Comparisons between Fractal Dimensions of Fatigue-Damaged Composite Material by Use of AE and Divider Techniques

Abstract

The tensile test is conducted on the FRPA with the crack initiated by the fatigue test, including fiber content n weight of 50% made by direct molding method. The fractal dimensions mAE by the AE amplitude distributions detected during the tensile test are compared with the fractal dimensions mS by the section shapes of fracture surface after the tensile test. The normalized fractal dimensions mAE/mAE (N) and mS/mS (N) are affected by the fatigue damage, and there is a correlation on the relation between mS/mS (N) and mAE/mAE (N), where the subscript (N) shows the nonfatigue specimen. The accuracy can be explained with the slope of straight line showing the relation between the normalized fractal dimension m/m(N) and the normalized strain energy w/w(N)．