title: Multi-layered bird beaks: a finite-element approach towards the role of keratin in stress dissipation.
abstract: Bird beaks are layered structures, which contain a bony core and an outer keratin layer. The elastic moduli of this bone and keratin were obtained in a previous study. However, the mechanical role and interaction of both materials in stress dissipation during seed crushing remain unknown. In this paper, a multi-layered finite-element (FE) model of the Java finch's upper beak (Padda oryzivora) is established. Validation measurements are conducted using in vivo bite forces and by comparing the displacements with those obtained by digital speckle pattern interferometry. Next, the Young modulus of bone and keratin in this FE model was optimized in order to obtain the smallest peak von Mises stress in the upper beak. To do so, we created a surrogate model, which also allows us to study the impact of changing material properties of both tissues on the peak stresses. The theoretically best values for both moduli in the Java finch are retrieved and correspond well with previous experimentally obtained values, suggesting that material properties are tuned to the mechanical demands imposed during seed crushing.
authors.affiliation: Laboratory of Biomedical Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium. joris.soons@ua.ac.be
authors.forename: Joris
authors.initials: J
authors.lastname: Soons
authors.forename: Anthony
authors.initials: A
authors.lastname: Herrel
authors.forename: Annelies
authors.initials: A
authors.lastname: Genbrugge
authors.forename: Dominique
authors.initials: D
authors.lastname: Adriaens
authors.forename: Peter
authors.initials: P
authors.lastname: Aerts
authors.forename: Joris
authors.initials: J
authors.lastname: Dirckx
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000737:chemistry / Q000378:metabolism*; D001502:Beak / Q000033:anatomy & histology / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D046369:Finches; D020342:Finite Element Analysis; D007633:Keratins / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D012886:Skull / Q000033:anatomy & histology / Q000502:physiology; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D030161:Avian Proteins; D007633:Keratins