Pattern Formation in Confined Core‐Shell Structures: Stiffness, Curvature, and Hierarchical Wrinkling

• Published in: Advanced materials interfaces 2024-03, Vol.11 (9), p.n/a
• Main Authors: Kim, Ji Hoon, Bae, Jung Gun, Yoon, Hyunsik, Lee, Won Bo
• Format: Article
• Language: English
• Subjects: Automobile industry; Constraint modelling; Core-shell structure; Curvature; Dimpling; hierarchical wrinkling; metal deposition; pattern formation; spherical wrinkling; Stiffness; Substrates; Synchronism
• ISSN: 2196-7350; 2196-7350
• DOI: 10.1002/admi.202300942

Adapting sheets to doubly curved surfaces is a longstanding challenge in various engineering disciplines, from flexible and stretchable electronics to the automotive industry. However, current understanding often focuses on specific scenarios and neglects the diverse range of substrate conditions encountered in nature. This study investigates the pattern formation in confined core‐shell structures by modulating the levels of stiffness and curvature of the substrate. Beginning with the Föppl–von Kármán equation, this theory uncovers how the degree of confinement determines the location of wrinkles within confined sheets. Furthermore, the synchronization of patterns is observed: the formation of dimple or buckyball patterns on curved surfaces simultaneously with hierarchical wrinkles due to boundary constraints. The analytical models elucidate these phenomena, and both macroscopic and microscopic features can be systematically engineered to align with quantitative predictions. This research expands the current understanding of the sheet conformation problem and paves the way for pattern engineering across a range of curved structures. Pattern engineering of confined metal sheets on substrates with varying levels of stiffness and curvatures. Energetically favorable dimple or buckyball patterns on curved surfaces are synchronized with hierarchical wrinkles induced by boundary constraints.