The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
M. A. Crisfield - One of the best experts on this subject based on the ideXlab platform.
-
a consistent co rotational formulation for shells using the constant stress constant moment triangle
International Journal for Numerical Methods in Engineering, 1992Co-Authors: X Peng, M. A. CrisfieldAbstract:The facet-shell formulation involves the combination of the constant-strain membrane triangle with a constant-curvature bending triangle. The paper describes a technique whereby this facet-formulation is extended to handle geometric non-linearity by means of a co-rotational procedure. Emphasis is placed on the derivation of a technique that is increment-independent with both the Internal Force Vector and tangent stiffness matrix being derived from the «total strain measures» in a «consistent manner».
-
A consistent co‐rotational formulation for shells using the constant stress/constant moment triangle
International Journal for Numerical Methods in Engineering, 1992Co-Authors: X Peng, M. A. CrisfieldAbstract:The facet-shell formulation involves the combination of the constant-strain membrane triangle with a constant-curvature bending triangle. The paper describes a technique whereby this facet-formulation is extended to handle geometric non-linearity by means of a co-rotational procedure. Emphasis is placed on the derivation of a technique that is increment-independent with both the Internal Force Vector and tangent stiffness matrix being derived from the «total strain measures» in a «consistent manner».
-
a consistent co rotational formulation for shells using the constant stress constant moment triangle
International Journal for Numerical Methods in Engineering, 1992Co-Authors: X Peng, M. A. CrisfieldAbstract:The simplest facet-shell formulation involves the combination of the constant-strain membrane triangle with a constant-curvature bending triangle. The paper describes a technique whereby this facet-formulation is extended to handle geometric non-linearity by means of a co-rotational procedure. Emphasis is placed on the derivation of a technique that is increment-independent with both the Internal Force Vector and tangent stiffness matrix being derived from the 'total strain measures' in a 'consistent manner'. Numerical examples are presented which demonstrate an excellent numerical performance.
X Peng - One of the best experts on this subject based on the ideXlab platform.
-
a consistent co rotational formulation for shells using the constant stress constant moment triangle
International Journal for Numerical Methods in Engineering, 1992Co-Authors: X Peng, M. A. CrisfieldAbstract:The facet-shell formulation involves the combination of the constant-strain membrane triangle with a constant-curvature bending triangle. The paper describes a technique whereby this facet-formulation is extended to handle geometric non-linearity by means of a co-rotational procedure. Emphasis is placed on the derivation of a technique that is increment-independent with both the Internal Force Vector and tangent stiffness matrix being derived from the «total strain measures» in a «consistent manner».
-
A consistent co‐rotational formulation for shells using the constant stress/constant moment triangle
International Journal for Numerical Methods in Engineering, 1992Co-Authors: X Peng, M. A. CrisfieldAbstract:The facet-shell formulation involves the combination of the constant-strain membrane triangle with a constant-curvature bending triangle. The paper describes a technique whereby this facet-formulation is extended to handle geometric non-linearity by means of a co-rotational procedure. Emphasis is placed on the derivation of a technique that is increment-independent with both the Internal Force Vector and tangent stiffness matrix being derived from the «total strain measures» in a «consistent manner».
-
a consistent co rotational formulation for shells using the constant stress constant moment triangle
International Journal for Numerical Methods in Engineering, 1992Co-Authors: X Peng, M. A. CrisfieldAbstract:The simplest facet-shell formulation involves the combination of the constant-strain membrane triangle with a constant-curvature bending triangle. The paper describes a technique whereby this facet-formulation is extended to handle geometric non-linearity by means of a co-rotational procedure. Emphasis is placed on the derivation of a technique that is increment-independent with both the Internal Force Vector and tangent stiffness matrix being derived from the 'total strain measures' in a 'consistent manner'. Numerical examples are presented which demonstrate an excellent numerical performance.
Roger Ohayon - One of the best experts on this subject based on the ideXlab platform.
-
Explicit thickness integration for three‐dimensional shell elements applied to non‐linear analysis
International Journal for Numerical Methods in Engineering, 1993Co-Authors: M. Mahe, J.-c. Sourisseau, Roger OhayonAbstract:The problem of multilayered degenerated 3-D shell elements for which the numerical integration is performed for each ply is that of the high generation time in non-linear analysis when the number of plies is important. But these elements give accurate results for thin and moderately thick shells, so in order to reduce the generation time explicit thickness integration is investigated. We first write an expansion of the strain-displacement matrix in power series of the thickness variable in order to obtain explicit expressions of the tangent stiffness matrix and Internal Force Vector, appearing in the non-linear formulation. Explicit expressions of non-linear stiffness matrices are presented, using the explicit integration-first approximation. Simple expressions of several matrices, sub-matrices and Vectors appearing in the formulation are given here in order to obtain an important computing-time gain. Next, some numerical validation tests comparing the classical element with numerical thickness integration and this one are discussed to prove validity of this formulation.
-
Explicit thickness integration for three-dimensional shell elements applied to non-linear analysis
International Journal for Numerical Methods in Engineering, 1993Co-Authors: M. Mahe, J.-c. Sourisseau, Roger OhayonAbstract:The problem of multilayered degenerated 3-D shell elements for which the numerical integration is performed for each ply is that of the high generation time in non-linear analysis when the number of plies is important. But these elements give accurate results for thin and moderately thick shells, so in order to reduce the generation time explicit thickness integration is investigated. We first write an expansion of the strain-displacement matrix in power series of the thickness variable in order to obtain explicit expressions of the tangent stiffness matrix and Internal Force Vector, appearing in the non-linear formulation. Explicit expressions of non-linear stiffness matrices are presented, using the explicit integration-first approximation. Simple expressions of several matrices, sub-matrices and Vectors appearing in the formulation are given here in order to obtain an important computing-time gain. Next, some numerical validation tests comparing the classical element with numerical thickness integration and this one are discussed to prove validity of this formulation.
Carlos A Felippa - One of the best experts on this subject based on the ideXlab platform.
-
plastic buckling and collapse of thin shell structures using layered plastic modeling and co rotational andes finite elements
Computer Methods in Applied Mechanics and Engineering, 2009Co-Authors: Nelvio Dal Cortivo, Carlos A Felippa, Henri Bavestrello, William Taylor Matias SilvaAbstract:This study reveals an analysis of plastic buckling and collapse of thin shell structures. For this purpose, the co-rotational and layered plastic model as well as ANDES (Assumed Natural Deviatoric Strain) finite element formulations are used. The co-rotational kinematics formulation splits the translational and rotational deformations in a small deformation analysis. The ANDES finite element is modified to elastoplastic ANDES finite element by the introduction of the von Mises yield criterion elastoplastic formulation on its original deformation model. In order to accommodate the plasticity formulation, the Gauss point layered integration is inserted through of thickness of the element to produce the Internal Force Vector and material stiffness matrix. Special effort is devoted to maintain the consistency of the Internal Forces and tangent stiffness as well as to enhance the robustness of element level computations. The arc-length method is used to follow the postbuckling equilibrium path. Results are presented for several benchmark elastoplastic shell problems available in the present literature, which are generally in agreement with the present work.
-
Superconducting axisymmetric finite elements based on a gauged potential variational principle—I. Formulation
Computing Systems in Engineering, 1994Co-Authors: James J. Schuler, Carlos A FelippaAbstract:Abstract The present work is part of a research program for the numerical simulation of electromagnetic (EM) fields within conventional Ginzburg-Landau (GL) superconductors. The final goal of this research is to formulate, develop and validate finite element (FE) models that can accurately capture electromagnetic, thermal and material phase changes in a superconductor. The formulations presented here are for a time-independent Ginzburg-Landau superconductor and are derived from a potential-based variational principle. In Part I of this paper, we develop an appropriate variational formulation of time-independent superconductivity for the general three-dimensional case and specialize it to the one-dimensional case. Also developed are expressions for the material-dependent parameters α and β of GL theory and their dependence upon the temperature T . The one-dimensional formulation is then discretized for finite element purposes and the first variation of these equations is obtained. The resultant Euler equations contain nonlinear terms in the primary variables. To solve these equations, an incremental-iterative solution method is used. Expressions for the Internal Force Vector, external Force Vector, loading Vector and tangent stiffness matrix are therefore developed for use with the solution procedure.
-
A three‐dimensional non‐linear Timoshenko beam based on the core‐congruential formulation
International Journal for Numerical Methods in Engineering, 1993Co-Authors: Luis Crivelli, Carlos A FelippaAbstract:A three-dimensional, geometrically non-linear, two-node Timoshenko beam element based on the total Lagrangian description is derived. The element behaviour is assumed to be linear elastic, but no restrictions are placed on the magnitude of finite rotations. The resulting element has twelve degrees of freedom: six translational components and six rotational-Vector components. The formulation uses the Green-Lagrange strains and second Piola-Kirchhoff stresses as energy-conjugate variables and accounts for bending-stretching and bending-torsional-coupling effects without special provisions. The core-congruential formulation (CCF) is used to derive the discrete equations in a staged manner. Core equations involving the Internal Force Vector and tangent stiffness matrix are developed at the particle level. A sequence of matrix transformations carries these equations to beam cross-sections and finally to the element nodal degrees of freedom. The choice of finite rotation measure is made in the next-to-last transformation stage, and the choice of over-the-element interpolation in the last one. The tangent stiffness matrix is found to retain symmetry if the rotational Vector is chosen to measure finite rotations. An extensive set of numerical examples are presented to test and validate the present element.
William Taylor Matias Silva - One of the best experts on this subject based on the ideXlab platform.
-
Uma abordagem analítica para detecção de pontos limites e de bifurcação
REEC - Revista Eletrônica de Engenharia Civil, 2016Co-Authors: William Taylor Matias Silva, María Paz Duque Gutiérrez, Wellington Andrade Da SilvaAbstract:RESUMO: Neste trabalho descreve-se analiticamente de maneira detalhada a deteccao e a classificacao de pontos criticos na trajetoria primaria de equilibrio de sistemas estruturais. Utiliza-se a Formulacao Lagrangiana Total para descrever a cinematica de um elemento de barra biarticulado 2D. Atraves desta formulacao obtem-se o vetor de forcas internas e a matriz de rigidez tangente que levam em conta os efeitos da nao linearidade geometrica. Assume-se um modelo constitutivo linear elastico para o estado uniaxial de tensao-deformacao, usando a deformacao de Green-Lagrange e a tensao axial do segundo tensor de Piola-Kirchhoff que sao energeticamente conjugados. Como estudo de caso apresenta-se uma trelica plana hiperestatica composta com 3 elementos biarticulados 2D e com dois graus de liberdade. Por fim, determinam-se as condicoes geometricas e fisicas para a coalescencia entre os pontos limites e de bifurcacao. A principal contribuicao deste trabalho e demonstrar a necessidade de compreender melhor os fenomenos nao lineares para projetar sistemas estruturais mais seguros. ABSTRACT: Using an analytical this paper describes in detail the detection and classification of critical points in the primary equilibrium path of structural systems. The Total Lagrangian formulation is employed to describe the kinematics of a 2D bar element. With this formulation, the Internal Force Vector and the tangent stiffness matrix including the geometric nonlinearity effects are obtained. An elastic linear constitutive model is assumed for the uniaxial stress-strain state. Such model uses the Green-Lagrange strain tensor and the second Piola-Kirchhoff axial stress tensor which are energetically conjugate tensors. As a study case, the article presents a statically inderminate plane truss discretized with three 2D bar elements. Finally, the geometrical and physical conditions for the coalescence between limit and bifurcation points are determined. The main contribution of this work is to demonstrate the need to better understanding the non linear phenomena. Such understanding is necessary for designing safer structural systems.
-
Uma abordagem analítica para detecção de pontos limites e de bifurcação
Universidade Federal de Goiás, 2016Co-Authors: William Taylor Matias Silva, María Paz Duque Gutiérrez, Wellington Andrade Da SilvaAbstract:RESUMO: Neste trabalho descreve-se analiticamente de maneira detalhada a detecção e a classificação de pontos críticos na trajetória primária de equilíbrio de sistemas estruturais. Utiliza-se a Formulação Lagrangiana Total para descrever a cinemática de um elemento de barra biarticulado 2D. Através desta formulação obtém-se o vetor de forças internas e a matriz de rigidez tangente que levam em conta os efeitos da não linearidade geométrica. Assume-se um modelo constitutivo linear elástico para o estado uniaxial de tensão-deformação, usando a deformação de Green-Lagrange e a tensão axial do segundo tensor de Piola-Kirchhoff que são energeticamente conjugados. Como estudo de caso apresenta-se uma treliça plana hiperestática composta com 3 elementos biarticulados 2D e com dois graus de liberdade. Por fim, determinam-se as condições geométricas e físicas para a coalescência entre os pontos limites e de bifurcação. A principal contribuição deste trabalho é demonstrar a necessidade de compreender melhor os fenômenos não lineares para projetar sistemas estruturais mais seguros. ABSTRACT: Using an analytical this paper describes in detail the detection and classification of critical points in the primary equilibrium path of structural systems. The Total Lagrangian formulation is employed to describe the kinematics of a 2D bar element. With this formulation, the Internal Force Vector and the tangent stiffness matrix including the geometric nonlinearity effects are obtained. An elastic linear constitutive model is assumed for the uniaxial stress-strain state. Such model uses the Green-Lagrange strain tensor and the second Piola-Kirchhoff axial stress tensor which are energetically conjugate tensors. As a study case, the article presents a statically inderminate plane truss discretized with three 2D bar elements. Finally, the geometrical and physical conditions for the coalescence between limit and bifurcation points are determined. The main contribution of this work is to demonstrate the need to better understanding the non linear phenomena. Such understanding is necessary for designing safer structural systems
-
NONLINEAR ANALYSIS OF PLANE FRAMES USING A COROTATIONAL FOMULATION AND PLASTICITY BY LAYERS IN A TIMOSHENKO BEAM EL-EMENT
2012Co-Authors: Sebastião Simão Da Silva, William Taylor Matias SilvaAbstract:The purpose of this work is to perform a nonlinear analysis of plane frame struc- ture using a corotational formulation and a layered plastic modeling. The plane frame is dis- cretized with a 2D Timoshenko beam element. Plasticity is introduced by rate-independent Von-Mises model with isotropic hardening. Numerical integration over the cross-section is performed for obtain the Internal Force Vector and tangent stiffness matrix of these elements. At each integration point, the backward-Euler algorithm is used for integration in the consti- tutive equations. Some examples are used in order to check the performances in the elements and the path-following procedures.
-
plastic buckling and collapse of thin shell structures using layered plastic modeling and co rotational andes finite elements
Computer Methods in Applied Mechanics and Engineering, 2009Co-Authors: Nelvio Dal Cortivo, Carlos A Felippa, Henri Bavestrello, William Taylor Matias SilvaAbstract:This study reveals an analysis of plastic buckling and collapse of thin shell structures. For this purpose, the co-rotational and layered plastic model as well as ANDES (Assumed Natural Deviatoric Strain) finite element formulations are used. The co-rotational kinematics formulation splits the translational and rotational deformations in a small deformation analysis. The ANDES finite element is modified to elastoplastic ANDES finite element by the introduction of the von Mises yield criterion elastoplastic formulation on its original deformation model. In order to accommodate the plasticity formulation, the Gauss point layered integration is inserted through of thickness of the element to produce the Internal Force Vector and material stiffness matrix. Special effort is devoted to maintain the consistency of the Internal Forces and tangent stiffness as well as to enhance the robustness of element level computations. The arc-length method is used to follow the postbuckling equilibrium path. Results are presented for several benchmark elastoplastic shell problems available in the present literature, which are generally in agreement with the present work.