Monash And RMIT Study Finds Moisture Causes Ageing In Aviation Carbon Fibre

Engineers at Monash University and RMIT have found that moisture absorption is the single most important factor in the degradation of carbon fibre materials used in aircraft construction – a discovery that could reshape how the aerospace industry approaches maintenance planning and structural design.

The research investigated how different carbon fibre laminate designs aged under various hot and humid environmental conditions. The central question was whether higher temperatures caused fundamentally different types of damage, or whether heat simply sped up the same ageing process.

The answer turned out to be straightforward. The amount of moisture absorbed by the material, rather than the specific temperature or humidity it was exposed to, is the dominant factor controlling how and when the material breaks down.

A Long-Standing Question Answered

Dr Katherine Grigoriou, from the Monash Department of Mechanical and Aerospace Engineering, explained that the finding addresses a question that has lingered in aerospace materials testing for some time.

“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,” Dr Grigoriou said.

“This means that if we understand how moisture builds up inside a composite structure, we can much more reliably predict how it will perform over many years in service.”

Carbon fibre reinforced polymers have become a staple of modern aircraft manufacturing. The materials are lightweight, strong and resistant to corrosion, making them attractive for airframe construction. But they carry a vulnerability that is less immediately obvious: over time, these composites slowly absorb moisture from the surrounding environment, gradually weakening from within.

That process of internal degradation has been well documented, but the relative importance of specific environmental variables – temperature, humidity and moisture content – has remained a subject of debate among researchers and engineers.

Implications For Accelerated Testing

The finding carries particular significance for how manufacturers and maintenance organisations test composite materials.

Aerospace engineers routinely use accelerated ageing tests to simulate decades of environmental exposure in compressed timeframes. These tests allow engineers to estimate how a material will perform after 20 or 30 years in service without waiting that long to find out.

The reliability of those accelerated tests has always depended on how well they replicate real-world degradation mechanisms. The Monash and RMIT research suggests the tests can remain accurate, provided one variable is properly accounted for.

“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 noted.

That conclusion could give manufacturers greater confidence in their existing testing regimes while also flagging the need to pay closer attention to moisture levels as the key metric.

Fibre Layout Matters Too

Beyond the moisture finding, the research revealed that the internal arrangement of carbon fibres within a composite plays a significant role in how well the material resists environmental damage.

Using advanced imaging techniques, the team observed microscopic internal damage forming as materials aged. The damage included tiny voids, cracks and a weakening of the bond between fibres and the surrounding polymer matrix.

Not all laminate designs responded the same way. Some fibre layouts retained their strength to a far greater degree, while others proved considerably more sensitive to moisture-related degradation. The variation suggests that careful selection of fibre arrangements during the design phase could meaningfully extend the service life of composite aircraft structures.

A Growing Reliance On Composites

The research arrives at a time when the aviation industry’s dependence on composite materials continues to increase. Modern commercial aircraft such as the Boeing 787 and Airbus A350 use carbon fibre composites for large portions of their airframes, including fuselage sections and wing structures.

As these aircraft accumulate years of service in varied climatic conditions around the world, understanding precisely how their composite structures age becomes increasingly important for both safety and cost management.

The findings from the Monash and RMIT team could help engineers design more durable composite structures, refine maintenance schedules and increase confidence in the long-term performance of aircraft components already in service.

The research paper can be found, here.

Last Updated on March 21, 2026 by Nick Ross