Carbon composite structures are critical to BMDO's missions. A structural failure has very expensive consequences and might affect our Nation's safety. Existing nondestructive inspection methods have a variety of drawbacks, and therefore the use of composites proceeds with both caution (e.g., overdesign, premature retirement of critical structures) and risk. Quantum Magnetics, Inc., is proposing a novel strain gauge that shows excellent promise for advancing nondestructive inspection and health monitoring of carbon composite structures. The proposed non-contact and non-intrusive method is based on Quadrupole Resonance (QR) and does not require an external load. A small percentage of a tiny and inert crystalline additive is either applied as a thin additive/resin coating on the structure's surface or embedded in the composite structure during its manufacture. A portable detector head transmits brief, non-harmful radio frequency pulses and detects the additive's strain dependent response. Maps of internal and surface strains will be helpful to make an informed decision on whether the structure is safe for use or whether repair/ retirement is needed. In Phase I we will study the feasibility of both QR based approaches in carbon composites, and in Phase II we will demonstrate detection of different types of flaws including fatigue-induced flaws. Anticipated Benefits/Commercial Applications: The proposed technology will significantly advance nondestructive evaluation and health monitoring of carbon composite structures and thereby provide the technical information to make sound judgment on their usability, safety and maintenance. The technology adds significant value because it can help to prevent catastrophic and extremely expensive failures, increase the structure's lifetime and cost effective- ness and even performance (less overdesign is needed). The technology also has a number of commercially important applications, e.g., in aerospace, natural gas containment via composite vessels, composite oil well tubulars, composite wind turbine blades for electrical power generation, in the automobile industry, and in the sports industry.
Keywords: Strain, Non-contact, Composite, Carbon, Flaw detection, Nondestructive inspection, Health monitoring, Quadrupole Resonance
