Dresden 2011 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 22: Granular Matter/ Contact Dynamics

DY 22.9: Talk

Wednesday, March 16, 2011, 16:15–16:30, HÜL 186

Refraction, exclusion and reflection of shear zones in layered granular materials — •Balázs Szabó¹, Sandra Wegner², Tamás Unger³, Frank Angenstein⁴, Ralf Stannarius², and Tamás Börzsönyi¹ — ¹Research Institute for Solid State Physics and Optics, H-1525 Budapest, PoB. 49, Hungary — ²Otto-von-Guericke-University, D-39106 Magdeburg, Germany — ³HAS-BUTE Condensed Matter Research Group, Budapest University of Technology and Economics H-1111 Budapest, Hungary — ⁴Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany

When granular materials deform under external stress the deformation is often localized into narrow regions. These shear zones develop along the most optimal path (weakest bonds break), thus, in an inhomogeneous material the shear zone tries to escape the high friction regions. In a layered system the zone can change direction when crossing the layer boundaries, which is very similar to the refraction of light beams in geometric optics [1]. We show experimentally and numerically, that for the case of shear zones the refraction law is in striking analogy with geometric optics, but here the frictional properties of the materials take the role of the optical index of refraction [2]. We also explore other configurations, where the zone is refracted from the layer boundary. Visualization of the zone inside the material was achieved by two independent techniques: (i) excavating the system layer by layer and (ii) Magnetic Resonance Imaging.

[1] T. Unger, Phys. Rev. Lett. 98, 018301 (2007). [2] T. Börzsönyi et al., Phys. Rev. E 80, 060302(R) (2009).