Structural and topological nature of plasticity in sheared granular materials

Yixin Cao (1) , Jindong Li (1) , Binquan Kou (1) , Chengjie Xia (1) , Zhifeng Li (1) , Rongchang Chen (2) , Honglan Xie (2) , Tiqiao Xiao (2) , Walter Kob (3) , Liang Hong (1) , Jie Zhang (1) , Yujie Wang (1)

1 Shanghai Jiao Tong University [Shanghai]
2 SIAP - Shanghai Institute of Applied Physics
3 L2C - Laboratoire Charles Coulomb

Upon mechanical loading, granular materials yield and undergo plastic deformation. The nature of plastic deformation is essential for the development of the macroscopic constitutive models and the understanding of shear band formation. However, we still do not fully understand the microscopic nature of plastic deformation in disordered granular materials. Here we used synchrotron X-ray tomography technique to track the structural evolutions of three-dimensional granular materials under shear. We establish that highly distorted coplanar tetrahedra are the structural defects responsible for microscopic plasticity in disordered granular packings. The elementary plastic events occur through flip events which correspond to a neighbor switching process among these coplanar tetrahedra (or equivalently as the rotation motion of 4-ring disclinations). These events are discrete in space and possess specific orientations with the principal stress direction.

Domaines: Mécanique des matériaux [physics.class-ph]

Yixin Cao, Jindong Li, Binquan Kou, Chengjie Xia, Zhifeng Li, et al.. Structural and topological nature of plasticity in sheared granular materials. Nature Communications, 2018, 9, pp.2911. ⟨10.1038/s41467-018-05329-8⟩. ⟨hal-01876145⟩