Detecção de dano estrutural em ambientes ruidosos baseada na impedância eletromecânica e ondas de Lamb com diafragmas piezelétricos excitados com sinais de alta frequência
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Data
2021-12-21
Autores
Campeiro, Leandro Melo
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Universidade Estadual Paulista (Unesp)
Resumo
Os sistemas de monitoramento estrutural (SHM) têm mostrado seu elevado potencial com o passar das décadas. Com o desenvolvimento da tecnologia, métodos de implementação desses sistemas através de processamento computacional têm sido amplamente aplicados. O grande valor desses sistemas está em proteger as estruturas e as pessoas envolvidas. O ideal é detectar danos em estágio inicial utilizando-se sinais de excitação de alta frequência. Como esses sistemas podem ser construídos utilizando sensores que são acoplados à estrutura, efeitos de temperatura e ruídos são inevitavelmente inseridos aos sinais lidos pelos seus sensores, podendo assim, gerar um falso positivo. O desenvolvimento e o conhecimento de sensores disponíveis no mercado que podem ser utilizados em sistemas SHM é de interesse global, pois oferecerem uma redução de custo no desenvolvimento desses sistemas bem como uma ampla possibilidade de escolha para uma determinada aplicação, devido ao amplo conhecimento dos sensores que podem ser utilizados. Os diafragmas piezelétricos são componentes sonoros amplamente utilizados nos aparelhos eletrônicos do dia-a-dia e, além do baixo custo, apresentam a vantagem de serem produzidos em série por diversos fabricantes em tamanhos padronizados e prontamente disponíveis. Com base nessas informações, o objetivo dessa tese é apresentar os resultados do estudo de viabilidade de diafragmas piezelétricos como transdutor alternativo para a técnica das ondas de Lamb, permitindo expandir a pesquisa, bem como acelerar a implementação de sistemas SHM com menores custos de instalação, esses diafragmas já são amplamente utilizados na técnica da impedância eletromecância (E/M). Para avaliar a viabilidade desses componentes utilizando as ondas de Lamb, análises básicas pelo método dos elementos finitos (FEM) e ensaios experimentais foram realizados em placas de alumínio e os resultados obtidos com os diafragmas foram comparados com os obtidos com as cerâmicas piezelétricas convencionais. Após verificado a eficácia desses componentes em gerar e detectar danos utilizando ondas de Lamb, prosseguiu-se a pesquisa efetuando-se uma análise comparativa dos efeitos do ruído na detecção de dano estrutural utilizando-se a técnica E/M e ondas de Lamb com sinais de excitação em alta frequência. Além disso, testes foram feitos para comparar a capacidade de cada técnica em detectar, quantificar e localizar o dano na estrutura antes da análise com ruído. Os resultados mostraram que ambas as técnicas são eficazes em detectar dano estrutural em um ambiente ruidoso e quantificar e localizar os danos em condições ideais.
Structural health monitoring (SHM) systems have shown their high potential over the decades. With the development of technology, methods of implementing these systems through computational processing have been widely applied. The great value of these systems is in protecting the structures and people involved. Ideally, detect early-stage damage using high-frequency excitation signals. As these systems can be built using sensors that are attached to the structure, temperature and noise effects will inevitably be inserted in the signals read by their sensors, thus generating a false positive. The development and knowledge of sensors available on the market that can be used in SHM systems is of global interest, as they offer a cost reduction in the development of these systems as well as a wide choice for a given application, due to the extensive knowledge of sensors that can be used. Piezoelectric diaphragms are sound components widely used in everyday electronic devices and, in addition to their low cost, they have the advantage of being mass produced by several manufacturers in standardized sizes and readily available. Based on this information, the objective of this thesis is to present the results of the feasibility study of piezoelectric diaphragms as an alternative transducer for the Lamb wave technique, allowing to expand the research, as well as to accelerate the implementation of SHM systems with lower installation costs, these diaphragms are already widely used in the electromechanical (EMI) impedance technique. To assess the viability of these components using Lamb waves, basic analyzes by the finite element method (FEM) and experimental tests were carried out on aluminum plates and the results obtained with the diaphragms were compared with those obtained with conventional piezoelectric ceramics. After verifying the effectiveness of these components in generating and detecting damage using Lamb waves, the research continued by carrying out a comparative analysis of the effects of noise in the detection of structural damage using the EMI technique and Lamb waves with signals of excitation at high frequency. In addition, tests were carried out to compare the ability of each technique to detect, quantify and locate damage in the structure before the analysis with noise. The results showed that both techniques are effective in detecting structural damage in a noisy environment and quantifying and locating damage under ideal conditions.
Structural health monitoring (SHM) systems have shown their high potential over the decades. With the development of technology, methods of implementing these systems through computational processing have been widely applied. The great value of these systems is in protecting the structures and people involved. Ideally, detect early-stage damage using high-frequency excitation signals. As these systems can be built using sensors that are attached to the structure, temperature and noise effects will inevitably be inserted in the signals read by their sensors, thus generating a false positive. The development and knowledge of sensors available on the market that can be used in SHM systems is of global interest, as they offer a cost reduction in the development of these systems as well as a wide choice for a given application, due to the extensive knowledge of sensors that can be used. Piezoelectric diaphragms are sound components widely used in everyday electronic devices and, in addition to their low cost, they have the advantage of being mass produced by several manufacturers in standardized sizes and readily available. Based on this information, the objective of this thesis is to present the results of the feasibility study of piezoelectric diaphragms as an alternative transducer for the Lamb wave technique, allowing to expand the research, as well as to accelerate the implementation of SHM systems with lower installation costs, these diaphragms are already widely used in the electromechanical (EMI) impedance technique. To assess the viability of these components using Lamb waves, basic analyzes by the finite element method (FEM) and experimental tests were carried out on aluminum plates and the results obtained with the diaphragms were compared with those obtained with conventional piezoelectric ceramics. After verifying the effectiveness of these components in generating and detecting damage using Lamb waves, the research continued by carrying out a comparative analysis of the effects of noise in the detection of structural damage using the EMI technique and Lamb waves with signals of excitation at high frequency. In addition, tests were carried out to compare the ability of each technique to detect, quantify and locate damage in the structure before the analysis with noise. The results showed that both techniques are effective in detecting structural damage in a noisy environment and quantifying and locating damage under ideal conditions.
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Palavras-chave
Transdutores piezelétricos, Impedância eletromecânica (E/M), Ondas de Lamb, Ruídos, Detecção de danos, Testes não destrutivos, Monitoramento da integridade estrutural (SHM), Piezoelectric transducers, Electromechanical impedance,, Electromechanical impedance, Lamb waves, Damage detection, Non-destructive testing, SHM