Researchers at North Carolina State University have developed a composite material capable of repairing itself over 1,000 times, demonstrating toughness beyond conventional fiber-reinforced composites used in aircraft, wind turbines, and turbine blades. The team estimates this approach could extend the operational life of standard composites from decades to centuries.
“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,” says Jason Patrick, corresponding author of the paper and an associate professor of civil, construction and environmental engineering at North Carolina State University.
The findings are published in the Proceedings of the National Academy of Sciences in the paper “Self-healing for the Long Haul: In situ Automation Delivers Century-scale Fracture Recovery in Structural Composites,” co-authored by Turicek, Zach Phillips, and Nakshatrala. The research was funded by the Strategic Environmental Research and Development Program (SERDP) and the National Science Foundation (grant 2137100).
How the Self-Healing Mechanism Works
Fiber-reinforced polymer (FRP) composites are valued for their strength-to-weight ratio and are widely used in aerospace, automotive, and renewable energy applications. The new self-healing technique specifically addresses interlaminar delamination, a failure mode in which the fiber layers separate from the matrix due to cracks.
The composite mimics traditional FRP materials but incorporates two new features. First, a thermoplastic healing agent is 3D printed onto the fiber layers, creating a polymer-patterned interlayer that increases resistance to delamination by two to four times. Second, thin carbon-based heaters are embedded in the material; when activated with electricity, they warm the thermoplastic, allowing it to flow into cracks and rebond the layers, restoring structural integrity.
To assess durability, the researchers built an automated system that subjected a 50-millimeter delamination to repeated tensile forces and triggered thermal healing. This cycle was repeated 1,000 times over 40 days, an order of magnitude beyond previous self-healing tests.
“We found the fracture resistance of the self-healing material starts out well above unmodified composites,” said Jack Turicek, lead author and NC State graduate student. “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 practice, healing would occur only when damage arises, such as from hail or bird strikes, or during maintenance. Modeling suggests that with quarterly repair cycles, the material could last 125 years, and up to 500 years with annual maintenance.
“This provides obvious value for large-scale and expensive technologies such as aircraft and wind turbines,” Patrick says. “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.”
Long-Term Performance and Commercialization
The researchers also explored the challenges associated with repeated self-healing, including the gradual loss of effectiveness. Over many cycles, fibers fracture and produce micro-debris that limits the rebonding area. Chemical interactions at the interface between the fibers, polymer matrix, and healing agent also decline over time. Nevertheless, statistical modeling indicates self-healing remains viable over extremely long timescales.
“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,” says Kalyana Nakshatrala, co-author of the paper and the Carl F. Gauss Professor of Civil and Environmental Engineering at the University of Houston.
Patrick holds the patents for the technology and has licensed it through his company, Structeryx Inc.
“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 says.
3D Printing Enables Self‑Healing Materials
Additive manufacturing is increasingly enabling materials that can autonomously repair damage, addressing a core challenge across several industries. Its potential is especially significant in aerospace and defense, where research on self-healing materials aims to extend component lifetimes while reducing maintenance demands. Advances in these materials improve reliability in environments where on-site repairs are difficult or impossible, lower operational risk, and support sustained readiness for mission-critical systems.
Projects supported by the U.S. Department of Defense illustrate this approach. Researchers at RIT are developing 3D printed polymers that autonomously repair cracks in load-bearing components, enhancing structural resilience under operational stress. Similarly, Texas A&M University and the U.S. Army Research Laboratory have produced self-healing elastomeric polymers that restore broken covalent bonds when heated, enabling rapid restoration of critical systems such as aircraft parts. Together, these efforts demonstrate how additive manufacturing can help mitigate supply chain and repair constraints in defense applications.
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Featured image shows 3D printed thermoplastic healing agent (blue overlay) on glass-fiber reinforcement (left); infrared thermograph during in situ self-healing of a fractured fiber-composite (middle); 3D printed healing agent (blue) on carbon-fiber reinforcement (right). Image via NC State University.
