Browsing by Author "Herskovits, J."
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- Combined numerical-experimental model for the identification of mechanical properties of laminated structuresPublication . Araújo, A.L.; Soares, C.M. Mota; Freitas, M.J.M.; Pedersen, P.; Herskovits, J.A combined numerical-experimental method for the identification of six elastic material modulus of generally thick composite plates is proposed in this paper. This technique can be used in composite plates made of different materials and with general stacking sequences. It makes use of experimental plate response data, corresponding numerical predictions and optimisation techniques. The plate response is a set of natural frequencies of flexural vibration. The numerical model is based on the finite element method using a higher-order displacement field. The model is applied to the identification of the elastic modulus of the plate specimen through optimisation techniques, using analytical sensitivities. The validity, efficiency and potentiality of the proposed technique is discussed through test cases.
- Identificação de parâmetros elásticos e piezoelétricos em estruturas activas tipo placa : técnicas de optimização clássica versus redes neuronais artificiaisPublication . Araújo, A.L.; Lopes, Hernani; Vaz, M.A.P.; Soares, C.M. Mota; Herskovits, J.Neste trabalho são apresentados dois métodos não destrutivos para a identificação de parâmetros elásticos e piezoeléctricos em estruturas laminadas activas do tipo placa, com sensores/actuadores de superfície. O primeiro destes métodos resolve o problema inverso através de métodos de optimização clássica, minimizando a diferença entre frequências naturais experimentais e as fornecidas por um modelo de elementos finitos. O segundo método baseia-se na construção de um “meta-modelo” do problema inverso, recorrendo a Redes Neuronais Artificiais. Os dois métodos são comparados recorrendo a resultados experimentais de uma placa em vibração livre.
- Parameter estimation in active plate structuresPublication . Araújo, A.L.; Lopes, Hernani; Vaz, M.A.P.; Soares, C.M. Mota; Herskovits, J.; Pedersen, P.In this paper two non-destructive methods for elastic and piezoelectric parameter estimation in active plate structures with surface bonded piezoelectric patches are presented. These methods rely on experimental undamped natural frequencies of free vibration. The first solves the inverse problem through gradient based optimization techniques, while the second is based on a metamodel of the inverse problem, using artificial neural networks. A numerical higher order finite element laminated plate model is used in both methods and results are compared and discussed through a simulated and an experimental test case.