Jason Patrick et al.
Microscopic view of the new material
The material is produced from fiber-reinforced composites. When cracks or microfractures appear, the heat melts a repair agent and corrects the damaged area.
A team of North American researchers has developed an innovative self-repairing material that could transform the durability of automobiles, airplanes or wind turbines.
The discovery, recently presented in a published in PNAS, points to a scenario in which vehicles could exceed 100 years of useful life.
As researchers explain in one at NC State, the self-healing composite is more resistant than materials currently used in aircraft wings and turbine blades, and capable of repair more than 1,000 times.
The researchers estimate that their self-healing strategy could extend the life of conventional fiber-reinforced composite materials for centuries, compared to the currently projected service life of decades.
The new material is based on fiber reinforced composite materialswidely used for their resistance and lightness in sectors such as automobiles and aeronautics. However, these materials have a historical limitation: the delaminationan internal flaw that causes its layers to separate and compromises its structural integrity.
This problem, which has been around for decades, has restricted to useful life of these composites over relatively short periods.
With this limitation in mind, researchers developed a system inspired by natural processes, capable of repairing structural damage repeatedly without the need for manual intervention, which represents a relevant advance in engineering.
The key to the new material lies in the incorporation of a thermal curing agent in its structure. This is combined with heating layers that are activated when an electric current is applied, generating the heat necessary to start the repair process in a controlled manner.
When they appear fissures or microfracturescaused by impacts or wear, the heat melts the repair agentwhich flows to the damaged areas and reestablishes structural connections, achieving a chemical reconnection which allows the material to recover much of its original strength in a short time.
Jason Patrick, NC State University
3D printed thermoplastic curing agent (blue overlay) on fiberglass reinforcement (left); infrared thermography during in situ self-healing of a fractured fiber composite (center); 3D printed curing agent (blue) on carbon fiber reinforcement (right)
“This would significantly reduce costs and labor associated with the replacement of damaged components, in addition to reducing energy consumption and waste generated”, highlights Jason PatrickNC State investigator and lead author of the study.
“We found that the fracture resistance of the self-healing material starts well above that of unmodified composites,” he says.
“As our composite is, in principle, significantly more resistant than conventional composites, this self-healing material resists cracking better than currently existing laminated composites, for at least 500 cycles,” he explains. Jack TuricekPhD student at NC State and first author on the paper.
In real scenarios, repairs would only be triggered after the material suffers damage caused by hail, bird strikes or other events, or during scheduled maintenance operations. Researchers estimate that the material could last 125 years with quarterly repairs or 500 years with annual repairs.
“This represents a clear value for large-scale technologies and high cost, such as aircraft and wind turbines,” says Patrick. “But it could be exceptionally important for technologies like spaceshipswhich operate in practically inaccessible environments, where repair using conventional methods on site would be difficult or even impossible”, he concludes.
