The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
G Eccher - One of the best experts on this subject based on the ideXlab platform.
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geometric nonlinear isoparametric spline finite Strip analysis of perforated thin walled structures
Thin-walled Structures, 2009Co-Authors: G Eccher, Kim J.r. Rasmussen, Riccardo ZandoniniAbstract:Abstract This paper presents the application of the isoparametric spline finite Strip Method to the geometric nonlinear analysis of perforated folded-plate structures. The general theory of the isoparametric spline finite Strip Method is introduced. Kinematics, strain–displacements and constitutive assumptions are described and applied to the spline finite Strip Method. The derivation of the tangential and secant stiffness matrices is presented by applying the equilibrium condition and its incremental form. The reliability of the Method is demonstrated by applying the Method to classical nonlinear complex plate and shell problems as well as the geometric nonlinear analysis of perforated flat and stiffened plates.
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isoparametric spline finite Strip Method for the bending of perforated plates
International Journal for Numerical Methods in Engineering, 2008Co-Authors: G Eccher, Kim J.r. Rasmussen, Riccardo ZandoniniAbstract:The isoparametric spline finite Strip Method was recently applied by the authors to the linear elastic in-plane stress analysis of perforated thin-walled structures. In this paper, the application of the Method is extended to the bending of perforated plates. The paper describes the theory of the isoparametric spline finite Strip Method in the context of Mindlin plate bending theory. It sets out the strain–displacement and stress–strain relationships and derives expressions for the local and global stiffness matrices. The reliability of the Method is demonstrated by comparisons with finely meshed finite element analysis results. Square plates in bending containing openings of different shapes are analysed. Copyright © 2007 John Wiley & Sons, Ltd.
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elastic buckling analysis of perforated thin walled structures by the isoparametric spline finite Strip Method
Thin-walled Structures, 2008Co-Authors: G Eccher, Kim J.r. Rasmussen, Riccardo ZandoniniAbstract:Abstract This paper presents the application of the isoparametric spline finite Strip Method to the elastic buckling analysis of perforated folded-plate structures. The general theory of the isoparametric spline finite Strip Method is introduced. The kinematics assumptions, strain–displacement and constitutive relations of the Mindlin plate theory are described and applied to the spline finite Strip Method. The corresponding matrix formulation is utilised in the equilibrium and stability equations to derive the stiffness and stability matrices. A number of numerical examples of flat and folded perforated plate structures illustrate the applicability and accuracy of the proposed Method.
Takashi Mikami - One of the best experts on this subject based on the ideXlab platform.
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Time-domain Strip Method with memory-effect function considering the body nonlinearity of ships in large waves (second report)
Journal of Marine Science and Technology, 2009Co-Authors: Takashi Mikami, Masashi KashiwagiAbstract:In the previous paper, one of the authors proposed a new time-domain nonlinear Strip Method for a rigid body, in which hydrodynamic forces are evaluated by a convolution integral with the memory function computed for the instantaneous submerged part of the transverse sections, and the Froude–Krylov and hydrostatic forces are evaluated on the instantaneous wetted hull surface. In this paper, first, that nonlinear Strip Method is extended for an elastic body using a Method of superposition of elastic mode functions, which enabled us to investigate whipping phenomena due to impulsive large waves. Second, the influence of different approximations of the pressure above the still-water surface is investigated, and then the results calculated by the proposed nonlinear Strip Method are compared with the experimental ones. Third, whipping phenomena observed for an elastic body at higher Froude numbers are studied through a comparison between computed and measured results. Higher-frequency vibrations in the vertical bending moment due to slamming are discussed. Furthermore, the wave load due to green water on deck is calculated by introducing a practical model, and the effects of the green water on responses of both rigid and elastic bodies are investigated.
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Time-domain Strip Method with memory-effect function considering the body nonlinearity of ships in large waves
Journal of Marine Science and Technology, 2006Co-Authors: Takashi Mikami, Kiyoshi ShimadaAbstract:A time-domain Strip Method with memory-effect function considering body nonlinearity is presented. In small waves, results from conventional linear Strip theory and the present Method for a modified Wigley model were compared with the results of linear theories and with experiments, and they were found to be in good agreement. In large waves, a 716 TEU containership was used to compare time histories of motions and vertical bending moments calculated using the present Method with experimental results. The time histories of motion were not strongly distorted, but those of the vertical bending moments were extremely distorted, especially for the fore part, and were far from sinusoidal signals. The time histories of the calculations and the experimental results were found to be, qualitatively and quantitatively, in good agreement. A post-Panamax containership was also used as an example of an up-to-date large bow-flare ship, and the calculated results were also found to be in good agreement with the experimental results.
Sayyed Amir M. Ghannadpour - One of the best experts on this subject based on the ideXlab platform.
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Pressure loading, end- shortening and through- thickness shearing effects on geometrically nonlinear response of composite laminated plates using higher order finite Strip Method
Structural Engineering and Mechanics, 2013Co-Authors: Mohammad H. Sherafat, Sayyed Amir M. Ghannadpour, Hamid Reza OvesyAbstract:A semi-analytical finite Strip Method is developed for analyzing the post-buckling behavior of rectangular composite laminated plates of arbitrary lay-up subjected to progressive end-shortening in their plane and to normal pressure loading. In this Method, all the displacements are postulated by the appropriate harmonic shape functions in the longitudinal direction and polynomial interpolation functions in the transverse direction. Thin or thick plates are assumed and correspondingly the Classical Plate Theory (CPT) or Higher Order Plate Theory (HOPT) is applied. The in-plane transverse deflection is allowed at the loaded ends of the plate, whilst the same deflection at the unloaded edges is either allowed to occur or completely restrained. Geometric non-linearity is introduced in the strain-displacement equations in the manner of the von-Karman assumptions. The formulations of the finite Strip Methods are based on the concept of the principle of the minimum potential energy. The Newton-Raphson Method is used to solve the non-linear equilibrium equations. A number of applications involving isotropic plates, symmetric and unsymmetric cross-ply laminates are described to investigate the through-thickness shearing effects as well as the effect of pressure loading, end-shortening and boundary conditions. The study of the results has revealed that the response of the composite laminated plates is particularly influenced by the application of the Higher Order Plate Theory (HOPT) and normal pressure loading. In the relatively thick plates, the HOPT results have more accuracy than CPT.
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Buckling Analysis of Laminated Composite Plates Using Higher Order Semi—Analytical Finite Strip Method
Applied Composite Materials, 2010Co-Authors: Hamid Reza Ovesy, Sayyed Amir M. Ghannadpour, Mohammad H. SherafatAbstract:Rectangular plates made of laminated composite material because of the advantageously high strength and stiffness to weight ratio are used frequently as structural component in various branches of engineering, chief of which are aerospace and marine engineering. Design concepts of these plates that lead to the increase in the buckling load can directly lower the structural cost and/or weight. The finite Strip Method is one of a number of procedures which can be used to solve the buckling problem of plate structures. In the present work the main concern is with the buckling behavior of plates with simply supported ends subjected to uni-axial pure compression loads. The solution is sought by implementing the higher order semi-analytical finite Strip Method which incorporates additional degrees of freedom for each nodal line by using Reddy’s higher order plate theory. Therefore the current Method is more universal in dealing with different plate thicknesses. In addition, in this semi-analytical finite Strip Method, all the displacements are postulated by the appropriate harmonic shape functions in the longitudinal direction and polynomial interpolation functions in the transverse direction. The solution is based on the concept of principle of minimum potential energy and an eigen-value analysis is subsequently carried out. From the presented results it can be concluded that the higher order semi-analytical finite Strip Method is very reliable for the preliminary design of composite plates especially in the case of buckling analysis of relatively thick plates.
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Post-buckling behavior of composite laminated plates under end shortening and pressure loading, using two versions of finite Strip Method
Composite Structures, 2006Co-Authors: Hamid Reza Ovesy, Sayyed Amir M. Ghannadpour, G MoradaAbstract:Abstract Two different versions of finite Strip Method, namely spline and semi-analytical Methods, are developed for analyzing the geometrically non-linear response of rectangular composite laminated plates of arbitrary lay-up to progressive end-shortening in their plane and to pressure loading. The plates are assumed to be thin so that the analysis can be carried out based on the classical plate theory. The in-plane lateral deflection υ is allowed at the loaded ends of the plate, whilst the lateral expansion of the unloaded edges is either free or completely prevented. Geometric non-linearity is introduced in the strain–displacement equations in the manner of the von Karman assumptions. The formulations of the finite Strip Methods are based on the concept of the principle of the minimum potential energy. A number of applications involving isotropic plates, symmetric and unsymmetric cross-ply laminates are described to investigate the effects of pressure loading. The comparison between the two sets of results obtained by different finite Strip Methods is very good. The study of the results revealed that the response of the laminates is significantly influenced by the application of the normal pressure loading. Particularly, the response of unsymmetric laminates is strongly affected by the sign of the normal pressure loading.
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Geometric non-linear analysis of imperfect composite laminated plates, under end shortening and pressure loading, using finite Strip Method
Composite Structures, 2006Co-Authors: Hamid Reza Ovesy, Sayyed Amir M. GhannadpourAbstract:Abstract Description is given of semi-analytical finite Strip Method for predicting the geometrically non-linear response of rectangular composite laminated plates with initial imperfections, when subjected to progressive end shortening and pressure loading. In the finite Strip formulations, the initial imperfections are all assumed to be of the sinusoidal shape in both of the longitudinal and transverse direction. The laminates are simply supported out of their plane at the loaded ends as well as unloaded edges. The plates are assumed to be thin so that the analysis can be carried out based on the classical plate theory. Geometric non-linearity is introduced in the strain–displacement equations in the manner of the von Karman assumptions. The formulations of the finite Strip Methods are based on the concept of the principle of the minimum potential energy. The Newton–Raphson Method is used to solve the non-linear equilibrium equations. A number of applications involving plates with both initial imperfection and pressure load are described and discussed.
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Geometric non-linear analysis of channel sections under end shortening, using different versions of the finite Strip Method
Computers & Structures, 2006Co-Authors: Hamid Reza Ovesy, J. Loughlan, Sayyed Amir M. GhannadpourAbstract:Two finite Strip Methods, namely the full-energy and the semi-energy FSM, are developed for predicting the geometrically non-linear response of channel sections with simply supported ends when subjected to uniform end shortening in their plane. The developed finite Strip Methods are then applied to analyze the post-local-buckling behaviour of some representative channel sections. The comparison of results revealed the fact that for the channel sections under study, the full-energy finite Strip Method is capable of predicting results with a greater degree of accuracy than that of the results obtained by the semi-energy finite Strip Method. This is due to the fact that a lower level of compressional stiffness is experienced in the case of the full-energy FSM results as compared to those observed in the case of semi-energy FSM. It is however worth noting that at the expense of slightly less accurate results, the current semi-energy analysis is benefiting from considerably less computer CPU time, due to the implementation of a fairly small number of degrees of freedom, as compared to the CPU time elapsed by the computer when the full-energy Method is applied. It is noted that in the current semi-energy approach only one term is utilized, whereas several terms are implemented in the formulation of the full-energy Method. Therefore, it is expected that the accuracy of the semi-energy approach will improve and correspondingly the required computer CPU time will increase if more than one term is utilized in its formulation.
Riccardo Zandonini - One of the best experts on this subject based on the ideXlab platform.
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geometric nonlinear isoparametric spline finite Strip analysis of perforated thin walled structures
Thin-walled Structures, 2009Co-Authors: G Eccher, Kim J.r. Rasmussen, Riccardo ZandoniniAbstract:Abstract This paper presents the application of the isoparametric spline finite Strip Method to the geometric nonlinear analysis of perforated folded-plate structures. The general theory of the isoparametric spline finite Strip Method is introduced. Kinematics, strain–displacements and constitutive assumptions are described and applied to the spline finite Strip Method. The derivation of the tangential and secant stiffness matrices is presented by applying the equilibrium condition and its incremental form. The reliability of the Method is demonstrated by applying the Method to classical nonlinear complex plate and shell problems as well as the geometric nonlinear analysis of perforated flat and stiffened plates.
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isoparametric spline finite Strip Method for the bending of perforated plates
International Journal for Numerical Methods in Engineering, 2008Co-Authors: G Eccher, Kim J.r. Rasmussen, Riccardo ZandoniniAbstract:The isoparametric spline finite Strip Method was recently applied by the authors to the linear elastic in-plane stress analysis of perforated thin-walled structures. In this paper, the application of the Method is extended to the bending of perforated plates. The paper describes the theory of the isoparametric spline finite Strip Method in the context of Mindlin plate bending theory. It sets out the strain–displacement and stress–strain relationships and derives expressions for the local and global stiffness matrices. The reliability of the Method is demonstrated by comparisons with finely meshed finite element analysis results. Square plates in bending containing openings of different shapes are analysed. Copyright © 2007 John Wiley & Sons, Ltd.
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elastic buckling analysis of perforated thin walled structures by the isoparametric spline finite Strip Method
Thin-walled Structures, 2008Co-Authors: G Eccher, Kim J.r. Rasmussen, Riccardo ZandoniniAbstract:Abstract This paper presents the application of the isoparametric spline finite Strip Method to the elastic buckling analysis of perforated folded-plate structures. The general theory of the isoparametric spline finite Strip Method is introduced. The kinematics assumptions, strain–displacement and constitutive relations of the Mindlin plate theory are described and applied to the spline finite Strip Method. The corresponding matrix formulation is utilised in the equilibrium and stability equations to derive the stiffness and stability matrices. A number of numerical examples of flat and folded perforated plate structures illustrate the applicability and accuracy of the proposed Method.
Bruno Ladevie - One of the best experts on this subject based on the ideXlab platform.
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Hot Strip Method: application to thermal characterisation of orthotropic media
International Journal of Thermal Sciences, 2004Co-Authors: Claire Gobbé, Sébastien Iserna, Bruno LadevieAbstract:This study deals with determination of the thermal conductivity tensor for orthotropic media and more specifically for multilayers with isotropic thermal characteristics in the planes parallel to the layers. The work described has been conducted using two ordinary experimental devices: a device based on the hot-wire Method and a device based on the hot-Strip Method. Hot-wire measurements give the thermal conductivity in the planes parallel to layers. Introducing this value in a model adequate to describe orthotropic behaviour and using an appropriate identification Method, hot-Strip measurements then give the transverse thermal conductivity. The validity of this approach is demonstrated by the results obtained on a stratified medium with known thermal characteristics. Then, transverse thermal measurements were made on a non-woven wood fibre insulator.
