Flexible, Compatible, Solid-State Eddy Current Probe for Detection of Defects Near Edges of Curved Components

ABSTRACT: Eddy current testing (ECT) is a widely practiced and critically important nondestructive evaluation (NDE) method used in aerospace, yet it relies on decades-old, wire-coil sensors. Flexible sensors are needed to inspect curved surfaces near the edges of components including wheel bead seats on landing gear and dove tail slots on turbine rotor disks. For many tests, the large signal generated by the nearby edge of a component overwhelms the small signal due to a defect. RMD, in collaboration with Wyle Laboratories, proposes a flexible, solid-state ECT sensor probe made from a linear array of microscopic, directionally-sensitive, solid-state eddy current sensors. The high sensitivity ECT probes will greatly enhance the probability of detection (POD) of measurements near the edges of curved components. The multiple element sensor arrays will allow faster, high resolution inspections. The modular sensor array will be compatible with existing ECT systems so that it can be adopted without the expense of buying new equipment, or training personnel in new ECT methodologies. The sensor array will be fabricated on thin durable plastic (approximately 100 um thick) that is highly flexible so that it can be used on tightly curved surfaces. BENEFIT: DOD APPLICATIONS The proposed technology provides superior sensors for ECT to achieve high resolution detection of minute defects near the edges of components and in difficult to access areas. The proposed ECT technology will be useful for inspecting landing gear, engine components, flight surfaces, support structures, titanium castings, hydraulic lines and other components that are made of standard or advanced metallic materials. The technology will permit inspection of thick components in 3-D. For materials testing and development, incipient defects can be detected and their propagation monitored and analyzed during aging. Since the technology can be used to improve manufacturing and the selection of materials, and to test finished components and aging systems, it will have a broad impact on the efficiency and effectiveness of DoD missions. COMMERCIAL APPLICATIONS The advanced ECT sensor technology proposed here will enable inspectors to detect extremely small defects near edges and other features of components. It will be simple to use and compatible with existing ECT systems. Eddy current testing is the most widely used NDE technique with a market value in excess of $200M/year in the US alone. Some of the commercial market areas where the new technology has promise include: pipelines, heat exchangers, oil refineries, aircraft, ship and other transport vehicle inspection, jet engine inspection, manufacturing and QA of metallic components.