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Greco G, Bosia F, Tramacere F, Mazzolai B, Pugno NM. The role of hairs in the adhesion of octopus suckers: a hierarchical peeling approach. BIOINSPIRATION & BIOMIMETICS 2020; 15:035006. [PMID: 32018231 DOI: 10.1088/1748-3190/ab72da] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Organisms like the octopus or the clingfish are a precious source of inspiration for the design of innovative adhesive systems based on suction cups, but a complete mechanical description of their attachment process is still lacking. In this paper, we exploit the recent discovery of the presence of hairs in the acetabulum roof of octopus suction cups to revise the current model for its adhesion to the acetabulum wall. We show how this additional feature, which can be considered an example of a hierarchical structure, can lead to an increase of adhesive strength, based on the analysis of the cases of a simple tape and an axisymmetrical membrane adhering to a substrate. Using peeling theory, we discuss in both cases the influence of hierarchical structure and the resulting variation of geometry on the adhesive energy, highlighting how an increase in number of hierarchical levels contributes to its increment, with a corresponding improvement in functionality for the octopus suckers.
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Affiliation(s)
- Gabriele Greco
- Laboratory of Bio-inspired, Bionic, Nano, Meta Materials & Mechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano, 77, 38123 Trento, Italy. Center for Micro-BioRobotics, Istituto Italiano di Tecnologia, Viale Rinaldo Piaggio 34, 56025 Pontedera, Italy
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Brely L, Bosia F, Palumbo S, Fraldi M, Dhinojwala A, Pugno NM. Competition between delamination and tearing in multiple peeling problems. J R Soc Interface 2019; 16:20190388. [PMID: 31771420 DOI: 10.1098/rsif.2019.0388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Adhesive attachment systems consisting of multiple tapes or strands are commonly found in nature, for example in spider web anchorages or in mussel byssal threads, and their structure has been found to be ingeniously architected in order to optimize mechanical properties: in particular, to maximize dissipated energy before full detachment. These properties emerge from the complex interplay between mechanical and geometric parameters, including tape stiffness, adhesive energy, attached and detached lengths and peeling angles, which determine the occurrence of three main mechanisms: elastic deformation, interface delamination and tape fracture. In this paper, we introduce a formalism to evaluate the mechanical performance of multiple tape attachments in different parameter ranges, where an optimal (not maximal) adhesion energy emerges. We also introduce a numerical model to simulate the multiple peeling behaviour of complex structures, illustrating its predictions in the case of the staple-pin architecture. Finally, we present a proof-of-principle experiment to illustrate the predicted behaviour. We expect the presented formalism and the numerical model to provide important tools for the design of bioinspired adhesive systems with tuneable or optimized detachment properties.
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Affiliation(s)
- Lucas Brely
- Department of Physics and 'Nanostructured Interfaces and Surfaces' Inter-Departmental Centre, Università di Torino, Via P. Giuria 1, 10125 Torino, Italy
| | - Federico Bosia
- Department of Physics and 'Nanostructured Interfaces and Surfaces' Inter-Departmental Centre, Università di Torino, Via P. Giuria 1, 10125 Torino, Italy
| | - Stefania Palumbo
- Department of Structures for Engineering and Architecture, University of Napoli Federico II, Naples, Italy
| | - Massimiliano Fraldi
- Department of Structures for Engineering and Architecture, University of Napoli Federico II, Naples, Italy
| | - Ali Dhinojwala
- Department of Polymer Science, The University of Akron, Akron, OH 44325-3909, USA
| | - Nicola M Pugno
- Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, Università di Trento, via Mesiano, 77, I-38123 Trento, Italy.,School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK.,Fondazione E. Amaldi, Ket Lab, Via del Politecnico snc, 00133 Rome, Italy
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