When high-strength materials are no match against water: how fibre composite fails when wet

Scientists from two Asian universities, namely Universiti Teknologi Malaysia (UTM) and Newcastle University in Singapore, have completed a study to understand how the mechanical behaviour of carbon fibre reinforced epoxy composite laminates could be compromised by moisture seepage.

Rain droplets on a hard surface

A team of researchers, led by KJ Wong (UTM, Malaysia), has developed a model for reliable prediction of the delamination behaviour as moisture progressively seeps into the fibre reinforced composites that are used in aircraft fuselage, such as Boeing B787 and Airbus A350. This model is known as the Bilinear-Exponential Traction-Separation (BETS) law. The model can account for how fibres bridge cracks, e.g. mode I delamination, of carbon fibre reinforced epoxy composite laminates in wet states. The BETS of the moisture-delamination problem was implemented with the help of a computer simulation approach known as Finite Element Analysis. By evaluating the effects of moisture content on the composite force-displacement behaviour under loading, the researchers found that the BETS law agreed very well with results from experiments derived from the double cantilever beam testing. 

Importantly, the proposed BETS law has the advantage of not requiring crack growth monitoring during experiment, and only one fitting parameter was needed to describe the bridging law at different moisture content levels. Consequently, the BETS law is an important step towards the development of structural fail-safe approaches, i.e. an early warning system to alert the engineers working in maintenance, repair & operations to fix the delamination problem early, before the problem becomes critical.

The work has been published in Polymer Composites. The paper can be viewed at https://DOI:10.1002/pc.27179.

KJ Wong, who did this study at UTM, now works at Curtin University Malaysia, The rest of the team members are Associate Professor William Woei Fong Chong, from Universiti Teknologi Malaysia, and Associate Professor/Reader Kheng Lim Goh, from Newcastle University in Singapore, who specialises in Materials Technology.

For further details and enquiry on potential collaboration, please contact Associate Professor K L Goh at [email protected].

Published: 05 Feb 2023

Contact details:

Dr Kheng Lim Goh

172A Ang Mo Kio Avenue 8 #05-01
SIT Building @ Nanyang Polytechnic
Singapore 567739

+65 6908 6073
Academic discipline: 
Content type: 

Fiber bridging mechanism in moisture-induced mode I delamination in carbon/epoxy composites: Finite element analysis and experimental investigation, Polymer Composites. 2022;1–16, https://DOI: 10.1002/pc.27179

Funding information:

Fundamental Research Grant Scheme (FRGS), Grant/Award Number: FRGS/1/2022/TK10/UTM/02/27; UTM Fundamental Research (UTMFR), Grant/Award Number: Q.J130000.3851.21H92