Delamination detection in an I-section glass fiber reinforced plastic beam with an optical fiber-based stress wave method

An optical fiber-based technique for the detection of the delamination at the web/flange junction of an I-section glass fiber reinforced plastic beam is presented. A fiber optical interferometric sensor is adhered to the surface of the web to serve as a stress wave receiver, and a piezoelectric transmitter (PZT) is employed to produce a stress wave in the structure. Several methods are applied to detect the delamination, and summing the frequency spectra from multiple measurements is proved to be effective. From the frequency components of the sensor output corresponding to various positions of the PZT, the delamination location can be revealed. The feasibility of delamination detection with the proposed technique is demonstrated.