A new self-healing material that engineering researchers have created enables structures to mend themselves in place without needing to be taken out of service. With the help of this most recent innovation, two long-standing problems with self-healing materials are now solved, and structural parts like airplane wings and wind turbine blades could live substantially longer.
According to Jason Patrick, corresponding author of the study and assistant professor of civil, construction, and environmental engineering at North Carolina State University, “researchers have developed a variety of self-healing materials, but previous strategies for self-healing composites have faced two practical challenges.”
“In order for the materials to heal, they frequently need to be taken out of service first.” Some parts, for instance, need to be heated in an oven, which can’t be done with large parts or when a part is being used. Second, the self-healing is only effective for a short time. For instance, the substance might be capable of healing a few times before its capacity for self-repair drastically declines. “We have developed a strategy that effectively tackles each of those issues while preserving the structural fiber composites’ strength and other performance qualities.”
This essentially means that consumers may depend on a certain structural element, like a wind turbine blade, for a lot longer without having to worry about it failing.
According to Patrick, “we make these composites more sustainable by extending their lifespan.” And while wind-turbine blades are a classic example, structural composites are used in a wide range of products, including sporting goods, automotive parts, aircraft wings, and satellites.
The innovative, self-healing fiber-reinforced composite operates as follows:
Layers of fibrous reinforcement, such as glass and carbon fiber, are bonded together to create laminated composites. Damage most frequently occurs when the “glue” holding these layers together starts to delaminate, or peel away from the reinforcement. In order to solve this issue, the study team 3D printed a thermoplastic healing agent pattern onto the reinforcing material. Additionally, the researchers added tiny “warmer” layers to the composite. The heater layers heat up when an electrical current is introduced to them. This causes the healing ingredient to melt, which then flows into any microcracks or cracks in the composite and fixes them.
The effectiveness of the self-healing can be maintained by repeating this technique at least 100 times, according to Patrick. “If there is an upper limit, we do not know what it is.”
Additionally, the printed thermoplastic increases its intrinsic resistance to fracture by up to 500%, making it harder for delamination to begin with. Additionally, the heater and healing agent layers are comprised of reasonably priced, easily accessible materials.
According to Patrick, “although producing composites using our design would be slightly more expensive, the cost would be more than offset by greatly increasing the material’s lifespan.”
Another benefit of the new technology is that it would enable airlines to stop using chemical deicing agents to remove ice from wings when aircraft are on the ground and to de-ice during flight if internal heating sources were installed into aircraft wings.
“We’ve shown that this multipurpose technology works,” says Patrick. We are looking for public and private partners to help us customize these polymer-based composites so they can be used in certain situations.
The work was made possible by grants from the Department of Defense’s Strategic Environmental Research and Development Program (W912HQ21C0044) and the U.S. Air Force Office of Scientific Research (FA9550-18-1-0048).
