Francisco Lopez Jimenez
"Geometry in the design of lightweight structures: thin composites and bee honeycomb construction"
Abstract: Lightweight materials and structures are essential in several applications, from enabling the large space structures required to advance science missions to reducing fuel consumption in vehicles. We will present two examples of how their behavior is often dominated by their geometry across different scales. First, we will study an example of the use of high strain composites in deployable space structures. We focus on the design of flexible hinges that fold elastically to deploy stiff panels. We combine theory and experiments to study the strains during stowage and their natural frequencies when deployed. We identify the geometric scalings controlling the mechanics of the system, and build and test prototypes to demonstrate the validity of our approach. Second, we will explore how honeybees adapt the construction of their honeycomb under different constraints. We 3D-print experimental frames with imprinted foundations, that the bees extend as they construct the comb. The panels impose a variety of constraints, ranging from crystal misalignment to cells of different sizes. The resulting constructed comb lattices show clear evidence of reoccurring patterns with non-regular geometry and topology that can be related to the behavior of other lattices and self-organized systems, such as graphene and crack networks, and that can be used of inspiration on the design of man-made cellular solids.
Bio: Francisco López Jiménez is an Assistant Professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences at the University of Colorado Boulder. He received his B.S. in Mechanical Engineering from the University of Seville, and a M.S. in Aerospace Engineering and a Ph.D. in Aeronautics from the California Institute of Technology. Before joining CU Boulder, he held postdoctoral research appointments at the Laboratoire de Mécanique des Solides (École Polytechnique, France) and the Massachusetts Institute of Technology. His research focuses on the design, fabrication, and analysis of lightweight materials and slender structures, with a focus on the interplay between mechanics and geometry. He is particularly interested in space deployable structures, composite materials, and multifunctional metamaterials.