Experimental study of the geometrical effects in the localization of deformation

We have studied the localization of deformation in a 2D packing model. The samples consist of regular packings of equal parallel cylinders (drinking straws). The local stress-strain characteristics, at the contact between two straws, shows a softening part, responsible for the localization of the deformation. We have analyzed the roughness of localization band, i.e., the width W of the localized zone versus its length L. Our results demonstrate the self-affine character of the localized zone: We find a power law, W{~}L^ζ with {ζ}=0.73±{}0.07, which is consistent with recent work on the ``weak'' disorder model.