Date of Award

2025

Degree Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical, Industrial and Systems Engineering

First Advisor

Helio Matos

Abstract

The buckling and collapse of thin-walled cylindrical shells under external hydrostatic pressure is an important issue in the mechanical design of underwater structures, especially as additive manufacturing enables rapid fabrication of complex geometries. In this study, large-scale 3D-printed ABS cylinders incorporating sinusoidal corrugated double-hull profiles were fabricated to examine their collapse mechanics under quasi-static pressurization. The shells were manufactured via FDM printing and post-processed with acetone vapor, which seals the surface by redistributing material and closing interlayer voids. Experiments revealed distinct failure pathways compared to traditional metallic shells, including localized outer-hull fracture, asymmetric water ingress, and mixed-mode collapse rather than classical global buckling. Corrugation geometry strongly affected collapse pressure, deformation patterns, and the progression of failure, while dimensional changes from both printing and post-processing were quantified to assess their mechanical implications. These results demonstrate that structural tailoring through corrugation and controlled post-processing can meaningfully modify the initiation of instability and the progression of collapse in polymer shells, establishing large-format FDM as a viable platform for investigating thin-shell mechanics and designing polymer-based underwater structures.

Available for download on Sunday, January 23, 2028

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