An Extended Thickness-Dependent Moisture Absorption Model for Unidirectional Carbon/Epoxy Composites.

Azisyahirah Azizan,Shahrum Abdullah,Mohd Nasir Tamin,Seyed Saeid Rahimian Koloor,Mahzan Johar,Michal Petrů,Salvinder Singh Karam Singh,King Jye Wong

doi:10.3390/polym13030440

Abstract

Moisture absorption tests for materials that exhibit non-Fickian behavior generally require a relatively long period to reach saturation. Therefore, it would be beneficial to establish a relationship between the moisture content and the thickness to minimize the experimental time and cost. This research characterizes the moisture absorption behavior of AS4/8552 carbon/epoxy composites. Specimens were prepared at 4, 8, and 16 plies and immersed in distilled water at 60 °C. The relationship between the non-Fickian parameters (Fickian to non-Fickian maximum moisture content ratio ϕ, non-Fickian diffusivity per square thickness α, and non-Fickian initiation time to) and thickness was characterized using a thickness-dependent model. A comparison with other materials revealed that all three non-Fickian parameters are able to be fitted using a power law. Nevertheless, the upper boundary for the applicability of this model was not determined in this study. The Weibull distribution plots indicate that the probability of non-Fickian moisture absorption is influenced by ϕ and α at approximately 62% within a normalized thickness range of 2–3. In regards to to, it is 82% at a normalized thickness of 6. Therefore, the Weibull distribution is proposed for the assessment of non-Fickian moisture absorption based on the material’s thickness.

Highlights

Carbon/epoxy composites are gaining importance as aircraft materials [1,2]
This study aims to assess the applicability of the thickness-dependent non-Fickian moisture absorption model at a greater thickness
The overall moisture absorption behavior foll same trend described by the thickness-dependent moisture absorption model, wh moisture content increases with the thickness

Summary

Introduction

Carbon/epoxy composites are gaining importance as aircraft materials [1,2]. When using carbon/epoxy laminated composites for aircraft applications, the materials are inevitably subjected to various environmental conditions. Upon prolonged moisture and heat attacks, the properties may degrade and lead to premature failure of the structures [3,4,5,6,7]. It is common to relate the residual properties to the absorbed moisture content of the materials [3,4,5]. Before characterizing the mechanical properties, studying the materials’. The relationship between the residual properties and moisture content can be established through the moisture uptake characteristics

Objectives

Discussion

Conclusion