An evaluation of acoustic emission from fibre-reinforced composites

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