Percorrer por autor "Pinto, Daniel Fernando Moreira"
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- Piezoresistive Sensing for Structural Health Monitoring: A Temperature Dependence CharacterisationPublication . Pinto, Daniel Fernando Moreira; Pereira, João Pedro Nunes; Silva, Abílio Manuel Pereira da; Parente, João Miguel NunesThe aeronautical industry holds safety as its core and its main drive for innovation, with sensors, materials science and self-governance to ensure safe travel through the skies. However, operational costs and maintenance requirements increase proportionally with the increase of number of sensors, which is a growing concern and makes cost-effective solutions desirable. This dissertation aims to advance the knowledge and viability of a promising candidate to resolve this issue, studying a type of what are called self-sensing materials as an alternative to the conventional structural health monitoring (SHM) sensors. This material is a type of piezoresistive nanocomposite (PNC) that, in theory, could replace an airplanes’ complicated arrays of sensors while providing even better performance. However, PNCs have a glaring fault that is hindering their commercial availability, namely their perceptual conditioning of operational temperature. Current state of the art has mostly neglected this correlation, especially in the SHM sector, an oversight that this dissertation aims to rectify. For this reason, electromechanical properties of a PNC specimen made of glass-fibre epoxy resin with 0.5%𝑤𝑡 multiwalled carbon nanotubes (MWCNT) as filler were thoroughly tested at three different test temperatures: 30°𝐶, 50°𝐶 and 70°𝐶. The experimental analysis, static and cyclical tests, revealed that temperature has a profound effect on sensing performance, outlining key factors of response change with temperature variation. Three gauge factors (GF) were calculated, one for each temperature, with values ranging from a maximum of 2.42 to a minimum of 0.83. For a broader scope on this effect, multiple variations of the basic three-point bending (3PB) tests were performed to determine which factors were application-specific and which were constant.