Creep and Residual Properties of Filament-Wound Composite Rings under Radial Compression in Harsh Environments

Characterization and modelling of the hygro-viscoelastic behaviour of polymer-based composites used in marine environment

This paper presents results from a study of the long-term behaviour of carbon/epoxy composites. The interactions between ageing in water and constant mechanical loads are described, first experimentally then using a simple modelling approach. An identification procedure for the model is carried out and test/model comparisons are discussed. The results show that a four-parameter Burgers model can provide a good fit of the experimental data. The analysis of the results indicates the impact of water diffusion on the viscoelastic behaviour with larger strains for both creep and recovery phases. Those changes tend to appear at the early stage of the moisture diffusion process and stabilize quite quickly. This article is part of the theme issue 'Ageing and durability of composite materials'.

Thickness-Prediction Method Involving Tow Redistribution for the Dome of Composite Hydrogen Storage Vessels

Traditional thickness-prediction methods underestimate the actual dome thickness at polar openings, leading to the inaccurate prediction of the load-bearing capacity of composite hydrogen storage vessels. A method of thickness prediction for the dome section of composite hydrogen storage vessels was proposed, which involved fiber slippage and tow redistribution. This method considered the blocking effect of the port on sliding fiber tows and introduced the thickness correlation to predict the dome thickness at polar openings. The arc length corresponding to the parallel circle radius was calculated, and then, the actual radius values corresponding to the bandwidth were obtained by the interpolation method. The predicted thickness values were compared with the actual measured thickness. The maximum relative error of the predicted thickness was 4.19%, and the mean absolute percentage error was 2.04%. The results show that the present method had a higher prediction accuracy. Eventually, this prediction method was used to perform progressive damage analysis on vessels. By comparing with the results of the cubic spline function method, the analysis results of the present method approached the actual case. This showed that the present method improved the accuracy of the design.

Predictions of Moisture Diffusion Behavior of Cellulose-Fiber-Reinforced Plain Weave Epoxy Composites

Cellulose-fiber-reinforced plain weave composites absorb lots of water from humid environments because of their inherent susceptibility to moisture. Moisture absorption experiments with cellulose fiber plain weave composites have been reported by some researchers; however, few theoretical studies have been performed to date to predict their moisture diffusion behavior. In this paper, the moisture diffusion behavior of cellulose-fiber-reinforced plain weave composite is predicted using a novel superposition method considering its microweave pattern. The overall moisture uptake of the composite is treated as moisture absorption superposition of the fiber bundles part, resin part, undulated fiber bundles and resin-rich part in the unit cell. The moisture diffusion of the undulated fiber bundles and resin-rich part is more complicated than the other parts; thus, a solution for a unique three-phase diffusion problem is used to solve this special moisture diffusion issue. Both finite element analysis and experiments are carried out to validate the proposed approach, with the results showing that the predictions can effectively characterize the moisture diffusion behavior of cellulose-fiber-reinforced plain weave composites.