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摘要：
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成形性是金属成形中材料最重要的性能之一。研究表明,高速下成形性有较大提高。本文综述了国外关于成形性的影响因素的研究现状,总结了高速率下成形性得到提高的主要原因:惯性是影响高速率成形性的主要因素,它有助于分散变形,抑制变形集中化;并对高速率下缩颈模式有很大影响,惯性力导致产生多处缩颈,并抑制缩颈集中化;高速的模具冲击作用同样是一个重要的影响因素,其产生惯性减薄挤压作用,从而使工件受到压缩应力而减少损伤参数,达到稳定变形的效果;应变速率的增加可能引起材料本构关系的改变,从而增加材料成形性。
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Formability may be the most important material property in metal forming.It was reported that the formability of some materials was improved dramatically at high velocities.The main purpose of this paper was to review the studies in the literatures about the factors influencing materials formability of sheet metals under high rate forming conditions.Some main effects were summarized,such as inertial,die impact and changes in constitutive behavior.Inertial was the dominating factor influencing high velocity formability.It acted to diffuse deformation and prevent localization,also responsible for the different necking pattern due to its resulting in multiple necking and preventing localized necking.High velocity impact was also a strong factor and had a stabilizing influence through inertial ironing and reduction in damage parameters due to compressive stresses.High strain rate might induce changes in constitutive behavior,which contributes to improve formability.
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基金项目：
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国家自然科学基金资助项目(50375114);;
塑性成形模拟及模具技术国家重点实验室资助项目(05-03)
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作者简介：
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参考文献：
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[1]李春峰.高能率成形技术[M].北京:机械工业出版社,2001.
[2]Balanethiram V S,Hu X,Altynova M,et al.Hyperplastici-ty:Enhanced formability at high rates[J].J.Mater.Process.Technol.,1994,45:595 600.
[3]Rajendran A M,Fyfe I M.Inertia effects on the ductile fail-ure of thin rings[J].J.Applied Mechanics,1982,49:3136.
[4]Hu X,Daehn G S.Effect of velocity on flow localization intension[J].Acta Mater.,1996,44:1021 1033.
[5]Hu X,Wagoner R H,Daehn G S,et al.Effect of inertia ontensile ductility[J].Metal.Trans.A,1994,25A:27232735.
[6]Balanethiram V S,Daehn G S.Hyperplasticity:Increasedforming limits at high workpiece velocity[J].Scripta Materi-alia,1994,30:515.
[7]Han J,Tvergaard V.Effect of inertia on the necking behaviorof ring specimens under rapid radial expansion[J].Eur.J.Mech.A/Solids,1995,14(2):287 307.
[8]Sorenson N J,Freund L B.Unstable neck formation in a duc-tile ring subjected to impulsive radial loading[J].Int.J.ofSolids and Structures,2000,37:2265 2283.
[9]Nilsson K.Effects of inertia on dynamic neck formations intensile bars[J].Eur.J.Mech.A/Solids,2001,20:713729.
[10]Pandolfi A,Krysl P,Ortiz M.Finite element simulation ofring expansion and fragmentation:The capturing of lengthand time scales through cohesive models of fracture[J].Int.J.Fracture,1999,95:279 297.
[11]Altynova M.The improved ductility of aluminum and copperrings by electromagnetic forming technique[D].Ohio:TheOhio State University,1995.
[12]Grady D E,Benson D A.Fragmentation of metal rings by e-lectromagnetic loading[J].Experimental Mechanics.1983,23(4):393 400.
[13]Sorenson N J,Freund L B.Dynamic bifurcations during high-rate planar extension of a thin rectangular block[J].Eur.J.Mech.A/Solids,1998,17:709 724.
[14]Shenoy V B,Freund L B.Necking bifurcations during highstrain rate extension[J].Journal of the Mechanics and Phys-ics of Solids,1999,47:2209 2233.
[15]Gurduru P R,Freund L B.The dynamics of multiple neck for-mation and fragmentation in high rate extension of ductile ma-terials[J].Int.J.of Solids and Structures,2002,39:56155632.
[16]Mercier S,Molinari A.Predictions of bifurcations and insta-bilities during dynamic extension[J].Int.J.of Solids andStructures,2003,40:1995 2016.
[17]Nilsson K.Effects of inertia on dynamic neck formations in tensilebars[J].Eur.J.Mech.A/Solids,2001,20:713 729.
[18]Han J,Tvergaard V.Effect of inertia on the necking behaviorof ring specimens under rapid radial expansion[J].Eur.J.Mech.A/Solids,1995,14(2):287 307.
[19]Seth M,Daehn G S.Effect of aspect ratio on high velocityformability of aluminum alloy[A].Trends in Materials andManufacturing Technologies for Transportation Industries,TMS,2005.
[20]Balanethiram V S.Hyperplasticity:Enhanced Formability ofSheet Metals at High Velocity[D].Ohio:The Ohio StateUniversity,1996.
[21]Balanethiram V S,Daehn G S,Enhanced Formability of In-terstitial Free Iron at High Strain Rates[J].Scripta Materia-lia,1992,27:1783.
[22]Seth M,High Velocity Formability of High Strength SteelSheet[D].Ohio:The Ohio State University,2002.
[23]Seth M,Vohnout V J,Daehn G S.Formability of steel sheetin high velocity impact[J].J.of Materials Processing Tech-nology,2005,168:390 400.
[24]Imbert J M,Winkler S L,Worswick M J,et al.The effect oftool/sheet interaction on damage evolution in electromagneticforming of Al alloy sheet[J].J.Eng.Mat.Tech.,2005,127:45 153.
[25]Imbert J M,Winkler S L,Worswick M J,et al.Formabilityand damage in electromagnetically formed AA5754 andAA6111[A].Ist International Conference on High SpeedForming[C].Dortmund,Germany,2004.
[26]Olieviera D A,Worswick M J,Finn M,et al.Electromagnet-ic forming of aluminum alloy sheet:Free-form and cavity fillexperiments and model[J].J.Mat.Processing Tech.,2005,170:350 362.
[27]Seth M.High velocity formability and factors affecting it[D].Ohio:The Ohio State University,2006.
[28]Follansbee P S,Kocks U F.A constitutive description of thedeformation of copper based on the use of mechanical thresh-old stress as an internal state variable[J].Acta Metallica,1988,36(1):81 93.
[29]Regazzoni G,Kocks U F,Follansbee P S.Dislocation Kineticsat high strain rates[J].Acta Metallica,1987,35(12):28652875.
[30]Gorham D A.An effect of specimen size in the high-strain ratecompression test[J].Journal De Physique III,1991,1:411418.
[31]Dioh N N,Leevers PS.Williams JG.Thickness effect in splitHopkinson pressure bar test[J].Polymer,1993,34:42304234.
[32]Dioh N N,Ivancovic A,Leevers P S,et al.Stress wavepropagation effects in split Hopkinson pressure bar tests[J].Mathematical and Physical Sciences,1995,449:187 204.
[33]Michel J F,Picart P.Size effects on the constitutive behaviorfor brass in sheet metal forming[J].J.Materials ProcessingTech.,2003,141:439 446.
[34]Oosterkamp L D,Ivankovic A,Venizelos G.High strain rateproperties of selected aluminum alloys[J].Materials Scienceand Engineering,2000,A278:225 235.
[35]Bro sius A,Beerwald C,Kleiner M.Determination of flowcurves at high strain rates using the electromagnetic formingprocess and an iterative finite element simulation scheme[J].J.Phys.IV France,2003,110:537 542.
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