The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform

Klausjurgen Bathe - One of the best experts on this subject based on the ideXlab platform.

  • A new 8-Node Element for analysis of three-dimensional solids
    Computers & Structures, 2018
    Co-Authors: Klausjurgen Bathe
    Abstract:

    Abstract We propose a new 8-Node hexahedral Element, the 3D-MITC8 Element, for the analysis of three-dimensional solids. We use the MITC method and find the assumed strain field from a thought experiment using a truss idealization. For geometric nonlinear analysis, when needed to suppress hour-glass deformations, the formulation also uses automatically displacement-based contributions to the shear strains. The Element shows a much better predictive capability than the displacement-based Element. It is computationally more effective than the 8-Node Element with incompatible modes, and considering accuracy, in linear analysis performs almost as well, and in nonlinear analyses we do not observe spurious instabilities. We show that the new 3D solid Element passes all basic tests (the isotropy, zero energy mode and patch tests) and present the finite Element solutions of various benchmark problems to illustrate the solution accuracy reached with the new Element.

  • 3D-shell Elements for structures in large strains
    Computers & Structures, 2013
    Co-Authors: Theodore Sussman, Klausjurgen Bathe
    Abstract:

    We present in this paper MITC shell Elements for large strain solutions of shell structures. While we focus on the 4-Node Element, the same formulation is also applicable to the 3-Node Element. Since the Elements are formulated using three-dimensional continuum theory with the full three-dimensional constitutive behavior, they are referred to as 3D-shell Elements. Specific contributions in this paper are that the Elements are formulated using two control vectors at each Node to describe the large deformations, MITC tying and volume preserving conditions acting directly on the material fiber vectors to avoid shear locking, and a pressure interpolation to circumvent volumetric locking. Also, we present solutions to some large strain shell problems that represent valuable benchmark tests for any large strain shell analysis capability.

  • insight into 3 Node triangular shell finite Elements the effects of Element isotropy and mesh patterns
    Computers & Structures, 2007
    Co-Authors: Phillseung Lee, Hyukchun Noh, Klausjurgen Bathe
    Abstract:

    In this paper, we study the convergence characteristics of some 3-Node triangular shell finite Elements. We review the formulations of three different isotropic 3-Node Elements and one non-isotropic 3-Node Element. We analyze a clamped plate problem and a hyperboloid shell problem using various mesh topologies and present the convergence curves using the s-norm. Considering simple bending tests, we also study the transverse shear strain fields of the shell finite Elements. The results and insight given are valuable for the proper use and the further development of triangular shell finite Elements.

  • On the stability of mixed finite Elements in large strain analysis of incompressible solids
    Finite Elements in Analysis and Design, 1997
    Co-Authors: Daniel Pantuso, Klausjurgen Bathe
    Abstract:

    Abstract Some mixed finite Elements for large deformation analysis of incompressible solids are studied. The Elements are based on the displacement/pressure and enhanced strain mixed formulations. Specifically, it is shown that a quadrilateral 4-Node Element that satisfies the inf-sup condition in linear analysis — and hence is an effective Element in such conditions — fails in large strain analysis. The reasons for this Element behavior are explored. Some comparisons of Element predictive capabilities are given.

Omer Civalek - One of the best experts on this subject based on the ideXlab platform.

  • a four Node discrete singular convolution for geometric transformation and its application to numerical solution of vibration problem of arbitrary straight sided quadrilateral plates
    Applied Mathematical Modelling, 2009
    Co-Authors: Omer Civalek
    Abstract:

    A four-Node discrete singular convolution (DSC) method is developed for free vibration analysis of arbitrary straight-sided quadrilateral plates. The straight-sided quadrilateral domain is mapped into a square domain in the computational space using a four-Node Element. By using the geometric transformation, the governing equations and boundary conditions of the plate are transformed from the physical domain into a square computational domain. Numerical examples illustrating the accuracy and convergence of the DSC method for skew, trapezoidal, rhombic and arbitrary quadrilateral plates are presented. The results obtained by DSC method were compared with those obtained by the other numerical methods.

  • Analysis of shear deformable laminated composite trapezoidal plates
    Materials & Design, 2009
    Co-Authors: Murat Gürses, Omer Civalek, Hakan Ersoy, Okyay Kiracioglu
    Abstract:

    This paper presents the discrete singular convolution (DSC) method for the free vibration analysis of laminated trapezoidal plates. The plate formulation is based on first-order shear deformation theory (FSDT). The straight-sided trapezoidal domain is mapped into a square domain in the computational space using a four-Node Element by using the geometric transformation. The frequency parameters are obtained for symmetric angle-ply and cross-ply laminated trapezoidal plate. The accuracy of the present method is demonstrated by comparing with numerical and analytical solutions available in the literature.

  • Eigenvalues of membranes having skew and rhombic geometry using discrete singular convolution algorithm
    Communications in Nonlinear Science and Numerical Simulation, 2009
    Co-Authors: Omer Civalek
    Abstract:

    Abstract Free vibration analysis of skew and rhombic membranes is presented. In the proposed approach, irregular physical domain is transformed into a rectangular domain by using geometric coordinate transformation. Four-Node Element is used for geometric mapping. For demonstration of the accuracy and convergence of the method, some numerical examples are provided. The results obtained by the DSC method are compared with those obtained by other numerical and analytical methods.

  • Free vibration and buckling analyses of composite plates with straight-sided quadrilateral domain based on DSC approach
    Finite Elements in Analysis and Design, 2007
    Co-Authors: Omer Civalek
    Abstract:

    Discrete singular convolution (DSC) method has been proposed to obtain the frequencies and buckling loads of composite plates. By using geometric transformation, the straight-sided quadrilateral domain is mapped into a square domain in the computational space using a four-Node Element. Plates having different geometries such as rectangular, skew, trapezoidal and rhombic plates are presented. The obtained results are compared with those of other numerical methods. Numerical results indicate that the DSC is a simple, accurate and reliable algorithm for vibration and buckling analyses of composite plates.

Jozef Bocko - One of the best experts on this subject based on the ideXlab platform.

A. Tessler - One of the best experts on this subject based on the ideXlab platform.

  • A robust four-Node quadrilateral Element for laminated composite and sandwich plates based on Refined Zigzag Theory
    Computers & Structures, 2021
    Co-Authors: Matteo Sorrenti, Marco Di Sciuva, A. Tessler
    Abstract:

    Abstract The paper presents a locking-free four-Node Element for laminated composite and sandwich plates based on Refined Zigzag Theory (RZT). Initially, two RZT-based plate Elements are derived using four-Node and eight-Node configurations, achieved by way of standard C0 isoparametric shape functions. In addition, with a view on improving the modelling of extremely thin plates, an anisoparametric four-Node Element is developed in which the transverse deflection variable is interpolated using quadratic polynomial shape functions, whereas the remaining kinematic variables are bilinear. A straightforward transverse-shear edge-constraint procedure gives rise to a four-Node anisoparametric Element. A further enhancement is achieved using an Element Shear Correction (ESC) factor that is derived from a strain-energy matching procedure. The resulting four-Node Element (ZQ4c) uses full Gauss quadrature, consistent load vector, and mass matrix. Furthermore, the ZQ4c stiffness matrix has no spurious zero-energy modes, and the Element is extremely robust when modelling ultra-thin plates. Several numerical studies are carried out to demonstrate the predictive capabilities of the four Elements examined in this investigation. It is concluded ZQ4c is a highly accurate Element over a wide range of material systems and span-to-thickness ratios, and is the best performing Element of the four Elements examined in this study.

Kam Yim Sze - One of the best experts on this subject based on the ideXlab platform.

  • New slave-Node constraints and Element for adaptive analysis of C 0 plates
    Structural Engineering and Mechanics, 2011
    Co-Authors: Kam Yim Sze
    Abstract:

    In the h-type adaptive analysis, when an Element is refined or subdivided, new Nodes are added. Among them are the transition Nodes which are the corner Nodes of the new Elements formed by subdivision and, simultaneously, the mid-side Nodes of the adjacent non-subdivided Elements. To secure displacement compatibility, the slave-Node approach in which the DOFs of a transition Node are constrained by those of the adjacent Nodes had been used. Alternatively, transition Elements which possess the transition Nodes as active mid-side/-face Nodes can be used. For C0 plate analyses, the conventional slave-Node constraints and the previously derived ANS transition Elements are implemented. In both implementations, the four-Node Element is the ANS Element. With reference to the predictions of the transition Elements, the slave-Node approach not only delivers erroneous results but also fails the patch test. In this paper, the patch test failure is resolved by developing a set of new constraints with which the slave-Node approach surpasses the transition-Element approach. The accuracy of the slave-Node approach is further improved by developing a hybrid four-Node Element in which the assumed moment and shear force modes are in strict equilibrium.

  • Control of spurious mechanisms for 20-Node and transition sub-integrated hexahedral Elements
    International Journal for Numerical Methods in Engineering, 1994
    Co-Authors: Kam Yim Sze
    Abstract:

    In this paper, control of spurious mechanisms for sub-integrated 20-Node and transition hexahedral Elements is devised by an assumed stress approach. The higher-order stress modes for stabilizing the sub-integrated Elements are identified by examining the spurious mechanisms. With an admissible simplification of the flexibility matrix, row vectors of the leverage matrix can be used as stabilization vectors. Numerical examples for the stabilized 20-Node Element are presented. Accuracy of the derived Element is far better than the fully integrated displacement Elements. Meanwhile, the former also consumes marginally less CPU time than the latter.