Thermoplastic composite tubular structures and methods of fabricating the same

A method of fabricating thermoplastic composite tubing, the method comprising:

• using a braiding apparatus to overbraid a single tubular mandrel with a continuous fiber thermoplastic composite material to form an overbraided mandrel, the tubular mandrel comprising a soluble, expandable ceramic material, the continuous fiber thermoplastic composite material consisting of a continuous slit tape thermoplastic composite material;
• installing the overbraided mandrel into a clamshell metallic tooling assembly;
• heating in a heating apparatus the clamshell metallic tooling assembly with the installed overbraided mandrel at a specified heating profile in order to consolidate the continuous fiber thermoplastic composite material and expand the expandable ceramic material of the tubular mandrel outwardly to exert pressure on the continuous fiber thermoplastic composite material against the clamshell metallic tooling assembly causing consolidation and formation of a thermoplastic composite tube, and wherein the pressure is in a range of from about 100 psi (pounds per square inch) to about 400 psi, wherein the heating apparatus is selected from the group consisting of a convection oven, an induction oven, an autoclave, and an integrally heated tooling assembly;
• cooling the clamshell metallic tooling assembly with the formed thermoplastic composite tube at a specified cooling profile;
• removing the formed thermoplastic composite tube from the clamshell metallic tooling assembly;
• and,
• washing out the tubular mandrel with water or a water-based solution to permanently remove the tubular mandrel from the formed thermoplastic composite tube.

A method of fabricating an aircraft thermoplastic composite tubular structure, the method comprising:

• providing a mandrel comprised of a soluble, expandable material, the mandrel having a mandrel cross-section defining a first closed geometric shape;
• using a braiding apparatus to overbraid a single mandrel with a continuous fiber thermoplastic composite material to form an overbraided mandrel, the mandrel comprising a soluble, expandable material and having a mandrel cross-section defining a first closed geometric shape, the continuous fiber thermoplastic composite material consisting of a continuous slit tape thermoplastic composite material;
• the overbraided mandrel having an overbraided mandrel cross-section defining a second closed geometric shape that corresponds to the first closed geometric shape of the mandrel cross-section;
• installing the overbraided mandrel into a metallic clamshell tooling assembly;
• heating in a heating apparatus the metallic clamshell tooling assembly with the installed overbraided mandrel at a specified heating profile in order to consolidate the continuous fiber thermoplastic composite material and expand the expandable material of the mandrel outwardly to exert pressure on the continuous fiber thermoplastic composite material against the metallic clamshell tooling assembly causing consolidation and formation of a thermoplastic composite tubular structure, and wherein the pressure is in a range of from about 100 psi (pounds per square inch) to about 400 psi, wherein the heating apparatus is selected from the group consisting of a convection oven, an induction oven, an autoclave, and an integrally heated tooling assembly;
• cooling the metallic clamshell tooling assembly with the formed thermoplastic composite structure at a specified cooling profile;
• removing the formed thermoplastic composite tubular structure from the metallic clamshell tooling assembly;
• solubilizing the mandrel with water or a water-based solution to permanently remove the mandrel from the formed thermoplastic composite tubular structure;
• and,
• using the formed thermoplastic composite tubular structure with the mandrel removed in an aircraft.