The Diffraction of Elastic Waves on the Tip of Slots

The diffraction of elastic waves on the tip of cracks has been widely used in detecting defects. It is always difficult to fabricate a real crack in the laboratory. In this investigation, a slot of width 0.3 mm is used as an alternative to simulate the fatigue crack. The slot of 0.3 mm width is embedded in a cylindrical block. The diffractions of elastic waves on the tip of the artificial slot are measured for three test blocks made of steel, aluminum, and brass, respectively. In the experiment, the amplitudes of diffracted waves at various receiving angles are recorded and compared with the theoretical predictions of diffraction on a fatigue crack tip. The influences of incident angle and frequency and material of the test block are presented. By examining the discrepancies of diffractions on the slots and cracks, one is able to evaluate the feasibility of replacing a real crack by an artificial slot, once the real crack is not available.