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Effect of welding current on morphology and microstructure of Al alloy T-joint in double-pulsed MIG welding 被引量:12
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作者 易杰 曹淑芬 +2 位作者 李落星 郭鹏程 刘开勇 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第10期3204-3211,共8页
The effect of current on the morphology of Al alloy T-joint in double-pulsed metal inert gas(DP-MIG) welding process was investigated by simulation and experiment.A three-dimensional finite element model and the DP-... The effect of current on the morphology of Al alloy T-joint in double-pulsed metal inert gas(DP-MIG) welding process was investigated by simulation and experiment.A three-dimensional finite element model and the DP-MIG heat source of double-ellipsoidal volumetric model were developed to simulate the temperature and stress fields under different welding conditions.The macro-morphology and microstructure of welding joints at the corresponding currents were observed in the experiment.The results show that the best condition is at an average current of 90 A and current difference of 40 A,when the maximum temperature is 200 °C higher than the fusion points,with the temperature difference of about 100 °C and stress change of 10 MPa between thermal pulse and thermal base.Under these conditions,Al alloy T-joint with proper fusion condition has smooth fish-scale welding appearance and finer microstructure.Furthermore,the thermal curves and stress distribution in the experiment are consistent with those in the simulation,verifying the precision of the welding simulation. 展开更多
关键词 double-pulsed MIG welding Al alloy t-joint welding current STRESS
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Bending properties and fracture mechanism of C/C composites with high density preform 被引量:9
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作者 张明瑜 苏哲安 +1 位作者 李建立 黄启忠 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第8期1795-1800,共6页
C/C composites with banded structure pyrocarbon were fabricated by fast chemical vapor infiltration(CVI),with C3H6 as carbon source,N2 as carrier gas,and three-dimensional(3D) 12K PAN-based carbon fabric with high... C/C composites with banded structure pyrocarbon were fabricated by fast chemical vapor infiltration(CVI),with C3H6 as carbon source,N2 as carrier gas,and three-dimensional(3D) 12K PAN-based carbon fabric with high density of 0.94 g/cm3 as preform.Experimental results indicated that the fracture characteristics of C/C composites were closely related to the frequency of high-temperature treatment(HTT) at the break of CVI process.According to the load?displacement curves,C/C composites showed a pseudoplastic fracture after twice of HTT.After three times of HTT,load?displacement curves tended to be stable with a decreasing bending strength at 177.5 MPa.Delamination failure and intrastratal fiber fracture were observed at the cross-section of C/C composites by scanning electronic microscope.Because the content of pyrocarbon and fibers has a different distribution in layers,the C/C composites show different fracture characteristics at various regions,which leads to good toughness and bending strength. 展开更多
关键词 C/C composites chemical vapor infiltration(CVI) high density preform bending properties fracture mechanism
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Formation, microstructure and mechanical properties of double-sided laser beam welded Ti-6Al-4V T-joint 被引量:4
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作者 马旭颐 巩水利 +2 位作者 张久兴 芦伟 杨璟 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第3期729-735,共7页
The T-joints of Ti?6Al?4V alloy were manufactured by double-sided synchronized laser beam welding with the homologous filler wire. The formation, microstructure and mechanical properties of welded joints as well as th... The T-joints of Ti?6Al?4V alloy were manufactured by double-sided synchronized laser beam welding with the homologous filler wire. The formation, microstructure and mechanical properties of welded joints as well as the correlations of each other were investigated. The results indicate that the quality of weld seams is good without defects such as discontinuity, beading, visible cracks or porosity, which is linked to the steady molten pool behavior and droplet transition. The morphologies of the heat affected zone (HAZ) located on the skin and stringer are disparate. The microstructure of the HAZ and fusion zone (FZ) is mainly comprised of acicular martensiticα′ phases. The microhardness of the HAZ and FZ is higher than that of the base metal (BM) and reaches a maximum value at the HAZ near FZ on the stringer. The tensile specimens along the skin and stringer fractured at the BM with ductile fracture surfaces. 展开更多
关键词 Ti-6Al-4V alloy double-sided laser beam welding t-joint high-speed photography microstructure mechanical property
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Sensitivity Analysis Based Multiple Objective Preform Die Shape Optimal Design in Metal Forging 被引量:10
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作者 Xinhai ZHAO Guoqun ZHAO Guangchun WANG Tonghai WANG 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2006年第2期273-278,共6页
The multiple objective preform design optimization was put forward. The final forging's shape and deformation uniformity were considered in the multiple objective. The objective is to optimize the shape and the defor... The multiple objective preform design optimization was put forward. The final forging's shape and deformation uniformity were considered in the multiple objective. The objective is to optimize the shape and the deformation uniformity of the final forging at the same time so that a more high integrate quality of the final forging can be obtained. The total objective was assembled by the shape and uniformity objective using the weight adding method. The preform die shape is presented by cubic B-spline curves. The control points of B-spline curves are used as the design variables. The forms of the total objective function, shape and uniformity sub-objective function are given. The sensitivities of the total objective function and the sub-objective functions with respect to the design variables are developed. Using this method, the preform die shape of an H-shaped forging process is optimally designed. The optimization results are very satisfactory. 展开更多
关键词 FORGING preform Sensitivity SHAPE Deformation uniformity
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Optimal Preform Die Design through Controlling Deformation Uniformity in Metal Forging 被引量:2
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作者 XinhaiZHAO GuoqunZHAO +1 位作者 GuangchunWANG TonghaiWANG 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2002年第5期465-467,共3页
A finite element based sensitivity analysis method for preform die shape design in metal forging is developed. The optimization goal is to obtain more uniform deformation within the final forging by controlling the de... A finite element based sensitivity analysis method for preform die shape design in metal forging is developed. The optimization goal is to obtain more uniform deformation within the final forging by controlling the deformation uniformity. The objective function expressed by the effective strain is constructed. The sensitivity equations of the objective function, elemental volume, elemental effective strain rate and the elemental strain rate with respect to the design variables are constituted. The preform die shapes of an H-shaped forging process in axisymmetric deformation are designed using this method. 展开更多
关键词 Metal forging preform design Sensitivity analysis DEFORMATION STRAIN
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Insight into the preformed albumin corona on in vitro and in vivo performances of albumin-selective nanoparticles 被引量:3
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作者 Zhenbao Li Dan Li +3 位作者 Wenjuan Zhang Peng Zhang Qiming Kan Jin Sun 《Asian Journal of Pharmaceutical Sciences》 SCIE 2019年第1期52-62,共11页
Preformed albumin corona of albumin-nonselective nanoparticles(NPs)is widely exploited to inhibit the unavoidable protein adsorption upon intravenous administration.However,very few studies have concerned the preforme... Preformed albumin corona of albumin-nonselective nanoparticles(NPs)is widely exploited to inhibit the unavoidable protein adsorption upon intravenous administration.However,very few studies have concerned the preformed albumin corona of albumin-selective NPs.Herein,we report a novel type of albumin-selective NPs by decorating 6-maleimidocaproyl polyethylene glycol stearate(SA)onto PLGA NPs(SP NPs)surface,taking albuminnonselective PLGA NPs as control.PLGA NPs and SP NPs were prepared by emulsion-solvent evaporation method and the resultant NPs were in spherical shape with an average diameter around 180 nm.The corresponding albumin-coating PLGA NPs(PLGA@BSA NPs)and albumin-coating SP NPs(SP@BSA NPs)were formulated by incubating SP NPs or PLGA NPs with bovine serum albumin solution,respectively.The impact of albumin corona on particle characteristics,stability,photothermal effect,cytotoxicity,cell uptake,spheroid penetration and pharmacokinetics was investigated.In line with previous findings of preformed albumin coating,PLGA@BSA NPs exhibited higher stability,cytotoxicity,cell internalization and spheroid penetration performances in vitro,and longer blood circulation time in vivo than those of albumin-nonselective PLGA NPs,but albumin-selective SP NPs is capable of achieving a comparable in vitro and in vivo performances with both SP@BSA NPs and PLGA@BSA NPs.Our results demonstrate that SA decorated albumin-selective NPs pave a versatile avenue for optimizing nanoparticulate delivery without preformed albumin corona. 展开更多
关键词 preformED ALBUMIN CORONA Albumin-nonselective PLGA NPS Albumin-selective SP NPS In vitro and in vivo performances
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Effect of Mg and Si on infiltration behavior of Al alloys pressureless infiltration into porous SiCp preforms 被引量:10
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作者 Shu-bin Ren Xiao-yu Shen Xuan-hui Qu Xin-bo He 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2011年第6期703-708,共6页
The effect of Mg and Si additon to Al matrix on infiltration kinetics and rates of Al alloys pressureless infiltration into porous SiCp preform was investigated by observing the change of infiltration distance with ti... The effect of Mg and Si additon to Al matrix on infiltration kinetics and rates of Al alloys pressureless infiltration into porous SiCp preform was investigated by observing the change of infiltration distance with time as the Al alloys infiltrate into SiCp preforms at different temperatures.The results show that infiltration of SiCp preforms by Al melt is a thermal activation process and there is an incubation period before the infiltration becomes stable.With the increase of Mg content in the Al alloys from 0wt% to 8wt%,the infiltration will become much easier,the incubation period becomes shorter and the infiltration rate is faster,but these effects are not obvious when the Mg content is higher than 8wt%.As for Si addition to the Al alloys,it has no obvious effect on the incubation period,but the infiltration rate increases markedly with the increase of Si content from 0wt% to 12wt% and the rate has no obvious change when the content is bigger than 12wt%.The effect of Mg and Si on the incubation period is related to the infiltration mechanism of Al pressureless infiltration into SiCp preforms and their impact on the infiltration rate is a combined result from viscosity and surface tension of Al melt and SiC-Al wetting ability. 展开更多
关键词 metallic matrix composites infiltration aluminum alloys silicon carbide preforms
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Numerical simulation of temperature fields for T-joint during TIG welding of titanium alloy 被引量:7
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作者 王敏 董志波 +1 位作者 于澜 魏艳红 《China Welding》 EI CAS 2008年第3期6-9,共4页
Three-dimensional finite element model was established to simulate temperature fields of T-joint titanium sheets during TIG welding with finite element method (FEM) software. Temperature dependent material propertie... Three-dimensional finite element model was established to simulate temperature fields of T-joint titanium sheets during TIG welding with finite element method (FEM) software. Temperature dependent material properties and the effect of latent heat were considered. A technique of element birth and death was used to simulate the process of welded metal filling. Dynamic variation process of temperature fields during T1G welding was achieved. The simulated results agreed well with the measured results. 展开更多
关键词 TIG welding TITANIUM t-joint temperature field finite element method
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Mechanical Properties of the Cured Laminates on the Hot-press Tackified Preforms in Vacuum Assisted Resin Transfer Molding 被引量:1
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作者 王长春 叶金蕊 +3 位作者 YUE Guangquan BAI Guanghui LIU Ling ZHANG Boming 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2018年第1期242-248,共7页
A hot-press tackified preform was used to improve the uniformity of the laminates thickness and the mechanical properties of the obtained laminates were studied using vacuum assisted resin transfer molding(VARTM). T... A hot-press tackified preform was used to improve the uniformity of the laminates thickness and the mechanical properties of the obtained laminates were studied using vacuum assisted resin transfer molding(VARTM). Two modified preforms were prepared under 0.1 and 0.6 MPa in an autoclave and then were used to fabricate the laminates via VARTM. Permeability and thickness distribution of the laminates were obtained by using a special device. Moreover, the tensile and compressive strengths of the obtained laminates were studied and compared with the unmodified ones. Results show that the tackified laminates present a maximum and minimum thickness under 0.1 and 0.6 MPa, respectively. The thicknesses and in-plane permeability of the tackified laminates, with better thickness uniformity, are significantly decreased compared with that of the unmodified cases, while the tensile and compressive strengths of the tackified laminates are improved obviously. Results show that the mechanical property of the tackified laminates prepared by hotpressing at 0.1 MPa is better than that processed at 0.6 MPa. 展开更多
关键词 hot-press tackified preforms thickness uniformity mechanical property PERMEABILITY VARTM
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Die sinter bonding in air using copper formate preform for formation of full-density bondline 被引量:3
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作者 Yun-Ju LEE Jong-Hyun LEE 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第6期1717-1728,共12页
Pressure-assisted sinter bonding was performed in air at 250−350℃ using a preform comprising copper formate particles to form a bondline that is sustainable at high temperatures.H2 and CO generated concurrently by th... Pressure-assisted sinter bonding was performed in air at 250−350℃ using a preform comprising copper formate particles to form a bondline that is sustainable at high temperatures.H2 and CO generated concurrently by the pyrolysis of copper formate at 210℃ during the sinter bonding removed the native oxide and other oxides grown on bulk Cu finishes,enabling interface bonding.Moreover,Cu produced in situ by the reduction of Cu(II)accelerated the sinter bonding.Consequently,the bonding achieved at 300−350℃ under 5 MPa exhibited sufficient shear strength of 20.0−31.5 MPa after 180−300 min of sinter bonding.In addition,an increase in pressure to 10 MPa resulted in shear strength of 21.9 MPa after an extremely short time of 30 s at 250℃,and a near-full-density bondline was achieved after 300 s.The obtained results indicate the promising potential of the preform comprising copper formate particles for high-speed sinter bonding. 展开更多
关键词 structural materials microstructure mechanical properties copper formate preform sinter bonding PYROLYSIS
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Design,preparation,and structure of particle preforms for Si_3N_(4(P))/Si_3N_4 radome composites prepared using chemical vapor infiltration process 被引量:1
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作者 Yongsheng Liu Laifei Cheng Litong Zhang Yongdong Xu Yi Liu 《Journal of University of Science and Technology Beijing》 CSCD 2008年第1期62-66,共5页
A particle preform was designed and prepared by conglomerating and cold-pressed process, which was condensed by chemical vapor infiltration (CVI) process to fabricate silicon nitride particles reinforced silicon nit... A particle preform was designed and prepared by conglomerating and cold-pressed process, which was condensed by chemical vapor infiltration (CVI) process to fabricate silicon nitride particles reinforced silicon nitride composites. The conglomerations are of almost sphericity after conglomerated. There are large pores among the conglomerations and small pores within themselves in the preform according to the design and the test of pore size distribution. The pore size of the preform is characterized by a double-peak distribution. The pore size distribution is influenced by conglomeration size. Large pores among the conglomerations still exist after infiltrated Si3N4 matrix. The conglomerations, however, are very compact. The CVI Si3N4 looks like cauliflowershaped structure. 2008 University of Science and Technology Beijing. All rights reserved. 展开更多
关键词 silicon nitride particle preform DESIGN microstructure chemical vapor infiltration (CVI)
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Spinel Castables for Steel Ladle Lining:In-Situ Versus Preformed 被引量:1
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作者 Andreas BUHR Marion SCHNABEL +3 位作者 LONG Bin Reinhard EXENBERGER Christian RAMPITSCH Jerry DUTTON 《China's Refractories》 CAS 2012年第3期7-15,共9页
The paper discusses the difference in the formulation concepts of alumina - spinel (spinel containing ) and alumina - magnesia ( spin, el forming) castables and the influence on their physical properties. The indi... The paper discusses the difference in the formulation concepts of alumina - spinel (spinel containing ) and alumina - magnesia ( spin, el forming) castables and the influence on their physical properties. The individual property profile is discussed with respect to the requirements of refactory lining materials for the different zones of a steel ladle. 展开更多
关键词 in-situ spinel preformed spinel steel ladle lining
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Infiltration of A6063 aluminium alloy into SiC-B_4C hybrid preforms using vacuum assisted block mould investment casting technique 被引量:2
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作者 Alptekin KISASOZ Kerem Altug GULER Ahmet KARAASLAN 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第7期1563-1567,共5页
Production of A6063/SiC-B4C hybrid composite using vacuum assisted block mould investment casting was investigated. Firstly,SiC-B4C hybrid preforms were fabricated in cylindrical shape.The preferred mean particle size... Production of A6063/SiC-B4C hybrid composite using vacuum assisted block mould investment casting was investigated. Firstly,SiC-B4C hybrid preforms were fabricated in cylindrical shape.The preferred mean particle size of the SiC and B4C powders were 60μm and 55μm respectively.In early experiments,single powder ratio of 85%SiC and 15%B4C was selected to produce the tough preforms.Subsequently,the preforms were placed into the cylindrical shape gypsum bonded block investment moulds and A6063 alloy was infiltrated into the preforms using vacuum assisted(-10 5 Pa)casting machine.Porosity fraction of preforms was determined using Archimedes’test.The fabricated cast specimens were characterized using hardness tests,image analysis and SEM observations and EDX analysis.The result indicates that,by the vacuum assisted block mould investment casting technique,the infiltration of the preforms by molten metal was successfully realized. 展开更多
关键词 AlMMC SIC B4C investment casting hybrid preform
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Development and Characterization of Fe-Based Friction Material Made by Hot Powder Preform Forging for Low Duty Applications 被引量:1
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作者 A.A.S. Ghazi K. Chandra P.S. Misra 《Journal of Minerals and Materials Characterization and Engineering》 2011年第13期1205-1212,共8页
This present paper investigates the friction and wear properties of friction material developed by ‘Hot Powder Preform Forging’ technique. The conventional technique to manufacture Metallo-ceramic brake pads was suc... This present paper investigates the friction and wear properties of friction material developed by ‘Hot Powder Preform Forging’ technique. The conventional technique to manufacture Metallo-ceramic brake pads was successfully and economically tried to replace the above process. Compacting and sintering technology suffers from certain major limitations such as inadequate joining of friction element with backing plate, poor density levels achieved in friction element owing to limited application of pressure during compacting, poor thermal conductivity due to high levels of porosity in the product, poor strength due to segregation of the impurities along prior particle boundaries (PPB’s) and, wide variations in final characteristics due to large number of variables involved. In contrast to these limitations, the present technique can offer brake pads of much simpler chemistry but with improved performance on account of simultaneous application of pressure and temperature and with better control of variables. Fade and recovery studies were carried out on a Krauss machine tester following the Economic Commission for Europe Regulation for replacement brake linings (ECE R-90). μfade, μrecovery, μperformance, % age fade , % age recovery & temperature rise lie within the range for friction materials used for low duty applications. The mechanical properties of these materials were characterized using ASTM standards. 展开更多
关键词 Friction material preform FORGING Brake PADS Fade.
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Effect of initiation manners on the scattering characteristics of semi-preformed fragment warhead 被引量:6
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作者 Xu-yang Wang Xiang-shao Kong +1 位作者 Cheng Zheng Wei-guo Wu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2018年第5期578-584,共7页
The lethality of a semi-preformed fragment warhead is closely related to the expand velocity and spatial distribution of the fragments from ruptured metal casing. The topic of how to improve the utilization of charge ... The lethality of a semi-preformed fragment warhead is closely related to the expand velocity and spatial distribution of the fragments from ruptured metal casing. The topic of how to improve the utilization of charge of have been drawing great attention from researchers and designer in this filed. In present paper,in order to investigate the influence of charge initiation manners on the scattering characteristics of semi-preformed fragment warhead, the numerical simulations and experimental test are conducted.Firstly, the influence of grid density on numerical results is investigated, and a proper numerical model with relatively high accuracy and effectiveness is determined. Then. numerical simulations of three kinds of different initiation position of a semi-preformed fragment warhead are carried out. An experimental test of the explosion of a semi-preformed fragment warhead is carried out. By comparing and analyzing the numerical results and experimental data, it is found that the initiation manners have great influence on scattering characteristics of semi-preformed fragment warhead. The researcher work of this paper would provide an effective alternative method to optimize the design of warhead. 展开更多
关键词 INITIATION MANNERS Semi-preformed FRAGMENT WARHEAD Deformation pattern
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Model of Preformed Hole-Pairs in c-Axis Transport in Cuprate Superconductors 被引量:1
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作者 Rana Janardan Singh 《World Journal of Condensed Matter Physics》 2012年第4期228-236,共9页
Model of hole-pairs in electrical transport along ab plane in cuprate superconductors has already been proposed. It has been found to be in the shape of 3dx2–y2 orbital of an electron in an atom. This time, model of ... Model of hole-pairs in electrical transport along ab plane in cuprate superconductors has already been proposed. It has been found to be in the shape of 3dx2–y2 orbital of an electron in an atom. This time, model of hole-pairs in transport along c-axis in cuprate superconductors is proposed. In ab-plane, hole-pairs are formed along CuO2 plane;one hole-pair covering 9 - 10 two dimensional CuO2 unit cells in 3dx2–y2 configuration. In the investigation of c-axis hole-pairs, cuprate superconductors have been sub-divided into three categories depending on the number of CuO2 planes/formula unit. There is a little different treatment for finding out the order parameter in each category. Coherence lengths along ab-planes are of the order of a few tens of Angstroms, whereas along c-axis, they are less than even their a-, b-lattice constants. In cuprates with 2 or 3 CuO2 planes, the order parameter is of 3dz2–x2 type in zx-plane with lobes along both the axes much constrained. For cuprates with a single CuO2 layer, the order parameter is of 3dx2–y2 type, but its dimensions are less than a-, b-lattice constants. 展开更多
关键词 CUPRATE SUPERCONDUCTORS preformED Hole-Pairs Electron PARAMAGNETIC Resonance 41 meV Peak in Neutron Diffraction
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Void Morphology in 3-D Braided Preform/phenolic Composites 被引量:1
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作者 吴晓青 郭启微 《Journal of Donghua University(English Edition)》 EI CAS 2009年第5期539-543,共5页
Improved Resin Transfer Molding (RTM) technology and equipment were established.Void content and morphology of the 3-D braided preform/phenolic composite were investigated using different RTM processes.The results sho... Improved Resin Transfer Molding (RTM) technology and equipment were established.Void content and morphology of the 3-D braided preform/phenolic composite were investigated using different RTM processes.The results showed that void content of the vacuum and compression co-assisted RTM process was the lowest.Void morphologies of the specimen cross-section were analyzed with metallographic microscope.In traditional RTM process,the crack of cross-section was in evidence.In vacuum assisted RTM process,the void shape was divided into three categories:irregular crack,triangle,rotundity and ellipse.The most voids distributed in resin rich areas and were observed as large void based on equivalent diameter.In compression assisted RTM,vacuum and compression co-assisted RTM process,the polygonal voids mostly existed inter tows.Void size was mainly intermediate and small based equivalent diameter separately. 展开更多
关键词 3-D braided preform phenolic resin void morphology RTM
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A Geometric Model of Multiaxial Warp-knitted Preform for Composite Reinforcement 被引量:1
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作者 周荣星 李炜 +1 位作者 陈南梁 冯勋伟 《Journal of Donghua University(English Edition)》 EI CAS 2003年第1期8-14,共7页
A new geometric model of Multiaxial Warp-Knitted (MWK) performs, which is based on the experimental observations and analysis of basic stitch, is developed to relate the geometric parameters and process variables. The... A new geometric model of Multiaxial Warp-Knitted (MWK) performs, which is based on the experimental observations and analysis of basic stitch, is developed to relate the geometric parameters and process variables. The fiber volume fraction and fibre orientation of MWK reinforced composites are described in terms of structural and processing parameters in the model. And this model provides a basis for the prediction of mechanical behavior of the MWK reinforced composites. 展开更多
关键词 Multiaxial Warp-Knitted (MWK) preforms geometric model basic stitch double loop pillar stitch.
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Experimental and Finite Element Analysis of a T-Joint Welding 被引量:1
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作者 Rabih Kamal Kassab Henri Champliaud +2 位作者 Ngan Van Le Jacques Lanteigne Marc Thomas 《Journal of Mechanics Engineering and Automation》 2012年第7期411-421,共11页
This paper presents the Finite Element (FE) modeling of a two-seam welding process for a T-joint with a V chamfer preparation: The aim of the model is to predict the deformations, distortions and residual stresses ... This paper presents the Finite Element (FE) modeling of a two-seam welding process for a T-joint with a V chamfer preparation: The aim of the model is to predict the deformations, distortions and residual stresses resulting from the welding of the plates and experiments have been carried out in order to compare to the FE model. The "birth and death" method is used in ANSYS to simulate the filler metal deposition and the heat generation and weld pool simulation are conducted accordingly with the double ellipsoid configuration as proposed by Goldak et al. The model takes into consideration the temperature dependent non-linear material properties and uses a new formulation to compute the temperature dependent combined coefficient of heat loss. Improvements in the calculation are achieved by combining two types of meshing. The FE simulation is divided into two consecutive parts: the thermal simulation followed by the structural simulation. The results of the numerical model are compared to experiments. 展开更多
关键词 WELDING t-joint finite element modeling residual stresses.
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Systematics of a-preformation factors in closed-shell regions 被引量:1
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作者 Da-Ming Deng Zhong-Zhou Ren 《Nuclear Science and Techniques》 SCIE CAS CSCD 2016年第6期54-60,共7页
The a-preformation factors of medium and heavy-mass nuclei are calculated by using the cluster-formation model.The obtained preformation factors of even–even,odd-A,and odd–odd nuclei consist in both magnitude and tr... The a-preformation factors of medium and heavy-mass nuclei are calculated by using the cluster-formation model.The obtained preformation factors of even–even,odd-A,and odd–odd nuclei consist in both magnitude and trend with the general features predicted by standard calculations.The variation of a clustering affected by the evolution of nuclear structure is observed from different behaviors of preformation factors.We typically analyze the variation of preformation factors in the closed-shell N =126 and Z =82 regions,and discuss in detail the structural effects on a-cluster formation.This work shows the strong correlation between a-preformation factors and the shell structure,which would be a useful reference for microscopic cluster-model calculations of a-decay half-lives. 展开更多
关键词 分类 外壳 封闭 结构演变 形成模型 行为观察 中重核 计算
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