FATIGUE-CRACK GROWTH AND STRESS REDISTRIBUTION AT INTERFACES

The role of the interface in redistributing stress around cracks in mu ltilayered ceramic/metal composites is investigated. The emphasis is o n the different effects of interfacial debonding or of plastic slip in the metal phase adjacent to strongly bonded interfaces. The experimen ts are conducted on alumina/aluminum multilayered composites. Monotoni c loading precracked test pieces causes plastic shear deformation with in the aluminum layer at the tip of the notch without debonding. Howev er, interfacial debonding can be induced by cyclic loading, in accorda nce with a classical fatigue mechanism. Measurements of the stress aro und the crack demonstrate that debonding is much more effective than s lip at reducing the stress ahead of the crack.