<p>Impact damage in composites can result in material failure in the composite matrix without visually apparent damage to the composite. It follows that measuring impact damage in these materials can be useful in detecting and predicting failure. Here, the use of a large-area electronic for this purpose is investigated. The studied large area electronic, termed soft elastomeric capacitor, transduces deformations into a measurable change in capacitance. Its signal is linearly proportional to strain, thus providing a direct measure of deformations under the surface it is adhered to. To explore the efficacy of the soft elastomeric capacitor at monitoring impacts, impact tests were conducted on fiberglass and resin composite plates where the nominal proof resilience of the material is approached and incrementally surpassed until the impacts resulted in small plastic deformations indicating failure of the material matrix. Results show the efficacy of the soft elastomeric capacitor in the state-based detection of impact damage in composites. It was found that the impact energy was directly related to the change in capacitance. The impacts at a higher energy level induced a measured increase of the capacitance after the impact. Impacts below the nominal proof resilience did not induce a consistent capacitance change, consistent with the materials' expected elastic behavior.</p>

State-Based Impact Damage Quantification Using Large Area Capacitive Sensors

Paper Proceedings: https://asmedigitalcollection.asme.org/qnde/QNDE2021/volume/85529

ASME 2021 48th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE2021)

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