Coating/Substrate Modulus Mismatches and Margin Geometry Effects on Contact Damage in Curved Brittle Coating Systems |
| Journal |
Advanced Materials Research (Volumes 41 - 42) |
| Volume |
Structural Integrity and Failure |
| Edited by |
Xiaozhi Hu, Brent Fillery, Tarek Qasim and Kai Duan |
| Pages |
49-55 |
| DOI |
10.4028/www.scientific.net/AMR.41-42.49 |
| Online since |
April, 2008 |
| Authors |
Tarek Qasim
|
| Keywords |
Brittle Coating, Dental Crowns, Margin Geometry, Radial Crack |
| Abstract |
The effects of coating/substrate modulus mismatch and margin geometry on contact
damage in bi-layer systems were investigated. Following an earlier study, convex specimens having
curvature of 12 mm inner coating diameter and 1mm thick brittle layer on a polymeric and dental
composite support bases were produced. Sample coating geometry at the margins was varied by
grinding the edge of the glass shells in various shapes. The specimens were tested by applying
single cycle load at the specimen’s axis of symmetry using flat indenter of low elastic modulus. The
effects of margin geometry and support layer modulus on radial crack initiation and damage
evolution was examined, with particular attention paid to the relevance of such damage to lifetimelimiting
failures of all- ceramic dental crowns. Finite element modeling was used to evaluate stress
distribution in the glass coating. Experimental trends interrupted with peak maximum principal
stresses at the margins. The results of this study illustrate that the fracture behaviour of brittle
layered structures is not dominated by certain variables. It is demonstrated that critical loads for
initiation of radial cracks are sensitive to support layer modulus as well as margin geometry.
Support layer modulus plays an important role in crack propagation and subsequent damage
patterns, especially at specimen side walls. |
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