Simplified hygromechanical coupling model and numerical simulation analysis of fibre reinforced composite deep-sea and underwater structures

Abstract

The water absorption of composites will affect the safety and performance of the structure, resulting in the inability to give full play to its excellent lightweight and high-strength characteristics. This key issue is currently being experienced by composite deep-sea and underwater structures. The water absorption of composites is a complex problem involving the coupling of multiple scales. At present, the expressions of some water absorption theories are generally more complicated, which makes it impossible to apply the theories directly to the design and verification of deep-sea and underwater structures. This research assumes the uniformity of fibre distribution, with cylindrical-cube unit cells as the research object. A simplified hygromechanical coupling model of composites was proposed. Furthermore, by adding subroutines and considering the uneven distribution of the diffusion coefficients of each layer, the finite element method was used to simulate the whole process of water absorption of the composite laminate. Finally, it is compared with the experimental results to verify the effectiveness of the simplified model. Based on this comparison, the water absorption distribution, diffusion coefficient and interlayer stress variation law of composites in different time periods are obtained.