Time-dependent methods for limit strains determination of sheet metal

Materia

Leonard, Martín Eduardo¹  Signorelli, Javier Walter² 

[1] UNR, Rosario, Argentina;Universidad Nacional de Rosario, Rosario, Argentina

关键词: Formability;    DIC analysis;    time-dependent methods;    duplex stainless steel 2205.;   

DOI  :  10.1590/s1517-707620180002.0332

学科分类：工程和技术（综合）

来源: Universidade Federal do Rio de Janeiro * Coordenacao dos Programas de Pos-Graduacao de Engenharia

【 摘 要 】

The forming limit diagram (FLD) –broadly used to characterize sheet-metal formability– is made by means of strain measurement over the surface of stretched samples and the subsequent determination of limit-strain values associated with the onset of necking. Currently, researchers can make strain measurements with digital image-correlation analysis (DIC). Data measured by DIC easily adapt to the traditional position-dependent method for evaluating limit strains, but this method is not applicable to materials that exhibit inhomogeneous deformation, like multiple necking. DIC analysis allows for the application of time-dependent methods, which are based on analysis of the temporal evolution of strains to define the onset of necking. This article compares three recently proposed time-dependent techniques for determining limit strains: a thickness-control method, the strain-control method and an acceleration-correlation method. For experimental purposes, duplex 2205 stainless-steel sheet, 0.92mm thick, was tested in uniaxial tension. The standard position-dependent method (ISO 12004-2) provides a reference for comparing results. We attribute differences in limit-strain values to the difficulty in objectively setting each method’s parameters. These differences show that there are still aspects of the temporal analyses that must be improved on before a precise and generalized methodology is available.

【 授权许可】

CC BY