A newly developed self-healing composite material could significantly increase the lifespan of aircraft and other high-tech structures. The material should be able to independently repair microscopic damage and thus prevent long-term fatigue.
Carbon fiber reinforced plastics are among the most important high-performance materials today. They ensure exceptional strength with a very low weight. That is why they are primarily used in demanding applications, such as in aerospace, automobile construction or wind turbines.
However, in these areas they are exposed to enormous stress. Over time, temperature fluctuations or environmental influences can cause fine cracks to form and the material to lose stability. Science calls this process delamination.
This in turn increases the effort required for regular checks, repairs or replacing entire components. But researchers at North Carolina State University (NCSU) want to change exactly that. They have developed a self-healing composite material that could extend the lifespan of aircraft etc. by centuries.
Self-healing material enables an enormous service life
The demand for carbon fiber reinforced plastics has continued to increase in recent years. While demand in 2017 was 70.5 thousand tons, forecasts for 2027 assume that this could rise to more than 200 thousand tons worldwide.
But as NCSU researchers develop, that number may be lower. This is because their self-healing composite material can repair itself more than 1,000 times. This should also be more robust than the materials currently used in aircraft wings, turbine blades and other applications.
The researchers therefore assume that the self-healing ability of the material can extend the lifespan of fiber-reinforced composite materials from decades to centuries. “This would significantly reduce the cost and labor of replacing damaged composite components,” said lead author Jason Patrick, an associate professor of civil, structural and environmental engineering at North Carolina State University.
At the same time, the required energy consumption and the amount of waste could be reduced in many industries. Fewer defective parts need to be manually inspected, repaired or discarded, Patrick said.
Can this material prevent delamination?
“Delamination has been a challenge for fiber composites since the 1930s,” says Patrick. “We are confident that the self-healing technology we have developed can provide a long-term solution to delamination and extend the life of components by centuries. This far exceeds the typical lifespan of conventional fiber composites of 15 to 40 years.”
The self-healing material has similar properties to conventional fiber composite materials. However, it has two additional features that allow it to heal itself.
To do this, the researchers applied a thermoplastic agent to the fiber reinforcement using 3D printing. A polymer-structured intermediate layer is created, making the material two to four times more resistant to delamination.
In addition, a thin, carbon-based heating layer is embedded in the material. This heats up when an electric current is applied, causing the healing agent to melt and flow into cracks and microcracks. In this way, the material reconnects separated interfaces, which in turn restores the structural performance of the material.
“This offers obvious added value for large-scale and expensive applications such as aircraft and wind turbines,” explains Patrick. “But it could be particularly important for technologies such as spacecraft, which operate in largely inaccessible environments and which would be difficult or impossible to repair using traditional methods in the field.”
In practice, self-healing could be used, for example, as part of scheduled maintenance work or after a hailstorm. The researchers believe the material could last 125 years if self-healed quarterly and 500 years if self-healed annually.
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