Abstract
The present work deals with the damage identification problem in mechanical structures from their impulse response. In the adopted model, the structural integrity is continually described by a cohesion parameter and the finite element model (FEM) is used to spatially discretize the displacement and cohesion fields. The damage identification problem is then posed as an optimization one, whose objective is to minimize, with respect to the vector of nodal cohesion parameters, a functional based on the difference between the experimentally obtained impulse response and the corresponding one predicted by an FEM of the structure. The damage identification problem built on the time domain presents some advantages, as the applicability in linear systems with high levels of damping an/or closed spaced modes, and in nonlinear systems. Numerical studies were carried out considering a simply supported Euler-Bernoulli beam. The D-optimal criterion was considered with the aim at determining the optimal position of the displacement sensor. The Differential Evolution (DE) optimization method was considered to solve the inverse problem of damage identification. Numerical analysis were carried out in order to assess the influence, on the identification results, of noise in the synthetic experimental data and of the sensor position. The presented results shown the potentiality of the proposed damage identification approach and also the importance of the optimal experiment design for the quality of the damage identification results.
Highlights
No Caso 2, considerou-se os 125 primeiros pontos da resposta impulsiva da estrutura, medida no no sensor de deslocamento S4 – que representa o sensor que produziu os menores valores para o determinante da matriz de informacao – e a mesma intensidade de ruıdo adicionado aos dados experimentais
The structural integrity is continually described by a cohesion parameter and the finite element model (FEM) is used to spatially discretize the displacement and cohesion fields
The damage identification problem is posed as an optimization one, whose objective is to minimize, with respect to the vector of nodal cohesion parameters, a functional based on the difference between the experimentally obtained impulse response and the corresponding one predicted by an FEM of the structure
Summary
Estruturas de engenharia estao expostas a processos de deterioracao e aocorrencia de dano durante sua vida util. As tecnicas de identificacao de danos fundamentados na resposta dinamica da estrutura sao, de forma geral, classificados em tres tipos, de acordo com o domınio dos dados utilizados: tecnicas no domınio do tempo [2], tecnicas no domınio da frequencia [5] e tecnicas modais [8]. O presente trabalho considera a identificacao de danos a partir da resposta impulsiva da estrutura, sendo portanto, uma tecnica fundamentada no domınio do tempo. Estuda-se o problema de identificacao de danos estruturais em uma viga de Euler-Bernoulli simplesmente apoiada. Na formulacao do problema direto apresenta-se a definicao do parametro de coesao β, utilizado para descrever o estado de dano na estrutura [6], e o modelo matematico do problema direto de vibracoes de uma viga de Euler-Bernoulli no domınio do tempo, via MEF. Sao apresentadas as conclusoes obtidas com a presente pesquisa e sao realizadas algumas sugestoes para trabalhos futuros
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