Ang, Siang FungSiang FungAngBortel, Emely LeaEmely LeaBortelSwain, Michael V.Michael V.SwainKlocke, ArndtArndtKlockeSchneider, Gerold A.Gerold A.Schneider2010-01-182010-01-182010Biomaterials vol. 31.2010(7), pp.1955-1963616621892http://tubdok.tub.tuhh.de/handle/11420/749The microstructure of enamel like most biological tissues has a hierarchical structure which determines their mechanical behavior. However, current studies of the mechanical behavior of enamel lack a systematic investigation of these hierarchical length scales. In this study, we performed macroscopic uni-axial compression tests and the spherical indentation with different indenter radii to probe enamel’s elastic/inelastic transition over four hierarchical length scales, namely: ‘bulk enamel’ (mm), ‘multiple-rod’ (10’s µm), intra-rod’ (100’s nm with multiple crystallites) and finally ‘single-crystallite’ (10’s nm with an area of approximately one hydroxyapatite crystallite). The enamel’s elastic/inelastic transitions were observed at 0.4-17GPa depending on the length scale and were compared with the values of synthetic hydroxyapatite crystallites. The elastic limit of a material is important as it provides insights into the deformability of the material before fracture. At the smallest investigated length scale (contact radius ~20nm), elastic limit is followed by plastic deformation. At the largest investigated length scale (contact size ~1mm), only elastic then micro-crack induced response was observed. A map of elastic/inelastic regions of enamel from millimeter to nanometer length scale is presented. Possible underlying mechanisms are also discussed.en0142-961220101019551963Elsevierhttp://doku.b.tu-harburg.de/doku/lic_ohne_pod.phphttps://creativecommons.org/licenses/by-nc-nd/4.0/elastisch-inelastischer ÜbergangMechanische EigenschaftenEindruckversuchDruckversuchhierarchische Struktursize-dependentelastic-inelastic transitionenamelmechanical propertiesnanoindentationIngenieurwissenschaftenJournal Article2010-01-18urn:nbn:de:101:1-20150527214210.15480/882.747Keramische Werkstoffe, HartstoffeWerkstoffprüfung, WerkstoffuntersuchungSonstige WerkstoffeWerkstoffkunde: SonstigesZahnschmelzZahntechnik11420/74910.1016/j.biomaterials.2009.11.04510.15480/882.747930768461Other