06 August 2011
Inherent influence of strain path in Nakazima FLC testing
Inherent influence of strain path in Nakazima FLC testing

Paper presented at the IDDRG 2011 conference, 05-08 June 2011, Bilboa, Spain

M. Abspoel, E.H. Atzema, J.M.M. Droog, T. Khandeparkar, M.E. Scholting, F.J. Schouten, H. Vegter; Tata Steel Research, Development & Technology, IJmuiden

To determine the limit of formability of a sheet metal material the Forming Limit Curve (FLC) is a generally accepted tool. The FLC is (or should be) determined by proportionally straining the material. Experimentally FLC’s are obtained via either Nakazima or Marciniak methods and it was believed that particularly in the Nakazima experiment the strains are not truly proportional. Instead, for all strain ratios to be tested the initial strain is bi-axial and gradually the strain path changes towards the final path imposed by the sample geometry and material properties. It will be demonstrated in this paper that for a forming grade the bi-axial pre-strain is noticeable and for an AHSS it is considerable. The reported results provide a solid foundation for a correction to be applied to the (Nakazima) FLC which is under discussion in the Arbeitskreis Nakazima.

Paper presented at the IDDRG 2011 conference, 05-08 June 2011, Bilboa, Spain

https://www.tatasteeleurope.com/static_files/StaticFiles/Automotive/Inherent%20influence%20of%20strain%20path%20in%20Nakazima%20FLC.pdf

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