Identificação de descontinuidades em peças metálicas utilizando sinais ultrassônicos e técnicas de problemas inversos

• Ano de defesa: 2015
• Autor(a) principal: Guarneri, Giovanni Alfredo
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Tecnológica Federal do Paraná; Curitiba; Programa de Pós-Graduação em Engenharia Elétrica e Informática Industrial
• Palavras-chave em Português: Processamento de sinais; Ultrassom; Algorítmos; Testes não-destrutivos; Problemas inversos (Equações diferenciais); Convoluções (Matemática); Reconstrução de imagens; Métodos de simulação; Engenharia elétrica; Signal processing; Ultrasonics; Algorithms; Non-destructive testing; Inverse problems (Differential equations); Convolutions (Mathematics); Image reconstruction; Simulation methods; Electric engineering
• Link de acesso: http://repositorio.utfpr.edu.br/jspui/handle/1/1370

The present work proposes an algorithm to identify internal discontinuities in metallic specimen from A-scan ultrasonic signals. Discontinuities are identified by their shape, size, orientation and location. This algorithm is based on inverse problems. The identification of discontinuities is modeled using a novel approach. The discontinuity is modeled by two distinct elements: its scattering amplitude and its center location. Through this approach, the identification problem is split into two sub problems. The first is a reconstruction problem to find the location of the discontinuity. The second is a model identification problem to estimate geometric parameters of the discontinuity. Simulations and experimental validation show that the localization problem is satisfactorily solved using the UTSR (ultrasonic sparse reconstruction) algorithm. The characterization of discontinuities is carried out by an algorithm based on non-linear least squares with l1 norm regularization. The results obtained with simulated data as well with experimental data show a fine estimation of discontinuities.