Mechanical and Civil Engineering Seminar
The field of shape morphing structures, i.e., mechanical systems designed to change shape in response to external stimuli, is already quite developed, with applications ranging from everyday objects to large Civil and Space structures. Recently-emerged needs and applications, e.g., the need to fit large deployable structures into ever-smaller satellites, or the birth of the soft robotics field, have pushed researchers to explore new directions in shape-morphing systems. A way to reduce the part count in these systems is to replace multiple jointed parts with continua featuring compliant hinges. This can be especially convenient for space applications, where harsh environments can interfere with the behavior of jointed systems. Another research direction is to expand the range of achievable shape changes, e.g., by obtaining extreme area changes or by morphing flat objects into complex surfaces. One last direction is the exploration of avenues for non-mechanical morphing, with the goal of designing structures that can morph due to environmental cues and without the need for motorized actuators.
In this presentation, I will illustrate my first steps into this branch of mechanics, that began when I joined the Daraio Group at Caltech in 2017. Our first goal was to answer the curiosity-driven question of finding a simple strategy to design flat sheets that can transform into 3D surfaces with non-zero Gaussian curvature. After illustrating a method to achieve this goal via frustrated compliant mechanisms, I will present the subsequent steps we took to try to bridge the gap from a strategy that is only bound to work at the tabletop scale using rubbery materials, to larger-scale structural applications. Along the way, I will make mechanistic considerations on how to construct metallic shape-morphing structures by resorting to assemblies of twisted ribbons, and on how to leverage displacement-amplification mechanisms to create structures that morph in response to temperature changes.