Characterization of the fracture process of notched glass fiber/aluminum hybrid laminates by acoustic emission

Acoustic emission (AE) characteristics during the fracture process of single-edge-notched (SEN) and glass fiber/aluminum hybrid laminates (GFML) were investigated according to different fiber ply orientations under tensile loads. The first and second peak frequencies were obtained from the frequency spectrum for the individual AE signals monitored during loading. The peak frequency distribution as a function of displacement represented characteristic changes of the fracture process in various SEN-GFML specimens. The high frequency distribution of the second peaks corresponded to the fiber breakages in the specimens, while delamination between Al and fiber layers and further microfracturing in the matrix and in the adhesive resin were generated at a high event rate. Fracture processes of single-edge-notched glass fiber aluminum hybrid laminates, such as the deformation and microfracture of the Al layer, the fracture of the fiber core layer, fiber breakages, and delamination, were elucidated through the characteristic features of the AE frequency in combination with AE amplitudes and event rates.