title: Compliant threads maximize spider silk connection strength and toughness.
abstract: Millions of years of evolution have adapted spider webs to achieve a range of functionalities, including the well-known capture of prey, with efficient use of material. One feature that has escaped extensive investigation is the silk-on-silk connection joints within spider webs, particularly from a structural mechanics perspective. We report a joint theoretical and computational analysis of an idealized silk-on-silk fibre junction. By modifying the theory of multiple peeling, we quantitatively compare the performance of the system while systematically increasing the rigidity of the anchor thread, by both scaling the stress-strain response and the introduction of an applied pre-strain. The results of our study indicate that compliance is a virtue-the more extensible the anchorage, the tougher and stronger the connection becomes. In consideration of the theoretical model, in comparison with rigid substrates, a compliant anchorage enormously increases the effective adhesion strength (work required to detach), independent of the adhered thread itself, attributed to a nonlinear alignment between thread and anchor (contact peeling angle). The results can direct novel engineering design principles to achieve possible load transfer from compliant fibre-to-fibre anchorages, be they silk-on-silk or another, as-yet undeveloped, system.
authors.affiliation: Laboratory for Nanotechnology in Civil Engineering (NICE), Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, MA 02115, USA.
authors.forename: Avery
authors.initials: A
authors.lastname: Meyer
authors.affiliation: Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, Università di Trento, via Mesiano 77, 38123 Trento, Italy Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo (Trento), Italy nicola.pugno@unitn.it.
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Pugno
authors.affiliation: Laboratory for Nanotechnology in Civil Engineering (NICE), Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, MA 02115, USA s.cranford@neu.edu.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Cranford
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D004548:Elasticity; D008422:Materials Testing; D047011:Silk / Q000737:chemistry / Q000502:physiology*; D013112:Spiders; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000502:physiology; D023822:Tissue Engineering / Q000379:methods
chemical_list: D047011:Silk
keywords: adhesion; biological material; compliance; silk; theory of multiple peeling