检索结果-南通市图书馆

A LOOP DRAWBEAD RESTRAINING FORCE MODEL IN SHEET METAL DEEP DRAWING PROCESS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2001年第5期14卷 380-386页

作者： y.j. Luo, S.P. Li, j.F. zheng, D.N. He, y.Q. Zhang, j.L. Cheng and j. y. jiang 1)National Mold & Die CAD Engineering Research Center, Shanghai 200030, China 2)Shanghai Volkswagen Automotive Company Ltd.(SVM), Shanghai 201805, China Shanghai jiaotong Univ. Shanghai 200030 China

In sheet metal forming, drawbeads are often used to control uneven material flow which may cause defects such as wrinkles, fracture, surface distortion and springback. Appropriate setting and adjusting the drawbead force is one of the most important pa- rameters in sheet metal forming process control. This paper derives the model of loop drawbead restraining force (DBRF) using plastic forming theory, and gives the min imum blankholding force. Experiments are carried out to verify the proposed DBRF model. The good agreement between the calculated values and experiments data justi- fies the proposed loop drawbead restraining force model.

关键词： drawbead restraining force sheet metal deep drawing

Simulation of Dynamic 3D Crack Propagation within the Material Point Method

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2017年第4期113卷 389-410页

作者： y.j.Guo j.A.Nairn Univ.of Utah Salt Lake CityUT 84112USA2119 Hillside Oak LnHoustonTX 77062USA Wood Science&Engineering Oregon State UniversityCorvallisOR 97330USA

This paper presents the principles and algorithms for simulation of dynamic crack propagation in elastic bodies by the material point method(MPM),from relatively simple two-dimensional cases to full three-dimensional,mixed-mode crack *** paper is intended to give a summary of the latest achievements on simulation of three-dimensional dynamic crack propagation,which is essentially an unexplored *** of the methodology presented in this paper to several dynamic crack propagation problems has shown that the MPM is a reliable and powerful approach for simulating three-dimensional,mixed-mode crack propagation.

关键词： Material point method (MPM) dynamic fracture crack propagation threedimensional cracks mixed-mode

Quantified evaluation of particle shape effects from micro-to-macro scales for non-convex grains

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2016年第2期14卷 23-35页

作者： y. yang j.F. Wang y.M. Cheng Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hong Kong China Department of Civil and Architectural Engineering City University of Hong Kong Hong Kong China

Particle shape plays an important role in both the micro and macro scales responses of a granular assem- bly. This paper presents a systematic way to interpret the shape effects of granular material during quasi-static shearing. A more suitable shape descriptor is suggested for the quantitative analysis of the macroscale strength indexes and contact parameters for non-convex grains, with special consid- eration given to the peak state and critical state. Through a series of numerical simulations and related post-processing analysis, particle shape is found to directly influence the strain localisation patterns, microscale fabric distributions, microscale mobilisation indexes, and probability distribution of the nor- malised contact normal force. Additionally, the accuracy of the stress-force-fabric relationship can be influenced by the average normal force and the distribution of contact vectors. Moreover, particle shape plays a more important role than do the confining pressures in determining the friction angle. Strong force chains and the dilation effect are also found to be strongly influenced by the high confinin~ oressure.

关键词： Quantitative analysis Shape factor Statistical analysis Micro-macro indexes

Incremental forming of free surface with magnesium alloy AZ31 sheet at warm temperatures

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2008年第A1期18卷 165-169页

作者： y.H.jI j.j.PARK Department of Mechanical and System Design Engineering Hongik University

The formabilityof AZ31 sheet begins to increase drastically at 150℃.The incremental forming technique was thus applied to AZ31 sheet at 150℃to utilize the formability to its fullest capacity at the lowest possible temperature for forming applications.A surface scanning technique was used followed by the tool path generation to incrementally form an egg *** thorough examination of various tool paths,the surface was most successfully produced by forming an intermediate shape followed by a series of tool *** scale stickers were devised to improve the accuracy in the measurement of grid deformation.

关键词：金属材料数控成形加工 AZ31镁合金板材

Sun's Log-concavity Conjecture on the Catalan–Larcombe–French Sequence

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2016年第5期32卷 553-558页

作者： james j.y.ZHAO Center for Applied Mathematics Tianjin University

Let {Pn},n≥0 denote the Catalan-Larcombe-French sequence, which naturally came from the series expansion of the complete elliptic integral of the first kind. In this paper, we prove the strict log-concavity of the sequence { n√Pn}n≥1, which was originally conjectured by Z. W. Sun. We also obtain the strict log-concavity of the sequence {n√Vn}n≥1, where {Vn}n≥0 is the Fennessey-Larcombe- French sequence arising from the series expansion of the complete elliptic integral of the second kind.

关键词： The Catalan-Larcombe-French sequence the Fennessey-Larcombe-French sequence logconcavity three-term recurrence relation

On the Bloch Constant for K-Quasiconformal Mappings in Several Complex Variables

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2001年第2期17卷 237-242页

作者： j. y. GAMALIEL Department of Mathematics. Nanjing Normal University. Nanjing 210097. P. R. China

We study the Bloch constant for K-quasiconformal holomorphic mappings of the unit ball B of Cn into Cn. The final result we prove in this paper is: If f is a K-quasiconformal holomorphic mapping of B into Cn such that det（f’（0））=1, then f（B） contains a schlicht ball of radius at least （CnK）1-n integral from n=0 to 1(（1+t）n-1/（1-t）2 exp{-（n+1）t/（1-t）}dt, where Cn>1 is a constant depending on n only, and Cn→101/2 as n→∞.

关键词： K-quasiconformal mapping Bloch constant

Two-stage Hall-Petch relationship in Cu with recrystallized structure

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2020年第13期47卷 31-35页

作者： y.Z.Tian y.P.Ren S.Gao R.X.zheng j.H.Wang H.C.Pan Z.F.Zhang N.Tsuji G.W.Qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Department of Materials Science and Engineering Kyoto UniversityYoshida-honmachiSakyo-kuKyoto 606-8501Japan Elements Strategy Initiative for Structural Materials(ESISM) Kyoto UniversityYoshida-honmachiSakyo-kuKyoto606-8501Japan Key Laboratory of Aerospace Advanced Materials and Performance of Ministry of Education School of Materials Science and EngineeringBeihang UniversityBeijing 100191China State Grid Urban and Rural Electric Power Design Research(Beijing)Co.Ltd Beijing 100078China Laboratory of Fatigue and Fracture for Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

Although Cu was studied extensively,the Hall-Petch relationship was mainly reported in the coarsegrained *** this work,fully recrystallized Cu specimens with a wide grain size regime of 0.51–14.93μm manifest a two-stage Hall-Petch *** is a critical grain size of 3μm that divides stagesⅠandⅡwhere the Hall-Petch slope k value are quite *** stageⅡis supposed to be validified down to 100 nm at least by comparing with a Cu-Ag *** critical grain size varies in different materials systems,and the underline mechanisms are discussed based on the dislocation glide modes.

关键词： Cu yield strength Hall-Petch relationship Ultrafine grain Recrystallization

Role of extrusion rate on the microstructure and tensile properties evolution of ultrahigh-strength low-alloy Mg-1.0Al-1.0Ca-0.4Mn(wt.%)alloy

在线全文

学校读者我要写书评

暂无评论

journal of Magnesium and Alloys 2023年第2期11卷 553-561页

作者： X.Q.Liu X.G.Qiao R.S.Pei y.Q.Chi L.yuan M.y.zheng School of Material Science and Engineering Harbin Institute of TechnologyHarbin 150001China Institut fur Metallkunde und Meterialphysik RWTH Aachen UniversityAachen D-52056Germany

Mg-1.0Al-1.0Ca-0.4Mn(AXM1104, wt.%) low alloy was extruded at 200 ℃ with an extrusion ratio of 25 and different ram speeds from 1.0 to 7.0 mm/s. The influence of extrusion rate on microstructure and mechanical properties of the AXM1104 alloy was systematically studied. With the increasing of extrusion rate, the mean dynamically recrystallized(DRXed) grain size of the low alloy and average particles diameter of precipitate second phases were increased, while the degree of grain boundary segregation and the intensity of the basal fiber texture were decreased. With the rising of extrusion rate from 1.0 to 7.0 mm/s, the tensile yield strength(TyS) of the as-extruded AXM1104 alloy was decreased from 445 MPa to 249 MPa, while the elongation to failure(EL) was increased from 5.0% to 17.6%. The TyS, ultimate tensile strength(UTS) and EL of the AXM1104 alloy extruded at the ram speed of 1.5 mm/s was 412 MPa, 419 MPa and 12.0%, respectively,exhibiting comprehensive tensile mechanical properties with ultra-high strength and excellent plasticity. The ultra-high TyS of 412 MPa was mainly due to the strengthening from ultra-fine DRXed grains with segregation of solute atoms at grain boundaries. The strain hardening rate is increase slightly with increasing extrusion speed, which may be ascribed to the increasing mean DRXed grain size with rising extrusion speed. The higher strain hardening rate contributes to the higher EL of these AXM1104 samples extruded at higher ram speed.

关键词： Mg-Al-Ca-Mn alloy Ultrafine grain Extrusion rate Grain boundary segregation Microstructure Ultrahigh strength

Nanocrystalline Ti49.2Ni50.8 shape memory alloy as orthopaedic implant material with better performance

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2019年第10期35卷 2156-2162页

作者： H.F.Li F.L.Nie y.F.zheng y.Cheng S.C.Wei R.Z.Valiev Department of Materials Science and Engineering College of EngineeringPeking UniversityBeijing 700877China Center for Biomedical Materials and Tissue Engineering Academy for Advanced Interdisciplinary StudiesPeking UniversityBeijing 100871China Department of Oral and Maxillofacial Surgery School of StomatologyPeking UniversityBeijing 100081China Institute of Physics of Advanced Materials Ufa State Aviation Technical UniversityUfaRussia Saint Petersburg State University Universitetskiy prospekt 28PeterhofSt.Petersburg198504Russia

Ti Ni alloys, with their unique shape memory effects and super elastic properties, occupy an indispensable place in the family of metallic biomaterials. In the past years, surface treatment is the main technique to improve the bioinert nature of microcrystalline Ti Ni alloys and inhibit on the release of toxic nickel ions to obtain excellent osteogenesis and osseointegration function. In the present study, nanocrystalline Ti49.2Ni50.8 alloy has been fabricated via equal channel angular pressing(ECAP), and the in vitro and in vivo studies revealed that it had enhanced cell viability, adhesion, proliferation, ALP(Alkaline phosphatase)activity and mineralization, and increased periphery thickness of new bone, in comparison to the commercial coarse-grained counterpart. These findings indicate that the reduction of grain size is beneficial to increasing the biocompatibility of Ti49.2Ni50.8 shape memory alloy.

关键词： Nanocrystallines Shape memory alloys Metallic biomaterials Orthopaedic implants TiNi alloys