Experimental and theoretical damage assessment in advanced marine composites

Fiber-reinforced composites have been widely used for load bearing structures because of their good specific stiffness and strength as well as excellent fatigue and corrosion resistance. However, they are variously susceptible to manufacturing defects, in-service damages, and environmental factors. Major challenges of using composites in ship-building and maritime structures are the construction requirement of high-strength structural joints such as scarf joints, T-joints, corner joints, and hat stiffeners. Bonding is often required to join composite components into complex marine structures, such as in the constructions of joints connecting a ship hull to the bulkheads, decks, and superstructure. Maritime materials are also highly susceptible to environmental corrosion, humidity, and saltwater conditions. Therefore, effective damage evaluation techniques for failure interrogation and continuous monitoring of structural integrity are of great interest, especially to marine vessels, weapon systems, and aircraft in which composite structures are extensively used. Different nondestructive damage evaluation techniques are discussed, including ultrasonic C-scan, x-ray, thermography and eddy current, fiber optic sensors, and acoustic emission. In situ damage detections for maritime composites are also discussed using Bragg grating strain sensors and pulsed thermography. Theoretical and numerical models for composite damages subjected to impulsive loadings are described to capture different failure modes of polymer-matrix composites.