A theoretical study on pure bending of hexagonal close-packed metal sheet

Hamed Mehrabi, Chunhui Yang

Research output: Chapter in Book / Conference PaperConference Paperpeer-review

5 Citations (Scopus)

Abstract

![CDATA[Hexagonal close-packed (HCP) metals have quite different mechanical behaviours in comparison to conventional cubic metals such as steels and aluminum alloys [1, 2]. They exhibit a significant tension-compression asymmetry in initial yielding and subsequent plastic hardening. The reason for this unique behaviour can be attributed to their limited symmetric crystal structure, which leads to twining deformation [3-5]. This unique behaviour strongly influences sheet metal forming of such metals, especially for roll forming, in which the bending is dominant. Hence, it is crucial to represent constitutive relations of HCP metals for accurate estimation of bending moment-curvature behaviours. In this paper, an analytical model for asymmetric elastoplastic pure bending with an application of Cazacu-Barlat asymmetric yield function [6] is presented. This yield function considers the asymmetrical tension-compression behaviour of HCP metals by using second and third invariants of the stress deviator tensor and a specified constant, which can be expressed in terms of uniaxial yield stresses in tension and compression. As a case study, the analytical model is applied to predict the moment-curvature behaviours of AZ31B magnesium alloy sheets under uniaxial loading condition. Furthermore, the analytical model is implemented as a user-defined material through the UMAT interface in Abaqus [7, 8] for conducting pure bending simulations. The results show that the analytical model can reasonably capture the asymmetric tension-compression behaviour of the magnesium alloy. The predicted moment-curvature behaviour has good agreement with the experimental results. Furthermore, numerical results show a better accuracy by the application of the Cazacu-Barlat yield function than those using the von-Mises yield function, which are more conservative than analytical results.]]
Original languageEnglish
Title of host publicationProceedings of the 21st International ESAFORM Conference on Material Forming (ESAFORM 2018), 23-25 April, 2018, Palermo, Italy
PublisherAmerican Institute of Physics
Pages170012-1-170012-6
Number of pages6
ISBN (Print)9780735416635
DOIs
Publication statusPublished - 2018
EventESAFORM Conference on Material Forming -
Duration: 23 Apr 2018 → …

Publication series

Name
ISSN (Print)0094-243X

Conference

ConferenceESAFORM Conference on Material Forming
Period23/04/18 → …

Keywords

  • magnesium alloys
  • mechanical properties
  • sheet-metal

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