Abstract
Since the turn of the millennium, driven by the advent of new synthesis and additive manufacturing processes capable of delivering materials with highly controllable nano- and microstructures, increasing efforts have been devoted to the investigation and design of advanced materials with unprecedented multifunctional properties. In this context, I will begin this talk by presenting two new classes of numerical methods capable to describe the macroscopic electromechanical and magnetomechanical behaviors—under arbitrarily large deformations, electric fields, and magnetic fields — of materials directly in terms of their (random or periodic) microstructure and microscopic behavior. The first method is based on a high-order WENO finite-difference scheme for Hamilton-Jacobi equations, while the second one is based on a conforming hybrid finite element discretization of Crouzeix-Raviart type. All the solutions generated by these methods share key functional features that lead in turn to a simple closed form approximation for the coupled and nonlinear macroscopic response of these classes of materials. By deploying the aforementioned methods, I will then present results that shed light on experimental findings on the response of emerging dielectric elastomer composites and magnetorheological elastomers that had remained challenging to interpret for more than a decade. What is more, the results also suggest two new paradigms—the presence of interphasial space charges in dielectric elastomer composites and ferrofluid inclusions as superior fillers in lieu of the more conventional iron particles in magnetorheological elastomers — for the bottom-up design of materials with a myriad of extreme macroscopic behaviors ranging from unusually large permittivities and electrostriction coefficients, to metamaterial-type properties featuring negative permittivities, to giant magnetostriction capabilities.
Bio:
Victor Lefèvre is an Assistant Professor in the Mechanical Engineering Department at Northwestern University. Prior to joining Northwestern, Victor was the Hibbitt Engineering Postdoctoral Fellow in the School of Engineering at Brown University after he obtained his Ph.D. in Civil Engineering from the University of Illinois at Urbana-Champaign. His research interests lie in the field of the mechanics of solids and structures, with an emphasis in the multi-physics behavior of emerging soft multifunctional composite materials.
Host: Professor Sascha Hilgenfeldt
