IWPDF2023

A thermo-mechanical investigation of textured Magnesium in an ef fort to validate crystal plasticity simulations

N. A. Özdur 1 , ∗ , S. C. Erman 1 , R. Seghir 2 , L. Stainier 2 , C. C. Aydıner 1

1 Department of Mechanical Engineering, Boğaziçi University, Istanbul 34342, Turkey 2 Research Institute in Civil and Mechanical Engineering, Ecole Centrale Nantes, Nantes 44321, France

∗ necdet.ozdur@boun.edu.tr

Keywords: magnesium, twinning, plastic dissipation, thermo-mechanical behavior

Magnesium is among the lightest structural metals with a high strength-to-weight ratio. A widespread adoption of magnesium alloys in the industry, however, is impeded by its unorthodox mechanical behavior. The vast differences between activation energies of the slip systems in HCP magnesium, combined with profuse (and abrupt) activity of tensile twinning leads to an extreme plastic anisotropy. On top, there is intense strain heterogeneity, primarily, linked to the spatial coordination of twinning (e.g., [1]) that also shows a strong dependence on crystallographic texture. The recent experimental efforts that target a better understanding of magnesium (and validate polycrystal simulations) include investigation of its mechanical response by measuring strain and texture for different starting textures, load paths, deformation rates, and temperatures. In contrast, this work aims to incorporate temperature measurements of dissipative response of Magnesium during deformation as well as the usual stress-strain measurements in order to obtain a high-fidelity thermo-mechanical description of its plastic deformation. To this end, the temperature of textured magnesium AZ31 samples under cyclic loading are recorded under an IR camera. The obtained deformation-history dependent curves of stress and temperature are then used to validate a coupled thermomechanical crystal plasticity model, posed in the variational framework devised by Ortiz and Stainier for viscoplastic constitutive relations [2] and later revised to incorporate thermomechanical coupling [3]. References [1] Shafaghi N, Kapan E, Aydıner CC (2020) Cyclic Strain Heterogeneity and DamageFormation in Rolled Magnesium Via In Situ Microscopic Image Correlation. Exp Mech60:735-751. [2] Ortiz M, Stainier L (1999) The variational formulation of viscoplastic constitutive updates.Computer Methods in Applied Mechanics and Engineering 171:419-444. [3] Yang Q, Stainier L, Ortiz M (2006) A variational formulation of the coupled thermomechanicalboundary value problem for general dissipative solids. Journal of the Mechanicsand Physics of Solids 54:401 424.

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