The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Jeanmarc Battini - One of the best experts on this subject based on the ideXlab platform.
-
corotational mixed finite element Formulation for thin walled beams with generic cross section
Computer Methods in Applied Mechanics and Engineering, 2010Co-Authors: Rabe Alsafadie, Mohammed Hjiaj, Jeanmarc BattiniAbstract:The corotational technique is adopted here for the analysis of three-dimensional beams. The technique exploits the technology that applies to a two-noded element, a coordinate system which continuously translates and rotates with the element. In this way, the rigid body motion is separated out from the deFormational motion. In this paper, a mixed Formulation are adopted for the derivation of the local element tangent stiffness matrix and nodal forces. The mixed finite element Formulation is based on an Incremental Form of the two-field Hellinger-Reissner variational principle to permit elasto-plastic material behavior. The local beam kinematics is based on a low-order nonlinear strain expression using Bernoulli assumption. The present Formulation captures both the Saint-Venant and warping torsional effects of thin-walled open cross-sections. Shape functions that satisfy the nonlinear local equilibrium equations are selected for the interpolation of the stress resultants. In particular, for the torsional forces and the twist rotation degree of freedom, a family of hyperbolic interpolation functions is adopted in lieu of conventional polynomials. Governing equations are expressed in a weak Form, and the constitutive equations are enforced at each integration cross-section along the element length. A consistent state determination algorithm is proposed. This local element, together with the corotational framework, can be used to analyze the nonlinear buckling and postbuckling of thin-walled beams with generic cross-section. The present corotational mixed element solution is compared against the results obtained from a corotational displacement-based model having the same beam kinematics and corotational framework. The superiority of the mixed Formulation is clearly demonstrated.
-
Corotational mixed finite element Formulation for thin-walled beams with generic cross-section
Computer Methods in Applied Mechanics and Engineering, 2010Co-Authors: Rabe Alsafadie, Mohammed Hjiaj, Jeanmarc BattiniAbstract:The corotational technique is adopted here for the analysis of three-dimensional beams. The technique exploits the technology that applies to a two-noded element, a coordinate system which continuously translates and rotates with the element. In this way, the rigid body motion is separated out from the deFormational motion. In this paper, a mixed Formulation are adopted for the derivation of the local element tangent stiffness matrix and nodal forces. The mixed finite element Formulation is based on an Incremental Form of the two-field Hellinger-Reissner variational principle to permit elasto-plastic material behavior. The local beam kinematics is based on a low-order nonlinear strain expression using Bernoulli assumption. The present Formulation captures both the Saint-Venant and warping torsional effects of thin-walled open cross-sections. Shape functions that satisfy the nonlinear local equilibrium equations are selected for the interpolation of the stress resultants. In particular, for the torsional forces and the twist rotation degree of freedom, a family of hyperbolic interpolation functions is adopted in lieu of conventional polynomials. Governing equations are expressed in a weak Form, and the constitutive equations are enforced at each integration cross-section along the element length. A consistent state determination algorithm is proposed. This local element, together with the corotational framework, can be used to analyze the nonlinear buckling and postbuckling of thin-walled beams with generic cross-section. The present corotational mixed element solution is compared against the results obtained from a corotational displacement-based model having the same beam kinematics and corotational framework. The superiority of the mixed Formulation is clearly demonstrated. (C) 2010 Elsevier B.V. All rights reserved.
Marco Savoia - One of the best experts on this subject based on the ideXlab platform.
-
a finite element model for linear viscoelastic behaviour of pultruded thin walled beams under general loadings
International Journal of Solids and Structures, 2008Co-Authors: Marina Bottoni, Claudio Mazzotti, Marco SavoiaAbstract:Abstract A finite element model for orthotropic thin-walled beams subject to long-term loadings is presented. The hypothesis, rather usual for thin-walled beams, of cross-sections remaining undistorted in their own planes after deFormation is introduced, so reducing the number of d.o.f.’s and, consequently, the computational effort of the analysis. The model is used to perForm linear viscoelastic analysis of prismatic beams with general cross-sections, i.e., open, closed or multi-cell. As far as the constitutive viscoelastic law is concerned, a generalized linear Maxwell model is adopted. Making use of the exponential algorithm, differential equations are written in Incremental Form and integration is perFormed adopting time intervals of variable length. Numerical examples are finally presented, concerning glass-fibre pultruded shapes under long-term loadings. Displacement evolution with time and stress redistribution adopting different creep laws are presented. Convergence features of the proposed finite element and time integration procedure are also shown.
Rabe Alsafadie - One of the best experts on this subject based on the ideXlab platform.
-
corotational mixed finite element Formulation for thin walled beams with generic cross section
Computer Methods in Applied Mechanics and Engineering, 2010Co-Authors: Rabe Alsafadie, Mohammed Hjiaj, Jeanmarc BattiniAbstract:The corotational technique is adopted here for the analysis of three-dimensional beams. The technique exploits the technology that applies to a two-noded element, a coordinate system which continuously translates and rotates with the element. In this way, the rigid body motion is separated out from the deFormational motion. In this paper, a mixed Formulation are adopted for the derivation of the local element tangent stiffness matrix and nodal forces. The mixed finite element Formulation is based on an Incremental Form of the two-field Hellinger-Reissner variational principle to permit elasto-plastic material behavior. The local beam kinematics is based on a low-order nonlinear strain expression using Bernoulli assumption. The present Formulation captures both the Saint-Venant and warping torsional effects of thin-walled open cross-sections. Shape functions that satisfy the nonlinear local equilibrium equations are selected for the interpolation of the stress resultants. In particular, for the torsional forces and the twist rotation degree of freedom, a family of hyperbolic interpolation functions is adopted in lieu of conventional polynomials. Governing equations are expressed in a weak Form, and the constitutive equations are enforced at each integration cross-section along the element length. A consistent state determination algorithm is proposed. This local element, together with the corotational framework, can be used to analyze the nonlinear buckling and postbuckling of thin-walled beams with generic cross-section. The present corotational mixed element solution is compared against the results obtained from a corotational displacement-based model having the same beam kinematics and corotational framework. The superiority of the mixed Formulation is clearly demonstrated.
-
Corotational mixed finite element Formulation for thin-walled beams with generic cross-section
Computer Methods in Applied Mechanics and Engineering, 2010Co-Authors: Rabe Alsafadie, Mohammed Hjiaj, Jeanmarc BattiniAbstract:The corotational technique is adopted here for the analysis of three-dimensional beams. The technique exploits the technology that applies to a two-noded element, a coordinate system which continuously translates and rotates with the element. In this way, the rigid body motion is separated out from the deFormational motion. In this paper, a mixed Formulation are adopted for the derivation of the local element tangent stiffness matrix and nodal forces. The mixed finite element Formulation is based on an Incremental Form of the two-field Hellinger-Reissner variational principle to permit elasto-plastic material behavior. The local beam kinematics is based on a low-order nonlinear strain expression using Bernoulli assumption. The present Formulation captures both the Saint-Venant and warping torsional effects of thin-walled open cross-sections. Shape functions that satisfy the nonlinear local equilibrium equations are selected for the interpolation of the stress resultants. In particular, for the torsional forces and the twist rotation degree of freedom, a family of hyperbolic interpolation functions is adopted in lieu of conventional polynomials. Governing equations are expressed in a weak Form, and the constitutive equations are enforced at each integration cross-section along the element length. A consistent state determination algorithm is proposed. This local element, together with the corotational framework, can be used to analyze the nonlinear buckling and postbuckling of thin-walled beams with generic cross-section. The present corotational mixed element solution is compared against the results obtained from a corotational displacement-based model having the same beam kinematics and corotational framework. The superiority of the mixed Formulation is clearly demonstrated. (C) 2010 Elsevier B.V. All rights reserved.
Ahmed S. H. Gendy - One of the best experts on this subject based on the ideXlab platform.
-
Shear-flexible models for spatial buckling of thin-walled curved beams
International Journal for Numerical Methods in Engineering, 1991Co-Authors: Atef F. Saleeb, Ahmed S. H. GendyAbstract:The governing non-linear finite element equations for the spatial stability analysis of curved beams, using a simple two-noded model, are derived based on the Incremental Form of a mixed variational principle with independent discretization for its generalized strain field and the reference line displacements as well as cross-sectional warping and bending/twisting rotations. The Formulation is valid for both open-and closed-type thin-walled sections, and this is accomplished by the use of a kinematic description based on a generalized beam theory in which shear deFormation due to both flexural-and warping-torsional actions is accounted for. The effect of finite rotations in space is included, resulting in a second-order accurate geometric stiffness matrix and ensuring that all significant instability modes can be predicted. Finally, the results obtained in a number of numerical simulations for lateral-torsional bifurcation buckling of circular arches are presented to illustrate the model effectiveness and practical usefulness, and to provide explanations for the source of discrepancies noted in the results obtained in previous investigations.
Marina Bottoni - One of the best experts on this subject based on the ideXlab platform.
-
a finite element model for linear viscoelastic behaviour of pultruded thin walled beams under general loadings
International Journal of Solids and Structures, 2008Co-Authors: Marina Bottoni, Claudio Mazzotti, Marco SavoiaAbstract:Abstract A finite element model for orthotropic thin-walled beams subject to long-term loadings is presented. The hypothesis, rather usual for thin-walled beams, of cross-sections remaining undistorted in their own planes after deFormation is introduced, so reducing the number of d.o.f.’s and, consequently, the computational effort of the analysis. The model is used to perForm linear viscoelastic analysis of prismatic beams with general cross-sections, i.e., open, closed or multi-cell. As far as the constitutive viscoelastic law is concerned, a generalized linear Maxwell model is adopted. Making use of the exponential algorithm, differential equations are written in Incremental Form and integration is perFormed adopting time intervals of variable length. Numerical examples are finally presented, concerning glass-fibre pultruded shapes under long-term loadings. Displacement evolution with time and stress redistribution adopting different creep laws are presented. Convergence features of the proposed finite element and time integration procedure are also shown.
