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Fasteners of the Future
October 6, 2011

high-temperature fastener systemThis is the high-temperature fastener system. (Photo courtesy Hyper-Therm High Temperature Composites) › View Larger Image Hyper-Therm High Temperature Composites of Huntington Beach, Calif., has developed a low-cost ceramic composite mechanical fastener system that may become an enabling technology for the next generation of propulsion systems and hypersonic and space vehicles.

As a result of NASA Small Business Innovative Research work Hyper-Therm completed with Dryden oversight, the company developed and validated the high-temperature fasteners. Currently, the company is in discussions with several large aerospace companies about potential uses for the technology.

For example, interest in Hyper Therm's high-temperature fastener has resulted in a partnership with a major turbine engine manufacturer. That company has invested more than $170,000 for continued development of the fasteners and fastening methods, said Wayne Steffier, Hyper-Therm president and principal investigator for the high-temperature fastener project. The partnership, which constitutes Phase III SBIR work and a technology development success story, also might result in a dual patent.

Hyper Therm received $650,000 from NASA for Dryden SBIR Phase II work, for development and validation of the high-temperature fasteners. The new fasteners are considered economical compared to alternative fasteners and fastening techniques, Steffier said. In addition, though metallic fasteners are incapable of withstanding the extreme temperatures of high-speed flight or combustion environments, Hyper-Therm fasteners can join load-bearing structures capable of withstanding high temperatures.

"What makes our two-dimensional, ceramic, mechanical fastener so unique is it is fabricated out of flat, laminated, plate-stock material. It does not look like a traditional bolt that you buy in a hardware store. We are able to greatly reduce the cost of a typical fastener because we are using flat, plate, laminated material and we don't need to machine threads into the ceramic composite element of this fastener," Steffier said.

"Because the fastener is fabricated with the same materials as the adjoining structure it is being used to fasten together, it is essentially thermal-stress free. This reduces a lot of the complexity associated with joining high-temperature structural assemblies."

How valuable was the SBIR work in advancing this concept?

composite lap joint test articlesThese are composite lap joint test articles. (Photo courtesy Hyper-Therm High Temperature Composites) › View Larger Image "It would still be sitting on the back burner if it were not for NASA funding the effort," Steffier said.

Dryden was helpful as the overseer of the work, he added. More specifically, he said Dryden contracting officer Craig Stephens helped focus the concept on applications NASA has interest in, such as hypersonic vehicles. That direction led to Lockheed Martin's interest in using the technology in development of a potential future hypersonic vehicle, Steffier said.

Stephens oversaw SBIR Phases I and II work.

"The original premise of the SBIR effort was to develop a high-temperature fastener that was lower-cost than traditional methods. Traditional high-temperature fasteners are usually made from three-dimensional, woven, high-temperature, composite materials, which are expensive to begin with and then you have to machine specific bolts or fasteners where the cost per bolt becomes fairly significant," Stephens said.

Hyper-Therm proposed a more cost effective, high-temperature fastener for SBIR Phase I work, which the company was awarded.

"The company developed a design based on plate material, making it a high-temperature fastener that is much more cost-effective. Phase I was to develop the concept and conduct initial mechanical testing of the fastener design.

"In Phase II the company began to acquire more data on the fastener's capability. Hyper-Therm completed planned room temperature and high-temperature testing of the fastener and ceramic composite lap joint sub-elements at different orientations relative to the primary orientation of the two-dimensional fastener. The research enabled them to characterize how the fastener would function under complex loading conditions," he said.

NASA is interested in high-temperature fasteners for joining sections of thermal protection systems, hypersonic engines and flight control surfaces, Stephens added.

Working with Hyper-Therm has gone well.

"Hyper-Therm is a good company and Wayne Steffier was very excited about this effort. He was very interested in the concept and spent a lot of time coming up with analysis techniques," Stephens said. "It is exciting to see an SBIR [project] that has this kind of business potential."

The SBIR program is an important tool for allowing businesses to explore new ideas and for NASA to determine if these ideas can be matured into new technologies, he added.

"Knowing that the NASA SBIR process is available provides NASA opportunities, when we are talking to companies, to direct them to the program and help them mature a potential technology that may be beneficial to both organizations," Stephens said. Hyper-Therm made a presentation at the 35th Annual Conference on Composite Materials and Structures in Florida in January as a result of its SBIR work. Several large aerospace companies approached the company to learn more about the high-temperature fasteners, Steffier said. For example, The Boeing Company's Phantom Works division in Huntington Beach inquired about the Hyper-Therm ceramic fasteners for use in a potential reentry vehicle, he said.

As discussions continue for tapping the new high-tech fasteners, it is the combination of bright ideas generated in private industry and insight from NASA through SBIR work that will ensure the technology is ready when it is needed.

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