- Optimum Design of Steel Sway Frames Using Big Bang-Big Crunch Algorithm.
- A. Kaveh ; H. Abbasgholiha
- Asian Journal of Civil Engineering (Building and Housing), Vol. 12, No. 3, pages 293-317.
- Book Title / Journal:
- Year: 2011 , Volume: , Series:
- Structural Analysis
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- Improved stresses for the 4-node tetrahedral element
- D.J. Payen ; K.J. Bathe
- Book Title / Journal: Computers and Structures
- Year: 2011 , Volume: 89 , Series:
- Structural Analysis
- Description
- The objective in this paper is to present the method for the calculation of improved stresses published by Payen and Bathe in [1] for the 4-node three-dimensional tetrahedral element. This element is widely used in engineering practice to obtain, in general only "guiding" results in the analysis of solids because the element is known to be poor in stress predictions. We show in this paper the potential of this novel approach to significanlty enhance the stress predictions with the 4-node tetrahedral element at a relatively low computational cost.
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- The quadratic MITC plate and MITC shell elements in plate bending
- P.S. Lee ; K.J. Bathe
- Book Title / Journal:
- Year: 2010 , Volume: , Series:
- Structural Analysis
- Keywords: Plate ; shell ; mixed formulation ; Finite elements
- Description
- The analysis of plates can be achieved using the quadratic MITC plate or MITC shell elements. The plate elements have a strong mathematical basis and have been shown to be optimal in their convergence behavior, theoretically and numerically. The shell elements have not (yet) been analyzed mathematically in depth for their rates of convergence, with the plate/shell thickness varying, but have been shown numerically to perform well. Since the shell elements are general and can be used for linear and nonlinear analyses of plates and shells, it is important to identify the differences in the performance of these elements when compared to the plate elements. We briefly review the quadratic quadrilateral and triangular
MITC plate and shell elements and study their performances in linear plate analyses.
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- A new modeling approach for planar beams: finite-element solutions based on mixed variational derivations
- F. Auricchio ; G. Balduzzi ; C. Lovadina
- Book Title / Journal: Journal of Mechanics of Materials and Structures
- Year: 2010 , Volume: 5 , Series:
- Structural Analysis
- Keywords: planar beams ; Finite elements
- Description
- This paper illustrates a new modeling approach for planar linear elastic beams. Referring to existing
models, we first introduce the variational principles that could be adopted for the beam model derivation, discussing their relative advantages and disadvantages. Then, starting from the Hellinger–Reissner functional we derive some homogeneous and multilayered beam models, discussing some properties of their analytical solutions. Finally, we develop a planar beam finite element, following an innovative approach that could be seen as the imposition of equilibrium in the cross-section and compatibility along the axis. The homogeneous model is capable of reproducing the behavior of the Timoshenko beam, with the advantage that the shear correction factor appears naturally from the variational derivation; the multilayered beam is capable of capturing the local effects produced by boundary constraints and load distributions; the finite element is capable of predicting the cross-section stress distribution with high accuracy, and more generally the behavior of planar structural elements.
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- Particle Methods for a 1D Elastic Model Problem: Error Analysis and Development of a Second-Order Accurate Formulation
- D. Asprone ; F. Auricchio ; G. Manfredi ; A. Prota ; A Reali ; G Sangalli
- Book Title / Journal: Computer Modeling in Engineering & Sciences
- Year: 2010 , Volume: 62 , Series:
- Structural Analysis
- Keywords: Meshless methods ; Particle methods ; Error Evaluation ; Kernel Particle Methods
- Description
- Particle methods represent some of the most investigated meshless approaches, applied to numerical problems, ranging from solid mechanics to fluiddynamics and thermo-dynamics. The objective of the present paper is to analyze some of the proposed particle formulations in one dimension, investigating in particular how the different approaches address second derivative approximation.
With respect to this issue, a rigorous analysis of the error is conducted and a novel second-order accurate formulation is proposed. Hence, as a benchmark, three numerical experiments are carried out on the investigated formulations, dealing
respectively with the approximation of the second derivative of given functions, as well as with the numerical solution of the static problem and with the approximation of the vibration frequencies for an elastic rod. In each test, the obtained numerical results are compared with exact solutions and the main criticalities of each formulation are addressed.
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- Insight into a model for large strain anisotropic elasto-plasticity
- D.N. Kim ; F.J. Montáns ; K.J. Bathe
- Book Title / Journal: Computational Mechanics
- Year: 2009 , Volume: , Series:
- Structural Analysis
- Keywords: Plasticity ; Anisotropic plasticity ; Orthotropy ; Plastic spin
- Description
- Efficient and accurate simulation of the deformations in anisotropic metallic sheets requires a constitutive model and an accompanying algorithm at large strains which take into account the anisotropy of both the elastic and plastic material behaviors, as well as their evolution with plastic
strains. Recently we proposed such a constitutive model based on continuum energy considerations, the Lee decomposition and an anisotropic stored energy function of the logarithmic strains in which the rotation of the orthotropic axes is also considered. We obtained a framework similar to the one used in isotropic elasto-plasticity. In the presentwork we give some physical insight into the parameters of the model and their effects on the predictions, both in proportional and in non-proportional loading problems.We also present a procedure to obtain the spin parameter of the model from Lankford R-values.
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- Advances in finite element provedures for non-linear dynamic response
- K.J. Bathe
- Book Title / Journal: 2nd South-East European Conference on Computational Mechanics
- Year: 2009 , Volume: , Series:
- Structural Analysis
- Description
- The objective in this presentation is to briefly survey some recent developments in finite element procedures that we have pursued to solve dynamic problems more accurately and more efficiently, and to solve new classes of problems. We present some developments regarding the finite element analysis of shells, the solution of wave propagation problems
with mode conversions, the time integration in long-time large deformation analyses, the solution of normal modes of proteins with the subspace iteration method in nonlinear conformations, and fluid flow-structure interactions.
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- A triangular six-node shell element
- D-N Kim ; K.J. Bathe
- Book Title / Journal: Computers and Structure
- Year: 2009 , Volume: 87 , Series:
- Structural Analysis
- Keywords: shells ; Finite element ; Triangular element ; Spatial isotropy ; MITC method ; Six-node element
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- A Holistic Method to Design an Optimized Energy Scenario and Quantitatively Evaluate Promising Technologies for Implementation
- C. Deilmann ; K.J. Bathe
- Book Title / Journal: International Journal of Green Energy
- Year: 2009 , Volume: 6 , Series:
- Structural Analysis
- Keywords: Energy system analysis ; Normative scenario technique ; Bottom-up analysis
- Description
- In this article we focus on today’s worldwide energy system, a fundamentally illogical and unsustainable system. Today, 85% of the world wide energy system depends on carbon-based fossil fuels. We develop a holistic method to analyze mankind’s use of energy in a broad way and to design optimized, normative energy scenarios that conform to important scientific principles. The procedure is based on an abstraction process and helps to overcome thinking barriers and prejudice. The proposed method is applied to a general analysis of energy and to a simplified normative energy scenario for the United States in 2060. Important technologies for the implementation are evaluated in a bottom-up analysis. Since research endeavors and
policies affect free-market decisions within the energy system, the developed method aims at
guiding researchers and politicians to embark on strategies toward sustainable and scientifically optimized energy concepts for the future.
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- Advances in Finite Element Procedures for Nonlinear Dynamic Response
- K.J. Bathe
- Book Title / Journal: 2nd South-East European Conference on Computational Mechanics
- Year: 2009 , Volume: , Series:
- Structural Analysis
- Keywords: dynamic ; nonlinear
- Description
- The objective in this presentation is to briefly survey some recent developments in finite element procedures that we have pursued to solve dynamic problems more accurately and more efficiently, and to solve new classes of problems. We present some developments regarding the finite element analysis of shells, the solution of wave propagation problems
with mode conversions, the time integration in long-time large deformation analyses, the solution of normal modes of proteins with the subspace iteration method in nonlinear conformations, and fluid flow-structure interactions.
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- A metric approach to plasticity via Hamilton-Jacobi equation
- F. Auricchio ; E. Bonetti ; A. Marigonda
- Book Title / Journal: Mathematical Models and Methods in Applied Sciences
- Year: 2009 , Volume: 20 , Series:
- Structural Analysis
- Keywords: plasticity models ; dissipative metric ; energetic formulation
- Description
- Thermodynamical consistency of plasticity models is usually written in terms of the so-called \maximum dissipation principle". In this paper, we discuss constitutive relations for dissipative materials writ-
ten through suitable generalized gradients of a (possibly non-convex) metric. This new framework allows us to generalize the classical results
providing an interpretation of the yield function in terms of Hamilton-Jacobi Equations theory.
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- Optimal Design of Geometrically Nonlinear Space Trusses Using an Adaptive Neuro-Fuzzy Inference System
- E. Salajegheh ; J. Salajegheh ; S.M. Seyedpoor ; M. Khatibinia
- Scientia Iranica, Transaction A: Civil Engineering, Vol. 16, No. 5, pp. 403-414, Sharif University of Technology
- Book Title / Journal:
- Year: 2009 , Volume: , Series:
- Structural Analysis
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- Static and dynamic structural excitation and response measurements: a manual.
- E. Reynders ; G. De Roeck ; D. De Prins
- Report BWM-2009-11, Department of Civil Engineering, Katholieke Universiteit, Leuven
- Book Title / Journal:
- Year: 2009 , Volume: , Series:
- Structural Analysis
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- eXtended finite element method(XFEM)- modeling arbitrary discontinuities and failure analysis
- A. Ahmed
- M. Sc Thesis, Istituto Universitario di Studi Superiori di Pavia and Universita degli Studi di Pavia.
- Book Title / Journal:
- Year: 2009 , Volume: , Series:
- Structural Analysis
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- On Finite Element Methods for Nonlinear Dynamic Response
- K.J. Bathe
- Book Title / Journal: Eurodyn 2008: 7th European Conference on Structural Dynamics
- Year: 2008 , Volume: , Series:
- Structural Analysis
- Keywords: Finite element method ; structural dynamics ; Nonlinear dynamic analysis
- Description
- In this paper we briefly focus on the nonlinear analysis of solids and structures when these undergo large deformations, possibly over long time durations, and perhaps subjected to fluidstructure interactions. The analysis should be conducted with finite element methods,
including the time integration, that are reliable and effective. The requirement of reliability is particularly important in nonlinear finite element analysis because physical test data are frequently not available.
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