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Simões Moita, José Mateus

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  • Design of laminated structures using piezoelectric materials
    Publication . Simões Moita, José Mateus; Herskovits, José; Soares, Cristovão M. Mota; Soares, Carlos A. Mota
    Composite structures incorporating piezoelectric sensors and actuators are increasingly becoming important due to the offer of potential benefits in a wide range of engineering applications such as vibration and noise supression, shape control and precisition positioning. This paper presents a finit element formulation based on classical laminated plate theory for laminated structures with integrated piezoelectric layers or patches, acting as actuators. The finite element model is a single layer triangular nonconforming plate/shell element with 18 degrees of freedom for the generalized displacements, and one electrical potential degree of freedom for each piezsoelectric elementlayer or patch, witch are surface bonded on the laminate. An optimization of the patches position is performed to maximize the piezoelectric actuators efficiency as well as, the electric potential distribuition is search to reach the specified structure transverse displacement distribuition (shape control). A gradient based algorithm is used for this purpose. The model is applied in the optimization of illustrative laminated plate cases, and the results are presented and discussed.
  • Elastoplastic and nonlinear analysis of functionally graded axisymmetric shell structures under thermal environment, using a conical frustum finite element model
    Publication . Simões Moita, José Mateus; Mota Soares, Cristovao M.; Mota Soares, Carlos A.; Ferreira, Antonio J. M.
    This work presents the formulation for static bending analysis of functionally graded axisymmetric plate/shell type structures under mechanical loading, and considering different structural behaviours: linear, geometric nonlinear and material nonlinear. The implemented model is based on a simple conical frustum finite element with 2 nodes, and 3 degrees of freedom per node, which includes shear deformation effects, and it shows to be extremely efficient in the analysis of axisymmetric shells subjected to axisymmetric loading. The used of reduced numerical integration procedure is essential for its success when applied to thin shells. The formulation accounts for the calculation of displacements and through-thickness stress distribution. The solutions for some illustrative examples involving variation of volume fractions are obtained, and the results are presented and compared with numerical alternative models when available, and discussed.