Moisture absorption in thick composite plates: modelling and experiments Giacomo Canale and Moustafa Kinawy Institute for Innovation in Sustainable Engineering (IISE), University of Derby, Derby, UK Prabhakar Sathujoda Department of Mechanical and Aerospace Engineering, Bennett University, Greater Noida, India Angelo Maligno University of Derby, Derby, UK, and Roberto Guglielmo Citarella Department of Industrial Engineering, University of Salerno, Salerno, Italy Abstract Purpose – When a thick structure is, on the contrary, subjected to moisture absorption, a fairly long time may be needed to reach full saturation. It is, therefore, important to understand and predict the areas of complex composite structures that are more prone to saturation. The material knock-down factors (proportional to the moisture content) may be applied only to these zones, in order to obtain a less pessimistic structural response prediction. The purpose of this paper is to investigate an FE diffusion model that was used to validate the absorption testing results of thick carbon epoxy laminates. Design/methodology/approach – The experimental results were validated by using a diffusion model in Abaqus FE code. Findings – The absorption results of three 15 mm thick carbon epoxy laminates are presented and reproduced via a mass diffusion model. The laminates were conditioned at 70°C and 85 per cent relative humidity in a moisture chamber. Areas more prone to saturation have been predicted by the FE model and the moisture content in the non-saturated areas has been calculated. Practical implications – The practical implications of the absorption model are discussed on an example of an aero-engine fan blade-like structure. Originality/value – Validation of thick panels’ absorption data is an important point of novelty of this paper, given the lack of experimental and modelling validation in the open literature. Keywords Composite fan blade, Moisture absorption, Thick composite laminates Paper type Research paper 1. Introduction Composite materials have been widely used in the aerospace industry in the latest 20 years. Organic matrix composite materials, in fact, offer some advantages when compared to metals such as their strength/weight ratio (Reddy, 1994), the opportunity to directionally tailor their stiffness and potentially exploit anisotropy (Shirk et al., 1986; Canale et al., 2018). Some challenges still remain when designing composite structures such as impact resistance (Cui et al., 2019) and electric conductivity (Kumar et al., 2018). Another challenge of composite material is the change (and often degradation) in structural material properties when moisture is absorbed. The organic matrix, in this work epoxy, tends to plasticize when absorbing moisture (Komorowski, 1977). Structural properties such as tensile and compressive strength (Candido et al., 2000; Ramani and Nelson, 1979), fatigue life (Ramani and Nelson, 1979) and fracture toughness (Le Blanc and LaPlante, 2016) are negatively affected. The amount of Multidiscipline Modeling in Materials and Structures Vol. 16 No. 3, 2020 pp. 439-447 © Emerald Publishing Limited 1573-6105 DOI 10.1108/MMMS-06-2019-0119 Received 26 June 2019 Revised 1 September 2019 Accepted 6 October 2019 The current issue and full text archive of this journal is available on Emerald Insight at: www.emeraldinsight.com/1573-6105.htm The authors would like to thank Dr Felice Rubino for his precious ongoing support. 439 Moisture absorption in thick composite plates