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dc.contributor.advisorXuanhe Zhao.en_US
dc.contributor.authorLin, Shaoting,Ph. D.Massachusetts Institute of Technology.en_US
dc.contributor.otherMassachusetts Institute of Technology. Department of Mechanical Engineering.en_US
dc.date.accessioned2020-02-10T21:43:49Z
dc.date.available2020-02-10T21:43:49Z
dc.date.copyright2019en_US
dc.date.issued2019en_US
dc.identifier.urihttps://hdl.handle.net/1721.1/123772
dc.descriptionThesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019en_US
dc.descriptionCataloged from PDF version of thesis.en_US
dc.descriptionIncludes bibliographical references (pages 210-228).en_US
dc.description.abstractHuman bodies are mostly made of soft, wet yet robust biological hydrogels such as cartilages, ligaments, and muscles. The biological hydrogels commonly possess mechanical properties such as high toughness, resilience and fatigue resistance to guarantee the bodies' reliable functions and activities. While hydrogels with tissue-like mechanical properties are highly desirable in applications as diverse as tissue engineering, drug delivery and soft machines, these properties are rarely achieved in synthetic hydrogels. The first part of this dissertation is aimed to design synthetic hydrogels that possess tissue-like mechanical properties, including high toughness, resilience and fatigue threshold, through combined theory, modeling and experiments. First, we develop a coupled cohesive-zone and Mullins effect model to predict the fracture energies of tough hydrogels. Based on the model, we further provide a toughening diagram that can guide the design of new tough hydrogels.en_US
dc.description.abstractSecond, we propose that delaying mechanical dissipations in tough hydrogels can make the hydrogels resilient under moderate deformation while still high toughness and high resilience for hydrogels. Third, we study fatigue fracture in hydrogels and show that the introduction of nanocrystalline domains and aligned nanofibrils can substantially increase hydrogels' fatigue-resistant properties. In the second part of this dissertation, we study mechanical instabilities in hydrogels. Under tension, a layer of confined elastic material such as hydrogel can exhibit various modes of mechanical instabilities, including cavitation, fingering and fringe instabilities. While the cavitation has been extensively studied, the fingering and fringe instabilities have not been well understood, and the relations and interactions of these instabilities have not been explored yet.en_US
dc.description.abstractWe systematically study the formation, transition, interaction and co-existence of mechanical instabilities in confined elastic layers under tension. Through combined experimental, numerical and theoretical analysis, we find that the mode of instability is determined by both geometry and mechanical properties of the elastic layer through two non-dimensional parameters: layer's lateral dimension over its thickness and elastocapillary length over the defect size. A phase diagram is calculated to quantitatively predict the occurrence of any mode of instability, which can help the design of robust adhesives by rationally harnessing the desired mode of instabilities while suppressing the other modes.en_US
dc.description.statementofresponsibilityby Shaoting Lin.en_US
dc.format.extent228 pagesen_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsMIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectMechanical Engineering.en_US
dc.titleTissue-like hydrogels by designen_US
dc.typeThesisen_US
dc.description.degreePh. D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Mechanical Engineeringen_US
dc.identifier.oclc1139345013en_US
dc.description.collectionPh.D. Massachusetts Institute of Technology, Department of Mechanical Engineeringen_US
dspace.imported2020-02-10T21:43:48Zen_US
mit.thesis.degreeDoctoralen_US
mit.thesis.departmentMechEen_US


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