2007 Volume 48 Issue 3 Pages 550-555
Cyclic-tension fatigue of aluminum alloy, Al-4Cu-1Mg, was determined by an analysis of diffracted SH and SV waves, passing through the surface and reflecting the bottom of the specimen, respectively. The propagation time of SH waves and the internal friction of SV waves begins to decrease and increase from fatigue damage ratio (=N⁄Nf) of 0.5, respectively, suggesting noticeable increase of movable dislocation. From the analysis of SH waves along the direction to the loading axis, the damping ratio decreases and the phase advances with increasing of the degree of fatigue. Assumed from SH wave flux model, the former behavior correlates well with increasing of the residual stress by cyclic tension. The latter may be characterized by viscoelasticity. These results show that ultrasonic transmission method is useful probe for evaluation of fatigue in aluminum alloy.