| Dislocation-Based Modeling and Numerical Analysis on the Formation of Kink Band Ryuichi Tarumi1; Shunsuke Kobayashi2; Sho Yamada3; Atsushi Suzuki4; Masao Ogino5; 1OSAKA UNIVERSITY, Toyonaka, Japan; 2, Minoh city, Japan; 3, Osaka, Japan; 4CYBERMEDIA CENTER, OSAKA UNIVERSITY, Osaka, Japan; 5DAIDO UNIVERSITY, Nagoya, Japan; PAPER: 313/Magnesium/Regular (Oral) SCHEDULED: 16:20/Thu. 24 Oct. 2019/Adonis ABSTRACT: Long period stacking-ordered (LPSO) magnesium and related alloys frequently show kink deformation under compressive loading. Recent experimental studies revealed that the kink microstructure improves the strength of Mg-based alloys [1]. The mechanism of the kink formation as well as the resulting strengthening, however, is still unclear and further investigation is required. In the present study, we conduct dislocation-based modeling and numerical analysis on the formation of kink bands using extended isogeometric analysis (XIGA). Our modeling is based on the growth of dislocation loops in the basal planes of hexagonal type elastic mediums. Dislocation loops or plastic displacements are introduced into the medium using the Peierls-Nabarro model, and the resulting elastic stress field is solved numerically using IGA. Here, the compressive loading is applied parallel to the Burgers vector of the dislocation loops. Present numerical analysis revealed that, under the uniform growth condition, screw components of the dislocation loop spread-out from the elastic medium since the side surfaces are traction-free. On the other hand, the edge components remained in the medium due to the compressive external loading. The edge dislocations form a polygonization microstructure that stabilizes the elastic strain energy. Although the edge dislocations form localized stress fields around the core of dislocations, the resulting macroscopic displacement induces the kink band. References: [1] K. Hagihara, Z.Li, M. Yamasaki, Y. Kawamura, T. Nakano, Acta Materialia, 163 (2019) 226-239. |
