Characterization of Stress-strain Relationship of Tailor Rolled Blank's Thickness Transition Zone

doi:10.3901/JME.2018.18.049

Abstract

Abstract: In view of the fact that tailor rolled blank (TRB) has the characteristics of structural differentiation and mechanical properties differentiation, a new type of tensile specimen suitable for TRB is proposed and a conventional tensile specimen with constant width is produced for comparison purpose. Uniaxial tensile experiments on above tensile specimens are carried out with digital speckle correlation method. The results show that strain distribution of the new type tensile specimen is relative homogeneous. True stress-true strain curves of materials in thickness transition zone are calculated. The material model of TRB is constructed by the method of interpolation and is applied to numerical simulation of TRB tensile specimen. It can be observed that the strain distribution of numerical and experimental results is similar and the force-displacement curves agree well. The error between the elongation of the specimen after test of experiment and simulation is between 9.0% and 14.0%. The experimental results are consistent with the FE results, the material model is accurate and practical. The variation in mechanical properties and thickness are considered in the new type of tensile specimen and the true stress-true stain curve of any region of TRB can be calculated through only one tensile test. The proposing of the tensile specimen has practical value for the investigation of mechanical properties and subsequent forming process of TRB.

Key words: digital speckle correlation method, material model, tailor rolled blank, true stress-strain curves

CLC Number:

TG142

ZHANG Sijia, LIU Xianghua, LIU Lizhong. Characterization of Stress-strain Relationship of Tailor Rolled Blank's Thickness Transition Zone[J]. Journal of Mechanical Engineering, 2018, 54(18): 49-54.

References

[1] MERKLEIN M,JOHANNES M,LECHNER M,et al. A review on tailored blanks-production,applications and evaluation[J]. Journal of Materials Processing Technology,2014,214(2):151-164.
[2] LIU Xianghua. Prospects for variable gauge rolling:technology,theory and application[J]. Journal of Iron & Steel Research International,2011,18(1):1-7.
[3] 童正国,林建平,田浩彬,等. 直线焊缝差厚拼焊板的成形规律[J]. 机械工程学报,2008,44(5):215-219. TONG Zhengguo,LIN Jianpin,TIAN Haobin,et al. Formability principles of linear-weld-line tailor-weld blanks (TWBs) with different thickness ratios[J]. Chinese Journal of Mechanical Engineering,2008,44(5):215-219.
[4] KOPP R,WIEDNER C,MEYER. A. Flexibly rolled sheet metal and its use in sheet metal forming[J]. Advanced Materials Research,2005,6-8:81-92.
[5] 王友华. 变截面板方盒件冲压成形性能研究[D]. 镇江:江苏大学,2008. WANG Youhua. A study on stamping formability of square box with tailor rolled blanks[D]. Zhenjiang:Jiangsu University,2008.
[6] MEYER A,WIETBROCK B,HIRT G. Increasing of the drawing depth using tailor tolled blanks-numerical and experimental analysis[J]. International Journal of Machine Tools & Manufacture,2008,48(5):522-531.
[7] EBERT A. Umformung von platinenmit local unterschiedlichen dicken[D]. Aachen:RWTH Aachen,2001. EBERT A. Deformation of plate with local different thickness[D]. Aachen:RWTH Aachen,2001.
[8] KLEINER M,KRUX R,HOMBERG W. High-pressure sheet metal forming of large scale structures from sheets with optimised thickness distribution[J]. Steel Research International,2005,76(2/3):177-181.
[9] CHATTI S,KLEINER M. Manufacturing of profiles for lightweight structures[C]//Proceedings of Esaform Conference on Material Forming. New York:American Institute of Physics,2007:584-589.
[10] 张华伟. 轧制差厚板成形性能研究[D]. 大连:大连理工大学,2012. ZHANG Huawei. Research on formability of tailor rolled blank[D]. Dalian:Dalian University of Technology,2012.
[11] 邓仁昡,张广基,刘相华. 轧制差厚板力学性能试验及数值模拟研究[J]. 锻压技术,2014,39(6):32-36. DENG Renxuan,ZHANG Guangji,LIU Xianghua. Research on experiment and numerical simulation of mechanical properties for tailor rolled blank[J]. Forging & Stamping Technology,2014,39(6):32-36.
[12] KIM H,LIM C. Annealing of flexible-rolled Al-5.5 wt% Mg alloy sheets for auto body application[J]. Materials & Design,2010,31(Suppl.1):71-75.
[13] 吴昊,杨兵,高永生,等. 变厚板材料模型表征方法的比较研究[J]. 锻压技术,2014,39(6):37-44. WU Hao,YANG Bin,GAO Yongsheng,et al. Comparison study of description methods for material model of variable thickness rolled blank[J]. Forging & Stamping Technology,2014,39(6):37-44.
[14] SHAFIEI E,DEHGHANI K. Tensile behavior of tailor rolled blanks with longitudinal thickness transition zone:introducing a new tensile specimen[J]. Vacuum,2017,143:71-86.
[15] YAMAGUCHI I. Speckle displacement and decorrelation in the diffraction and image fields for small object deformation[J]. Journal of Modern Optics,1981,28(10):1359-1376.
[16] PETERS W H,RAMSON W F. Digital imaging techniques in experimental stress analysis[J]. Optical engineering,1982,21(3):213427.
[17] EBERL C,THOMPSON R,GIANOLA D,et al. Digital image correlation and tracking[EB/OL]. 2006,http://www.mathworks.com/matlabcentral/fileexchange/12143
[18] XU Z,PENG L,LAI X,et al. Geometry and grain size effects on the forming limit of sheet metals in micro-scaled plastic deformation[J]. Materials Science and Engineering:A,2014,611(31):345-353.
[19] 陈忠,张宪民,周晓峰. 基于散斑数字图像相关的柔顺结构力传感单元设计与试验研究[J]. 机械工程学报,2013,49(9):12-16. CHEN Zhong,ZHANG Xianmin,ZHOU Xiaofeng. Design and experimental study of compliant structural force cell based on digital image correlation[J]. Journal of Mechanical Engineering,2013,49(9):12-16.