@article{dansereau_demery_berthier_weiss_ponson_2019, title={Collective Damage Growth Controls Fault Orientation in Quasibrittle Compressive Failure}, volume={122}, ISSN={["1079-7114"]}, DOI={10.1103/PhysRevLett.122.085501}, abstractNote={The Mohr-Coulomb criterion is widely used in geosciences and solid mechanics to relate the state of stress at failure to the observed orientation of the resulting faults. This relation is based on the assumption that macroscopic failure takes place along the plane that maximizes the Coulomb stress. Here, this hypothesis is assessed by simulating compressive tests on an elastodamageable material that follows the Mohr-Coulomb criterion at the mesoscopic scale. We find that the macroscopic fault orientation is not given by the Mohr-Coulomb criterion. Instead, for a weakly disordered material, it corresponds to the most unstable mode of damage growth, which we determine through a linear stability analysis of its homogeneously damaged state. Our study reveals that compressive failure emerges from the coalescence of damaged clusters within the material and that this collective process is suitably described at the continuum scale by introducing an elastic kernel that describes the interactions between these clusters.}, number={8}, journal={PHYSICAL REVIEW LETTERS}, author={Dansereau, Veronique and Demery, Vincent and Berthier, Estelle and Weiss, Jerome and Ponson, Laurent}, year={2019}, month={Feb} }
 @article{berthier_kollmer_henkes_liu_schwarz_daniels_2019, title={Rigidity percolation control of the brittle-ductile transition in disordered networks}, volume={3}, ISBN={2475-9953}, url={http://dx.doi.org/10.1103/physrevmaterials.3.075602}, DOI={10.1103/PhysRevMaterials.3.075602}, abstractNote={In ordinary solids, material disorder is known to increase the size of the process zone in which stress concentrates at the crack tip, causing a transition from localized to diffuse failure. Here, we report experiments on disordered 2D lattices, derived from frictional particle packings, in which the mean coordination number $\langle z \rangle$ of the underlying network provides a similar control. Our experiments show that tuning the connectivity of the network provides access to a range of behaviors from brittle to ductile failure. We elucidate the cooperative origins of this transition using a frictional pebble game algorithm on the original, intact lattices. We find that the transition corresponds to the isostatic value $\langle z \rangle = 3$ in the large-friction limit, with brittle failure occurring for structures vertically spanned by a rigid cluster, and ductile failure for floppy networks containing nonspanning rigid clusters. Furthermore, we find that individual failure events typically occur within the floppy regions separated by the rigid clusters.}, number={7}, journal={Physical Review Materials}, author={Berthier, Estelle and Kollmer, Jonathan E. and Henkes, Silke E. and Liu, Kuang and Schwarz, J. M. and Daniels, Karen E.}, year={2019} }