4.1. X-ray backscatter imaging of stringer components
Fig. 6 shows the geometry of the light-weight stringer compo-
nent examined in this work. This component is made-up of plate
like aluminium (Al) metal sheets and is generally used in the
aerospace industry. It can be seen from Fig. 7 that the stringer
component contains variations in the material thickness (between
2 mm and 4.8 mm) and this complex geometry requires a single-
sided access NDT method for the reliable inspection. The experi-
mental setup used for the inspection of stringer specimen is
shown in Fig. 4. The experimental investigation was carried out
using 600 kV X-ray tube voltage, 2.5 mA as tube current and 3 min
of exposure time. A slit width of 1.4 mm was used for allowing
scattered radiation from the interrogated object through the X-ray
backscatter camera.
Fig. 8(a) shows the X-ray backscatter image of the stringer
component. This image was captured after successfully calibrating
the unprocessed backscatter image data by using the calibration
procedure as described in Section 3.1 and subsequently applying the
parallelepiped algorithm for geometrical correction. The variations