Getting into Shape – Pushing for Exotic Particulate Media Mechanics

Discrete particle based media such as gravel, coffee beans, but also emulsion droplets and foams represent 70% of the Tera-ton scale, global human construction, food and feed materials manufacturing industry. At the same time, biological tissues are assemblies of deformable, reactive cells. These evidently important materials come with a wide variety of mechanical functionalities. On a macroscopic scale, they can be simultaneously elastic, plastic and viscous. There is a great need to understand how this rich mechanical behavior emerges from the microscopic features of the particles and the way they assemble. We still do not clearly understand how ingredients such as interparticle forces, particle shape, orientation and the many other microscopic variables that are potentially relevant for shear resistance, compressibility and other mechanical features. More importantly, do we understand which of these microscopic ingredients have significant macroscopic consequences? The answer to this question is surprisingly hard to find. Understanding this micro-macro link can have huge implications, for example in guiding to make more failure resistant materials, finding cheaper and more light weight ingredients, more reusable ingredients or simple increase the energy efficiency of materials production. Understanding how cells collectively determine the mechanics of tissues will allow us to engineer biological materials.

For simple, low-dimensional systems such as sphere packings, the emergence of mechanical functionality from its microscopic ingredients has been clarified to a great extent. Packings made of rigid, frictionless spherical particles, which are exposed to simple deformation scenarios, are well understood. However, it has become increasingly evident that convex and non-convex particle shapes and deformation anisotropy provide a tremendous space of opportunities for new bottom-up understanding of the mechanical functionality of realistic discrete particle-based media and the emergence of mechanical behavior in general.

In this Workshop, we will consider the spectrum of shape effects, ranging from intrinsically anisometric grains to easily deformable particles. The former is imbued by construction with a sense of direction; the latter obtains non-trivial shape due to its local deformation environment. The workshop therefore aims to bring together a selection of upcoming and leading academic and private sector scientists, from various fields that consider such particle shape effects, to discuss the most fruitful experimental, numerical and theoretical directions for future work and application development in the field.