סמינר מחלקתי של אסף דנה- הרכבה ופירוק של מוצקים באמצעות פעולה קולקטיבית
Assembling and Disassembling Solids using Collective Action
Monday August 4th 2025 at 14:00
Wolfson Building of Mechanical Engineering, Room 206
Abstract:
Swarm robotics is a promising methodology for accomplishing complicated tasks through the collective behavior of multiple active units. Interactions between active individuals in animal collectives (like fire ants and worms) lead to emergent responses that remain elusive in synthetic systems. In this talk, I present shape-morphing polymers as a framework to create bio-inspired transient swarms that can self-assemble into a stable solid structure, modulate their mechanical properties, and disassemble on demand. The solids are composed of aggregates of many magnetic, heat-responsive liquid crystal elastomer ribbons. Dilute-suspensions of curved and moving ribbons mechanically interlock, inducing reversible aggregation. The degree of bend and twist of the ribbon and the motion of the ribbon in a rotating external field control how ribbons interact with one another. A mathematical model is developed that sheds light on the role of topological mechanisms in aggregation. The ribbon suspensions reversibly transition between fluid- and solid-like states, exhibiting up to 6 orders-of-magnitude increase in the storage moduli of the entangled aggregates compared with the liquid dispersions. Subsequent heating resulted in a 2-fold increase in both stiffness and yield stress. Controlled dissociation is induced by imparting kinetic energy to the individual ribbons at high magnetic field rotation speeds. Study results provide insights that can lead to advancements in control and task programming of such swarming systems, specifically, by designing mechanical and chemo-mechanical switches for system manipulation. Imparting dynamic collective behaviors into synthetic systems may enable a range of potential applications from autonomous bio-inspired soft robotics to injectable biomaterials.
Bio:
Dr. Asaf Dana is an incoming assistant professor in the Department of Mechanical and Materials Engineering at the University of Nebraska – Lincoln. Until recently, he was a postdoctoral researcher in the Departments of Biomedical Engineering and Materials Science and Engineering at Texas A&M University. His current research focuses on developing soft stimuli-responsive material platforms for applications in tissue engineering, soft robotics and materials processing. Dr. Dana received his Ph.D. (2022) from the Department of Mechanical Engineering at the Technion – Israel Institute of Technology, focusing on the design of a previously unaccessed high-rate actuation mode of shape memory alloys. His research interests include the mechanics of responsive materials with emphasis on processes involving phase transitions in fabrication and actuation. In his research, he develops new experimental systems and methods to study the fundamental relations between microstructural evolution and macro-scale response and employs this knowledge for the development of new engineering design tools for smart and responsive systems.
