Composite Fracture Detection Capabilities of FBG Sensor and AE Sensor

Abstract

Non-destructive testing methods of composite materials are very important for improving materialreliability and safety. AE measurement is based on the detection of microscopic surface movements from stress wavesin a material during the fracture process. The examination of AE is a useful tool for the sensitive detection andlocation of active damage in polymer and composite materials. FBG (Fiber Bragg Grating) sensors have attractedmuch interest owing to the important advantages of optical fiber sensing. Compared to conventional electronicsensors, fiber-optical sensors are known for their high resolution and high accuracy. Furthermore, they offerimportant advantages such as immunity to electromagnetic interference, and electrically passive operation. In thispaper, the crack detection capability of AE (Acoustic Emission) measurement was compared with that of an FBGsensor under tensile testing and buckling test of composite materials. The AE signals of the PVDF sensor weremeasured and an AE signal analyzer, which had a low pass filter and a resonance filter, was designed and fabricated. Also, the wavelength variation of the FBG sensor was measured and its strain was calculated. Calculated strains werecompared with those determined by finite element analysis.