Softening-induced instability of a stretched cohesive granular layer.
J.-C. Géminard, L. Champougny, P. Lidon and F. Vittoz.
H. Alarcon and F. Melo (USACH, Chile); L. Vanel, O. Ramos (LPMCN, Lyon).
We report on a cellular pattern which spontaneously forms at the surface of a thin layer of a cohesive granular material submitted to in-plane stretching or out-of-plane flexural deformation. We present a simple model in which the mechanism responsible of the instability is the "strain softening" exhibited by humid granular materials above a typical strain. Detailed analysis of the fracture characteristics as a function of the humidity content and grain size indicates that the clustering plays an important role in the observed mechanical response of the granular material. Moreover, our analysis indicates that such type of instability should be observed in any system presenting a negative stress sensitivity to strain perturbations.
H. Alarcon, O. Ramos, L. Vanel, F. Vittoz, F. Melo and J.-C. Géminard., Phys. Rev. Lett. 105, (2010) 208001.
J.-C. Géminard, L. Champougny, P. Lidon and F. Melo, Phys. Rev. E. 85, (2012) 012301.
J.-C. Géminard, Rev. Cub. Fis. 29 (2012) 1E13.
H. Alarcón, J.-C. Géminard and F. Melo, Phys. Rev. E 86 (2012) 061303.