• Martin, Eric
• Leguillon, Dominique
• Bermejo, Raúl
• Ševeček, Oldřich
• Kotoul, Michal

Abstract

<p>This contribution gives an overview of different fracture-mechanics issues occurring in layered ceramics designed with internal compressive residual stresses (such as the edge cracking, crack arrest by the compressive layer or crack deflection/bifurcation) and proposes an effective approach to describe the initiation and/or propagation of cracks in such materials. The finite fracture mechanics (FFM) theory and the coupled stress-energy criterion (CC) are discussed and applied to understand their fracture behavior. The stress-energy coupled criterion is based on the tensile strength and toughness data of investigated material and it does not contain any adjustable parameter, which is its indisputable advantage. It could thus (in the considered brittle materials) predict both crack initiation and crack propagation under consideration of both thermal and external mechanical loading. A case study is investigated, where edge cracking in compressive layers can be predicted as a function of the thickness of the compressive layer and the magnitude of residual stresses. Another case study concerns the onset of a crack in a notched sample of a layered ceramic submitted to bending. The propagation of the crack through the ceramic laminate is studied as a function of the volume ratio of particular material components and corresponding magnitude of residual stresses in both compressive and tensile layers. Under certain combination of residual stress and layered architecture, the CC predicts crack arrest in the internal compressive layer of the laminate in accordance with experimental observations under similar loading conditions.</p>

Topics

• impedance spectroscopy
• theory
• crack
• strength
• layered
• tensile strength
• ceramic
• fracture behavior