Researchers at North Carolina State University have developed a self-healing composite material that could significantly extend the lifespan of components used in aircraft, automobiles, wind turbines, and spacecraft. The new material is designed to repair itself more than 1,000 times and is estimated to last for centuries, compared to the current decades-long lifespan of conventional fiber-reinforced polymer (FRP) composites.
“This would significantly drive down costs and labor associated with replacing damaged composite components, and reduce the amount of energy consumed and waste produced by many industrial sectors – because they’ll have fewer broken parts to manually inspect, repair or throw away,” said Jason Patrick, corresponding author of the study and associate professor of civil, construction and environmental engineering at North Carolina State University.
FRP composites are widely used due to their high strength-to-weight ratio but are prone to interlaminar delamination—a process where cracks cause fiber layers to separate from the matrix. The research team’s approach involves two key features: 3D-printing a thermoplastic healing agent onto the fiber reinforcement to create a tougher interlayer, and embedding thin carbon-based heater layers that activate when an electrical current is applied. This heating melts the healing agent so it can flow into cracks and re-bond separated layers.
“Delamination has been a challenge for FRP composites since the 1930s,” Patrick said. “We believe the self-healing technology that we’ve developed could be a long-term solution for delamination, allowing components to last for centuries. That’s far beyond the typical lifespan of conventional FRP composites, which ranges from 15-40 years.”
To test durability, researchers built an automated system that repeatedly fractured and healed samples over 1,000 cycles across 40 days. After each cycle, they measured how much load the material could handle before delaminating again.
“We found the fracture resistance of the self-healing material starts out well above unmodified composites,” said Jack Turicek, lead author of the paper and graduate student at NC State. “Because our composite starts off significantly tougher than conventional composites, this self-healing material resists cracking better than the laminated composites currently out there for at least 500 cycles. And while its interlaminar toughness does decline after repeated healing, it does so very slowly.”
In practical terms, healing would only be activated after events like hail or bird strikes or during scheduled maintenance checks. According to researchers’ estimates based on these scenarios, quarterly activation could allow materials to last about 125 years; annual activation could extend longevity up to 500 years.
“This provides obvious value for large-scale and expensive technologies such as aircraft and wind turbines,” Patrick said. “But it could be exceptionally important for technologies such as spacecraft, which operate in largely inaccessible environments that would be difficult or impossible to repair via conventional methods on-site.”
The study also examined why recovery declines gradually over time: continued cycling causes reinforcing fibers to break down into micro-debris that hinders rebonding sites; chemical reactions between healing agents and other materials also weaken over time. However, modeling suggests perpetual repair remains possible through statistical approaches suited for these phenomena.
“Despite the inherent chemo-physical mechanisms that slowly reduce healing efficacy, we have predicted that perpetual repair is possible through statistical modeling that is well suited for capturing such phenomena,” said Kalyana Nakshatrala co-author of the paper from University of Houston.
Jason Patrick has patented this technology through his startup company Structeryx Inc., aiming for integration with existing manufacturing processes in collaboration with industry partners.
“We’re excited to work with industry and government partners to explore how this self-healing approach could be incorporated into their technologies, which has been strategically designed to integrate with existing composite manufacturing processes,” Patrick said.
The research was published January 9 in Proceedings of the National Academy of Sciences under DOI: 10.1073/pnas.2523447123.
