Optical fiber sensing technique for edge-induced and internal delamination detection in composites

Abstract

A novel technique for effective detection of edge-induced and local internal delamination caused by cyclic loading of composite materials is proposed. This scheme employs the highly sensitive extrinsic Fabry-Perot interferometric optical fiber-based sensor for detecting discontinuities along the composite transverse axis. Sensors in surface-mounted and completely embedded configurations provide real-time, on-line information about damage initiation and propagation within the composite. This method is extended to monitoring delamination between pairs of off-axis plies by employing path-matching multiplexing of conventional EFPI sensors in a white light interferometry configuration. Such multiple-sensor-element in situ monitoring may increase the probability of detection of flaws of critical size that may lead to premature structural failure.