The invention is directed to the joining of structural elements and more particularly to the joining of structural elements formed form carbon-carbon composites.
One of the most pressing challenges in the development of carbon-carbon composite material as a structural material for aerospace and other applications, is the joining and fastening of the various elements together.
A common method of joining materials with metal pins is to chill the pins, i.e. shrink the pins, and then insert the pins through tight tolerance apertures. The pins increase in size when returned to ambient temperatures and bind the joined materials to the pin. This type of joinder of carbon-carbon structural materials with a carbon pin cannot be accomplished by this method as the carbon pin remains the same size when chilled or at ambient temperature due to the coefficient of thermal expansion (CTE) of carbon.
U.S. Pat. No. 4,478,544 teaches a deformable reinforced plastic rivet comprising a plurality of substantially continuous carbon fibers encapsulated in a partially polymerized thermoset resin matrix and enveloped in a high tensile strength low modulus tubular sheath. A portion of the rivet is deformable to form a head and fully polymerizable upon heating thereof.
U.S. Pat. No. 4,505,979 teaches a pin for connecting machine parts with one another, which is of optimally light weight, the pin is of a compound structure comprising a core rolled-reinforced synthetic plastics resin and a metallic envelope. A filler of quartz sand or carbon fibers is used. The envelope is preferably seated on the core under circumferential tensile bias. The manufacture of the pin takes place, for example, by pressing the filler and matrix resin system directly into the suitably prepared envelope.
U.S. Pat. No. 4,685,822 teaches a threaded connection between a graphite shaft and a metal shaft, such as is used to drive a rotating nozzle in the refining of aluminum, is strengthened by coating the graphite surface that contact the flange portion of the metal shaft with a refectory cement prior to the fastening of the shafts together. The coating of the graphite shaft serves to greatly strengthen the threaded connection and the ability of the connection to transmit driving torque from the metal shaft to the graphite shaft.
U.S. Pat. No. 4,723,862 teaches a ceramic-metal joint structure. A thin sheet of ceramic material is inserted between the metal and ceramic to be joined, a brazing material is positioned between the thin sheet of ceramic material and metal and ceramic material to be joined. The joint is then sintered.
One of the most pressing and continuing challenges in the development of carbon-carbon composite material as a structural material for aerospace and other applications, is the joining and fastening together of the various elements.