Seminars

The term tensegrity, derived from tensional integrity, refers to a class of structural systems composed of bars and strings that achieve mechanical stability through pre-stressing of their string members. Conventional models of these structures assume rigid bars, linear elastic cables, and treat the Euler buckling load of any bar as a failure threshold. In practice, these assumptions break down under dynamic loading. In the first part of this talk, we introduce a physics-based reduced-order model for studying the dynamic and nonlinear response of tensegrity-based planetary landers. Using this model, we demonstrate that buckling of individual members does not necessarily imply structural failure; on the contrary, post-buckling behavior acts as a load-limiting mechanism that distributes forces evenly throughout the structure, dramatically increasing the amount of energy that can be stored elastically. This finding reframes post-buckling as a design opportunity rather than a failure mode. In the second part, we show how these insights translate into the design of novel metamaterials. We introduce the first realizable three-dimensional tensegrity lattice and demonstrate that it exhibits a previously unobserved mechanical behavior: severe deformation without strain localization. Unlike conventional materials, which fail through localized deformation bands, these lattices distribute deformation broadly throughout their architecture, enabling exceptional energy absorption and failure resistance. In the third and final part, we address the fundamental question of why delocalization occurs. Using graph theory, we represent each lattice as a pair of coupled networks—one carrying tension, the other compression—and show that delocalization arises from an intrinsic asymmetry in their connectivity: when the tension network remains more connected than the compression network, deformation spreads throughout the structure instead of localizing. This framework, recently published in Nature Metamaterials, provides the first mechanistic and predictive foundation for designing architected structures that intrinsically resist failure localization.

Bio: Julián J. Rimoli is the Department Chair and Dean’s Professor of Mechanical and Aerospace Engineering at the University of California, Irvine. He obtained his Engineering Diploma in Aeronautics from Universidad Nacional de La Plata, Argentina, in 2001, and received his M.Sc. and Ph.D. in Aeronautics from Caltech in 2005 and 2009, respectively. Following a postdoctoral appointment at the Department of Aeronautics and Astronautics at MIT, he joined Georgia Tech in 2011, where he held the Pratt & Whitney Professorship in Aerospace Engineering until moving to UC Irvine in 2022. His research lies at the intersection of computational mechanics, architected materials, and aerospace structures. He is a Fellow of ASME and an Associate Fellow of AIAA, and was selected for the National Academy of Engineering’s U.S. Frontiers of Engineering Symposium. He is the recipient of the NSF CAREER Award, the Ernest E. Sechler Memorial Award in Aeronautics, and the James Clerk Maxwell Young Writers Prize.