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Estrutura auxética multifuncional: Caracterização mecânica e piezoresistiva para monitorização estrutural em tempo real
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Resumo(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.
Descrição
Palavras-chave
Coeficiente de Poisson Negativo Esterolitografia Estrutura Reentrante Estruturas Auxéticas Estruturas Piezoresistivas Fabrico Aditivo Flexão em 3 Pontos Mwcnt Shm