Non-Destructive Evaluation of Composite Laminates by Using Fiber Optic AE Sensor

Considering the damage that composite material under loading may occur, acoustic emission (AE) technique is adopted to perform non-destructive evaluation (NDE). In order to obtain the acoustic emission emitted from the composite material, a novel fiber optic AE sensor which is based on single mode fiber optical fused-tapered coupler design is developed. Futhermore, its fabrication process was described and performance was studied. Results of a pencil break test on the composite laminate show that the fiber optic AE sensor have better frequency response than the commercial piezoelectric sensor. During a tension experiment of a carbon fiber composite specimen , the fiber optic sensor which was mounted on it detected the enormous acoustic emission signals. To analyze their characteristic parameter, such as amplitude, duration, can identify the type of failure to composite materials, including Matrix cracking , Interface stripping, fiber breakage. Experimental results would offer the reference to damage identification to complicate composite structures.