NDE for Ablative Thermal Protection Systems

This program addresses the need for non-destructive evaluation (NDE) methods for quality assessment and defect evaluation of thermal protection systems (TPS). Novel linear drive eddy current methods are proposed for NDE of carbon-based TPS materials, such as felts, rigid materials, and three dimensional woven fiber composites. Using a combination of physics-based models of layered media, including an eddy current micromechanical model extension for composites, multivariate inverse methods, high resolution imaging, and innovative sensor array constructs, the developed methods will independently measure the material characteristics of interest. In Phase I, the focus was on adapting methods developed for carbon-based composite structures and laminates and demonstrating feasibility of these methods for felts, rigid materials, and three-dimensional woven composites. In Phase II, the focus is on maturing this method, including the instrumentation hardware, models, and sensor designs, to provide scanning assessment and in-situ monitoring capabilities for TPS material condition assessment. JENTEK's MWM-Arrays have a linear drive that permits both scanned type imaging and permanent installation for monitoring of anisotropic properties, temperature, and stresses at multiple depths. The projected depth of the magnetic field into the test material can be adjusted through the sensor dimensions and excitation frequencies; this enables inspection of materials more than 1.0-in. thick and supports measuring far-side surface recession in ablator materials. JENTEK delivered the MWM-Array solution used by NASA KSC on the Space Shuttle Leading Edge to detect damage of the Reinforced Carbon-Carbon (RCC) thermal protection tiles; thus JENTEK is well-positioned to deliver a practical TPS NDE solution.