AN EVALUATION OF ACOUSTIC-EMISSION FROM FIBER-REINFORCED COMPOSITES .2. THE APPLICATION OF ACOUSTIC-EMISSION TECHNIQUES TO ARAMID FIBER-REINFORCED MODEL COMPOSITES

An analysis of acoustic emission (AE) from model composites consisting of a single aramid fiber and different epoxy matrix systems has been carried out to identify the source of acoustic emission. The AE activity was observed in a narrow range of strain when fiber fracture occurred, whereas in a relatively wide range of strain, debonding occurred at the fiber-matrix interface. Ion-etched fibers showed a good adhesion of the fibers to the matrix so as to produce fiber fracture in place of interfacial debonding. The total number of AE events has one to one correspondence with the number of broken fibers. The effect of surface treatment and matrix systems on the shear fracture strength between the fiber and matrix were described based on the critical length of the broken fibers using AE results.