The EU-project EVITA (Non-Destructive EValuation, Inspection and Testing of Primary Aeronautical Composite Structures Using Phase Contrast X-Ray Imaging) aims at bringing Grating-based Phase Contrast X-ray imaging technology to Non-Destructive Evaluation and Inspection of advanced primary and/or complex aerospace composite structures. Grating-based Phase Contrast X-Ray Imaging is based on the so-called Talbot-Lau interferometer, which is made of the combination of a standard X-ray apparatus with three transmission gratings as documented in the literature. This paper presents a comparison of two traditional non-destructive techniques (NDT): ultrasonic through transmission (immersed and water jet) and ultrasonic phased-array pulse echo, with the developed phase contrast XRay Imaging applied to advanced aerospace carbon fibre reinforced polymer. Typical defects produced during manufacture is examined as part of the testing and validation procedure. The following defects have been identified as being those most likely to be detected more effectively by the Grating-based Phase Contrast X-Ray Imaging process than other state of the art industrial NDT techniques: porosity, foreign objects, cracks, resin rich, cut fibres, and wavy fibres. The introduction of this innovative methodology is expected to provide the aeronautical industry with a reliable and detailed insight of the integrity of thin and thick Appl Compos Mater (2017)
The incorporation of sensors and actuators inside composite structures has become a new trend. Such structures are usually called ‘smart’, due to their capability for sensing and responding to the surrounding environmental stimulus. Among the many different types of sensors used for this purpose, the most popular are those that measure strain. In this paper, we investigated several inductive (noncontact) strain-sensing methods. The basic idea was to incorporate magnetostrictive wires inside composite laminates to act as both structural and sensing elements. The proposed technique does not require the connection of the sensing element (magnetostrictive wire) to the measuring device. Using a single transducer (which is connected to the measuring device), we can acquire strain measurements at any point. This facilitates installation, especially in cases where a large number of sensing elements are involved. In addition, the experimental results showed that the minimum detectable strain value could be around 0.25 mStrain and the resolution up to 0.1 mStrain, which indicates high sensitivity. Using these wires as strain-sensing elements could enable inspections at regular maintenance intervals in order to retrieve the structure’s ‘strain signature’. The retrieved strain signature could then be compared to previous readings in order to trace potential differences and/or anomalies.
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