Discrete curvature-based shape configuration of composite pipes for local buckling detection based on fiber Bragg grating sensors

For the high strength, good corrosion resistance and stability, carbon fiber reinforced polymer (CFRP) composites can be made into pipes to transfer gasses and oils in submarine environment. Structural performance and shape of CFRP composite pipes are particularly important to sustain the regular operation of the delivery system. To obtain the in-field shape and identify the local buckling of CFRP composite pipes, quasi-distributed optical fiber sensing techniques have been developed based on the multiplex of fiber Bragg grating (FBG) sensors. Theoretical investigation on shape profile configuration of the pipes based on the measured strains has been performed. Relationship between the accuracy of configuration algorithm and the sensor layout has also been explored. Experiments have been conducted to check the effectiveness and accuracy of the proposed sensing technique and curve configuration algorithm. Results validate good measurement performance of the proposed sensors and high accuracy of the shape-configuration algorithm. Suggestions on the sensor layout of long-distance pipe structures are provided with the comprehensive consideration of overall structural shape control and economical factor. The study can be adopted to instruct the establishment of the structural health monitoring system, identify the buckling and assess the safety operation of pipe structures.