钢板拉伸颈缩致断裂的应变局部化过程
|
摘要
利用MTS810实验机和Zwick HTM5020高速拉伸实验机对钢板进行不同应变率加载下的拉伸实验。利用数字图像相关性方法 (Digital Image Correlation,DIC)对拉伸过程中试件表面的应变场进行分析,得到标距段和颈缩区两个区域沿拉伸方向的平均应变历史曲线,其结果显示两曲线的分离时刻即为非局部化颈缩起始点;该分离时刻点与准静态下的Considere判据和动态下的Batra理论得到的颈缩点一致。DIC分析云图形象的显示了试样拉伸过程中从颈缩开始致断裂的应变局部化演化过程。提取云图中典型位置的应变分布曲线,获得不同时刻相同位置的真应变大小。此外,试样的局部断裂应变随应变率的增加而增大。
The tensile tests with different strain rates of steel sheet were carried out on MTS810 and Zwick HTM5020 mechanical simulator.Digital image correlation(DIC) was used to analyze the strain field on the surface of the specimen during the stretching processes,and the average strain history curves along the tensile direction of gauge section and necking area were obtained.The results show that the separation moment of the two curves is the onset of non-localized necking.The separation moment point is consistent with the onset non-localized necking obtained via Considere criterion in quasi-static tension and the Batra theory in dynamic tension.The strain maps got from DIC show the evolutionary processes of the localization of strain from necking to fracture in the tensile process of specimens.The strain distribution curves in typical position were extracted from strain maps to obtain the true strain of neck area in the same position and different moments.Moreover,the localized fracture strain of specimens increases with the increase of strain rate.
The tensile tests with different strain rates of steel sheet were carried out on MTS810 and Zwick HTM5020 mechanical simulator.Digital image correlation(DIC) was used to analyze the strain field on the surface of the specimen during the stretching processes,and the average strain history curves along the tensile direction of gauge section and necking area were obtained.The results show that the separation moment of the two curves is the onset of non-localized necking.The separation moment point is consistent with the onset non-localized necking obtained via Considere criterion in quasi-static tension and the Batra theory in dynamic tension.The strain maps got from DIC show the evolutionary processes of the localization of strain from necking to fracture in the tensile process of specimens.The strain distribution curves in typical position were extracted from strain maps to obtain the true strain of neck area in the same position and different moments.Moreover,the localized fracture strain of specimens increases with the increase of strain rate.
引文
[1]刘大海,孟维金,蒙骏鹏.DP780高强钢板材高应变率变形行为及本构模型[J].塑性工程学报,2018,25(1):161-166.LIU Dahai,MENG Weijin,MENG Junpeng.Deformation behavior and constitutive model of DP780 high strength steel at high strain rates[J].Journal of Plasticity Engineering,2018,25(1):161-166.
[2]邱霖,唐建敏,刘洪光.基于热拉伸试验的DP590高强钢变形本构关系及热加工图[J].锻压技术,2017,42(1):121-125.QIU Lin,TANG Jianmin,LIU Hongguang.Constitutive relationship and hot processing pattern of high strength steel DP590 based on hot tensile test[J].Forging&Stamping Technology,2017,42(1):121-125.
[3]CONSIDERE M.L'emoploi du fer et l'acier dans les constructions[J].Annales des Ponts et Chausse'es,1885,9:574.
[4]HILL R.On discontinuous plastic states,with special reference to localized necking in thin sheets[J].Journal of the Mechanics and Physics of Solids,1952,1(1):19-30.
[5]MCCLINTOCK F A,ZHENG Z M.Ductile fracture in sheets under transverse strain gradients[J].International Journal of Fracture,1993,64(4):321-337.
[6]NOBLE J P,GOLDTHORPE B D,CHURCH P,et al.The use of the Hopkinson bar to validate constitutive relations at high rates of strain[J].Journal of the Mechanics and Physics of Solids,1999,47(5):1187-1206.
[7]STEPANOV G V,BABUTSKII A I.Strain localization kinetics in a metal strip in tension[J].Strength of Materials,2005,37(5):515-524.
[8]BESNARD G,HILD F,LAGRANGE J M,et al.Analysis of necking in high speed experiments by stereocorrelation[J].International Journal of Impact Engineering,2012,49(2):179-191.
[9]MIRONE G.The dynamic effect of necking in Hopkinson bar tension tests[J].Mechanics of Materials,2013,58(3):84-96.
[10]TARIGOPULA V,HOPPERSTAD O S,LANGSETH M,et al.Astudy of localisation in dual-phase high-strength steels under dynamic loading using digital image correlation and FE analysis[J].International Journal of Solids and Structures,2008,45(2):601-619.
[11]SATO K,YU Q,HIRAMOTO J,et al.A method to investigate strain rate effects on necking and fracture behaviors of advanced high-strength steels using digital imaging strain analysis[J].International Journal of Impact Engineering,2015,75:11-26.
[12]GB/T 30069.1-2013,金属材料高应变速率拉伸试验第1部分:弹性杆型系统[S].GB/T 30069.1-2013,Metallic materials-tensile tests at high strain rates-part 1:elastic rod-type systems[S].
[13]BATRA R C,WEI Z G.Instability strain and shear band spacing in simple tensile/compressive deformations of thermoviscoplastic materials[J].International Journal of Impact Engineering,2007,34(3):448-463.
[14]WANG W,LI M,HE C,et al.Experimental study on high strain rate behavior of high strength 600-1000 MPa dual phase steels and 1200 MPa fully martensitic steels[J].Materials and Design,2013,47(9):510-521.
[2]邱霖,唐建敏,刘洪光.基于热拉伸试验的DP590高强钢变形本构关系及热加工图[J].锻压技术,2017,42(1):121-125.QIU Lin,TANG Jianmin,LIU Hongguang.Constitutive relationship and hot processing pattern of high strength steel DP590 based on hot tensile test[J].Forging&Stamping Technology,2017,42(1):121-125.
[3]CONSIDERE M.L'emoploi du fer et l'acier dans les constructions[J].Annales des Ponts et Chausse'es,1885,9:574.
[4]HILL R.On discontinuous plastic states,with special reference to localized necking in thin sheets[J].Journal of the Mechanics and Physics of Solids,1952,1(1):19-30.
[5]MCCLINTOCK F A,ZHENG Z M.Ductile fracture in sheets under transverse strain gradients[J].International Journal of Fracture,1993,64(4):321-337.
[6]NOBLE J P,GOLDTHORPE B D,CHURCH P,et al.The use of the Hopkinson bar to validate constitutive relations at high rates of strain[J].Journal of the Mechanics and Physics of Solids,1999,47(5):1187-1206.
[7]STEPANOV G V,BABUTSKII A I.Strain localization kinetics in a metal strip in tension[J].Strength of Materials,2005,37(5):515-524.
[8]BESNARD G,HILD F,LAGRANGE J M,et al.Analysis of necking in high speed experiments by stereocorrelation[J].International Journal of Impact Engineering,2012,49(2):179-191.
[9]MIRONE G.The dynamic effect of necking in Hopkinson bar tension tests[J].Mechanics of Materials,2013,58(3):84-96.
[10]TARIGOPULA V,HOPPERSTAD O S,LANGSETH M,et al.Astudy of localisation in dual-phase high-strength steels under dynamic loading using digital image correlation and FE analysis[J].International Journal of Solids and Structures,2008,45(2):601-619.
[11]SATO K,YU Q,HIRAMOTO J,et al.A method to investigate strain rate effects on necking and fracture behaviors of advanced high-strength steels using digital imaging strain analysis[J].International Journal of Impact Engineering,2015,75:11-26.
[12]GB/T 30069.1-2013,金属材料高应变速率拉伸试验第1部分:弹性杆型系统[S].GB/T 30069.1-2013,Metallic materials-tensile tests at high strain rates-part 1:elastic rod-type systems[S].
[13]BATRA R C,WEI Z G.Instability strain and shear band spacing in simple tensile/compressive deformations of thermoviscoplastic materials[J].International Journal of Impact Engineering,2007,34(3):448-463.
[14]WANG W,LI M,HE C,et al.Experimental study on high strain rate behavior of high strength 600-1000 MPa dual phase steels and 1200 MPa fully martensitic steels[J].Materials and Design,2013,47(9):510-521.