Experimental investigation of fatigue crack growth in thin-foil Ni-base sandwich structures

The fatigue crack growth behavior of Ni-base honeycomb panels was studied at room temperature. Edge-notched panels were subjected to either tension–tension or fully reversed tension–compression fatigue cycles at a loading frequency of 2 Hz. The experimental data could be described by a Paris relation with a stress intensity range exponent between 3 and 6. The crack propagation was governed primarily by the crack growth rate in the thin face-sheets; the honeycomb core did not contribute significantly to the overall crack growth behavior. In addition to details concerning the experimental approach used to study crack growth, possible methods for improving the crack growth resistance of thin face-sheet metallic sandwich panels are discussed.