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Estrutura auxética multifuncional: Caracterização mecânica e piezoresistiva para monitorização estrutural em tempo real
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Abstract(s)
Neste trabalho, propõe-se uma estrutura multifuncional com coeficiente de Poisson
negativo e sensibilidade piezoresistiva, com potencial para ser incorporada numa
nervura de uma aeronave de pequenas dimensões, para monitorização estrutural. Esta
estrutura explora tecnologias promissoras na Engenharia Aeronáutica, nomeadamente:
-manufatura aditiva, que tem sido usada graças à sua capacidade de produzir peças mais
leves com igual resistência e com geometrias mais complexas; -sensores de
monitorização da saúde estrutural (SHM), que permitem monitorizar os componentes
das aeronaves; -estruturas auxéticas, com coeficiente de Poisson negativo, que lhes
conferem uma capacidade superior de absorção de energia. Para tal, foi fabricada e
caracterizada uma estrutura piezoresistiva, de geometria auxética reentrante, através de
estereolitografia (SLA), aditivando-se uma resina comercial fotopolimérica com
nanotubos de carbono (MWCNT). As estruturas foram testadas em ensaios mecânicos
de flexão em três pontos, tendo sido avaliada a sua resposta piezoresistiva.
Dos ensaios cíclicos e de rutura, observou-se uma excelente correlação entre a resposta
mecânica e piezoresistiva, com uma sensibilidade (Gauge Factor) de -0,78. A adição do
nano reforço condutor promoveu um aumento de 300% na resistência mecânica. Estes
resultados demonstram o potencial para futuros estudos sobre estruturas de geometria
auxética aplicadas a componentes aeronáuticos.
This work proposes a multifunctional structure with negative Poisson's ratio and piezoresistive sensitivity, which has the potential to be incorporated into a rib of a small aircraft for structural monitoring. It explores promising technologies in aeronautical engineering, namely: -additive manufacturing, which has been used thanks to its ability to produce lighter parts with the same strength and more complex geometries; - structural health monitoring (SHM) sensors, which make it possible to monitor aircraft components; -auxetic structures, with a negative Poisson's ratio, giving them a unique energy absorption capacity. To this end, a piezoresistive structure with a re-entrant auxetic geometry was manufactured and characterized using stereolithography (SLA) by adding a commercial photopolymer resin with multi-walled carbon nanotubes (MWCNT). The structures were tested in three-point bending and piezoresistive tests. The cyclic and fracture bending tests showed an excellent correlation between the mechanical and piezoresistive response with a sensitivity (Gauge Factor) of -0.78. The addition of the MWCNT filler showed an increase in mechanical properties of approximately 300%. These results pave the way for future studies on auxetic geometry structures for aeronautical components, allowing this technology to be further developed.
This work proposes a multifunctional structure with negative Poisson's ratio and piezoresistive sensitivity, which has the potential to be incorporated into a rib of a small aircraft for structural monitoring. It explores promising technologies in aeronautical engineering, namely: -additive manufacturing, which has been used thanks to its ability to produce lighter parts with the same strength and more complex geometries; - structural health monitoring (SHM) sensors, which make it possible to monitor aircraft components; -auxetic structures, with a negative Poisson's ratio, giving them a unique energy absorption capacity. To this end, a piezoresistive structure with a re-entrant auxetic geometry was manufactured and characterized using stereolithography (SLA) by adding a commercial photopolymer resin with multi-walled carbon nanotubes (MWCNT). The structures were tested in three-point bending and piezoresistive tests. The cyclic and fracture bending tests showed an excellent correlation between the mechanical and piezoresistive response with a sensitivity (Gauge Factor) of -0.78. The addition of the MWCNT filler showed an increase in mechanical properties of approximately 300%. These results pave the way for future studies on auxetic geometry structures for aeronautical components, allowing this technology to be further developed.
Description
Keywords
Coeficiente de Poisson Negativo Esterolitografia Estrutura Reentrante Estruturas Auxéticas Estruturas Piezoresistivas Fabrico Aditivo Flexão em 3 Pontos Mwcnt Shm