Composite repair method for internally damaged cylinders subjected to external pressure

Abstract

In deep ocean environment, it is feasible to effectively repair damaged cylinders by externally wrapping them with lightweight composite materials. An analytical method was developed to determine the optimal thickness and length for composite repairs of internally damaged cylinders under uniform external pressure. The repair layer thickness was evaluated based on the assumption of full thickness reduction, and the repair length was determined by axial shearing theory. Repairs were designed for three groups of damaged cylinders, and the repaired and damaged cylinders were compared with pristine cylinders. The finite-element method was used to validate the analytical method and investigate the failure modes of the cylinders. Furthermore, the analytical and numerical results were validated through experiments. The results indicate that the load-bearing capacity of damaged cylinders can be completely restored using the designed repair method. Moreover, at collapse, the instability locations of the repaired cylinders exist near an end instead of the middle region. The analytical, numerical, and experimental results are in favorable agreement. The research contributes to offering a robust solution to repairing internally damaged cylindrical structures, promising substantial advantages in terms of maintenance and extending the lifespan of these structures.