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Tissue Stress [MPa]Tissue Stress [MPa]604020000.511.52Tissue Strain [%]60402000 0.5 1 1.5 2Impact Resistance ofCrustacean ShellsStomatopod (Fig. 5) cuticle at thenanoscale consists of mineralised chitinfibres and calcified protein matrix,which form (at the microscale) plywood(Bouligand) layers with interpenetratingpore-canal fibres. My colleague DrGupta (from Queen Mary University ofLondon) used sophisticated synchrotronX-ray diffraction to visualise, forthe first time, the Bouligand structureduring the deformation. Using a mathematicalmodel known as the laminatetheory for orthotropic thin plates, wewere able to quantify how much thechitin fibres reorient and align with theloading direction, to better withstandthe load. Our calculated reorientationangles matched the ones measured experimentally.Tissue Strain [%]Fig. 4: Energy absorption in cyclically loaded antler bone. Top: mathematical model of the bonewith elastic and plastic fibrils and damageable interfaces. Bottom: experimental stress-strain curveobtained with synchrotron X-ray diffraction.Fig. 6: The hierarchicalstructure in a stomatopodcuticle. From topto bottom: Bouligandstructure, lamellar structurewith different fibreorientation, a single fiberas a bundle of fibrils.Fig. 5: An example of stomatopod: the peacockmantis shrimp is a marine crustaceans, famousfor its deadly club. If kept in an aquarium, theforce of its strikes is such than can shatter theglass of the water tank.Silke Baron (,[References]1.“Towards in situ determination of 3D strainand reorientation in the interpenetratingnanofibre networks of cuticle,”Y Zhang, PDe Falco, Y Wang, E Barbieri, O Paris, NJTerrill, G Falkenberg, NM Pugno, HS Gupta,Nanoscale, 9 (31), 11249-11260 (2017)2.“Staggered Fibrils and Damageable InterfacesLead Concurrently and Independently toHysteretic Energy Absorption and InhomogeneousStrain Fields in Cyclically LoadedAntler Bone,”P De Falco, E Barbieri, NPugno, HS Gupta, ACS Biomaterials Science &Engineering, 3 (11), 2779-2787 (2017)3.”Protein disorder-order interplay to guidethe growth of hierarchical mineralizedstructures,”S Elsharkawy, M Al-Jawad, MFPantano, E Tejeda-Montes, K Mehta, H Jamal,S Agarwal, K Shuturminska, A Rice, NTarakina, R Wilson, A Bushby, Me Alonso,JC Rodriguez-Cabello, E Barbieri, A del RioHernandez, M Stevens, NM Pugno, P Anderson,A Mata, Nature Communications , (2018),acceptedMathematical ModelIt is a description of a physical systemthough mathematical equations. Thesimulation is the process of obtainingthe solutions to such equations.Elasticity/Plasticity/ViscoelasticityDeformations in materials can be reversible(deformation disappears afterunloading) or irreversible (deformationremains after unloading). Elastic deformationsare reversible, while plasticdeformations are irreversible. Deformationscan also be time-independent (notime delay between force and deformation)or time-dependent (materialresponds with a time delay). Viscoelasticityis a time-dependent reversibledeformation.Synchrotron X-ray diffractionA method for determining structure bydirecting a beam of X-rays at the sampleand detecting the positions and intensitiesof the diffracted X-rays as a patternof spots on a photographic plate.Bouligand StructureA layered and rotated microstructure resemblingplywood. It consists of multiplelamella, or layers, each one composedof aligned fibers. Adjacent lamellaare progressively rotated with respect tothe its neighbors.Hierarchical StructureA structure composed of building blocksthat themselves have structure (Fig. 6).Elastic HysteresisIn a material, it is the dependence of itsmechanical response on the previousloading history. The resulting stressstraincurve will have loops. The areainside the loops is the energy dissipateddue to internal friction.KeywordsEttoreBarbieri役職研究員E-mail e.barbieri@jamstec.go.jp所属学会欧州機械学会(EUROMECH)Fellow of the Higher EducationAcademy (UK)専門分野破壊力学・非線形力学MAT Toolbox 2018 9