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STUdY ON dYNAMIC J-INTEGRAL OF MECHANICAL HETEROGENEOUS WELdEd JOINT

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 934-939页

作者： F.q.Tian d.Y.He x.Y.Li Y.W.Shi d.Zhang InstituteofCompositeMaterials ShanghaiJiaotongUniversityShanghai200030China SchoolofMaterialsScienceandEngineering BeijingPolytechnicUniversityBeijing100022China

Welded joint is a mechanical heterogeneous body, and mechanical heterogeneity has great effect on dynamic fracture behaviour of welded joints. In the present investigation, dynamic response curve and dynamic J-integral of practical undermatched welded joint and whole base and whole weld three-point-bend (TPB) models containing longitudinal crack are com- puted. dynamic J-integral is evaluated using virtual crack extension (VCE) method and the computation is performed using MARC finite element code. Because of the effect of inertia, dynamic load response curve of computed model waves periodically. dynamic J-integral evaluated by VCE method is path independent. The effect of inertia has little influence on dynamic J-integral curve. The value of dynamic J-integral of undermatched welded joint is lower than that of whole base metal and higher than that of whole weld metal. The results establish the foundation of safety evaluation for dynamic loaded welded structures.

关键词： virtual crack extension welded joint dynamic response curve dynamic J-integral

ACTIVATION OF AB_2 TYPE Zr-BASEd HYdRIdE ELECTROdES

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Acta Metallurgica Sinica(English Letters) 1998年第2期11卷 107-110页

作者： x.G.Yang K.Y.Shu x.B.Zhang Y.q.Lei q.d.Wang W.K.Zhang G.L.Lu Zhejiang Univ Hangzhou China

The effect of La alloying on the crystalline characteristics, electrochemical capacity and activity of AB2 type Zr-Cr-Ni hydride electrodes was investigated. It was found that La alloying was able to shorten the activating process from 15 cycles of La-free alloy to 2 cycles, and that the main phase shifts from C14 to C15 by xRd analysis. It may be attributed to the modification of surface chemical states and change in internal microstructures. However, the cycling stability was also found to degrade severely for La-containing hydride electrode because of the collapse of its distorted lattice.

关键词： Zr-Cr-Ni hydrogen storage alloy La alloying electrode performance

FATIGUE CRACK GROWTH FEATURE OF Fe-Cr-Ni MATRIx COMPOSITE REINFORCEd BY TITANIUM CARBIdE PARTICULATE AT 1023K

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Acta Metallurgica Sinica(English Letters) 1999年第6期12卷 0-0,0-0+0-0页

作者： Z. F. Wan x.d. Hui G.q. Yuan Y. S. Yang x.C Chen Shandong University of Technology Jinan 250061 China Institute of Metal Research The Chinese Academy of Sciences Shenyang 110015 China Institute of Physics The Chinese Academy of Sciences Beijing 100080 China

The initiation and propagation of the short fatigue crack in a 10vol% titanium carbide particulate reichreed cast Fe-26Cr-14Ni mathe coopsite at 1023K were *** is shown that the titanium carbide particulate may hinder the crack propagation and fatigue fracture of the composite. The relationships between fatigue crack propagation rate and stress intensity factor are da/dN=4.2×10-c(△K)4 for the matrix alloy and da/dN=1.4×10-19(△K)c for the composite. The fatigue thresholds of the composite and mathe alloy are 78 and 3.2MPa.m1/2, respectively. Microcracks initiate at the intedece between titanium carbide particulate and austenite and then propagate in carkide particles. The fracture sudece of the composite shows a distinct transition from wavy and serated cleavage near the threshold regime to striation-type splitting in the stable fatigue crack propagation stage and to a veined morphology characteristic in unstable rapid region.

关键词： fatigue crack initiation and propagation Fe-Cr-Ni matrix composite titanium carbide particulate

A new model for the expansion tube considering the stress coupling:Theory,experiments and simulations

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defence Technology（防务技术） 2022年第7期18卷 1190-1204页

作者： M.Z.Wu x.W.Zhang q.M.Zhang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyHaidian DistrictBeijing10081China

Based on the two-arc profile assumption,the expansion deformation and energy absorption of circular tubes compressed by conical-cylindrical dies were ***,the deformation of the two arcs was analyzed independently and an improved model denoted as Model-I was ***,by further involving the coupling between the bending moment and membrane forces,a more elaborate model,i.e.,Model-II was ***,experiments and simulations were conducted to verify the models,which show that,compared with previous theoretical models,Model-II could not only capture the prominent features of the deformation,but also improve the prediction accuracy of the steady driving force *** means of this model,it was found that the critical semi-conical angle,which makes the driving force minimum,increases with the increase of the friction coefficient,expansion ratio as well as the radius/thickness ratio of the ***,the energy dissipation due to stretching is always greater than that of bending,while the friction dissipation can account for the largest proportion at small semi-conical angle or large friction *** a certain friction and die conditions,the specific energy absorption of expanded tubes can be much higher than that under progressive collapse mode.

关键词： Expansion Circular tube Stress coupling Strain hardening Energy absorption

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辽东地区金矿床成因与资源潜力

中国科学：地球科学 2024年第3期54卷 677-692页

作者：朱日祥杨进辉王功文曾庆栋薛国强徐涛李兴辉张朋雷达朱光中国科学院地质与地球物理研究所岩石圈演化国家重点实验室北京100029 中国地质大学(北京)地球科学与资源学院北京100083 中国地质调查局沈阳地质调查中心沈阳110034 合肥工业大学资源与环境工程学院合肥230009

华北东部广泛分布着与晚中生代克拉通破坏相关的金矿床,但不同地区金矿床在研究程度、成矿特征、探明储量等方面存在显著差异.华北东部的辽东具有与胶东相似的区域地质特征,并共同经历了晚中生代克拉通破坏作用,但其金成矿的理论研究和... 详细信息

华北东部广泛分布着与晚中生代克拉通破坏相关的金矿床,但不同地区金矿床在研究程度、成矿特征、探明储量等方面存在显著差异.华北东部的辽东具有与胶东相似的区域地质特征,并共同经历了晚中生代克拉通破坏作用,但其金成矿的理论研究和探明的黄金资源量却存在巨大差异.本文在分析研究辽东区域地质、中生代岩浆-构造演化和矿床地质基础上,通过深部-浅部综合地球物理探测和大数据AI资源量预测,提出了辽东晚中生代金元素富集主体来自于克拉通破坏诱发的幔源熔流体,金矿床主要受北东-北北东向断裂控制,金矿类型以破碎带蚀变岩型和含硫化物石英脉型为主.明确了鸭绿江主断裂带及相关的次级断裂、已知矿集区外围与深部是未来金矿资源勘查的重要区域,预测鸭绿江成矿带黄金资源潜力巨大,具备新增数千吨级黄金资源的潜力.

关键词：辽东金矿综合地球物理勘查找矿潜力找矿突破方向

Analysis of Convolution quadrature Applied to the Time-domain Electric Field Integral Equation

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Communications in Computational Physics 2012年第2期11卷 383-399页

作者： q.Chen P.Monk x.Wang d.Weile department ofMathematical Sciences University of DelawareNewarkDE 19716USA department of Electrical and Computer Engineering University ofDelawareNewarkDE 19716USA

We show how to apply convolution quadrature(Cq)to approximate the time domain electric field integral equation(EFIE)for electromagnetic *** a suitable choice of Cq,we prove that the method is unconditionally stable and has the optimal order of ***,the resulting semi discrete EFIE is dispersive and dissipative,and we analyze this ***,we present numerical results supporting and extending our convergence analysis.

关键词： Electromagnetism scattering time-domain integral equation EFIE convolution quadrature multistep method

Towards a unified nonlocal, peridynamics framework for the coarse-graining of molecular dynamics data with fractures

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Applied Mathematics and Mechanics(English Edition) 2023年第7期44卷 1125-1150页

作者： H.q.YOU x.xU Y.YU S.SILLING M.d'ELIA J.FOSTER department of Mathematics Lehigh UniversityBethlehemPA 18015U.S.A department of Petroleum and Geosystems Engineering The University of Texas at AustinTX 78712-1139U.S.A. Center for Computing Research Sandia National LaboratoriesCA 94551-0969U.S.A.

Molecular dynamics(Md)has served as a powerful tool for designing materials with reduced reliance on laboratory ***,the use of Md directly to treat the deformation and failure of materials at the mesoscale is still largely beyond *** this work,we propose a learning framework to extract a peridynamics model as a mesoscale continuum surrogate from Md simulated material fracture data ***,we develop a novel coarse-graining method,to automatically handle the material fracture and its corresponding discontinuities in the Md displacement data *** by the weighted essentially non-oscillatory(WENO)scheme,the key idea lies at an adaptive procedure to automatically choose the locally smoothest stencil,then reconstruct the coarse-grained material displacement field as the piecewise smooth solutions containing ***,based on the coarse-grained Md data,a two-phase optimizationbased learning approach is proposed to infer the optimal peridynamics model with damage *** the first phase,we identify the optimal nonlocal kernel function from the data sets without material damage to capture the material stiffness ***,in the second phase,the material damage criterion is learnt as a smoothed step function from the data with *** a result,a peridynamics surrogate is *** a continuum model,our peridynamics surrogate model can be employed in further prediction tasks with different grid resolutions from training,and hence allows for substantial reductions in computational cost compared with *** illustrate the efficacy of the proposed approach with several numerical tests for the dynamic crack propagation problem in a single-layer *** tests show that the proposed data-driven model is robust and generalizable,in the sense that it is capable of modeling the initialization and growth of fractures under discretization and loading settings that are different from the ones used during training.

关键词： nonlocal model machine learning homogenization peridynamics material fracture

WIdE-BANd LASER CLAddING: WEAR ANd CORROSION RESISTANCE OF A Ni-BASEd ALLOY

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Acta Metallurgica Sinica(English Letters) 1997年第5期10卷 445-452页

作者： Pan, q.Y. Huang, W.d. Li, Y.M. Lin, x. Zhou, Y.H. Yang, x.C. Northwestern Polytechnical Univ Xi'an China

A novel wide-band laser cladding system, with high rate of cladding, has been developed in the present work. The system mainly consisted of a 5kW CO2 laser, an automatic powder feeder and a wide-band scanning rotative polygon mirror which can produce a linear or rectangular focused laser beam. Using this system, a Ni-Cr-Si-B alloy powder was cladded on the surface of type 321 austenitic stainless steel in order to improve its wear and corrosion resistance. The pitting corrosion, high temperature oxidation and wear tests were conducted in order to evaluate the properties of the laser cladded layer. The results demonstrated that the cladded layer can significantly improve the adhesive wear and pitting corrosion resistance of the substrate. Moreover, the cladded layer exhibited good oxidation resistance, which is almost the same as that of GMR-235d Ni-based superalloy.

关键词： Boron Chromium alloys Cladding (coating) Laser applications Nickel alloys Silicon alloys Wear resistance

ExPERIMENTAL STUdY ON BEd RESISTANCE CHARACTERISTICS OF NONUNIFORM SEdIMENT

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Journal of Hydrodynamics 2000年第4期12卷 66-74页

作者： Zhou, G.d. Liu, q.Y. Wang, G.x. Hui, Y.J. Pang, d.M. Tsinghua Univ. Beijing 100084 China

Under natural circumstances, the bed of fluvial river is composed of nonuniform sediment, and its nonuniform property influences very much the bed resistance and flow characteristics. By using a one-dimensional laser velocimeter, flume experiments are carried out to analyze the resistance characteristics of open channel flow with the bed sediment composed of different representative particles and having different nonuniform properties. By means of separating factors, the factors affecting the bed resistance, including particle diameter, nonuniform property and flow conditions, are studied. A great number of laboratory test results and field data from other investigators have been analyzed.

关键词： Sediments