Abstract
Fatigue damage of interfacial delamination of notched CFRP has been observed by a scanning acoustic microscope (SAM), and the delamination resistances against fatigue cycles are discussed.
By using a pulse wave of 50MHz, the delamination images at each interfacial site were clearly observed by a SAM. The delamination was quite different at each interface, and the interfacial delamination ahead of a notch was hardly observed between the 1st and the 2nd laminae but firstly observed between the 2nd and the 3rd laminae. The length of interfacial delamination evaluated in terms of specimen compliance was well corresponded with the saw-cut notch of the equal length, and the delaminated portion lost its load carrying capacity. Axial splits in 0° plies had the effect of separating the 0° plies into two outer strips containing the notch and an inner strip without a notch, thereby reducing the notch-tip stress concentration. The growth rate of interfacial delamination judged in terms of the compliance change was accelerated with an increase in notch length as well as with an increase in maximum ligament stress. The notch sensitivity of CFRP was quite different from the one of uniform materials.
