Material enabled thermography

This paper is focused on the analysis of a novel structural health monitoring technique based on the inclusion of a thermoresistive network within the structure of a traditional CFRP laminate. By exploiting the thermoelectrical properties of shape memory alloys (SMA) it is possible to employ them as an embedded heat source to rapidly identify the presence of internal defects in composite structures by monitoring the time history of the superficial thermal contrast. The sensitivity of the methodology was evaluated by testing several samples characterised by embedded defects in different positions and with different sizes, together with an analysis of the effect of the position of the SMA grid and the intensity of the feeding current. The results obtained were compared with traditional NDT inspections such as ultrasonic C-Scan and Shearography and showed that material-enabled thermography is able to give results comparable with other techniques, saving inspection time and reducing the total costs of the analysis. In addition, because the only requirements for the test are the presence of an embedded heat source and simple electrical contacts, the inspection does not need any external heaters, therefore it is possible to rapidly monitor the health status of complex parts without dismounting them from the structure.

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