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Bounds on the overall properties of composites with ellipsoidal inclusions

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Acta Mechanica Sinica 2012年第5期28卷 1340-1355页

作者： lin-zhi wu Shi-Dong Pan Center for Composite Materials Harbin Institute of Technology

A new model is put forward to bound the effective elastic moduli of composites with ellipsoidal inclusions. In the present paper, transition layer for each ellipsoidal inclusion is introduced to make the trial displacement field for the upper bound and the trial stress field for the lower bound satisfy the continuous interface conditions which are absolutely necessary for the application of variational principles. According to the principles of minimum potential energy and minimum complementary energy, the upper and lower bounds on the effective elastic moduli of composites with ellipsoidal inclusions are rigorously derived. The effects of the distribution and geometric parameters of ellipsoidal in- clusions on the bounds of the effective elastic moduli are an- alyzed in details. The present upper and lower bounds are still finite when the bulk and shear moduli of ellipsoidal inclusions tend to infinity and zero, respectively. It should be mentioned that the present method is simple and needs not calculate the complex integrals of multi-point correlation functions. Meanwhile, the present paper provides an entirely different way to bound the effective elastic moduli of composites with ellipsoidal inclusions, which can be developed to obtain a series of bounds by taking different trial displacement and stress fields.

关键词： Composites Ellipsoidal inclusions Effectiveelastic moduli Upper and lower bounds Transition layer

Energy dissipation and contour integral characterizing fracture behavior of incremental plasticity

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Acta Mechanica Sinica 2011年第2期27卷 251-258页

作者： Qi-lin He lin-zhi wu Ming Li Hong-Bo Chen Chen Center for Composite Materials Harbin Institute of Technology 150080 Harbin China

J ep -integral is derived for characterizing the frac- ture behavior of elastic-plastic materials. The J ep -integral differs from Rice’s J-integral in that the free energy density rather than the stress working density is employed to define energy-momentum tensor. The J ep -integral is proved to be path-dependent regardless of incremental plasticity and deformation plasticity. The J epintegral possesses clearly clear physical meaning：（1） the value J ep tip evaluated on the infinitely small contour surrounding the crack tip represents the crack tip energy dissipation; （2） when the global steadystate crack growth condition is approached, the value of J ep farss calculated along the boundary contour equals to the sum of crack tip dissipation and bulk dissipation of plastic zone. The theoretical results are verified by simulating mode I crack problems.

关键词： J-integral · Energy dissipation · Proportional loading · Deformation plasticity · Incremental plasticity

An experiment evaluating how the tiny mass eccentricities in spinstabilized projectiles affect the position of impact points

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Defence Technology（防务技术） 2021年第3期17卷 948-960页

作者： Chuan-lin Chen Hui Xu Chen-lei Huang Zhong-xin Li zhi-lin wu School of Mechanical Engineering Nanjing University of Science and TechnologyNanjingJiangsu210094China

This study investigates and quantifies some possible sources affecting the position of impact points of small caliber spin-stabilized projectiles(such as 12.7 mm bullets).A comparative experiment utilizing the control variable method was designed to figure out the influence of tiny eccentric centroids on the *** study critically analyzes data obtained from characteristic parameter measurements and precision *** also combines Sobol’s algorithm with an artificial intelligence algorithmdAdaptive Neuro-Fuzzy Inference Systems(ANFIS)ein order to conduct global sensitivity analysis and determine which parameters were most *** results indicate that the impact points of projectiles with an entry angle of 0°deflected to the left to that of projectiles with an entry angle of 90°.The difference of the mean coordinates of impact points was about 12.61 cm at a target range of 200 *** analysis indicated that the entry *** initial position of mass eccentricityehad a notable *** global sensitivity analysis,the significance of the effect of mass eccentricity was confirmed again and the most influential factors were determined to be the axial moment and transverse moment of inertia(Izz Iyy),the mass of a projectile(m),the distance between nose and center of mass along the symmetry axis for a projectile(Lm),and the eccentric distance of the centroid(Lr).The results imply that the control scheme by means of modifying mass center(moving mass or mass eccentricity)is promising for designing small-caliber spin-stabilized projectiles.

关键词： Tiny mass eccentricity Small-caliber projectile Bullet Artificial intelligence algorithm Global sensitivity analyses Precision trials ANFIS Sobol’s algorithm

Theoretical and numerical investigations on the headspace of cartridge cases considering axial deformation and movement

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Defence Technology（防务技术） 2020年第1期16卷 88-95页

作者： Song Cai Chen-lei Huang Kun Liu Zhong-xin Li zhi-lin wu School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina

The cartridge case headspace is the axial clearance between the cartridge and bolt of an automatic weapon,and influences the reliability and security of the ***,theoretical and numerical studies were conducted to analyze the dynamic response of cartridge cases during internal impact considering the initial radial clearances between the cartridge case and chamber.A theoretical model was proposed to predict the cartridge case headspace considering both the deformation and movement of the cartridge case and confirmed by the results of nonlinear finite element *** differences between the results of the conventional static model and the dynamic model were then comprehensively *** effects of the angle between the cartridge and chamber,the cartridge case material,and the intermal impact pressure on the predicted headspace value were also *** dynamic response of the cartridge case predicted by the dynamic model was more accurate than that predicted by the conventional static *** internal impact pressure,pressure change rate,and cartridge material were all found to affect the predicted headspace.

关键词： Cartridge case headspace Radial clearance Thick-walled cylinder Dynamic response

Strain concentration caused by the closed end contributes to cartridge case failure at the bottom

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Defence Technology（防务技术） 2020年第6期16卷 1151-1159页

作者： Song Cai Jie Feng Hui Xu Kun Liu Zhong-xin Li zhi-lin wu School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094JiangsuChina

Ruptures at the bottom of cartridges are a common cause of failure of ammunitions,which directly threatens the safety of weapons and *** on plastic tube theory,this study analyses the radial and axial deformation of a cartridge,considering the radial constraint of the closed end at the bottom of the *** to the influence of the closed end,the bottom of a cartridge does not establish complete contact with the *** to strain concentration in the non-contact area,this area is more amenable to the occurrence of cartridge *** theory predicts the location of the fracture more accurately than the traditional *** maximum axial deformation of a cartridge comprises bending and friction *** maximum strain at the bottom of the cartridge increased by 135%owing to the introduction of bending strain caused by the closed *** strain distribution of a cartridge was measured using digital image correlation technology,and the measured result was consistent with the predicted results of the bending deformation theory and rupture *** effects of wall thickness,radial clearance,friction coefficient,and axial clearance on the axial deformation of the cylinder were *** the wall thickness and reducing radial clearance were found to reduce bending deformation;furthermore,lubrication and reduction in axial clearance reduce frictional deformation,which in turn reduce cartridge rupture.

关键词： Closed end Cartridge case failures Strain concentration Bending deformation

Delamination process in cross-ply UHMWPE laminates under ballistic penetration

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Defence Technology（防务技术） 2021年第1期17卷 278-286页

作者： Gen-lin Mo Qian-wen Ma Yong-xi Jin Wen-min Yan Zhong-xin Li zhi-lin wu Institute of Advanced Manufacturing Jiangsu UniversityZhenjiang212013China Key Laboratory of Transient Shock Beijing102202China Zhenjiang Hospital of Traditional Chinese Medicine 212013China School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094China

Cross-ply unidirectional laminates made of ultra-high molecular weight polyethylene fibers are widely used as components of bullet-proof *** simulate the delamination process of the material under penetration,we constructed a numerical mechanical model,which was validated by tests using 7.6239 mm rifle bullets penetrating laminates of different *** results show that the delamination region is essentially *** simulated delamination region is in good agreement with the experimental *** is found that the delamination region increases with the compression modulus along the fiber *** delamination region increases when the shear strength between the fabric layers decreases;However,it is little influenced by the normal *** delamination region of the front face of the laminate is little influenced by the failure strain of the material and the initial velocity of the *** delamination region of the back face increases with the failure strain and decreases with the initial velocity.

关键词： proof process modulus

Electrochemical regioselective synthesis of N-substituted/unsubstituted 4-selanylisoquinolin-1(2H)-ones

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Chinese Chemical Letters 2022年第3期33卷 1501-1504页

作者： zhi-lin wu Jin-Yang Chen Xian-zhi Tian Wen-Tao Ouyang Zhuo-Tao Zhang Wei-Min He School of Chemistry and Chemical Engineering University of South ChinaHengyang 421001China

A novel and efficient electro-chemical initiated radical strategy was developed for the preparation of both N-substituted and N-unsubstituted 4-selanylisoquinolin-1(2H)-ones through selenylation of isoquinolin-1(2H)-o... 详细信息

关键词： Organodiselenide Electrochemistry Radical Atom economy Additives-free

Anesthesia,Anesthetics,and Postoperative Cognitive Dysfunction in Elderly Patients

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Current Medical Science 2024年第2期44卷 291-297页

作者： Hong-yu ZHU Jian-li YAN Min ZHANG Tian-yun XU Chen CHEN zhi-lin wu Department of Anesthesiology Linhe District People's HospitalBayannur 015000China Department of Neurosurgery Xinzhou District People's HospitalWuhan 430408China Department of Anesthesiology Union HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430022China

Postoperative cognitive dysfunction(POCD)remains a major issue that worsens the prognosis of elderly surgery *** article reviews the current research on the effect of different anesthesia methods and commonly utilized anesthetics on the incidence of POCD in elderly patients,aiming to provide an understanding of the underlying mechanisms contributing to this condition and facilitate the development of more reasonable anesthesia protocols,ultimately reducing the incidence of POCD in elderly surgery patients.

关键词： anesthesia anesthetics postoperative cognitive dysfunction elderly patients

Visible-light-initiated malic acid-promoted cascade coupling/cyclization of aromatic amines and KSCN to 2-aminobenzothiazoles without photocatalyst

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Chinese Chemical Letters 2020年第7期31卷 1895-1898页

作者： Wei-Bao He Lan-Qing Gao Xin-Jie Chen zhi-lin wu Ying Huang Zhong Cao Xin-Hua Xu Wei-Min He Department of Chemistry Hunan UniversityChangsha 410082China Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation Changsha University of Science and TechnologyChangsha 410114China School of Chemistry and Chemical Engineering Hunan University of Science and TechnologyXiangtan 411201China School of Chemistry and Chemical Engineering University of South ChinaHengyang 421001China

By using ambient air as the oxidant and malic acid as the promoter,a practical method for the preparation of 2-aminobenzothiazoles through visible-light-initiated cascade reaction of aromatic amines and KSCN in eco-fr... 详细信息

关键词： Air Photocatalysis Cascade reaction Photocatalyst-free 2-Aminobenzothiazoles