Fracture Mechanisms of Short-Fiber-Reinforced PETby Acoustic Emission Method. (Effects of Fiber Content and Loading Direction).

The fracture mechanisms of short-fiber-reinforced PET (FRPET) are studied by the acoustic emission (AE) method to examine the effects of fiber content and loading direction. The maximum loads of test specimens increase with increase in the fiber content, and the loads decrease with increase in the angle between the directions of injection and loading. The cumulative AE event count and the total AE energy are affected by the fiber content and the loading direction. The effects of the fiber content and the loading direction on the total AE energy can be explained by AE amplitude distribution. The loads of Pb and Pc determined by the stress intensity factor method are in agreement with the loads determined by the AE energy gradient method. Damage is generated by the debonding between fiber and resin at the load point of Pb and by the fiber breaking at the load point of Pc in materials with fiber content of 15 and 30% by weight.