检索结果-南通市图书馆

Numerical simulation of effect of rotational tool with screw on material flow behavior of friction stir welding of Ti6Al4V alloy

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

Acta Metallurgica Sinica(English Letters) 2012年第5期25卷 365-373页

作者： Shude JI Aili ZOU Yumei YUE Guohong L UAN Yanye JIN Fu LI Faculty of Aerospace Engineering Shenyang Aerospace University Shenyang 110136 China Beijing Aeronautical Manufacturing Technology Research Institute Beijing 100024 China

The rotational tool is put forward, which is composed of the one-spiral-flute shoul- der and the rotational pin with screw. Using the turbulent model of the FLUENT software, material plastic flow behavior during the process of friction stir welding of Ti6A14V alloy is researched by the numerical simulation method and then the effect of rotational tool geometry on material flow during the welding process is attained. The results show that the flow direction of the material near the rotational tool is mainly the same as the rotational direction of the tool while the material near tool flows more violently than the other regions. For the tapered rotational pin, the flow velocity of material inside the workpiece decreases with the increase of the distance away from the workpiece surface because of the change of pin diameter. For the rotational tool, the flute added to the shoulder and the screw added to the pin can greatly increase the flow velocity of material during the welding process while the peak value of the flow velocity of material appears on the flute or the screw. Moreover, the rotational tool with the one-spiral-flute shoulder is better than the tool with the concentric- circles-flute shoulder. Decreasing the width of pin screw and increasing the diameter of pin tip are both good for the increase of flow velocity.

关键词： Friction stir welding Titanium alloy plastic flow Numericalsimulation

Effects of Cr and Al Contents on the Preparation of SiC Fiber-Reinforced NiCrAl Alloy Matrix Composite

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2020年第10期33卷 1416-1422页

作者： Haoqiang Zhang Xixi Niu Zhiliang Pei Nanlin Shi Jun Gong Chao Sun Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China

In this work,the effects of Cr and Al contents on the preparation of SiC fiber-reinforced NiCrAl alloy matrix composites(SiCf/Ni-20Cr-5Al,SiCf/Ni-15Cr-5Al,SiCf/Ni-10Cr-5Al and SiCf/Ni-10Cr-3Al)were thoroughly *** composites were prepared by vacuum hot pressing process using matrix-coated *** was found that Cr solute atoms played a significant role in retarding the recrystallization of NiCrAl alloy matrix,and the Al elements in the form of γ'-Ni3Al phase had a suppression effect on the plastic flow of the ***,the reduction in Cr and Al contents was conductive to the recrystallization and plastic flow of NiCrAl alloy matrix,thereby reduced the size and number of micro-voids in the *** addition,this work provides some guidance for designing and manufacturing reasonable SiC fiber-reinforced Ni alloy matrix composites.

关键词： SiC fiber NiCrAl alloy Composite Recrystallization plastic flow

Friction Stir Welding of Al Alloy Thin Plate by Rotational Tool without Pin

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2011年第7期27卷 647-652页

作者： Liguo Zhang Shude Ji Guohong Luan Chunlin Dong Li Fu School of Aerospace Engineering Shenyang Aerospace University Shenyang 110136 China China FSW Center Beijing 100024 China Shenyang Aircraft Design & Research Institute Shenyang 110035 China State Key Laboratory for Manufacturing Systems Engineering Xi an Jiaotong University Xi an 710049 China

For friction stir welding （FSW）, a new idea is put forward in this paper to weld the thin plate of Al alloy by using the rotational tool without pin. The experiments of FSW are carried out by using the tools with inner-concave-flute shoulder, concentric-circles-flute shoulder and three-spiral-flute shoulder, respectively. The experimental results show that the grain size in weld nugget zone attained by the tool with three-spiral-flute shoulder is nearly the same while the grain sizes decrease with the decrease of welding velocity. The displacement of material flow in the heat-mechanical affected zone by the tool with three-spiral-flute shoulder is much larger than that by the tool with inner-concave-flute shoulder or concentric-circles–flute shoulder. The above-mentioned results are verified by numerical simulation. For the tool with three-spiral-flute shoulder, the tensile strength of FSW joint increases with the decrease of welding velocity while the value of tensile strength attained by the welding velocity of 20 mm/min and the rotation speed of 1800 r/min is about 398 MPa, which is 80% more than that of parent mental tensile strength. Those verify that the tool with three-spiral-flute shoulder can be used to join the thin plate of Al alloy.

关键词： Friction stir welding Rotational tool without pin Shoulder shape plastic flow

Recent progress in studies of experimental rock mechanics and tectonophysics in China

在线全文

学校读者我要写书评

暂无评论

Acta Seismologica Sinica(English Edition) 2003年第5期16卷 561-567页

作者：马胜利马瑾 Laboratory of Tectonophysics Institute of GeologyChina Seismological Bureau

This paper reviews the recent progress in the studies of experimental rock mechanics and tectonophysics concerning seismology and physics of the Earths interior in China. The progress is presented in the following aspects: a) A lot of results of experiment and numerical simulation enrich our knowledge of the brittle fracturing process under the condition with heterogeneity in material and structure; b) Some new results on frictional behavior of non-homogeneous faults reveal the complexity of faulting behavior; c) Some new results on the brittle-plastic transition and plastic flow are obtained; especially the important progress is obtained on rheological properties of rocks in the lower crust and the upper mantle; d) A lot of experimental results are obtained on rock physics at high temperature and pressure and have been used in study of material composition and state. These results provide useful information for understanding the physical properties and deformation mechanisms of material of the Earths interior and earthquake physics.

关键词： brittle fracture fault friction plastic flow rock physics earthquake mechanism

STUDY ON flow STRESS OF 7022 ALUMINUM ALLOY SHEET UNDER DIFFERENT TEMPERATURES AND STRAIN RATES

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2010年第3期27卷 248-254页

作者：汪洪峰左敦稳黄铭敏陈明和缪宏南京航空航天大学机电学院

Warm tensile tests for aluminum alloy 7022 sheet are held at different temperatures and strain rates. The range of temperature is 293-773 K and that of the strain rate is 0. 001-0.1 s^-1. The warm tensile properties,relations among temperature,strain rate,and the flow stress are discussed. Constitutive equations under the warm tension are obtained based on revised Hooke law and Grosman equation. It is concluded that flow stress declines with the increase of the temperature and the decrease of the strain rates. The elongation percentage increases with the increase of the temperature and the decrease of strain rate.

关键词： constitutive equations plastic flow elastic-plastic warm tension 7022 aluminum alloy

INSTANTANEOUS THERMAL EXPANSION BEHAVIOR OF HETEROGENEOUS MATERIALS WITH A WORK-HARDENING ELASTOplastic MATRIX AND ELASTIC SPHEROIDAL INHOMOGENEITIES

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 1995年第3期8卷 202-219页

作者： ZHANG, QJ NAN, CW YUAN, RZ WUHAN UNIV TECHNOL STATE KEY LAB MAT SYNTH & PROCWUHAN 430071PEOPLES R CHINA

The instantaneous thermal expansion behavior of-two-phase heterogeneous materials subjected to a uniform temperature change is explored in the present study. The matrix phase is assumed to be a work-hardening ductile metal and the dispersive phase is assumed to consist of either aligned or randomly-oriented, elastic,, spheroidal inhomogeneities. The plastic flow and decreasing stiffness of the matrix during Eshelby's transformation strain of the equivalent inclusions are accounted for by using the deformation theory of plasticity. The explicit results of the instantaneous overall thermal expansion coefficients and the critical inelastic temperature changes are presented for aligned disc- and fiber-inclusions. For the spherical and randomly-oriented spheroidal inclusion, the present study demonstrates that when the yielding of the composites is governed by the average matrix stress, the overall response is always elastic in spite of the temperature change.

关键词： WORK-HARDENING plastic flow AVERAGE MATRIX STRESS

ON NONPROPORTIONAL CYCLIC plastic BEHAVIOR OF STEEL 40

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 1995年第1期8卷 84-93页

作者： Cai Lixun Yang Xianjie, Southwest Jiaotong University, Chengdu 610031, P. R. China Southwest Jiaptomg University Chengdu 610031 P. R. China

An experimental investigation was carried out on the flow characteristic and hardening of steel 40 subjected to complex combined axial-torsional cyclic straining. For a specific cyclic strain path, the steel has mainly cyclic softening behavior when the strain amplitude is small. While with an increase of the effective strain amplitude, the softening becomes small, but there is the cyclic softening even though the steel is subjected to the cyclic loading by a square strain path. However, the steel has cyclic additional hardening by a nonproportional path, compared with the proportional cycling. Generally, the additional hardening is small and its historical effect is not obvious at small strain amplitude. The additional hardening is remarkable by a cross-triangular strain path of large strain amplitude. The memory of the history of nonproportional cyclic loading, the direction of plastic flow and the plastic modulus of the steel were also studied.

关键词： steel 40 nonproportional cyclic loading plastic flow hardening softening

Evaluation of embankment foundation creep in conditions of deep bedding of roof in permafrost soils

在线全文

学校读者我要写书评

暂无评论

Research in Cold and Arid Regions 2013年第5期5卷 534-539页

作者： Evgeny Ashpiz Lev Khrustalev Department of Track and Track Facilities Moscow State University of Railway Department of Geology Lenynskie goryLomonosow Moscow State University

Railroad operating experience in permafrost conditions has shown that deformations of embankments on thawing foun- dations last for a long time. After an initial period of heat settlement due to permafrost degradation, the determining factor is the plastic flow of seasonal thawed soils of the foundation upper layer under the embankment. This paper provides a method to evaluate these deformations, and calculation examples using data from line sections of the Chum-Labytnangi Railway in northwestern Russia. It also discusses several methods of embankment stabilization, including the use of ver- tical thermosiphons.

关键词： permafrost railway plastic flow embankment stabilization methods thermosiphons

Depinning Dynamics of Fluid Monolayer on a Quenched Substrate

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2010年第11期 893-896页

作者：曹义刚刘嘉付根义 School of Physics and Engineering Zhengzhou University

Langevin simulations are preformed on the depinning dynamics of fluid monolayer on a quenched substrate. With increase in the strength of the substrate, we find for the first time a crossover from elastic crystal to smectic flows as well as a crossover from smectic to plastic flows above the depinning. A power-law scaling relationship can be derived between the drift velocity and the driving force for both the elastic crystal and smectic flows, but fails to be obtained for the plastic flow. The power-law exponents are found to be no larger than 1 for the elastic crystal flow and larger than 1 for the smeetic flow. The critical driving force and the averaged intensity of Bragg peaks remain invariant basically in the regime of smectic flow. A sudden increase in the critical driving force is observed within the crossover from the smeetic to plastic flows, and the averaged intensity of Bragg peaks shows sudden decreases within the crossovers both from the elastic crystal to smectic flows and from the smectic to plastic flows. The results are helpful for understanding the slip dynamics of fluids on a molecular level.

关键词： fluid elastic crystal flow smectic flow plastic flow