Complex bounded assemblies can pose difficult inspection problems when multiple materials and constructions are combined into a single part. Ultrasonic resonance inspection is often used to identify distinct changes in the condition of a bounded structure. these changed can be created by the geometry of the part or by defects in the part. MAUS V resonance C-scans effectively illustrate the condition of these complex parts since the effects due to part geometry are easily discerned from sensor effects due to defective structure.
Pulse-echo ultrasonics are the preferred method to detect delimitations in composite laminates. The pulse-echo time-of-flight C-scan identifies the depth in the test piece where the flaw occurs. The attenuation C-scan identified the amount of sound reflected at any location. The C-scans shown here include delaminations at various depths in a composite laminate from near surface (light blue) to back surface (red).
The standard also includes teflon inserted within the laminate causing a ply separation. These defects (small rectangles) simulate separations in the laminate that are extremely close to the back of the part. Two pieces of metal substructure bonded to the back surface of the laminate appear at the top of the C-scan. A disbond between the laminate and the substructure appears in the center of the bonded pieces.
The MAUS flexible track provides fully automated, hands free scanning capability. It attaches to the part surface using vacuum pressure created from a shop air source. Two track sections are provided to allow the operator to "leap frog" the sections for a long continuous inspection such as on an aircraft lap joint. Any of the scanners may be attached to the track to provide fully automated data collections.
Corrosion detection programs often center on visual inspection of the inner and outer surface of the fuselage skin. Unfortunately, the ability to detect corrosion located between skin layers is limited in a visual inspection. MAUS IV eddy current C-scans easily identify hidden corrosion in these structures. Inspection programs have been performed since 1997 to detect hidden corrosion under doubled surfaces in large commercial and military aircraft. Software features include automatic gap compensation capabilities and corrosion quantification algorithms.
Cracks emanating from fastener holes are easily repaired if they are detected when the cracks are still quite small. A simple repair may require fastener removal, enlargement of the hole to remove the crack, and installation of an oversize fastener. The MAUS IV rotational scanner is a versatile tool that enables rapid inspection of many fastener holes without fastener removal.
An overall raster scan of the fastener area identifies fastener centers using either a pulse-echo or eddy current centering sensor. the fastener centers are identified automatically by the software allowing the operator to select the fasteners of interest. The rotational scanner is automatically positioned over each fastener center and the sensors are rotated around the center. Up to four channels of full waveform ultrasonic or impedance plane eddy current data are collected at preset intervals as small as 1 degree. This data is stored on the computer disk and can be recalled anytime for further review. Operator aids are available to support rotational data interpretation for complex inspections.