Traditionally, the properties of bulk materials such as elastic moduli or plasticity have been understood from the characteristic scales and symmetries of underlying ordered structures, e.g., atomic crystals or colloidal lattices. However, disordered materials, such as glasses or granular media, have great untapped potential: they can exist in a multitude of metastable states that are distinguished by their microstructure. Recent work has shown that while the vast majority of these states have similar (boring!) bulk properties, some rare cases have spectacular behavior, e.g., greatly enhanced stability to plastic rearrangements or allosteric actuation. The challenge, of course, is to direct the material to such targeted useful states that would never be discovered by chance alone. Analyzing the mechanics of networks and packings as prototypical disordered systems, we meet this challenge by introducing material training protocols that result in systematic evolution toward those desired states. One very successful and broadly applicable strategy we suggest is the transient introduction of extra degrees of freedom (such as particle radii in packings). In the augmented state space, extraordinary states can be found much more straightforwardly, after which the additional degrees of freedom are removed again. Choosing different transient degrees of freedom leads to different behaviors, such as the mechanical ultra-stability of the trained system. Whether employed for Soft Matter, biomaterials, or glassy solids, the framework presented here provides a systematic approach (into which data-driven and AI-based tools can be easily incorporated) to create novel materials and meta-materials by recognizing disorder as a crucial opportunity for versatile design of function.
About the Speaker
Varda Hagh is a postdoctoral researcher at the James Franck Institute at the University of Chicago and a member of the Simons Collaboration on Cracking the Glass Problem. Varda is interested in using the inherent complexity of disordered solids to develop extraordinary mechanical functionality in materials. After undergraduate degrees from the University of Tehran and a Ph.D. from Arizona State University in Soft Matter, as a postdoc, Varda has studied various fundamental aspects relating the mechanics and structure of amorphous solids, establishing multiple collaborations with internationally renowned groups. During this time, Varda has contributed to several major advances in the emerging field of material training.
Aside from their research, Varda is committed to promoting STEM education and computational literacy. They are an instructor at the Software Carpentry Foundation and have led numerous programming workshops at research centers and universities throughout the United States. Additionally, Varda has chaired and co-organized several conferences and schools in the United States and Europe, and and has translated and published several science books to make science education accessible to public schools in Iran.
Host: Professor Iwona Jasiuk