I’m happy to note that tomorrow’s Physics Department colloquium will feature Heinrich Jaeger from the University of Chicago, co-invited by me and Eric Corwin, who were both graduate students of Heinrich. He’s both brilliant and imaginative, with research spanning such things as making soft robots , granular materials in general, complex fluids (as in the movie below), and nanostructures. Heinrich has a real talent for finding deep physics in “simple” things!
Seminar: Thursday May 23, 2013, 4pm, Willamette 100
Adapting granular materials through artificial evolution
Despite research dating back more than 200 years, it is still unknown how to connect the mechanical response of an amorphous granular material unambiguously to the shape of its constituents. From a practical point of view, this is problematic since granular materials like sand, grain, and pharmaceuticals are essential in engineering and industry. At a fundamental level, granular systems represent prototypes for far-from-equilibrium behavior. Thus, understanding the relationship between microscopic shape and macroscopic response can shed light on other amorphous systems like foams, dense colloids and molecular glasses. A key difficulty arises from the vast range of possible shapes, making it seem infeasible to isolate which candidates generate a particular response. In this talk I will demonstrate that particle shape can, however, be explored efficiently when viewed in a fresh context: artificial evolution. Representing arbitrary particle shapes by “granular molecules” consisting of bonded spheres, we have used simulations to evolve these shapes and 3D printing to verify the results experimentally. Using this approach, we find predictive motifs linking particle shape to packing stiffness and have discovered a particle shape that self-confines to produce granular packings that stiffen, rather than weaken, under compression. I will discuss opportunities to explore particle shape for effective jamming and to design granular matter with optimized properties for applications ranging from soft robotics to architecture.