FiberJoints
Advanced reinforcement patch technology for composite bolted joints
Published online: 11.09.2023
FiberJoints
Advanced reinforcement patch technology for composite bolted joints
Published online: 11.09.2023
Composite bolted joints are used extensively in applications such as wind turbine blades, cars, airplanes, satellites etc. Some of these joints are critical to the functionality of the product and in case of failure the structural integrity may be jeopardized. Therefore, having a technology providing a strong joint is highly relevant and needed.
FiberJoints, a spin-out company from Aalborg University established in 2023, has developed an innovative, patented patch technology as a cost-effective solution to this problem.
JOINING METHODS FOR FIBER COMPOSITE MATERIALS
Today, joining methods for fiber composite structures are primarily divided into adhesive bonded joining and bolted joining. Adhesive bonded joining provides a strong and light joining method for composite materials, however, an issue associated with adhesive bonding is the difficulties faced in disassembling and separating the bonded materials if e.g. a part is worn out or damaged.
On the other hand, the bolted joining method provides the possibility to disassemble parts, hence, a natural solution would be to utilize bolted joining. However, fiber composite materials are sensitive to stress concentrations which are introduced in case of a bolted joint – therefore, bolted joints are over designed, through increased material use, resulting in higher weight and cost. An additional problem is that joints fail either instantly when mechanically overloaded or gradually when subjected to repeated loadings.
FiberJoints’ innovative mechanical load transferring patch provides mechanical joints with easy assembly and disassembly capabilities, and simultaneously an efficient load transfer between structural members because stresses near the bolt are redistributed smarter.
The technology consists of a patch-type insert comprised of three elements: an inner metal ring, a fiber ring, and a braided sleeve. These components work together to effectively redistribute the force, otherwise concentrated at the hole, to the remaining composite laminate.
Tests in lab have shown that the new method can provide about:
- 2-3 times higher static strength compared to a non-reinforced hole, and
- 80% of the fatigue strength of the neat composite material
The solution is not limited to a single production method, making it applicable in several techniques. Many parts have been completed using the vacuum infusion technique but also techniques like RTM, filament winding, and hand lamination are possible.
APPLICABLE IN SEVERAL MARKETS
The patch technology is expected to find broad application in the composite industry:
- 1
The aerospace industry is one of the major users of fiber-reinforced composites due to their high strength-to-weight ratio, fatigue endurance, corrosion resistance, and ability to withstand large temperature variations. The technology can reduce maintenance costs for aircraft and other aviation applications as well as increase structure lifetime and time between overhauls.
- 2
The automotive industry is increasing the use of composite materials in components to reduce weight and improve fuel efficiency for cars, trucks, etc. FiberJoints can help increase the strength and durability of these components.
- 3
Furthermore, the technology could also be applied to boat hulls or other marine structures, helping to improve performance and make it easier to detect any damage or wear over time in the marine industry.
- 4
In the construction industry, composite materials are being used to create more durable and energy-efficient structures. FiberJoints can provide enhanced performance and reduce maintenance costs for buildings, bridges, and other infrastructure projects.
- 5
The technology is also applicable in the wind energy industry to provide improved efficiency and reliability for strong and lightweight wind turbine blade made by fiber composite.
- 6
Lastly, FiberJoints can enhance the reliability, increase damage tolerance, and improve crack resistance and safety for military vehicles, aircraft, and other defense applications.
DEVELOPED BY RESEARCHERS
The patented technology is developed by the two co-founders Associate Professor Johnny Jakobsen and Associate Professor Benny Endelt, both from the Department of Materials and Production at Aalborg University.
Johnny and Benny initiated their research focused on composite bolted joints back in 2019. Combining more than 20 years of experience within both composite materials and mechanical simulation, the collaboration led to the development of the reinforcing patch technology and the founding of FiberJoints.
THE COMMERCIALIZATION PROCESS
Prior to the establishment of FiberJoints, AAU Technology Transfer Office reached out to a local investor with early-stage investment interest. This investor saw the potential of the technology and market. In 2023, the investor joined the team to further the commercialization of the technology.
AAU Technology Transfer Office have helped uncovering the commercial potential and possible IPR rights of the technology. Furthermore, the team has received sparring and guidance regarding the development of the company's business model, pitch training, and funding opportunities.