This article is based on an official press release from Monash University and RMIT.

Moisture Absorption Identified as Primary Driver of Carbon Fibre Degradation in Aircraft

Modern commercial aviation has increasingly turned to carbon fibre reinforced polymers (CFRP) to build lighter, more fuel-efficient Commercial-Aircraft. While these advanced composites are celebrated for their immense strength and resistance to traditional rust, they possess a hidden vulnerability: the slow absorption of environmental moisture during service. According to a recent press release detailing joint research from Monash University and RMIT University, engineers have definitively identified moisture absorption as the most critical factor in how these aerospace materials degrade over time.

The study, published in February 2026 in the journal Composites Part A: Applied Science and Manufacturing, resolves a long-standing debate within the aerospace engineering community. Historically, industry experts have questioned whether high temperatures cause unique types of structural damage to composite materials, or if heat simply accelerates the natural aging process. The new findings confirm that the total volume of moisture absorbed by the material dictates its degradation, overriding the specific temperature or humidity levels present during exposure.

The Mechanics of Hygrothermal Aging

Carbon fibre reinforced polymers are favored in modern Manufacturing because they replace heavier traditional metals like aluminum, offering exceptional durability without the risk of conventional corrosion. However, as noted in the research report, these materials are susceptible to “hygrothermal aging”, a process where prolonged exposure to heat and environmental moisture causes the material to slowly weaken from the inside out.

Microscopic Damage and Fibre Orientation

Utilizing advanced imaging techniques, the research team observed the exact nature of this internal degradation. As the composite materials aged, they developed tiny voids and microscopic cracks. Furthermore, the absorbed moisture caused “interfacial debonding,” which is a weakening of the critical chemical bond between the carbon fibres and the surrounding polymer matrix.

The official press release highlights that the internal geometric arrangement of the carbon fibres plays a massive role in environmental resistance. The researchers found that certain fibre layouts retain their structural integrity significantly better than others when exposed to moisture, making some designs inherently more sensitive to moisture-related degradation.

Validating Accelerated Ageing Tests

To ensure aircraft components will remain safe and functional for decades, aerospace engineers rely on “accelerated ageing” tests. These tests expose materials to extreme environmental conditions to simulate years of wear in a highly compressed timeframe. The Monash and RMIT study provides crucial validation for these industry-standard testing methods.

“What we found is that it’s not the exact ageing temperature or humidity that matters most, it’s how much moisture the material ultimately absorbs,” said Dr. Katherine Grigoriou, a researcher and lecturer at the Monash Department of Mechanical and Aerospace Engineering.

Dr. Grigoriou further explained in the release that understanding moisture buildup allows engineers to reliably predict long-term performance.

“Our results show that accelerated ageing methods can still provide reliable predictions of long-term performance, as long as the moisture content in the material is properly understood and controlled,” Dr. Grigoriou added.

Industry Implications for MRO

The implications of this research extend directly to airline operations and aircraft manufacturing. By establishing moisture absorption as the primary metric for composite degradation, Airlines can develop highly accurate predictive models for material aging. According to the research team, these insights will help engineers design more durable composite structures, improve maintenance strategies, and increase overall confidence in the long-term safety of aircraft components.

AirPro News analysis

At AirPro News, we view these findings as a critical stepping stone for the next generation of aircraft design. As the aviation industry continues its aggressive pivot away from metal toward lightweight composites to save fuel and reduce carbon emissions, understanding the exact environmental limits of these materials is paramount. The confirmation that accelerated ageing tests remain valid, provided moisture is tracked, should offer a sigh of relief to regulatory bodies and Manufacturers alike. Furthermore, the revelation that specific fibre orientations can mitigate moisture damage provides manufacturers with an immediate, actionable pathway to design inherently safer and longer-lasting airframes. We anticipate that future aircraft maintenance schedules will increasingly incorporate advanced moisture-tracking diagnostics to ensure passenger safety over the multi-decade lifespan of commercial jets.

Frequently Asked Questions (FAQ)

What is hygrothermal aging?

Hygrothermal aging refers to the degradation of materials, particularly composites, caused by prolonged exposure to a combination of heat and environmental moisture. In carbon fibre composites, this can lead to the weakening of the bond between the fibres and the polymer resin.

Why do modern aircraft use carbon fibre composites?

Carbon fibre reinforced polymers (CFRP) are exceptionally lightweight, extremely strong, and highly resistant to traditional rust and corrosion. Using these materials instead of heavier metals like aluminum helps aircraft burn less fuel and reduce emissions.

Does high temperature directly damage carbon fibre in aircraft?

According to the recent study by Monash University and RMIT, it is not the exact temperature or humidity that matters most, but rather the total amount of moisture the material ultimately absorbs. Heat primarily serves to accelerate this moisture absorption process.

Sources:
Monash University and RMIT Press Release via Medianet