Abstract
Fracture toughness tests were performed for glass/epoxy cross-ply laminates. The fracture toughness was evaluated following 5% offset procedure of ASTM standard of linear elastic plane strain fracture toughness. As a result, it is found that the fracture toughness for interply cracking depends on the fiber orientation of the ply which contains the interply crack. Next, examination of the behavior of the interply cracking and acoustic emission characteristics during the fracture toughness tests reveals that the acoustic emission signals with high energy correspond to matrix breakage which occurs after debonding of the fiber and matrix. From the results of the spectrum analysis of the acoustic emission signals, the acoustic emission events can be classified into two types. The first type having wide frequency components corresponds to the matrix breakage and the second type having peak frequency components at about 50 kHz and 100-300 kHz corresponds to the pulling-out of fibers.
