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Shell Element (shell + element)

Distribution by Scientific Domains
Engineering100%

Kinds of Shell Element

  • flat shell element
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    Selected Abstracts

    Classes of Anisotropic Finite Plasticity Models and their Implementation in a Brick-Type Shell Element

    PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003
    N. Apel
    We discuss two constitutive models formulated in terms of logarithmic strains suitable for the description of elastoplastic material response. We consider two different approaches to the definition of the plastic deformation. The first is based on the introduction of a plastic map yielding a multiplicative decomposition of the deformation gradient into an elastic and plastic part. The second one uses an additive decomposition of the current metric. A quantitative analysis of both approaches by means of numerical examples of sheet metal forming processes are presented. [source]

    Coupling of 3D Boundary Elements with Curved Finite Shell Elements

    PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2006
    Bastian Helldörfer
    The mixed-dimensional coupling of finite shells and 3D boundary elements is presented. A stiffness formulation for the boundary element domain is generated by the Symmetric Galerkin Boundary Element Method and is assembled to the global finite element system. Multipoint constraints are derived in an integral sense by equating the work at the coupling interface. They are evaluated numerically during the analysis and avoid spurious stress concentrations also for curved interfaces. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Eight-node shell element based on incompatible modes

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 2 2009
    Desheng Xu
    Abstract This paper concerns the shell element formulation used for linear analysis. Introduction of hierarchical incompatible modes into the ordinary 8-node solid element is very effective to obtain the rational deflection,rotation relationship. An efficient revision scheme without using numerical volume integration is developed to ensure the satisfaction of the patch test. A lot of numerical tests are carried out for the validation of the present element. Numerical results show that the element can give satisfactory accuracy and convergence, especially for moderately thick shells. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    A non-linear triangular curved shell element

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 4 2004
    T. Wenzel
    Abstract The objective of this paper is to present and test a simple triangular finite shell element that uses five degrees of freedom at each node. The element is characterized by three position vectors and three unit directors. It depicts the plane stress state version of the element presented (Comput. Struct. 1989; 32(2):379). The element is of the ANS-type (assumed natural strain (J. Appl. Mech. 1981; 48:587). All strains inside the element contain dot products of the six actual element nodal vectors. The construction of the element also allows non-linear material behaviour. Since an enhancement of the membrane strains by the EAS (enhanced assumed strain method) is not possible inside a three node triangle element, the membrane strains perform poor. But via the DKT (discrete Kirchhoff theory) the three directors reveal an excellent bending behaviour for thin shells. The main concern of this paper is to test, if superimposing the CST (constant srain) with the classic DKT leads to good results in standard benchmark tests. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    A quadrilateral thin shell element based on area co-ordinate for explicit dynamic analysis

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3 2003
    Zhu Yaqun
    Abstract The mechanism of explicit dynamic finite element method for shell deformation analysis and the key influential factors on computation precision and efficiency are briefly described. A new area co-ordinate-based quadrilateral thin shell element is put forward and combined with the co-rotational theory and velocity strain formulation in the shell stress and strain analysis. A new local co-ordinate system is constructed in which normal vector is much closer to the material axis. The more accurate integration can be obtained and the hourglass control is avoided. Therefore simulation precision and efficiency of thin shells are improved. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    A new 3-node triangular flat shell element

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3 2002
    J. G. Kim
    Abstract The purpose of this work is to propose a new 3-node triangular flat shell element with 18 degrees of freedom. The element is constructed by superimposing the local membrane formulation due to Bergan and Felippa with the well-known DKT bending formulation due to Batoz. The numerical performance of the present element has been compared with several reported 18 degrees-of-freedom triangular shell elements in a number of benchmark test problems. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    An efficient co-rotational formulation for curved triangular shell element

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2007
    Zhongxue Li
    Abstract A 6-node curved triangular shell element formulation based on a co-rotational framework is proposed to solve large-displacement and large-rotation problems, in which part of the rigid-body translations and all rigid-body rotations in the global co-ordinate system are excluded in calculating the element strain energy. Thus, an element-independent formulation is achieved. Besides three translational displacement variables, two components of the mid-surface normal vector at each node are defined as vectorial rotational variables; these two additional variables render all nodal variables additive in an incremental solution procedure. To alleviate the membrane and shear locking phenomena, the membrane strains and the out-of-plane shear strains are replaced with assumed strains in calculating the element strain energy. The strategy used in the mixed interpolation of tensorial components approach is employed in defining the assumed strains. The internal force vector and the element tangent stiffness matrix are obtained from calculating directly the first derivative and second derivative of the element strain energy with respect to the nodal variables, respectively. Different from most other existing co-rotational element formulations, all nodal variables in the present curved triangular shell formulation are commutative in calculating the second derivative of the strain energy; as a result, the element tangent stiffness matrix is symmetric and is updated by using the total values of the nodal variables in an incremental solution procedure. Such update procedure is advantageous in solving dynamic problems. Finally, several elastic plate and shell problems are solved to demonstrate the reliability, efficiency, and convergence of the present formulation. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Optimal solid shell element for large deformable composite structures with piezoelectric layers and active vibration control

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 15 2005
    X. G. Tan
    Abstract In this paper, we present an optimal low-order accurate piezoelectric solid-shell element formulation to model active composite shell structures that can undergo large deformation and large overall motion. This element has only displacement and electric degrees of freedom (dofs), with no rotational dofs, and an optimal number of enhancing assumed strain (EAS) parameters to pass the patch tests (both membrane and out-of-plane bending). The combination of the present optimal piezoelectric solid-shell element and the optimal solid-shell element previously developed allows for efficient and accurate analyses of large deformable composite multilayer shell structures with piezoelectric layers. To make the 3-D analysis of active composite shells containing discrete piezoelectric sensors and actuators even more efficient, the composite solid-shell element is further developed here. Based on the mixed Fraeijs de Veubeke,Hu,Washizu (FHW) variational principle, the in-plane and out-of-plane bending behaviours are improved via a new and efficient enhancement of the strain tensor. Shear-locking and curvature thickness locking are resolved effectively by using the assumed natural strain (ANS) method. We also present an optimal-control design for vibration suppression of a large deformable structure based on the general finite element approach. The linear-quadratic regulator control scheme with output feedback is used as a control law on the basis of the state space model of the system. Numerical examples involving static analyses and dynamic analyses of active shell structures having a large range of element aspect ratios are presented. Active vibration control of a composite multilayer shell with distributed piezoelectric sensors and actuators is performed to test the present element and the control design procedure. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    A finite-strain quadrilateral shell element based on discrete Kirchhoff,Love constraints

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2005
    Pedro M. A. Areias
    Abstract This paper improves the 16 degrees-of-freedom quadrilateral shell element based on pointwise Kirchhoff,Love constraints and introduces a consistent large strain formulation for this element. The model is based on classical shell kinematics combined with continuum constitutive laws. The resulting element is valid for large rotations and displacements. The degrees-of-freedom are the displacements at the corner nodes and one rotation at each mid-side node. The formulation is free of enhancements, it is almost fully integrated and is found to be immune to locking or unstable modes. The patch test is satisfied. In addition, the formulation is simple and amenable to efficient incorporation in large-scale codes as no internal degrees-of-freedom are employed, and the overall calculations are very efficient. Results are presented for linear and non-linear problems. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Integration of geometric design and mechanical analysis using B-spline functions on surface

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2005
    Hee Yuel Roh
    Abstract B-spline finite element method which integrates geometric design and mechanical analysis of shell structures is presented. To link geometric design and analysis modules completely, the non-periodic cubic B-spline functions are used for the description of geometry and for the displacement interpolation function in the formulation of an isoparametric B-spline finite element. Non-periodic B-spline functions satisfy Kronecker delta properties at the boundaries of domain intervals and allow the handling of the boundary conditions in a conventional finite element formulation. In addition, in this interpolation, interior supports such as nodes can be introduced in a conventional finite element formulation. In the formulation of the mechanical analysis of shells, a general tensor-based shell element with geometrically exact surface representation is employed. In addition, assumed natural strain fields are proposed to alleviate the locking problems. Various numerical examples are provided to assess the performance of the present B-spline finite element. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    A finite element model for thermomechanical analysis of sheet metal forming

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2004
    G. Bergman
    Abstract A thermal model based on explicit time integration is developed and implemented into the explicit finite element code DYNA3D to model simultaneous forming and quenching of thin-walled structures. A staggered approach is used for coupling the thermal and mechanical analysis, wherein each analysis is performed with different time step sizes. The implementation includes a thermal shell element with linear temperature approximation in the plane and quadratic in the thickness direction, and contact heat transfer. The material behaviour is described by a temperature-dependent elastic,plastic model with a non-linear isotropic hardening law. Transformation plasticity is included in the model. Examples are presented to validate and evaluate the proposed model. The model is evaluated by comparison with a one-sided forming and quenching experiment. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Ductility of Reinforced Concrete Flat Slab-Column Connections

    COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 3 2005
    Maria Anna Polak
    Post peak-load ductility of connections in reinforced concrete framed structures is essential for ensuring structural integrity and preventing local failure that may lead to progressive collapse of such systems. The importance of ductility for resistance against abnormal loading and the role of transverse reinforcement in providing ductility is discussed, and a new shear-strengthening technique, shear bolts, is presented. Shear bolts are a special type of reinforcement developed specially for retrofitting of existing, previously built, flat slabs. The results of an experimental work are presented which show how transverse reinforcement increases punching shear capacity and post-failure ductility of slab-column connections. The described work also applies a specially developed finite element formulation based on layered shell elements, to the analysis of continuous reinforced concrete slabs. The formulation is applicable for global structural analysis of slabs failing in flexure or punching modes. The finite element and experimental results are compared in the article. [source]

    Three-dimensional finite element analysis of lined tunnels

    INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 3 2001
    C. E. Augarde
    Abstract This paper describes finite element procedures that have been developed to model the ground movements that occur when a shallow tunnel is installed in a clay soil. This study is part of a wider project concerned with the development of new methods to predict the likely extent of damage to surface structures caused by nearby shallow tunnelling. This particular paper, however, is concerned only with the numerical model of tunnel installation. The structural liner is an important component of this tunnel installation model; two different ways of modelling the liner (based on continuum elements and shell elements) are discussed in the paper. A test problem consisting of the installation of a lined tunnel in an elastic continuum is used to investigate the merits of these different approaches. When continuum elements are used to model the liner, the numerical results agree well with an analytical solution to the problem. When shell elements are used to model the liner, however, the results were found to be significantly influenced by the particular formulation adopted for the shell elements. Example analyses, involving incremental tunnel construction in a clay soil where the soil is modelled using a kinematic hardening plasticity model, are described. These analyses confirm that a thin layer of continuum elements may be used, satisfactorily, to model tunnel linings in a soil,structure interaction analysis of this sort. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Heat conduction and radiative heat exchange in cellular structures using flat shell elements

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3 2006
    J. B. Colliat
    Abstract We developed in this paper a variational formulation of heat diffusion equation applicable to the flat shell context and cellular structures. For this purpose, we introduce the average mid-surface temperature field, through-the-thickness gradient and their dual generalized fluxes. Moreover, we introduced radiative heat exchange in the same way, which leads to a non-linear and unsymmetrical thermal discrete problem. The model performance is illustrated by several numerical examples concerning cellular structures like hollow clay bricks submitted to thermal loading. Thermo-mechanical coupling for such structure which is well adapted to the shell-like modelling approach, is presented in the elastic regime with the numerical results concerning temperature field and forces. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    A new 3-node triangular flat shell element

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3 2002
    J. G. Kim
    Abstract The purpose of this work is to propose a new 3-node triangular flat shell element with 18 degrees of freedom. The element is constructed by superimposing the local membrane formulation due to Bergan and Felippa with the well-known DKT bending formulation due to Batoz. The numerical performance of the present element has been compared with several reported 18 degrees-of-freedom triangular shell elements in a number of benchmark test problems. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Adaptive through-thickness integration for accurate springback prediction

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2008
    I. A. Burchitz
    Abstract Accurate numerical prediction of springback in sheet metal forming is essential for the automotive industry. Numerous factors influence the accuracy of prediction of this complex phenomenon by using the finite element method. One of them is the numerical integration through the thickness of shell elements. It is known that the traditional numerical schemes are very inefficient in elastic,plastic analysis and even for simple problems they require up to 50 integration points for an accurate springback prediction. An adaptive through-thickness integration strategy can be a good alternative. The main characteristic feature of the strategy is that it defines abscissas and weights depending on the integrand's properties and, thus, can adapt itself to improve the accuracy of integration. A concept of an adaptive through-thickness integration strategy for shell elements is presented in this paper. Its potential is demonstrated using two examples. Calculations of a simple test,bending a beam under tension,show that for a similar set of material and process parameters the adaptive rule with seven integration points performs significantly better than the traditional trapezoidal rule with 50 points. Simulations of an unconstrained cylindrical bending problem demonstrate that the adaptive through-thickness integration strategy for shell elements can guarantee an accurate springback prediction at minimal costs. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    A new approach to reduce membrane and transverse shear locking for one-point quadrature shell elements: linear formulation

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2006
    Rui P. R. Cardoso
    Abstract In the last decade, one-point quadrature shell elements attracted many academic and industrial researchers because of their computational performance, especially if applied for explicit finite element simulations. Nowadays, one-point quadrature finite element technology is not only applied for explicit codes, but also for implicit finite element simulations, essentially because of their efficiency in speed and memory usage as well as accuracy. In this work, one-point quadrature shell elements are combined with the enhanced assumed strain (EAS) method to develop a finite element formulation for shell analysis that is, simultaneously, computationally efficient and more accurate. The EAS method is formulated to alleviate locking pathologies existing in the stabilization matrices of one-point quadrature shell elements. An enhanced membrane field is first constructed based on the quadrilateral area coordinate method, to improve element's accuracy under in-plane loads. The finite element matrices were projected following the work of Wilson et al. (Numerical and Computer Methods in Structural Mechanics, Fenven ST et al. (eds). Academic Press: New York, 1973; 43,57) for the incompatible modes approach, but the present implementation led to more accurate results for distorted meshes because of the area coordinate method for quadrilateral interpolation. The EAS method is also used to include two more displacement vectors in the subspace basis of the mixed interpolation of tensorial components (MITC) formulation, thus increasing the dimension of the null space for the transverse shear strains. These two enhancing vectors are shown to be fundamental for the Morley skew plate example in particular, and in improving the element's transverse shear locking behaviour in general. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Consistent coupling of beam and shell models for thermo-elastic analysis

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2004
    K. S. Chavan
    Abstract In this paper, the finite element formulation of a transition element for consistent coupling between shell and beam finite element models of thin-walled beam-like structures in thermo-elastic problems is presented. Thin-walled beam-like structures modelled only with beam elements cannot be used to study local stress concentrations or to provide local mechanical or thermal boundary conditions. For this purpose, the structure has to be modelled using shell elements. However, computations using shell elements are a lot more expensive as compared to beam elements. The finite element model can be more efficient when the shell elements are used only in regions where the local effects are to be studied or local boundary conditions have to be provided. The remaining part of the structure can be modelled with beam elements. To couple these two models (i.e. shell and beam models) at transitional cross-sections, transition elements are derived here for thermo-elastic problems. The formulation encloses large displacement and rotational behaviour, which is important in case of thin-walled beam-like structures. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Efficient mixed Timoshenko,Mindlin shell elements

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 10 2002
    G. M. Kulikov
    Abstract The precise representation of rigid body motions in the displacement patterns of curved Timoshenko,Mindlin (TM) shell elements is considered. This consideration requires the development of the strain,displacement relationships of the TM shell theory with regard to their consistency with the rigid body motions. For this purpose a refined TM theory of multilayered anisotropic shells is elaborated. The effects of transverse shear deformation and bending-extension coupling are included. The fundamental unknowns consist of five displacements and eight strains of the face surfaces of the shell, and eight stress resultants. On the basis of this theory the simple and efficient mixed models are developed. The elemental arrays are derived using the Hu,Washizu mixed variational principle. Numerical results are presented to demonstrate the high accuracy and effectiveness of the developed 4-node shell elements and to compare their performance with other finite elements reported in the literature. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    On the classical shell model underlying bilinear degenerated shell finite elements

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2001
    Mika MalinenArticle first published online: 2 AUG 200
    Abstract We study the shell models arising in the numerical modelling of shells by bilinear degenerated shell finite elements. The numerical model of a cylindrical shell obtained by using flat shell elements is given an equivalent formulation based on a classical two-dimensional shell model. We use the connection between the models to explain how a parametric error amplification difficulty or locking is avoided by some elements. Copyright © 2001 John Wiley & Sons, Ltd. [source]