Piezo-resistive response of embedded PVA-CNT fibers in glass fiber reinforced polymers under quasi-static and cyclic loadings
Composite materials have grown to be of great importance to the aerospace industry, owing to their high specific strength and stiffness, and generally superior and unique mechanical and physical properties. Nevertheless, their complexity regarding damage initiation and evolution makes it difficult t...
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| Κύριος συγγραφέας: | |
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| Άλλοι συγγραφείς: | |
| Γλώσσα: | English |
| Δημοσίευση: |
2020
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| Θέματα: | |
| Διαθέσιμο Online: | http://hdl.handle.net/11610/21295 |
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| Περίληψη: | Composite materials have grown to be of great importance to the aerospace industry, owing to their high specific strength and stiffness, and generally superior and unique mechanical and physical properties. Nevertheless, their complexity regarding damage initiation and evolution makes it difficult to assess their structural health, and as a result safety concerns arise. Therefore, in-service load monitoring and damage detecting sensors are required, in order to ensure structural integrity and thus maintain safety. All state-of-the-art embedded sensors exhibit their individual limitations concerning high costs of fabrication, application and maintenance, resolution or clearness of the measured data, and reduction of the material’s properties.
Polyvinyl alcohol–carbon nanotube (PVA-CNT) fibers can be successfully used as strain sensors for damage monitoring, by measuring their electrical resistance change (ERC), while mechanically loaded. In the present study, PVA-CNT fibers, pre-stretched at different ratios, were embedded into glass fiber reinforced polymer (GFRP) specimens in order to in-situ measure their ERC during quasi-static incremental tensile and cyclic loading tests. Both tensile and cyclic test results showed a direct correlation between the mechanical loading and the ERC, for the investigated specimens. Additionally, the electrical response from both tests was calibrated and correlated to measurements using both internal and external strain gauges. Residual resistance measurements as well as hysteresis loops after each unloading step/cycle were observed for the PVA-CNT fiber, which were correlated to accumulated damage within the composite. Furthermore, it was demonstrated that a significant increase in the fiber’s electrical resistance response can be achieved, by increasing its pre-stretch ratio. The established correlation between the above parameters changed according to the specimens’ loading history. |
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