Structural damage identification in plates based on a model continuum damage

O presente trabalho aborda o problema de identificação de danos estruturais em placas a partir da matriz de flexibilidade. O dano é continuamente descrito por um parâmetro de coesão definido no domínio da estrutura. O problema de identificação de danos é, então, definido como um problema de otimização, onde o objetivo é minimizar, com relação ao campo de coesão, um funcional definido a partir da diferença entre a matriz de flexibilidade obtida experimentalmente e a correspondente matriz prevista por um modelo de elementos finitos da estrutura. O método de otimização enxame de partículas foi considerado para a resolução do problema de otimização. A avaliação numérica do método de identificação de danos proposto foi realizada considerando-se uma placa de Kirchhoff retangular, engastada em uma das extremidades. O cenário de dano constituiu-se de um dano duplo e com as formas modais corrompidas com diferentes níveis de ruído aditivo. Os resultados numéricos mostram a potencialidade do método em identificar a presença de danos a partir de uma quantidade reduzida de dados experimentais corrompidos com ruído.The present work addresses the structural damage identification problem in plates by using the flexibility matrix. The damage is continuously described by a cohesion parameter defined in the elastic structure domain. The damage identification problem is, then, defined as an optimization one, whose aim is to minimize, with respect to the cohesion field, a functional based on the difference between the experimental flexibility matrix and the corresponding one predicted by a finite element model of the structure. The particle swarm optimization method was considered to solve the optimization problem. The numerical tests of the proposed damage identification method are carried out taking into account a rectangular Kirchhoff plate with one clamped edge. The considered damage scenario is composed by two damaged regions and the mode shapes are corrupted with different additive noise levels. The numerical results show the potentiality of the proposed method in identifying damages from a reduced number of noise corrupted experimental data.Peer Reviewe

On the emergent Semantic Web and overlooked issues

The emergent Semantic Web, despite being in its infancy, has already received a lotof attention from academia and industry. This resulted in an abundance of prototype systems and discussion most of which are centred around the underlying infrastructure. However, when we critically review the work done to date we realise that there is little discussion with respect to the vision of the Semantic Web. In particular, there is an observed dearth of discussion on how to deliver knowledge sharing in an environment such as the Semantic Web in effective and efficient manners. There are a lot of overlooked issues, associated with agents and trust to hidden assumptions made with respect to knowledge representation and robust reasoning in a distributed environment. These issues could potentially hinder further development if not considered at the early stages of designing Semantic Web systems. In this perspectives paper, we aim to help engineers and practitioners of the Semantic Web by raising awareness of these issues