Background and selected applications of conformable eddy current sensor networks for monitoring fatigue damage in complex geometry regions of specimens, components and structures are presented. Also, capability to use the same sensors to monitor stress in ferromagnetic materials is described. These eddy current sensors, called MWM-Arrays, use model-based multivariate inversion methods to provide reliable early detection and monitoring of fatigue cracks and real-time monitoring of stress through paint or coatings. Proven capabilities are illustrated by results for aluminum alloy, titanium alloy, and high-strength steel fatigue specimens, with MWM-Arrays mounted inside holes and on other cylindrical surfaces. Linear and circular MWM configurations (MWM-Rosettes) also provide the capability to detect and monitor fatigue cracks in embedded (between layers) sensor formats and with sensors placed under bolt heads as "smart washers." This paper describes implementations of this capability for aircraft focused applications, including past and ongoing coupon, subcomponent, component and full-scale aircraft fatigue tests as well as for structural health monitoring.
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