Profusion of transition pathways for interacting hysterons

Biological and Soft Matter Physic

Jamming of soft particles: geometry, mechanics, scaling and isostaticity

Amorphous materials as diverse as foams, emulsions, colloidal suspensions and granular media can jam into a rigid, disordered state where they withstand finite shear stresses before yielding. Here we review the current understanding of the transition to jamming and the nature of the jammed state for disordered packings of particles that act through repulsive contact interactions and are at zero temperature and zero shear stress. We first discuss the breakdown of affine assumptions that underlies the rich mechanics near jamming. We then extensively discuss jamming of frictionless soft spheres. At the jamming point, these systems are marginally stable (isostatic) in the sense of constraint counting, and many geometric and mechanical properties scale with distance to this jamming point. Finally, we discuss current explorations of jamming of frictional and non-spherical (ellipsoidal) particles. Both friction and asphericity tune the contact number at jamming away from the isostatic limit, but in opposite directions. This allows one to disentangle the distance to jamming and the distance to isostaticity. The picture that emerges is that most quantities are governed by the contact number and scale with the distance to isostaticity, while the contact number itself scales with the distance to jamming.Biological and Soft Matter Physic

Packing geometry and statistics of force networks in granular media

Article / Letter to editorLeiden Instituut Onderzoek Natuurkund

Anisotropy of weakly vibrated granular flows

Biological and Soft Matter Physic

Flow Induced Fluctuations Create a Granular Fluid: Effective Viscosity and Fluctuations

061309Biological and Soft Matter Physic

Design of pseudo-mechanisms and multistable units for mechanical metamaterials

Mechanisms-collections of rigid elements coupled by perfect hinges which exhibit a zero-energy motion-motivate the design of a variety of mechanical metamaterials. We enlarge this design space by considering pseudo-mechanisms, collections of elastically coupled elements that exhibit motions with very low energy costs. We show that their geometric design generally is distinct from those of true mechanisms, thus opening up a large and virtually unexplored design space. We further extend this space by designing building blocks with bistable and tristable energy landscapes, realize these by 3D printing, and show how these form unit cells for multistable metamaterials.Biological and Soft Matter Physic

MR Imaging of Reynolds Dilatancy in the Bulk of Smooth Granular Flows

Article / Letter to editorLeiden Instituut Onderzoek Natuurkund

Comment on "Absolute and convective instabilities in nonlinear systems"

Theoretical Physic