Advances in characterization of sheet metal forming limits

10th International Conference and Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes

Stoughton, Thomas B.^1 ; Carsley, John E.^1 ; Min, Junying^2 ; Lin, Jianping^3

General Motors Global Research and Development Center, United States^1

Ruhr-University Bochum, Germany^2

Tongji University, China^3

关键词: Complex processing;    Forming limit curve;    In-plane stretching;    Linear strains;    Nonlinear strain;    Through-thickness;    Tool contact;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/734/3/032073/pdf
DOI  :  10.1088/1742-6596/734/3/032073

来源: IOP

【 摘 要 】

This paper accounts for nonlinear strain path, sheet curvature, and sheet-tool contact pressure to explain the differences in measured forming limit curves (FLCs) obtained by Marciniak and Nakajima Tests. While many engineers working in the sheet metal forming industry use the raw data from one or the other of these tests without consideration that they reflect the convolution of material properties with the complex processing conditions involved in these two tests, the method described in this paper has the objective to obtain a single FLC for onset of necking for perfectly linear strain paths in the absence of through-thickness pressure and restricted to purely in-plane stretching conditions, which is proposed to reflect a true material property. The validity of the result is checked using a more severe test in which the magnitude of the nonlinearity, curvature, and pressure are doubled those involved in the Nakajima Test.