Simulation of crack bifurcation in single crystal nickel base superalloys under mixed mode conditions

PhD position available at the Centre des Matériaux , ParisTech , starting fall 2009.

This 3-year project is fully funded by Mines ParisTech, SNECMA and ONERA.

Abstract: Flexible electronic devices often require hermetic coatings that can withstand applied strains. This paper calculates the critical strains for various configurations of channel cracks in a coating consisting of organic and inorganic layers. We show that the coating can sustain the largest strain when the organic layer is of some intermediate thicknesses.

Flexible electronics are promising for diverse applications, such as rollable displays, conformal sensors, and printable solar cells. These systems are thin, rugged, and lightweight. They can be manufactured at low costs, for example, by roll-to-roll printing. The development of flexible electronics has raised many issues concerning the mechanical behavior of materials. This paper examines a particular issue: channel cracks in hermetic coatings.

Electronic devices (e.g., organic light-emitting devices, OLEDs) often degrade when exposed to air. Developing hermetic coatings has been a significant challenge. Organic films are permeable to gases, and inorganic films inevitably contain processing flaws, so that neither by themselves are effective gas barriers. These considerations have led to the development of multilayer coatings consisting of alternating organic and inorganic films. To be used in flexible electronics, these coatings must also withstand applied strains without forming channel cracks...

The Max Planck Society (MPS) aims at promoting young international scientists by enabling them to perform their research (in all fields pursued by the MPS) at a Max Planck Institute of their choice.

The MPS offers Independent Junior Research Group Leader positions (W2; equivalent to associate professor level without tenure) granted for a period of 5 years with the option for prolonging twice for 2 years. The deadline for application is January 10, 2007.