A comparison study of water diffusion in unidirectional and 2D woven carbon/epoxy composites

Abstract

The use of CFRP composites is significantly increasing in the aerospace, automotive, and marine industries, particularly in safety critical primary structures. This work presents a newly developed experimental approach to investigate the directional diffusion of water in CFRP composites with the use of Fick's law.The approach is used to study the effect of fiber architecture on directional diffusion rates, with a particular focus on the role of fiber waviness in the diffusion process. A comparison of water diffusion is made in three different fiber architectures: Unidirectional (UD), plain weave, and twill weave. The specimens were fully immersed in 90 C purified water until their maximum moisture saturation was achieved, with some specimens being selectively exposed from the edges only to obtain the directional diffusion coefficients. The water penetration process into the CFRP structure initiate from the micro-cracks and defects. The experimental work of this study shows sharp mass increases within the first stage followed by an equilibrium stage where saturation is present. The interfacial region is found to be a critical parameter where detachment of the interfacial fiber/matrix bonding is observed further demonstrating the potential effect of different fiber architecture in this region. UD fiber architecture showed $20% higher diffusion coefficient in the D x,y direction compared with plain and twill woven architectures. The weave patterns in 2D woven fiber architectures are therefore believed to play a key role on the moisture ingress mechanism and subsequently contributed in slowing down the capillary process in the interfacial region. This has implications for materials development and selection for CFRP composites used in moist environments.

Experimental and numerical evaluation of the surface‐localized heating capacity of the photothermal nanocomposite‐incorporated knit fabrics

“…When liquid wets the fibers and reaches the space between the fibers, then capillary pressure is developed. [22,23] Currently, great effort has been devoted to generating surface-localized heating, in order to achieve the performance of cold protection and to enhance the efficiency of sweat-moisture evaporation. For instance, Xueping et al [14] developed an ultra-hygroscopic material based on cobalt composite then incorporated this material into polytetrafluoroethylene (PTFE) membrane, which can quickly absorb moisture from human sweat and evaporate the moisture by natural sunlight radiation to prevent sweat accumulation.…”

“…When liquid wets the fibers and reaches the space between the fibers, then capillary pressure is developed. [ 22,23 ]…”

Hydrothermal aging behavior and effects on carbon fabric/polyphenylene sulfide composite

“…There are many studies investigated the moisture absorption mechanism on fiber reinforced composites, [6][7][8] and the Fickian model is a widespread approach to characterize the diffusion behavior. Almudaihesh et al 9 studied the effect of fiber architecture, namely unidirectional (UD) and 2D woven carbon/epoxy, on directional diffusion rates by using Fick's law, and proved the in-plane diffusion coefficient of UD fiber architecture was $20% higher than that of 2D woven architectures. Sang et al 10 used the Fickian model to analyze the hydrothermal aging behavior of carbon fiber/polyamide 6 (PA6), and extended the model to capture the post-saturation behavior in relatively high temperature.…”

Evaluation of tensile properties on glass/carbon fiber epoxy pure, interply, and locally nested intraply hybrid composites

“…[8,9] GFRP composites have excellent thermal insulation, chemical resistance, and electrical insulation, [10] while CFRP composites have excellent fatigue and corrosion resistance. [11,12] Nanoparticles are also used to improve the properties of composites. [13][14][15][16] In a situation where all these features and more are desired, hybrid composites in which glass, carbon, or other fibers are used together in accordance with the spirit of composite materials come to the fore.…”