Over the past four years, the Montana State University research team has developed an innovative method for producing carbon fiber using the Stretch Break method, according to a Dec. 5 report from Composites World. This carbon fiber is easier to handle the molding of aircraft's complex shapes and can significantly reduce manufacturing costs. The project was funded by the U.S. Army with a total investment of $25.8 million.
Montana State University says researchers have invested heavily in the relevant areas of research and are now approaching a major milestone. Researchers plan to validate small-scale actual manufacturing capabilities before fully industrializing the technology. Traditional carbon fiber is widely used in aerospace due to its high strength, light weight and durability. But these fibers are not easily bent, so making a tight curve that fits perfectly into an aircraft's wings requires complex and expensive production tools and often metal structures as auxiliary support, which cost the U.S. military billions of dollars a year to maintain and repair. In contrast, new carbon fiber materials -- developed at Montana State University -- are mainly made of precisely stretched materials, in which some fibers have broken down at naturally weak points. Studies have shown that 'stretching and breaking' carbon fiber can be formed by about 8 times more with approximately the same intensity. This means that materials can be molded using simpler equipment without the aid of metal structures. Because the fiber is easier to form, conservatives expect to cut manufacturing costs by a quarter, the researchers said. Although the concept of improving the shapeability of carbon fiber by destroying parts of the structure has existed for decades, some of the methods used in the past (such as random cutting materials, etc.) have proved to be used. It will significantly reduce the strength of the material. The idea of tensile fracture is not a recent innovation either, but until now there has been no effective way to consistently and effectively pull fracture in a way that can be extended to industrial production. It can be said that the concept of 'stretching and breaking' carbon fiber sounds easy, but very difficult to control.
The Montana State University research team collaborated with more than 20 companies from Montana to design and process a new tensile fracture tool called Bobcat Head. When a flat beam of wire containing thousands of carbon fiber monofilaments passes quickly through a series of rollers, precise force is applied to destroy the defective fibers. Researchers noted that only about 2 percent of fiber breaks were made in a given range. Subsequently, the researchers analyzed the properties of the material obtained, bending the fibers after "stretching and breaking" into complex shapes and fixing them with resins, focusing on testing how difficult it is to form. Experiments have proved that the fiber has the same mechanical properties as the material made of continuous fibers, but is easier to form. Next, the researchers plan to scale up the production of this "stretch-break" manufacturing device, launching pilot demonstration applications to validate its ability to be used in actual manufacturing. This will lay the foundation for technical authorisation to aerospace companies that produce military and civilian aircraft. Researchers say they believe the material is expected to begin being used in industry over the next few years. Currently, the program has caught the eye of advanced materials suppliers and aerospace manufacturers, and relevant scientists and engineers have come to Montana State University to see the materials in person and eager to get samples of the materials provided by the research team. Both aerospace manufacturers and material suppliers have shown strong interest in the research and believe that once conditions for use are in place, it will have a significant impact on aerospace equipment manufacturing, the researchers said.
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