Title: Comparison of Fusion Welding Hand-Lay vs. AFP of a Stepped-Lap Joint for Thermoplastic Carbon Fiber-Reinforced Composites

Authors: Alan Austin, Sam Pint

DOI:

Abstract: Scarf joints are used as a joining and repair method for composite laminates. However, most work done for composite joining methods has been performed using adhesive bonds while minimal to no information is available for similar joining by welding of a thermoplastic matrix. The aerostructures industry needs a way to join smaller components without a significant weight penalty to enable rapid fabrication using lower cost equipment. For this study, two ways of manufacturing welded stepped-overlap joints on thermoplastic carbon fiber reinforced polymer laminates were evaluated for their effectiveness as a joining technique. Syensqo AS4D/PEKKFC was the material selected for hand-layup fabrication. Toray TC1225/T1100 LMPAEK was the material used for automated fiber placement. Stepped-overlap scarf panels with ramp rates of 20:1 and 40:1 were fabricated, then overlapped and welded. The automated fiber placement panels in the ± 45° fiber orientation have a crenulated edge, while the ± 45° fiber orientation hand-layup panels have a straight edge in the stepped-overlap joint, which could have an impact on the mechanical strength of the stepped-scarf joint. The stepped-overlap panels were consolidated and welded using vacuum-bag-only with Spirit’s patented Co-Fusion process. The quality of the stepped-overlap joint was characterized using pulse-echo ultrasonic nondestructive inspection (NDI), photo micrographs, mechanical testing, and fracture surface analysis. The mechanical performance of pristine specimens made using the same material and consolidation cycle were directly compared to the stepped-overlap scarf specimens to determine the efficiency of the welded joint.

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Conference: SAMPE 2026

Publication Date: 2026/04/27

SKU: 209

Pages: 15

Price: $30.00