FEATURE / AERONAUTICAL FUSELAGE PARTS Similar results were observed visually on the opposite face (Figure 13). At first sight, composite and copper mesh integrity seems correct. The rectangle with dashed line border shows the stringer location on the upper surface. The composite integrity was controlled by ultrasonic non-destructive inspection (Figure 14). The areas around the thermocouples, the start and end of the assembly are excluded from the inspection because the weld quality was not optimised for these areas. The aerospace criterion of amplitude damping is less than 12dB on the whole surface. These amplitude damping are represented in green (<6dB) and blue (between 6dB and 12dB) in Figure Figure 13. Detail point of view on LSP grid. Figure 14. damped amplitude cartography from ultrasonic inspection for the welded interface stringer/skin. Table 1. Ultrasonic NDI, mean surface part result. Damping < 12dB 67% Time-of-flight indication (welding defects) 35% Figure 15. Micrographic cross-sections. 14. The major central part has good integrity according to this criterion (green and blue central strip). Signal along the free edge and radius is not matching the criterion, especially on stringer free edge side, for which a quarter of the width from this free side does not pass the criterion. Thermal overheat along the free-edge side can explain this result (red line on Figure 10). Time-of-flight analysis confirmed the presence of defects (Table 1). The depth of the signal points out intralaminar porosity in the stringer as defects. On the radius side, time-of-flight analysis does not show a stringer defect but an interface indication, such as non-welding. Nevertheless, the temperature reached in the radius side and in central areas were found to be close (Figure 10). The pressure applied 22 | SAMPE JOURNAL | MARCH/APRIL 2022 www. sampe.orghttp://www.sampe.org