Steady-state mechanics of a growing crack paralleling an elastically constrained thin ductile layer

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The steady-state near tip mechanics of brittle cracks growing under mixed mode conditions parallel and at close proximity to a thin ductile layer in a sandwich specimen morphology are examined. The plastic dissipation in the elastically constrained ductile layer is determined analytically through an approximate method and numerically via rigorous finite element calculations. Sensitivity studies regarding the effects of plasticity, layer thickness and crack location are presented. Thus, crack shielding characteristics are addressed and relationships between the remote (Qapp) and near tip (Gtip) energy release rates are established. The associated crack tip phase angle Ψtip is extracted numerically via the method of finite elements. The above analysis is used to interpret experimental data for a sapphire/gold/sapphire system obtained using the plane strain four-point flexure model specimen geometry. © 1990 American Society of Mechanical Engineers.

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Applied Mechanics Reviews