnel.

关键词： Anabolic-androgenic steroid Cardiovascular risk Toxicity effects

Rational surface charge engineering of haloalkane dehalogenase for boosting the enzymatic performance in organic solvent solutions

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Chinese Journal of Chemical Engineering 2024年第1期65卷 276-285页

作者： Yin wu yan Sun Department of Biochemical Engineering School of Chemical Engineering and Technology and Key Laboratory of Systems Bioengineering and Frontiers Science Center for Synthetic Biology(Ministry of Education)Tianjin UniversityTianjin 300350China

Biocatalysis in organic solvents(OSs)has numerous important applications,but native enzymes in OSs often exhibit limited catalytic ***,we proposed a computation-aided surface charge engineering strategy to improve the catalytic performance of haloalkane dehalogenase DhaA in OSs based on the energetic analysis of substrate binding to the DhaA *** variants with enhanced OS resistance were obtained by replacing negative charged residues on the surface with positive charged residue(Arg).Particularly,a four-substitution variant E16R/E93R/E121R/E257R exhibited the best catalytic performance(five-fold improvement in OS resistance and seven-fold half-life increase in 40%(vol)dimethylsulfoxide).As a result,the overall catalytic performance of the variant could be at least 26 times higher than the wild-type *** spectroscopy and molecular dynamics simulation studies revealed that the residue substitution mainly enhanced OS resistance from four aspects:(a)improved the overall structural stability,(b)increased the hydrophobicity of the local microenvironment around the catalytic triad,(c)enriched the hydrophobic substrate around the enzyme molecule,and(d)lowered the contact frequency between OS molecules and the catalytic *** findings validate that computationaided surface charge engineering is an effective and ingenious rational strategy for tailoring enzyme performance in OSs.

关键词： Surface charge engineering Organic solvent resistance Molecular dynamics simulation Haloalkane dehalogenase

Single thiolate replacement of metal nanoclusters

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Science China Chemistry 2024年第2期67卷 523-528页

作者： Ambreen Ambreen Yue Zhou Wanmiao Gu qing You Liang Fang Guoqing Bian Nan yan Nan Xia Zhikun wu Key Laboratory of Materials Physics Anhui Key Laboratory of Nanomaterials and NanotechnologyInstitute of Solid State PhysicsHefei Institutes of Physical Science(HFIPS)Chinese Academy of SciencesHefei230031China University of Science and Technology of China Hefei230601China Institute of Physical Science and Information Technology Anhui UniversityHefei230601China

Surface thiolates play important roles in evincing the structures and properties of thiolated metal nanoclusters—one type of recently emerging inorganic-organic hybrids,and thus the thiolate substitution,especially single thiolate substitution,is highly desirable for subtly tailoring the structures and properties of metal ***,such a single-thiolate substituting is challenging,and its influence on the metal-metal and metal-sulfur bonds remains mysterious due to the absence of the singlethiolate-substituted ***,we developed a combined method,concurrently synthesized the single-thiolate-substituted nanocluster and its parent nanocluster,and successfully resolved their structures by single crystal X-ray crystallography,which reveals that the single thiolate substitute has an obvious influence on the metal-metal and metal-sulfur bond lengths although it has no effect on the absorption ***,the metal-metal and metal-sulfur bonds show various thermal extensibility and even the negative thermal expansion phenomena of the Au–S bond were observed in the single-thiolate-substituted *** bond length-related stability was also ***,this study highlights a novel synthesis method and offers novel structural insights and an in-depth structure-property correlation of thiolated metal nanoclusters.

关键词： metal nanoclusters single thiolate replacement thermal expansion stability intercluster interaction