2026-09-20T00:40:24Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/1137592022-01-13T07:54:05Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Pedro M. Reis.
Al-Rashed, Rashed Abdulazeez
Massachusetts Institute of Technology. Department of Mechanical Engineering.
Massachusetts Institute of Technology. Department of Mechanical Engineering
2018-02-16T20:04:40Z
2018-02-16T20:04:40Z
2017
2017
http://hdl.handle.net/1721.1/113759
1022267832
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-63).
We introduce a new experimental system to study the effects of pre-stretch on the buckling patterns that emerge from the biaxial compression of elastomeric bilayer shells. After fabricating our samples, releasing the pre-stretch in the substrate by deflation places the outer film in a state of biaxial compression and yields a variety of buckling patterns. We systematically explore the parameter space by varying the pre-stretch of the substrate and the ratio of film stiffness to substrate stiffness. The phase diagram of the system exhibits a variety of buckling patterns: from the classic periodic wrinkle to creases, folds, and high aspect ratio ridges. Our system is capable of easily transitioning between these buckling patterns, a first for biaxial systems. We focus on the wrinkle to ridge transition, where we find that pre-stretch plays an essential role in ridge formation, and that the ridge geometry (width, height) remains approximately constant throughout the process. For the localized ridge patterns, we find that the propagation of the ridge tip depends strongly on both strain and stiffness ratio, in a way that is akin to hierarchical fracture of brittle coatings.
by Rashed Abdulazeez Al-Rashed.
S.M.
63 pages
eng
Massachusetts Institute of Technology
MIT 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.
http://dspace.mit.edu/handle/1721.1/7582
Mechanical Engineering.
Buckling patterns on pre-stretched bilayer shells
Thesis
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<Abstract>We introduce a new experimental system to study the effects of pre-stretch on the buckling patterns that emerge from the biaxial compression of elastomeric bilayer shells. After fabricating our samples, releasing the pre-stretch in the substrate by deflation places the outer film in a state of biaxial compression and yields a variety of buckling patterns. We systematically explore the parameter space by varying the pre-stretch of the substrate and the ratio of film stiffness to substrate stiffness. The phase diagram of the system exhibits a variety of buckling patterns: from the classic periodic wrinkle to creases, folds, and high aspect ratio ridges. Our system is capable of easily transitioning between these buckling patterns, a first for biaxial systems. We focus on the wrinkle to ridge transition, where we find that pre-stretch plays an essential role in ridge formation, and that the ridge geometry (width, height) remains approximately constant throughout the process. For the localized ridge patterns, we find that the propagation of the ridge tip depends strongly on both strain and stiffness ratio, in a way that is akin to hierarchical fracture of brittle coatings.</Abstract>
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