Please use this identifier to cite or link to this item: https://doi.org/10.15480/882.990
Publisher DOI: 10.1016/j.jmbbm.2010.12.003
Title: Sub-10-micrometer toughening and crack tip toughness of dental enamel
Language: English
Authors: Ang, Siang Fung 
Schulz, Anja 
Pacher Fernandes, Rodrigo 
Schneider, Gerold A. 
Keywords: Werkstoffoberflächeneigenschaften;enamel;crack tip toughness;cohesive zone;hierarchical structure;toughening mechanisms
Issue Date: Apr-2011
Source: Journal of the mechanical behavior of biomedical materials ; 4.2011, pp. 423-432
Journal or Series Name: Journal of the mechanical behavior of biomedical materials 
Abstract (english): In previous studies, enamel showed indications to occlude small cracks in-vivo and exhibited R-curve behaviors for bigger cracks ex-vivo. This study quantifies the crack tip toughness (KI0, KIII0), the crack closure stress and the cohesive zone size at the crack tip of enamel and investigates the toughening mechanisms near the crack tip down to the length scale of a single enamel crystallite. The crack-opening-displacement (COD) profile of cracks induced by Vickers indents on mature bovine enamel was studied using atomic force microscopy (AFM). The mode I crack tip toughness KI0 of cracks along enamel rod boundaries and across enamel rods exhibit similar range of values: KI0,Ir=0.5-1.6MPa.m0.5 (based on Irwin’s ‘nearfield’ solution) and KI0,cz=0.8-1.5MPa.m0.5 (based on the cohesive zone solution of the Dugdale-Muskhelishvili (DM) crack model). The mode III crack tip toughness KIII0,Ir was computed as 0.02-0.15MPa.m0.5. The crack-closure stress at the crack tip was computed as 163-770MPa with a cohesive zone length and width 1.6-10.1μm and 24-44nm utilizing the cohesive zone solution. Toughening elements were observed under AFM and SEM: crack bridging due to protein ligament and hydroxyapatite fibres (micro- and nanometer scale) as well as microcracks were identified.
URI: http://tubdok.tub.tuhh.de/handle/11420/992
DOI: 10.15480/882.990
ISSN: 1878-0180
Institute: Keramische Hochleistungswerkstoffe M-9 
Type: (wissenschaftlicher) Artikel
Appears in Collections:Publications (tub.dok)

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