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Experimental detection of the onset of local necking in an aluminium sheet

Abstract

Forming limit diagrams (FLDs) are widely used to assess metal sheet formability. Experimental FLDs are obtained by performing formability tests and determining failure strains. The standard method for detection of forming limits is based on the spatial distribution of the strains and requires formation of a single local neck. Some aluminium alloys, such as AA6016, have a tendency to form multiple strain localizations in formability tests, which can be interpreted as multiple local necks. Thus, use of the standard method is questionable for these aluminium alloys. The present paper presents an alternative, digital-image-correlation-based method for experimental detection of the onset of local necking in an aluminium sheet. The method is based on monitoring the sheet-thickness evolution, and is developed to be user independent and resistant to noise in the measurements. The method can be used in combination with different types of formability tests. The main requirement is that digital image correlation is used for strain measurements. Here, the method is initially tested on uniaxial tension tests of AA6016 aluminium alloy sheets and then extended to formability tests.

Category

Academic article

Language

English

Author(s)

  • Dmitry Vysochinskiy
  • Térence Coudert
  • Odd Sture Hopperstad
  • Odd-Geir Lademo
  • Aase Gavina Roberg Reyes

Affiliation

  • SINTEF Industry / Materials and Nanotechnology
  • Norwegian University of Science and Technology

Year

2014

Published in

Materials Science Forum

ISSN

0255-5476

Volume

794-796

Page(s)

590 - 595

View this publication at Norwegian Research Information Repository