Flexible mechanical metamaterials: solitary waves and phase transitions
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Deng, Bolei
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Deng, Bolei. 2021. Flexible mechanical metamaterials: solitary waves and phase transitions. Doctoral dissertation, Harvard University Graduate School of Arts and Sciences.Abstract
Over the last two decades, metamaterials — materials whose properties are defined by their structure rather than their composition — have been a magnet for scientists, generating significant interest in the research community. In this dissertation, I explore the nonlinear mechanics of flexible mechanical metamaterials (flexMMs) focusing on: (i) the propagation of solitary waves, and (ii) structural phase transitions. I first investigate the nonlinear dynamic behavior of flexMMs based on the rotating squares mechanism. I experimentally and numerically demonstrate that this system supports the propagation of elastic vector solitons and construct a theoretical framework to capture them. Next, I investigate the formation of multiple phases in the rotating squares systems and the evolution of domain walls between these phases. I derive an analytical solution that captures the profiles and locations of such domain walls and exploits it to guide the design of flexMMs with new functionalities. Finally, I explore topological phase transitions in micrometer-scale cellular flexMMs. I present a two-tiered strategy based on swelling that is able to fast, reversibly, and robustly change the fundamental topology of cellular lattices, e.g., connectivity and number of the nodes. I then harness these topological changes to design active surfaces with tunable properties and functionalities.Terms of Use
This article is made available under the terms and conditions applicable to Other Posted Material, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#LAACitable link to this page
https://nrs.harvard.edu/URN-3:HUL.INSTREPOS:37370241
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