The Experts below are selected from a list of 5916 Experts worldwide ranked by ideXlab platform

Erik Lund - One of the best experts on this subject based on the ideXlab platform.

  • buckling topology optimization of laminated multi material Composite Shell structures
    Composite Structures, 2009
    Co-Authors: Erik Lund
    Abstract:

    The design problem of maximizing the buckling load factor of laminated multi-material Composite Shell structures is investigated using the so-called Discrete Material Optimization (DMO) approach. The design optimization method is based on ideas from multi-phase topology optimization where the material stiffness is computed as a weighted sum of candidate materials, thus making it possible to solve discrete optimization problems using gradient based techniques and mathematical programming. The potential of the DMO method to solve the combinatorial problem of proper choice of material and fiber orientation simultaneously is illustrated for multilayered plate examples and a simplified Shell model of a spar cap of a wind turbine blade.

  • Buckling topology optimization of laminated multi-material Composite Shell structures
    Composite Structures, 2009
    Co-Authors: Erik Lund
    Abstract:

    The design problem of maximizing the buckling load factor of laminated multi-material Composite Shell structures is investigated using the so-called Discrete Material Optimization (DMO) approach. The design optimization method is based on ideas from multi-phase topology optimization where the material stiffness is computed as a weighted sum of candidate materials, thus making it possible to solve discrete optimization problems using gradient based techniques and mathematical programming. The potential of the DMO method to solve the combinatorial problem of proper choice of material and fiber orientation simultaneously is illustrated for multilayered plate examples and a simplified Shell model of a spar cap of a wind turbine blade. © 2009 Elsevier Ltd. All rights reserved.

  • discrete material optimization of general Composite Shell structures
    International Journal for Numerical Methods in Engineering, 2005
    Co-Authors: Joachim Stegmann, Erik Lund
    Abstract:

    A novel method for doing material optimization of general Composite laminate Shell structures is presented and its capabilities are illustrated with three examples. The method is labelled Discrete Material Optimization (DMO) but uses gradient information combined with mathematical programming to solve a discrete optimization problem. The method can be used to solve the orientation problem of orthotropic materials and the material selection problem as well as problems involving both. The method relies on ideas from multiphase topology optimization to achieve a parametrization which is very general and reduces the risk of obtaining a local optimum solution for the tested configurations. The applicability of the DMO method is demonstrated for fibre angle optimization of a cantilever beam and combined fibre angle and material selection optimization of a four-point beam bending problem and a doubly curved laminated Shell. Copyright © 2005 John Wiley & Sons, Ltd.

  • Discrete material optimization of general Composite Shell structures
    International Journal for Numerical Methods in Engineering, 2005
    Co-Authors: Joachim Stegmann, Erik Lund
    Abstract:

    A novel method for doing material optimization of general Composite laminate Shell structures is presented and its capabilities are illustrated with three examples. The method is labelled Discrete Material Optimization (DMO) but uses gradient information combined with mathematical programming to solve a discrete optimization problem. The method can be used to solve the orientation problem of orthotropic materials and the material selection problem as well as problems involving both. The method relies on ideas from multiphase topology optimization to achieve a parametrization which is very general and reduces the risk of obtaining a local optimum solution for the tested configurations. The applicability of the DMO method is demonstrated for fibre angle optimization of a cantilever beam and combined fibre angle and material selection optimization of a four-point beam bending problem and a doubly curved laminated Shell.

  • on structural optimization of Composite Shell structures using a discrete constitutive parametrization
    Wind Energy, 2005
    Co-Authors: Erik Lund, Joachim Stegmann
    Abstract:

    In this article a novel method for structural optimization of laminated Composite Shell structures such as wind turbine blades is presented. The outer shape of a wind turbine blade is typically determined by aerodynamic considerations and therefore not subject to change. Furthermore, the thicknesses of the Shell structures are also considered fixed. The design objective is chosen to be a global quantity such as maximum stiffness or lowest eigenfrequency with a constraint on the total mass, such that the cost of material can be considered. The design optimization method is based on ideas from multiphase topology optimization where the material stiffness (or density) is computed as a weighted sum of candidate materials, and the method is easy to implement in existing finite element codes. The potential of the method to solve the combinatorial problem of proper choice of material, stacking sequence and fibre orientation simultaneously for maximum stiffness or lowest eigenfrequency design is illustrated on both small test examples and a real-life main spar from a wind turbine blade. Copyright © 2004 John Wiley & Sons, Ltd.

Joachim Stegmann - One of the best experts on this subject based on the ideXlab platform.

  • discrete material optimization of general Composite Shell structures
    International Journal for Numerical Methods in Engineering, 2005
    Co-Authors: Joachim Stegmann, Erik Lund
    Abstract:

    A novel method for doing material optimization of general Composite laminate Shell structures is presented and its capabilities are illustrated with three examples. The method is labelled Discrete Material Optimization (DMO) but uses gradient information combined with mathematical programming to solve a discrete optimization problem. The method can be used to solve the orientation problem of orthotropic materials and the material selection problem as well as problems involving both. The method relies on ideas from multiphase topology optimization to achieve a parametrization which is very general and reduces the risk of obtaining a local optimum solution for the tested configurations. The applicability of the DMO method is demonstrated for fibre angle optimization of a cantilever beam and combined fibre angle and material selection optimization of a four-point beam bending problem and a doubly curved laminated Shell. Copyright © 2005 John Wiley & Sons, Ltd.

  • Discrete material optimization of general Composite Shell structures
    International Journal for Numerical Methods in Engineering, 2005
    Co-Authors: Joachim Stegmann, Erik Lund
    Abstract:

    A novel method for doing material optimization of general Composite laminate Shell structures is presented and its capabilities are illustrated with three examples. The method is labelled Discrete Material Optimization (DMO) but uses gradient information combined with mathematical programming to solve a discrete optimization problem. The method can be used to solve the orientation problem of orthotropic materials and the material selection problem as well as problems involving both. The method relies on ideas from multiphase topology optimization to achieve a parametrization which is very general and reduces the risk of obtaining a local optimum solution for the tested configurations. The applicability of the DMO method is demonstrated for fibre angle optimization of a cantilever beam and combined fibre angle and material selection optimization of a four-point beam bending problem and a doubly curved laminated Shell.

  • on structural optimization of Composite Shell structures using a discrete constitutive parametrization
    Wind Energy, 2005
    Co-Authors: Erik Lund, Joachim Stegmann
    Abstract:

    In this article a novel method for structural optimization of laminated Composite Shell structures such as wind turbine blades is presented. The outer shape of a wind turbine blade is typically determined by aerodynamic considerations and therefore not subject to change. Furthermore, the thicknesses of the Shell structures are also considered fixed. The design objective is chosen to be a global quantity such as maximum stiffness or lowest eigenfrequency with a constraint on the total mass, such that the cost of material can be considered. The design optimization method is based on ideas from multiphase topology optimization where the material stiffness (or density) is computed as a weighted sum of candidate materials, and the method is easy to implement in existing finite element codes. The potential of the method to solve the combinatorial problem of proper choice of material, stacking sequence and fibre orientation simultaneously for maximum stiffness or lowest eigenfrequency design is illustrated on both small test examples and a real-life main spar from a wind turbine blade. Copyright © 2004 John Wiley & Sons, Ltd.

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

  • Identification by modal analysis of Composite structures modelled with FSDT and HSDT laminated Shell finite elements
    Composites Part A: Applied Science and Manufacturing, 2004
    Co-Authors: J. Cugnoni, Thomas Gmür, A. Schorderet
    Abstract:

    This paper presents an improvement and an extension to modal analysis of an existing multilayered Composite Shell finite element. Generalising the formulation to a set of elements, the proposed models are based upon the first- and higher-order shear deformation theories and are well suited for evaluating the global dynamic response of thin and thick laminated Shells respectively. Characterized by a through-the-thickness displacement approximation of a freely chosen order, they display excellent convergence properties when the polynomial order is increased and present a higher computational effectiveness in comparison to the classical layerwise models. The models considered are compared to closed-form solutions based on the layerwise plate theory and the so-called zig-zag formulation. Experimental and numerical modal test cases on thin and thick plates are next investigated in order to validate the proposed Shell models. Good agreement is found with the analytical, experimental and numerical references. © 2004 Elsevier Ltd. All rights reserved.

  • Modal validation of a set of C0-compatible Composite Shell finite elements
    Composites Science and Technology, 2004
    Co-Authors: J. Cugnoni, Thomas Gmür, Zhong Zhang, Hui Zhang, A. Schorderet
    Abstract:

    This paper presents efficient C0-compatible finite elements for modelling laminated Composite Shells under free vibrations. Derived from the first-order shear deformation theory (equivalent single-layer laminate model), the elements are well adapted for evaluating the global dynamic response (natural frequencies and mode shapes) of moderately thick multilayered Shells. The components of their structural matrices are based on an exact integration per layer, which results in a higher solution accuracy than with standard explicit through-the-thickness schemes. The described finite element formulation, which can be easily implemented in commercial finite element codes, is next validated by means of several experimental modal test cases on thin to relatively thick plates or Shells. © 2004 Elsevier Ltd. All rights reserved.

F. Rostam-abadi - One of the best experts on this subject based on the ideXlab platform.

  • Nonlinear finite element analysis of laminated Composite Shells with actuating layers
    Finite Elements in Analysis and Design, 2006
    Co-Authors: S. J. Lee, J. N. Reddy, F. Rostam-abadi
    Abstract:

    Nonlinear finite element analysis of laminated Composite Shell structures with smart material laminae is presented in the study. Third-order shear deformation theory based on Sanders nonlinear Shell kinematics is chosen for the Shell formulation and it is used to study deflection suppression characteristics of laminated Composite Shells. The smart material used in this study to achieve damping of transverse deflection is a magnetostrictive material, Terfenol-D, with a linear constitutive model. A negative velocity feedback control is used with a constant control gain. Newmark's time integration scheme and Newton-Raphson iteration method are used to solve the resulting nonlinear equations. A number of parametric studies are carried out to understand the damping characteristics of laminated Composite Shells with embedded smart material layers. ?? 2006.

C. Guedes Soares - One of the best experts on this subject based on the ideXlab platform.

  • Longitudinal strength analysis of ship hulls of Composite materials under sagging moments
    Composite Structures, 2007
    Co-Authors: Nian-zhong Chen, C. Guedes Soares
    Abstract:

    An approach to estimate the longitudinal strength of ship hulls in Composite materials is presented in the paper. Typical ship configurations have as dominant failure mode the failure of the deck under compression associated with sagging moments. Ship hulls are modeled as assemblies of stiffened Composite panels. Buckling, material failure and ultimate collapse of the stiffened panels are predicted by nonlinear finite element analysis, which is based on a degenerated three-dimensional laminated Composite Shell element with updated Lagrangian formulation and first-order shear deformable kinematics. According to buckling, material failure and ultimate collapse of stiffened panels, the corresponding longitudinal strengths of ship hull are derived from a simplified method. A ship hull under sagging is analysed as an example application. © 2005 Elsevier Ltd. All rights reserved.