Compton Scattering Three-dimensional Imaging System for in situ Nondestructive Inspection of Large Honeycomb Sandwich Structures

ABSTRACT: To address the Air Force need for a reliable method to inspect large honeycomb sandwich structures on aircraft, Physical Optics Corporation (POC) proposes to develop a new automatic, three-dimensional (3D) Compton Scattering Imaging System for in situ NDI of Large Honeycomb Sandwich Structures (IMHOS) used in aircraft and spacecraft, providing accurate detection, identification, and precise 3D localizations and measurements of possible disbonds, core and skin defects, and intrusion of different fluids. The proposed IMHOS NDI system is based on the POC-developed high-contrast Compton imaging tomography technique, optimized for NDI of honeycomb sandwich structures, and POC-patented apodized coded aperture X-ray optics. The IMHOS is a low-dose in-field noncontact, one-sided NDE system. In Phase I, POC will demonstrate the feasibility of the IMHOS in POC X-ray lab experiments with honeycomb sandwich structures. In Phase II, POC plans to completely test the developed fully functional TRL-6 IMHOS, demonstrating accurate detection, precise spatial localization, and measurements of disbands and different skin and core defects of different (metal and nonmetal) large honeycomb sandwich structures with varied geometric forms, and also liquid intrusion detection with liquid type differentiation (fresh and salt water, oil, other organic liquids). BENEFIT: Military applications of the IMHOS system will include NDI of large honeycomb sandwich structures of aircraft for accurate identification, localization, and measurements of disbonds, skin and core different defects, and liquid intrusions, including identification of the detected liquid (e.g., fresh and salt water, oil) during aircraft depot maintenance, or in-field for the U.S. Air Force. The IMHOS system can be incorporated by the U.S. Navy, Army, and Air Force as a reliable, rapid, automatic, easy-to-use NDI system of large honeycomb sandwich structures used in aircraft and other military platforms. With minor modification, the IMHOS system can also be used as an NDI system for parts containing different heterogeneous light materials (e.g., explosives, adhesives, electronic components, composites, plastics). An expansion of most of the techniques developed under IMHOS Phase II can transition to the commercial application as an NDI system of large honeycomb sandwich structures, of civilian aircraft, spacecraft, light vessels, and so forth, or any application requiring control of honeycomb sandwich structures. With minor modifications, the IMHOS system can also be used for detection of hidden objects inside airframe cavities in fuselages, wings, etc.