title: Hypothesis: bones toughness arises from the suppression of elastic waves.
abstract: Bone and other natural material exhibit a combination of strength and toughness that far exceeds that of synthetic structural materials. Bone's toughness is a result of numerous extrinsic and intrinsic toughening mechanisms that operate synergistically at multiple length scales to produce a tough material. At the system level however no theory or organizational principle exists to explain how so many individual toughening mechanisms can work together. In this paper, we utilize the concept of phonon localization to explain, at the system level, the role of hierarchy, material heterogeneity, and the nanoscale dimensions of biological materials in producing tough composites. We show that phonon localization and attenuation, using a simple energy balance, dynamically arrests crack growth, prevents the cooperative growth of cracks, and allows for multiple toughening mechanisms to work simultaneously in heterogeneous materials. In turn, the heterogeneous, hierarchal, and multiscale structure of bone (which is generic to biological materials such as bone and nacre) can be rationalized because of the unique ability of such a structure to localize phonons of all wavelengths.
authors.affiliation: 1] School of Aerospace, Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technologies, University of Sydney, NSW. 2006, Australia [2] Laboratory for Sustainable Technology, School of Chemical and Biomolecular Engineering, University of Sydney, NSW. 2006.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Davies
authors.affiliation: Laboratory for Sustainable Technology, School of Chemical and Biomolecular Engineering, University of Sydney, NSW. 2006.
authors.forename: Alice
authors.initials: A
authors.lastname: King
authors.affiliation: 1] School of Aerospace, Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technologies, University of Sydney, NSW. 2006, Australia [2] Laboratory for Sustainable Technology, School of Chemical and Biomolecular Engineering, University of Sydney, NSW. 2006.
authors.forename: Peter
authors.initials: P
authors.lastname: Newman
authors.affiliation: Laboratory for Sustainable Technology, School of Chemical and Biomolecular Engineering, University of Sydney, NSW. 2006.
authors.forename: Andrew
authors.initials: A
authors.lastname: Minett
authors.affiliation: School of Aerospace, Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technologies, University of Sydney, NSW. 2006, Australia.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Dunstan
authors.affiliation: School of Aerospace, Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technologies, University of Sydney, NSW. 2006, Australia.
authors.forename: Hala
authors.initials: H
authors.lastname: Zreiqat
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology*; D032701:Biomimetics / Q000379:methods; D001842:Bone and Bones / Q000502:physiology*; D006244:Hardness / Q000502:physiology*; D006801:Humans; D008422:Materials Testing; D008954:Models, Biological; D049329:Nanostructures / Q000737:chemistry; D060739:Phonons; D013016:Sound