Compton Imaging Tomography for Nondestructive Evaluation of Large Multilayer Aircraft Components and Structures

摘要

Novel nondestructive evaluation (NDE) systems based on a recently pioneered Compton Imaging Tomography (CIT) technique [1-4 are currently being developed by Physical Optics Corporation (POC). CIT provides high-resolution, three-dimensional (3D), Compton scattered X-ray imaging of the internal structure of evaluated objects, using a set of acquired two-dimensional Compton scattered X-ray images of consecutive cross sections of these objects. Unlike conventional computerized tomography, CIT requires only one-sided access to objects, has no limitation on the dimensions and geometry of such objects, and can be applied to large, multilayer, nonuniform objects. Also, CIT does not require any contact with objects during its application.POC is developing CIT-based tools that address Air Force needs for depot or in-field in situ NDE of various large, nonuniform, multilayer aluminum/titanium/composite and honeycomb sandwich aircraft/spacecraft structures with complex geometries, and provide accurate detection, identification, and precise 3D localization and measurement of possible internal and surface defects (corrosion, cracks, voids, delaminations, porosity, and inclusions), and also disbonds, core and skin defects, and intrusion of foreign fluids (e.g., fresh and salt water, oil) inside honeycomb sandwich structures. The feasibility of the tool was successfully demonstrated in NDE of various aircraft structure samples provided by the Air Force, Lockheed Martin, Boeing, SpaceX, Virgin Galactic, etc., and in situ NDE of C-5 and C-130 aircraft. Such tools can detect and localize individual internal defects with dimensions about 2 mm3, and honeycomb disbond defects less than 6 mm by 6 mm by the thickness of the adhesive of ≤100 μm. The current scanning speed of aircraft/spacecraft structures is about 2-3 min/ft2 (20-30 min/m2).