Localização de impactos em materiais compósitos
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Data
2017-05-08
Autores
Razzini, Adrielly Hokama [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Materiais compósitos têm sido cada vez mais utilizados na indústria aeronáutica, devido a inúmeras vantagens que serão apresentadas nesse trabalho. Entretanto, impactos podem comprometer significativamente a estrutura. Tais impactos podem ocorrer a “baixa velocidade”, através de ferramentas derrubadas e contato com veículos/equipe de manutenção, e também a “alta velocidade”, como colisões com aves, raios elétricos, detritos de pneus ou pequenas pedras na pista. Conhecer a ocorrência e localização dos mesmos, assim como o progresso de danos subsequentes, permite realizar inspeções mais focadas e otimizar o custo e eficiência de manutenção. Este trabalho propõe a utilização de transdutores piezelétricos em formato de rosetas piezelétricas para localização de impacto em estruturas de materiais compósitos. As rosetas são compostas de transdutores retangulares de Macro-Fiber Composite (MFC), que apresentam uma resposta altamente diretiva para ondas ultrassonoras, o que foi explorado para determinar a localização da onda emitida, independente da velocidade de propagação da onda na estrutura. A acuracidade do mé- todo foi demonstrada experimentalmente em uma placa de fibra de carbono/ resina epóxi de dimensões 1060 ×1100×2mm, formada de 13 camadas plain-weave com duas rosetas piezelétricas coladas à superfície via adesivo cianoacrilato. Os impactos foram conduzidos utilizando um pequeno martelo com ponta metálica, simulando impactos realísticos sofridos por uma estrutura em serviço. O ponto de impacto foi determinado pelo método proposto e comparado com a localização real do impacto.
The usage of composite materials has been experiencing a continuous growth in aeronautic industry, due to countless advantages. However, impacts can significantly compromise the structure. These impacts can occur at "low velocity", by tools dropped, contact with maintenance vehicles or personnel and also at "high velocity", by bird/hail strikes, runaway debris from tires os lightnings. Knowing the occurrence and location of the impacts, as well as the progression of any subsequent damage, allows performing focused follow-up inspections, which can optimize maintenance cost and effectiveness. This work proposes using piezoelectric transducers arranged as rosettes to locate impacts on composite materials structures. The rosettes are comprised of rectangular transducers of Macro-Fiber Composite (MFC), which exhibit an highly directive response to ultrasonic waves that will were explored to determine the source of the incoming wave, regardless of the wave velocity. The accuracy of this method is experimentally demonstrated on a 1060x1100x2mm carbon/epoxy plate, formed by 13 plain-weave layers with two piezoelectric rosettes bounded to the surface via cyanoacrylate. The impacts were carried out using a small hammer with hardened steel tip, simulating realistic impacts suffered by an in-service structure. The impact point is determined by the proposed method and compared with the actual location of impact.
The usage of composite materials has been experiencing a continuous growth in aeronautic industry, due to countless advantages. However, impacts can significantly compromise the structure. These impacts can occur at "low velocity", by tools dropped, contact with maintenance vehicles or personnel and also at "high velocity", by bird/hail strikes, runaway debris from tires os lightnings. Knowing the occurrence and location of the impacts, as well as the progression of any subsequent damage, allows performing focused follow-up inspections, which can optimize maintenance cost and effectiveness. This work proposes using piezoelectric transducers arranged as rosettes to locate impacts on composite materials structures. The rosettes are comprised of rectangular transducers of Macro-Fiber Composite (MFC), which exhibit an highly directive response to ultrasonic waves that will were explored to determine the source of the incoming wave, regardless of the wave velocity. The accuracy of this method is experimentally demonstrated on a 1060x1100x2mm carbon/epoxy plate, formed by 13 plain-weave layers with two piezoelectric rosettes bounded to the surface via cyanoacrylate. The impacts were carried out using a small hammer with hardened steel tip, simulating realistic impacts suffered by an in-service structure. The impact point is determined by the proposed method and compared with the actual location of impact.
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Palavras-chave
Materiais compósitos, Localização de impactos, Rosetas piezelétricas, Location of impacts, Composite materials, Piezoelectric rosettes