Abstract: Metamaterials are synthetic materials engineered to have properties not found in naturally occurring materials. They are being designed for a broad set of applications ranging from light modulation, wearable electronic devices, supercapacitors, solar cells, and battery electrodes to mention just a few. In this seminar, I will discuss two classes of metamaterials we have investigated, kirigami and 2D metamaterials. Kirigami have their origin in the Japanese art based on paper cutting. In this presentation, I will discuss the results of fabrication and mechanical testing of kirigami metamaterials exhibiting a variety of 3D configurations. I will also introduce an inverse design methodology based on machine learning algorithms in the context of applications ranging from bioinspired surface texturing to a curvature-guided organization for light modulation. In the second part of this presentation, I will discuss strategies for the in-situ electron microscopy fracture testing of 2D materials as well as advances in the parameterization of interatomic potentials (force fields) for accurate description of crack tips' atomic lattice reconstructions and bond dissociations. Using monolayer MoSe2 as a testbed, I will illustrate the effectiveness of the combined experimental-computational approach in measuring and predicting the toughness of the material, demonstrating in the process the advantages of ML-interatomic potentials in developing computational approaches with predictive capabilities in the spirit of the materials genome initiative.

Biosketch: Horacio D. Espinosa is the Walter P. Murphy Professor of Mechanical Engineering, and the Director of the Theoretical and Applied Mechanics Program at the McCormick School of Engineering, Northwestern University. He received his Ph.D. in Solid Mechanics from Brown University in 1992. Espinosa has made contributions in the areas of deformation and failure of materials, design of micro- and nano-systems, in situ microscopy characterization of nanomaterials, and microfluidics for single cell manipulation and analysis. He has published over 300 technical papers on these topics. Espinosa received several awards including the Prager Medal from the Society of Engineering Science, the Society for Experimental Mechanics Murray, and Sia Nemat Nasser Medals, and the ASME Drucker and Thurston awards. He is a member of the National Academy of Engineering (NAE), National Academy of Inventors (NAI), foreign member of Academia Europaea, the European Academy of Arts and Sciences, the Russian Academy of Engineering, and Fellow of AAAS, ASME, SEM, and AAM. He was the President of the Society of Engineering Science in 2012 and is currently the past chair of the US National Committee on Theoretical and Applied Mechanics and a member of the IUTAM General Assembly.