The Experts below are selected from a list of 135 Experts worldwide ranked by ideXlab platform
Christian Soize - One of the best experts on this subject based on the ideXlab platform.
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Uncertainty quantification in computational linear structural dynamics for viscoelastic composite structures
Computer Methods in Applied Mechanics and Engineering, 2017Co-Authors: Rémi Capillon, Christophe Desceliers, Christian SoizeAbstract:This paper deals with the analysis of a stochastic reduced-order computational model in computational linear dynamics for linear viscoelastic composite structures in the presence of uncertainties. The computational framework proposed is based on a recent theoretical work that allows for constructing the stochastic reduced-order model using the nonparametric probabilistic approach. In the frequency domain, the generalized damping matrix and the generalized stiffness matrix of the stochastic computational reduced-order model are random matrices. Due to the causality of the dynamical system, these two frequency-dependent random matrices are statistically dependent and are linked by a Compatibility Equation induced by the causality of the system, involving a Hilbert transform. The computational aspects related to the nonparametric stochastic modeling of the reduced stiffness matrix and the reduced damping matrix that are frequency-dependent random matrices are presented. A dedicated numerical approach is developed for obtaining an efficient computation of the Cauchy principal value integrals involved in those Equations for which an integration over a broad frequency domain is required. A computational analysis of the propagation of uncertainties is conducted for a composite viscoelastic structure in the frequency range. It is shown that the uncertainties on the damping matrix have a strong influence on the observed statistical dispersion of the stiffness matrix.
Hamid Reza Ovesy - One of the best experts on this subject based on the ideXlab platform.
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High accuracy postbuckling analysis of channel section struts
International Journal of Non-linear Mechanics, 2012Co-Authors: S.a.m. Ghannadpour, Hamid Reza OvesyAbstract:Abstract This paper presents the theoretical developments of a high accuracy method for the post-buckling analysis of some channel section struts. In this method, the Von-Karman's equilibrium Equation is solved exactly to obtain the buckling loads and the corresponding form of out-of-plane buckling deflection modes. The investigation of channel section buckling behaviour is then extended to the post-buckling study with the assumption that the deflected form after the buckling is the combination of first, second and higher (if required) modes of buckling. Thus, the full-analytical post-buckling study is effectively a multi term analysis, which is attempted by utilizing the so-called semi-energy method. In this method the Von-Karman Compatibility Equation is used together with a consideration of the total strain energy of the strut. Through the solution of the Compatibility Equation, the in-plane displacement functions which are themselves related to the Airy stress function are developed in terms of the unknown coefficients in the assumed out-of-plane deflection function. The in-plane and out-of-plane deflection functions are substituted in the total strain energy expressions and the theorem of minimum total potential energy is applied to solve for the unknown coefficients. It is noted that the Classical Plate Theory (CPT) is applied throughout the theoretical developments. Through the comparison of the results and the appropriate discussion, the knowledge of the level of capability of the method is significantly promoted.
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An exact finite strip for the initial postbuckling analysis of channel section struts
Computers & Structures, 2011Co-Authors: Hamid Reza Ovesy, S.a.m. GhannadpourAbstract:This paper presents the theoretical developments of an exact finite strip for the buckling and initial post-buckling analyses of channel section struts. The presented method provides an efficient and extremely accurate buckling solution. The Von-Karman's equilibrium Equation is solved exactly to obtain the buckling loads and mode shapes for the channel section struts. The investigation of buckling behavior is then extended to an initial post-buckling study with the assumption that the deflected form immediately after the buckling is the same as that obtained for the buckling. Through the solution of the Von-Karman's Compatibility Equation, the in-plane displacement functions which are themselves related to the Airy stress function are developed in terms of the unknown coefficient in the assumed out-of-plane deflection function. All the displacement functions are then substituted in the total strain energy expressions. The theorem of minimum total potential energy is subsequently applied to solve for the unknown coefficient. The developed method is subsequently applied to analyze the initial post-buckling behavior of some representative channel sections for which the results were also obtained through the application of a semi-energy finite strip method. Through the comparison of the results and the appropriate discussion, the knowledge of the level of capability of the developed method is significantly promoted.
S.a.m. Ghannadpour - One of the best experts on this subject based on the ideXlab platform.
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High accuracy postbuckling analysis of channel section struts
International Journal of Non-linear Mechanics, 2012Co-Authors: S.a.m. Ghannadpour, Hamid Reza OvesyAbstract:Abstract This paper presents the theoretical developments of a high accuracy method for the post-buckling analysis of some channel section struts. In this method, the Von-Karman's equilibrium Equation is solved exactly to obtain the buckling loads and the corresponding form of out-of-plane buckling deflection modes. The investigation of channel section buckling behaviour is then extended to the post-buckling study with the assumption that the deflected form after the buckling is the combination of first, second and higher (if required) modes of buckling. Thus, the full-analytical post-buckling study is effectively a multi term analysis, which is attempted by utilizing the so-called semi-energy method. In this method the Von-Karman Compatibility Equation is used together with a consideration of the total strain energy of the strut. Through the solution of the Compatibility Equation, the in-plane displacement functions which are themselves related to the Airy stress function are developed in terms of the unknown coefficients in the assumed out-of-plane deflection function. The in-plane and out-of-plane deflection functions are substituted in the total strain energy expressions and the theorem of minimum total potential energy is applied to solve for the unknown coefficients. It is noted that the Classical Plate Theory (CPT) is applied throughout the theoretical developments. Through the comparison of the results and the appropriate discussion, the knowledge of the level of capability of the method is significantly promoted.
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An exact finite strip for the initial postbuckling analysis of channel section struts
Computers & Structures, 2011Co-Authors: Hamid Reza Ovesy, S.a.m. GhannadpourAbstract:This paper presents the theoretical developments of an exact finite strip for the buckling and initial post-buckling analyses of channel section struts. The presented method provides an efficient and extremely accurate buckling solution. The Von-Karman's equilibrium Equation is solved exactly to obtain the buckling loads and mode shapes for the channel section struts. The investigation of buckling behavior is then extended to an initial post-buckling study with the assumption that the deflected form immediately after the buckling is the same as that obtained for the buckling. Through the solution of the Von-Karman's Compatibility Equation, the in-plane displacement functions which are themselves related to the Airy stress function are developed in terms of the unknown coefficient in the assumed out-of-plane deflection function. All the displacement functions are then substituted in the total strain energy expressions. The theorem of minimum total potential energy is subsequently applied to solve for the unknown coefficient. The developed method is subsequently applied to analyze the initial post-buckling behavior of some representative channel sections for which the results were also obtained through the application of a semi-energy finite strip method. Through the comparison of the results and the appropriate discussion, the knowledge of the level of capability of the developed method is significantly promoted.
Rémi Capillon - One of the best experts on this subject based on the ideXlab platform.
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Uncertainty quantification in computational linear structural dynamics for viscoelastic composite structures
Computer Methods in Applied Mechanics and Engineering, 2017Co-Authors: Rémi Capillon, Christophe Desceliers, Christian SoizeAbstract:This paper deals with the analysis of a stochastic reduced-order computational model in computational linear dynamics for linear viscoelastic composite structures in the presence of uncertainties. The computational framework proposed is based on a recent theoretical work that allows for constructing the stochastic reduced-order model using the nonparametric probabilistic approach. In the frequency domain, the generalized damping matrix and the generalized stiffness matrix of the stochastic computational reduced-order model are random matrices. Due to the causality of the dynamical system, these two frequency-dependent random matrices are statistically dependent and are linked by a Compatibility Equation induced by the causality of the system, involving a Hilbert transform. The computational aspects related to the nonparametric stochastic modeling of the reduced stiffness matrix and the reduced damping matrix that are frequency-dependent random matrices are presented. A dedicated numerical approach is developed for obtaining an efficient computation of the Cauchy principal value integrals involved in those Equations for which an integration over a broad frequency domain is required. A computational analysis of the propagation of uncertainties is conducted for a composite viscoelastic structure in the frequency range. It is shown that the uncertainties on the damping matrix have a strong influence on the observed statistical dispersion of the stiffness matrix.
M Mohammadi - One of the best experts on this subject based on the ideXlab platform.
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nonlocal nonlinear plate model for large amplitude vibration of magneto electro elastic nanoplates
Composite Structures, 2016Co-Authors: Ali Farajpour, M Hairi R Yazdi, Abbas Rastgoo, Masih Loghmani, M MohammadiAbstract:Abstract In the present work, a nonlocal continuum model is developed for the nonlinear free vibration of size-dependent magneto-electro-elastic nanoplates subjected to external electric and magnetic potentials. Using the nonlocal elasticity theory and Hamilton’s principle, the nonlinear differential Equations of motion and corresponding boundary conditions are derived. The effect of geometric nonlinearity is taken into account based on the von Karman’s assumptions. Various non-classical plate theories are introduced by considering two additional scale parameters. The coupled nonlinear differential Equations are solved analytically using a perturbation technique. Closed-form solutions are obtained for the nonlinear natural frequencies, critical external electric voltages and critical magnetic potentials of magneto-electro-elastic nanoplates with immovable and movable edges. The present nonlocal continuum model and method of solution are validated by comparing the results with available results in the literature. It is found that the natural frequencies of magneto-electro-elastic nanoplates can be tuned by adjusting the values of external electric and magnetic potentials. The nonlinear frequency ratio decreases by considering the effect of length scale on the Compatibility Equation.