FEATURE / THERMOPLASTIC UNIDIRECTIONAL TAPE Figure 4. Process parameter - weld temperature (NDI, DSC curve, and failed coupon). Figure 5. LSS vs. % crystallinity and time above melt vs. % crystallinity. Baseline An autoclave consolidated lap shear specimen was fabricated to use as a baseline for our results. The results from the baseline were compared with our induction welding results to determine the efficacy of our process. The non-destructive inspection (NDI) of the weld joint and the DSC curve showing no cold crystallization is shown in Figure 3. The failed lap shear specimen shows torn fibers and laminate fracturing across multiple plies. The autoclave specimen yielded strengths that aligned Figure 6. Fiber squeeze-out. with previous testing done at Qarbon Aerospace, at an average of 39.1 ± 1.5 MPa. Evaluation of Process Variables Results Temperature A series of lap shear panels were welded at temperatures ranging from 330-450°C. These panels were all welded at 6.35 mm/s. After welding, the laminates were ultrasonically inspected and DSC tested. DSC showed cold crystallization on all specimens. A representative inspection and DSC 32 | SAMPE JOURNAL | MARCH/APRIL 2022 www. sampe.orghttp://www.sampe.org