ENIDH - EMM - Artigo Científico
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Browsing ENIDH - EMM - Artigo Científico by Author "Araújo, A.L."
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- Deformations and stresses of multilayered plates with embedded functionally graded material layers using a layerwise mixed modelPublication . Moleiro, F.; M. Franco Correia, V.; Araújo, A.L.; Mota Soares, C.M.; Ferreira, A.J.M.; Reddy, J.N.This work presents a new layerwise mixed model for the static analysis of multilayered plates with embedded functionally graded material (FGM) layers subjected to transverse mechanical loads. This model is capable to fully describe a two-constituent metal-ceramic FGM layer continuous variation of material properties in the thickness direction, using any given homogenization method to estimate its effective properties. The present model is based on a mixed least-squares formulation with a layerwise variable description for displacements, transverse stresses and in-plane strains, chosen as independent variables. This mixed formulation ensures that the interlaminar continuity requirements at the layers interfaces, where the material properties actually change, are fully fulfilled a priori for all independent variables. The order of the in-plane two-dimensional finite element approximations and the order of the z-expansion through each layer thickness, as well as the number of layers, whether FGM layers or not, are considered free parameters. The full description of the FGM effective properties is achieved by applying to the z-continuous elastic coefficients a z-expansion through the layer thickness of a given order, set as an added free parameter, in a similar approach to finite element approximations. The numerical results consider both single-layer and multilayered functionally graded plates with different side-to-thickness ratios, using either Mori-Tanaka or the rule of mixtures estimates for the FGM effective properties with different material gradation profiles. The present model results are assessed by comparison with three-dimensional (3D) exact solutions and closed form solutions, which demonstrate its capability to predict a highly accurate quasi-3D description of the displacements and stresses distributions altogether.
- Multiobjective optimization of functionally graded material plates with thermo- mechanical loadingPublication . M.Franco Correia, V.; Aguilar Madeira, J.F.; Araújo, A.L.; Mota Soares, C.M.This work addresses the design optimization of ceramic–metal composite plates with functionally graded material properties, varying through the thickness direction, subjected to thermo-mechanical loadings. Constrained multiobjective optimization is performed for mass minimization and material cost minimization as well as the minimization of stress failure criteria or maximization of natural frequency. The optimization problems are constrained by stress based failure criteria among other structural response constraints and manufacturing limitations. The design variables are the index of the power-law distribution in the metal-ceramic graded material and the thicknesses of the graded material and, eventually, also the metal and ceramic faces. A finite element plate model based on a higher order shear deformation theory, accounting for the transverse shear and transverse normal deformations and considering the temperature dependency of the material properties, is applied for the optimal design of ceramic-metal functionally graded plates. The optimization problems are solved with two direct search derivative-free algorithms: GLODS (Global and Local Optimization using Direct Search) and DMS (Direct MultiSearch). A few multiobjective optimization problems are studied and the results are presented for benchmarking purposes.