<p class="Paragraph SCXW110308767 BCX2" style="font-weight: normal; font-style: normal; vertical-align: baseline; background-color: transparent; color: windowtext; text-align: left; margin-left: 0px; margin-right: 0px; padding-left: 0px; padding-right: 0px; text-indent: 0px">Three-dimensional (3D) buckled mesostructures have potential applications in a wide range of fields owing to the ease with which they can be produced on a flat surface and buckled under compression into a complex 3D shape. Many of these structures are multistable, offering controlled shape and functionality without the need for persistent external stimuli. Of particular interest are those inspired by origami which allow for localized folding, providing additional stable states and greater control over these various configurations. Many studies have laid solid foundations for the design and development of 3D mesostructures with multistability. However, difficulties remain in designing a structure to obtain targeted reconfigurability. First is the issue of additional undesired states which can trap the structure midway through reconfiguration between target states or create additional pathways which reduce their stability. Secondly, the reconfiguration pathways of these structures are highly non-linear and complex, posing a challenge for identifying or tailoring the reconfigurational modes of a given structure.&nbsp;</p><p class="Paragraph SCXW110308767 BCX2" style="font-weight: normal; font-style: normal; vertical-align: baseline; background-color: transparent; color: windowtext; text-align: left; margin-left: 0px; margin-right: 0px; padding-left: 0px; padding-right: 0px; text-indent: 0px">&nbsp;&nbsp;</p><p class="Paragraph SCXW110308767 BCX2" style="font-weight: normal; font-style: normal; vertical-align: baseline; background-color: transparent; color: windowtext; text-align: left; margin-left: 0px; margin-right: 0px; padding-left: 0px; padding-right: 0px; text-indent: 0px">Here, we focus on a computational study of these buckled structures by analyzing their high-dimensional energy landscapes where stable states correspond to local minima configurations. The structures are represented by 2D triangulated surfaces, and a discrete shell model is used to represent their energy. Using this approach, we are able to identify both the stable states and the most energy-efficient pathways between them. We study how material and geometric parameters affect the available configurations for two different mesostructures, one of uniform thickness and the other a simple origami inspired structure (a single ribbon with multiple, uniformly separated folds). For each, phase diagrams of the stable states are generated which can be utilized to tailor the structures to select for target states or remove those which are undesired. For example, in the case of the origami ribbon structure, the degree of multistability depends upon the number of folds, with the most stable states for 3 folds and decreasing to just a single state as the number of folds increases. Furthermore, the variation in the reconfiguration energy barriers is observed, revealing dynamic changes to the available and most efficient paths, as well as the instability modes at points when individual configurations become unstable. Finally, these computational results are then compared with those obtained experimentally using ferromagnetic structures which can be quickly and reversibly reconfigured using a magnet, and we find excellent agreement for both the stable states and pathways. Taken together, these results demonstrate the potential offered by energy landscape methods for the study of complex reconfigurable behavior. This can be utilized to aid in the design and development of multistable functional structures in soft robotics, microelectronics, and more.&nbsp;</p>

Surveying the Energy Landscapes and Reconfiguration Pathways of Multistable Buckled Structures

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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