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Numerical investigation of the failure mechanism of cubic concrete specimens in SHPB tests

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Defence Technology（防务技术） 2022年第1期18卷 1-11页

作者： mei li Hong Hao jian cui Yi-fei Hao Labomtory of Coast Civil Structure Safety of Ministry of Education Tianjin UniversityTiarjin300072China chool of Civil Engineering.Tianin University Tianjin300072China entre for Infrastructural Monitoring and Protection School of Civil and Mechanical Engineering Curtin UniversityPerth Western Australia6845Australia

Cylindrical specimens are commonly used in Split Hopkinson pressure bar(SHPB)tests to study the uniaxial dynamic properties of concrete-like *** recent years,true tri-axial SHPB equipment has also been developed or is under development to investigate the material dynamic properties under tri-axial impact *** such tests,cubic specimens are *** is well understood that static material strength obtained from cylinder and cube specimens are *** factors are obtained and adopted in some guidelines to convert the material streng th obtained from the two types of *** uniaxial impact tests have also demonstrated that the failure mode and the strain rate effect of cubic specimens are very different from that of cylindrical ***,the mechanical background of these findings is *** an extension of the previous laboratory study,this study performs numerical SHPB tests of cubic and cylindrical concrete specimens subjected to uniaxial impact load with the validated numerical *** stress states of cubic specimens in relation to its failure mode under different strain rates is analyzed and compared with cylindrical *** detailed analyses of the numerical simulation results show that the lateral inertial confinement of the cylindrical specimen is higher than that of the cubic specimen under the same strain *** cubic specimen,the corners aremore severely damaged because of the lower lateral confinement and the occurrence of the tensile radial stress which is not observed in cylindrical *** results explain why the dynamic material strengths obtained from the two types of specimens are different and are strain rate *** on the simulation results,an empirical formula of conversion factor as a function of strain rate is proposed,which supplements the traditional conversion factor for quasi-static material *** can be used for transforming the dynamic compressive strength from

关键词： Concrete Lateral inertial confinement Shape effet Dynamic failure mechanism Strain rate

Experimental study on the size effect on the equation of state of concretes under shock loading

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Defence Technology（防务技术） 2024年第3期33卷 160-167页

作者： mei li jian cui Yanchao Shi Baijian Tang Xin Chen Key Laboratory of Coast Civil Structural Safety of the Ministry of Education Tianjin UniversityTianjin 300072China School of Civil Engineering Suzhou University of Science and Technology1701 Binhe RoadSuzhou 215011JiangsuChina School of Civil Engineering Tianjin UniversityTianjin 300072China

Adopting the classical theory of hydrocodes,the constitutive relations of concretes are separated into an equation of state(EoS)which describes the volumetric behavior of concrete material and a strength model which depicts the shear properties of *** experiments on the EoS of concrete is always challenging due to the technical difficulties and equipment limitations,especially for the specimen size effect on the *** some researchers investigate the shock properties of concretes by fly-plate impact tests,the specimens used in their tests are usually in one *** this paper,the fly-plate impact tests on concrete specimens with different sizes are performed to investigate the size effect on the shock properties of concrete *** mechanical background of the size effect on the shock properties are revealed,which is related to the lateral rarefaction effect and the deviatoric stress produced in the *** to the tests results,the modified EoS considering the size effect on the shock properties of concrete are proposed,which the bulk modulus of concrete is unpredicted by up to 20% if size effects are not accounted for.

关键词： Concrete Equation of state Size effect Shock wave Fly-plate impact test

Yttrium-catalyzed cis-1,4-Selective Polymerization of 2-(4-Halophenyl)-1,3-butadienes and Their Copolymerization with Isoprene

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Chinese Journal of Polymer Science 2021年第3期39卷 309-315,I0005页

作者： jian-Ming Huang Chang-Guang Yao Shi-Hui li Dong-mei cui State Key Loboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022Chino School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026China

Polymerization of 2-(4-halophenyl)-1,3-butadiene(2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex(1) activated by [Ph_3 C][B(C_(6) F_(5))_(4)] and Ali Bu3 shows high cis-1,4-selectivity(>98%) for the polymerization of 2-XPB(2-XPB = 2-FPB, 2-Cl PB and 2-Br PB) to afford halogenated plastic poly(dienes) with glass transition temperatures of30–55 ℃. Moreover, the copolymerization of 2-XPB with isoprene(IP) has also been achieved by this catalyst, and the insertion ratios of 2-XPB can be facilely tuned in a full range of 0%–100% simply by changing the 2-XPB-to-IP ratio. Quantitative hydrogenation of cis-1,4-poly(2-XPB) results in perfect alternating ethylene-halostyrene copolymers, and an alternating copolymer of 4-vinylbenzoic acid with ethylene is obtained by a consecutive reaction of ethylene-4-bromostyrene copolymer with ^(n)Bu li, CO_(2) and HCl.

关键词： cis-1,4-Selective Coordination(co)polymerization Poly(dienes) Alternating copolymer Post-polymerization modification

Evolution of insoluble eutectic Si particles in anodic oxidation films during adipic–sulfuric acid anodizing processes of ZL114A aluminum alloys

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International Journal of Minerals,Metallurgy and Materials 2015年第3期22卷 302-308页

作者： Lei Hua jian-hua liu Song-mei li mei Yu Lei Wang Yong-xin cui School of Materials Science and Engineering Beihang University Beijing Xinghang Mechanical-electrical Equipment CO. LTD.

The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were in- vestigated by optical microscopy （OM） and scanning electron microscopy （SEM）. The anodic oxidation was performed at 25℃ and a con- stant voltage of 15 V in a solution containing 50 g/L sulfuric acid and 10 g/L adipic acid. The thickness of the formed anodic oxidation film was approximately 7.13 μm. The interpore distance and the diameters of the major pores in the porous layer of the film were within the ap- proximate ranges of 10~20 nm and 5-10 nm, respectively. Insoluble eutectic Si particles strongly influenced the morphology of the anodic oxidation films. The anodic oxidation films exhibited minimal defects and a uniform thickness on the ZL114A substrates; in contrast, when the front of the oxide oxidation films encountered eutectic Si particles, defects such as pits and non-uniform thickness were observed, and pits were observed in the films.

关键词： aluminum alloys anodizing anodic oxidation thin films eutectic silicon particles

Carbon Emissions Abatement(CEA)Allocation Based on Inverse Slack-Based Model(SBM)

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Journal of the Operations Research Society of China 2021年第3期9卷 475-498页

作者： Xiao-yin Hu jian-Shu li Xiao-Ya li Jin-Chuan cui Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

Carbon emissions abatement(CEA)is an important issue that draws attention from both academicians and *** envelopment analysis(DEA)has been a popular tool to allocate the CEA,and most previous works are based on radial DEA ***,as shown in our paper,these models may give biased results due to their ignorance of *** avoid such problems,we propose an allocation model based on the slack-based model and multiple-objective nonlinear programming to find the CEA allocation plan,which can minimize the GDP *** property of nonconvexity makes the model difficult to ***,we construct an approximation algorithm to solve this model with guaranteed error bounds and *** the empirical application,we take regions of china as an illustrative example and find there is a significant region gap in ***,we group the regions into eastern,central,and western,and give the main results,as well as the superiority of our allocation models compared with radial models.

关键词： Carbon emissions abatement(CEA) Allocation data envelopment analysis(DEA) Inverse slack-based method(ISBM)

Photopromoted methoxycarbonylation of olefin with methyl formate by Co(OAc)2

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Chinese Chemical Letters 2007年第1期18卷 17-20页

作者： ying Na cui Jing mei yin da Bin Gao ying Ping Jia Guang Yun Zhou Shen Min li liaoning Key Laboratory of Bio-Organic Chemistry Dalian University Dalian 116622 China

The photopromoted methoxycarbonylation of olefin with methyl formate catalyzed by Co（OAc）2 at ambient conditions has been carried out. The results indicated that the reaction activity increased with the increasing temperature. Methyl formate decomposed into CO and CH3OH firstly under irradiation, and then the methoxycarbonylation of olefin proceeded under catalysis of Co（OAc）2. The mechanism of methyl formate participating in the methoxycarbonylation is verified by the IR analysis and the labeling experiments of CDHOD and CH3^18OH.

关键词： Mcthoxycarbonylation Methyl formate Olefin Photopromoted Cobalt acetate

Photopromoted carbonylation of bromobenzene under ambient conditions

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Chinese Chemical Letters 2009年第5期20卷 531-534页

作者： li Zhuo Mu ying Ping Jia Jing mei yin Guang Yun Zhou ying Na cui da Bin Gao liaoning Key Laboratory of Bio-organic Chemistry Dalian University Dalian 116622 China

The photopromoted carbonylation of bromobenzene with carbon monoxide catalyzed by inexpensive commercially available cobalt salts [Co（OAc）2, COCl2] was carried out under ambient conditions. The results revealed that methyl benzoate was produced in the presence of basic additives （CH3ONa, NaOAc or （n-C4H9）3N）. The catalytic activity of Co（OAc）2 was higher than that of COCl2. Furthermore, the activity of the carbonylation was greatly improved by addition of acetophenone, e.g. both the yield and selectivity of the ester were increased from 47% to 91% with Co（OAc）2 as catalyst and CH3ONa as additive, while the yield of byproduct benzene from hydrodehalogenation of bromobenzene decreased from 32% to 8%.

关键词： Photopromoted carbonylation Bromobenzene Cobalt salts Sodium methoxide Acetophenone

Aseismic performances of constrained damping lining structures made of rubber-sand-concrete

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1522-1537页

作者： Xiancheng mei Qian Sheng jian Chen Zhen cui jianhe li Chuanqi li daniel Dias State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China Key Laboratory of Water Grid Project and Regulation of Ministry of Water Resources Changjiang Institute of SurveyPlanningDesign and ResearchWuhan430010China Laboratory 3SR CNRS UMR 5521Grenoble Alpes UniversityGrenoble38000France School of Automotive and Transportation Engineering Hefei University of TechnologyHefei23009China

Flexible damping technology considering aseismic materials and aseismic structures seems be a good solution for engineering *** this study,a constrained damping structure for underground tunnel lining,using a rubber-sand-concrete(RSC)as the aseismic material,is *** aseismic performances of constrained damping structure were investigated by a series of hammer impact *** damping layer thickness and shape effects on the aseismic performance such as effective duration and acceleration amplitude of time-domain analysis,composite loss factor and damping ratio of the transfer function analysis,and total vibration level of octave spectrum analysis were *** hammer impact tests revealed that the relationship between the aseismic performance and damping layer thickness was not linear,and that the hollow damping layer had a better aseismic performance than the flat damping layer *** aseismic performances of constrained damping structure under different seismicity magnitudes and geological conditions were *** effects of the peak ground acceleration(PGA)and tunnel overburden depth on the aseismic performances such as the maximum principal stress and equivalent plastic strain(PEEQ)were *** numerical results show the constrained damping structure proposed in this paper has a good aseismic performance,with PGA in the range(0.2-1.2)g and tunnel overburden depth in the range of 0-300 m.

关键词： Constrained damping structure Aseismic performance Hammer impact tests damping layer Peak ground acceleration Overburden depth

Rich defects and nanograins boosted formaldehyde sensing performance of mesoporous polycrystalline ZnO nanosheets

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Rare Metals 2022年第7期41卷 2292-2304页

作者： Le-Xi Zhang Ming-mei Zhao Yan-Yan yin Yue Xing li-jian Bie School of Materials Science and Engineering Tianjin Key Laboratory for Photoelectric Materials and DevicesKey Laboratory of Display Materials and Photoelectric Devices(Ministry of Education)National Demonstration Center for Experimental Function Materials EducationTianjin University of TechnologyTianjin 300384China Department of Environmental Science and Engineering Nankai University Binhai CollegeTianjin 300270China

Comprehensive consideration of structural and electronic sensitization is of significant importance for rational design and assembly of high-performance gas sensors based on metal *** this work,hierarchically mesoporous ZnO nanosheets are synthesized via a hydrothermal method followed by *** characterization reveals polycrystalline feature of these ZnO nanosheets rich in mesopores and *** sensing performance of as-synthesized ZnO nanosheets was sys-tematically investigated,taking formaldehyde as probe *** with commercial ZnO nanoparticles,ZnO nanosheets exhibited enhanced formaldehyde sensing properties,including lower operation temperature,higher sensitivity,faster response,and smaller detection ***,the response(S=227.4)of ZnO nanosheets to 200×10^(-6) formaldehyde is about 17 times larger than that of ZnO nanoparticles(S=13.5).Excluding effects of grain size and surface area,enhanced sensing properties,especially response value,are credited in large part to synergistic actions of surface defects,grain boundaries,as well as unique structural advantage of ZnO ***,this work offers a guideline for boosting performance of metal oxide-based gas sensors via surface defect control and grain boundary construction.

关键词： performance polycrystalline grain