Computational fluid dynamics analysis of moisture ingress in aircraft structural composite materials

Beg, OA; Islam, B; Shamshuddin, MD; Beg, TA

Abstract

Moisture in composite materials has been proven to be an important issue leading to significant deterioration of
commercial aircraft wing structures. Lingering problems associated with this issue which is initiated with defects
during manufacturing and finishing include delamination, de-bonding, potential fracture, debris etc. Despite
extensive investigation and refinement in structural design, the water ingress problem persists as no general
mitigation technique has yet been developed. Developing sustainable solutions to the water ingress problem can
be very time-consuming and costly. The increasing use of composites in the aviation industry, in, for example,
honeycomb sandwich components highlights the significant need to address the moisture ingress problem and
develop deeper insights which can assist in combatting this problem. Experimental testing, although the most
dependable approach, can take months, if not years. Numerical simulations provide a powerful and alternative
approach to experimental studies for obtaining an insight into the mechanisms and impact of moisture ingress in
aircraft composites. The principal advantage is that they can be conducted considerably faster, are less costly
than laboratory testing, and furthermore can also utilize the results of laboratory studies to aid in visualizing
practical problems. Therefore, the present study applies a computational fluid dynamics (CFD) methodology,
specifically ANSYS finite volume software and the three fluid-based solvers, Fluent, CFX and ANSYS fluid
structure interaction (FSI), to simulate water ingress in composite aerospace structures. It is demonstrated that
ANSYS Fluent is a satisfactory computational solver for fundamental studies, providing reasonably accurate
results relatively quickly, especially while simulating two-dimensional components. Three-dimensional
components are ideally simulated on CFX, although the accuracy achievable is reduced. The structural-fluid
based solver, ANSYS FSI (fluid structure interaction), unfortunately does not fully implement the material studied
leading to reduced accuracy. The simulations reveal interesting features associated with different inlet velocities,
inlet fastener hole numbers, void number and dimensions. Pressure, velocity, streamline, total deformation and
normal stress plots are presented with extensive interpretation. Furthermore, some possible mitigation pathways
for water ingress effects including hydrophobic coatings are outlined.
KEY WORDS: Aircraft composites, Computational Fluid Dynamics, ANSYS, moisture ingress, Fluent, CFX,
(fluid structure interaction) FSI, velocity, pressure, total deformation; elevator, mesh density.

Citation

Beg, O., Islam, B., Shamshuddin, M., & Beg, T. (2019). Computational fluid dynamics analysis of moisture ingress in aircraft structural composite materials. Arabian Journal for Science and Engineering, 44, 7809-7831. https://doi.org/10.1007/s13369-019-03917-4

• Journal Article Type: Article
• Acceptance Date: May 13, 2019
• Online Publication Date: May 20, 2019
• Publication Date: Sep 1, 2019
• Deposit Date: May 14, 2019
• Publicly Available Date: May 20, 2020
• Journal: Arabian Journal for Science and Engineering
• Electronic ISSN: 2191-4281
• Publisher: Springer Verlag
• Volume: 44
• Pages: 7809-7831
• DOI: https://doi.org/10.1007/s13369-019-03917-4
• Publisher URL: https://doi.org/10.1007/s13369-019-03917-4
• Related Public URLs: https://link.springer.com/journal/13369
• Additional Information: Access Information : This is a post-peer-review, pre-copyedit version of an article published in Arabian Journal for Science and Engineering. The final authenticated version is available online at: http://dx.doi.org/10.1007/s13369-019-03917-4