ENIDH - EMM - Engenharia de Máquinas Marítimas
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Browsing ENIDH - EMM - Engenharia de Máquinas Marítimas by Author "Araújo, A. L."
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- Advances in Engineering SoftwarePublication . Madeira, J.F. Aguilar; Camotim, D.; Basaglia, C.; Santos, J.V. Araujo dos; Lopes, H.M.R.; Topping, B. H. V.; Pina, H.; Poroseva, S. V.; Mota, Soares, C. M.; Araújo, A. L.; Moleiro, Duarte, F.; Sarrate, J.; Ledoux, F.; Kruis, J.; Dumont, S.; Lebon, F.
- Buckling and Geometrically Nonlinear Analysis of Sandwich StructuresPublication . Moita, J. S.; Araújo, A. L.; Correia, Victor M. Franco; Soares, C. M. Mota; Soares, C. A. MotaIn this work a finite element model is presented for buckling and nonlinear analysis of multilayer sandwich plates and shells, with a soft core sandwiched between stiff elastic layers. The finite element is obtained by assembling all element-layers through the thickness using specific assumptions on the displacement continuity at the interfaces between layers, but allowing for different behaviors of the layers. The stiff elastic layers are modelled using the classic plate theory and the core is modelled using Reddy׳s third order shear deformation theory. The present finite element model is a non-conforming triangular plate/shell element with 24 degrees of freedom for the generalized displacements. This model is applied in the solution of illustrative examples and the results are presented and discussed.
- Computers and StructuresPublication . Camotin, C.; Basaglia, C.; Madeira, J. F. Aguilar; Pina, H.; Ilanko, S.; Kennedy, D.; Rabczuk, T.; Soares, C. M. Mota; Araújo, A. L.; Duarte, F. M.; Pallares, L.; Pallares, F. J.; B. H. V.
- Engineering Optimization IV – Proceedings of the 4th International Conference on Engineering OptimizationPublication . Rodrigues, H. C.; Herskovits, J.; Soares, C.M. Mota; Guedes, J. M.; Araújo, A. L.; Folgado, J.O.; Duarte, F.M.; Madeira, J.F.A.
- Free Vibrations Analysis of Composite and Hybrid Axisymmetric ShellsPublication . Moita, José S.; Araújo, A. L.; Correia, Victor Franco; Soares, C. M. MotaThe free vibration of laminated composite (C) and hybrid axisymmetric shell structures, consisting of a composite laminated material sandwiched between two functionally graded material laminas (F1/C/F2), is analysed in the present work. The numerical solutions are obtained by expanding the variables in Fourier series in the circumferential direction and using conical frustum finite elements in the meridional direction. The implemented finite element is a simple conical frustum with two nodal circles, with ten degrees of freedom per nodal circle. This model requires only a reduced number of finite elements to model the geometry of axisymmetric structures, the integration procedures use one Gauss point, and the through the thickness properties variation in FGM laminas is modelled by a small number of virtual layers, resulting a very high computational efficiency. The in-house developed code presents very good solutions when compared with results obtained by alternative available models.
- Mechanical and thermal buckling of functionally graded axisymmetric shellsPublication . Moita, J. S.; Araújo, A. L.; Soares, C. M. M.; Correia, V. F.The buckling analysis of functionally graded materials (FGM) axisymmetric plate-shell type structures under mechanical and termal loading is presented in this work. A numerical solution is obtained by expanding the variables in Fourier series in the circumferential direction and using conical frustum finite elements in the meridional direction. The finite element model, having two nodal circles and ten degrees of freedom per node, is based in the Kirchhoff-Love theory that includes the transverse shear deformations by introducing a penalty function, which corresponds to the first order shear deformation theory (FSDT), is suitable for both thin and thick axisymmetric plate/shell structures. The reduced number of finite elements, which are required to model even complex structures, combined with the use of a small number of discrete layers to model the continuous variation of the mechanical properties through the thickness of the structure, results in an extremely low computational time required for FGM buckling applications. An in-house program has been developed, and applications in a variety of axisymmetric shells are solved, including circular plates. The solutions obtained in mechanical and thermal buckling are discussed and compared with alternative models.
- Optimization on Elastoplasticity of Functionally Graded Shells of Revolution, under Axisymmetric LoadingPublication . Moita, J. S.; Araújo, A. L.; Correia, V.F.; Soares, C.M.M.; Herskovits, J.Depending on the load level, structures can experience a material nonlinearity known as elastoplasticity, which has an important role in the behaviour of structures. In order to avoid the elastoplastic behaviour, it is necessary to find the optimal thickness distribution, which corresponds to the minimum mass that provides an elastic behaviour for a certain load level. The elastoplasticity analysis of functionally graded axisymmetric shells under axisymmetric mechanical loading, and the subsequent optimization, was performed by using a simple conical frustum finite element model with two nodal circles; three degrees of freedom per node, which was based on Kirchhoff’s theory allowing for shear deformation; and using a reduced numerical integration procedure that is essential for its success when applied to thin shells. The formulation accounts for the calculation of the displacements and through-thickness stress distribution, including the effective stress. In this work, the thickness was the design variable in the optimization procedure and the mass was the objective function that needed to be minimized subject to a constraint imposed on the effective stress. The optimization solutions were obtained by using a feasible arc interior point gradient-based algorithm. Some illustrative examples were performed, and the corresponding results are presented and discussed.
- Vibrations of functionally graded material axisymmetric shells.Publication . Moita, J. S.; Araújo, A. L.; Correia, V. F.; Soares, C. M. M.The free-vibration analysis of functionally graded materials (FGM) axisymmetric plate-shell type structures are presented in this work. A numerical solution is obtained by expanding the variables in Fourier series in the circumferential direction and using conical frustum finite elements in the meridional direction. The finite element model, having two nodal circles and ten degrees of freedom per node, is based in the Kirchhoff-Love theory that include the transverse shear deformations by introducing a penalty function, and using one Gauss point integration scheme which gave excellent results for both thin and thick axisymmetric plate/shells structures. The reduced number of finite elements, which are required to model even complex structures, combined with the use of a small number of discrete layers to model the continuous variation of the mechanical properties through the thickness of the structure, result in an extremely low computational time required for FGM applications. An in-house program has been developed, and applications in a variety of axysimetric shells are solved, including circular plates. The solutions obtained are discussed and compared with solutions obtained by alternative models.