Damage Inspection Of Composite Materials Using Fibre Optic Acoustic Emission Sensor

Advanced composite materials have been widely used in aviation,spaceflight, architecture, traffic, etc. by virtue of their high strength-to-weight and stiffness-to-weight characteristics, as well as excellent corrosion and fatigue resistance and molding techniques. But fiber reinforced composite materials shows the notable anisotropy in mechanism and physics performance, meanwhile it can be effected by the complicate load, thus all sorts of damage will threat the safety and life of composite structure. With regard to this, it is very important to study the new method of composite structural health monitoring.The traditional NDE methods has been not applied to monitoring the composite material with the complicated damage type, therefore, the way that the fibre optic acoustic emission sensor is used to monitoring the failure of composite materials is put forward. The fiber optic sensor is based on fused-taper fiber coupler design, which offers some advantage including low-cost, small structure and high precise. In order to monitor the failure of composite materials, this paper finished the following work:Fibre optic acoustic emission sensor that is based on a fused-tapered fiber coupler is made, and fused-tapered fibre optic coupler is also made by the fused–tapered method. The effect of the structure of fused-tapered fibre optic coupler to sensitivity of the sensor is investigated with many experiments, and some regularity has been obtained.The principle of fibre optic acoustic emission sensor is analyzed, then is calibrated through pencil break. The experimental results confirms that the sensor is precise.Fibre optic sensor and piezoelectric sensor are used to monitoring the acoustic emission in tensile test of composite laminates. Relationship of acoustic emission waveform detected from the experiment with failure mode has been studied. In addition, pressure vessel is also monitored by fiber optic acoustic emission sensor, which offers beneficial reference to asses the damage type of composite materials.