AGC AeroComposites, a UK-based supplier of composite structures, assemblies and components for aerospace and defense, has completed an 18-month project to develop a low-cost thermoplastic composite welding process.

AGC and its partners say they demonstrated that carbon/polyphenylene sulfide, PPS, composite thermoformed components can be reliably welded to form complex assemblies using resistive composite welding elements that contain no metal meshes or inserts.

The technique was developed with funding from the UK’s National Aerospace Technology Exploitation Programme. The technique was developed with funding from the UK’s National Aerospace Technology Exploitation Programme. The resulting welded components demonstrated consistent high strength and fatigue properties. Moreover, low-cost equipment and materials can be used and the heating-to-welding temperature takes three minutes, AGC says.

The process is not limited to flat components; panels with significant curvature also can be reliably welded, the company says. When tested, all resulting welds proved to be high quality with no voids, passing standard ultrasonic non-destructive testing (NDT) specifications, the company says.

Welded top-hat sandwich panels were produced and structurally compared by torsional strength and fatigue testing to identical riveted parts. The welded component had higher stiffness and greater strength reaching five times that of the riveted component. Fatigue performance of the welded component was also superior with no damage at 350,000 cycles in comparison to the riveted parts that survived 50,000 cycles, AGC says.

Named “CoFusion,” the project’s aim was to optimize the efficiency and applicability of an innovative, low-cost thermoplastic composite welding process. The project was funded in part by the National Aerospace Technology Exploitation Programme, or NATEP, in partnership with the UK National Composites Centre, TenCate Advanced Composites and Rolls Royce.

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