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Effect of off‐axis concentrated loading on failure of curved brittle layer structures
Author(s) -
Qasim Tarek,
Ford Christopher,
Bush Mark B.,
Hu Xiaozhi,
Lawn Brian R.
Publication year - 2006
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.30373
Subject(s) - materials science , composite material , indentation , brittleness , tension (geology) , ceramic , epoxy , curvature , radius of curvature , radius , layer (electronics) , stress (linguistics) , ultimate tensile strength , geometry , linguistics , mean curvature , mathematics , computer security , philosophy , mean curvature flow , computer science
A study is made of the effects of superposed tangential force by off‐axis indentation loading on curved bilayers consisting of brittle shells filled with polymer support material. Such loadings are pertinent to all‐ceramic crown structures on tooth dentin in occlusal function. Layer flexure places the ceramic undersurfaces in tension, leading to fracture by initiation and propagation of radial cracks. Following an earlier study, model specimens with curved surfaces are prepared by pressing glass plates 1 mm thick onto steel spherical dies with radius of curvature 20 mm to 8 mm at elevated temperatures, and bonding the resultant hemispherical shells onto an epoxy support base. The specimens are tested by indentation with spheres loaded vertically but off‐center, with the contact center located at 30° to the hemisphere axis. The applied loads to initiate radial cracks are little affected by the resultant tangential component, but the loads to propagate the same cracks to the specimen edges are substantially reduced. Finite element calculations are used to evaluate stress states in the specimens for correlation with the experimental data. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006