Articles | Volume 8, issue 5
Research article
18 Sep 2017
Research article |  | 18 Sep 2017

Strain field evolution at the ductile-to-brittle transition: a case study on ice

Thomas Chauve, Maurine Montagnat, Cedric Lachaud, David Georges, and Pierre Vacher

Abstract. This paper presents, for the first time, the evolution of the local heterogeneous strain field around intra-granular cracking in polycrystalline ice, at the onset of tertiary creep. Owing to the high homologous temperature conditions and relatively low compressive stress applied, stress concentration at the crack tips is relaxed by plastic mechanisms associated with dynamic recrystallization. Strain field evolution followed by digital image correlation (DIC) directly shows the redistribution of strain during crack opening, but also the redistribution driven by crack tip plasticity mechanisms and recrystallization. Associated local changes in microstructure induce modifications of the local stress field evidenced by crack closure during deformation. At the ductile-to-brittle transition in ice, micro-cracking and dynamic recrystallization mechanisms can co-exist and interact, the later being efficient to relax stress concentration at the crack tips.

Short summary
For the first time, digital image correlation was used to follow strain field development and evolution during micro-cracking, at the ductile-to-brittle transition in polycrystalline ice. Owing to the high-temperature conditions of the tests, dynamic recrystallization mechanisms (nucleation and sub-grain rotation) efficiently participate in the stress redistribution during and after crack opening, and even lead to local crack closure.