The Experts below are selected from a list of 32457 Experts worldwide ranked by ideXlab platform

S Tangaramvong - One of the best experts on this subject based on the ideXlab platform.

  • The influence of Geometric effects on the behavior of strain softening frames
    Computational Mechanics, 2010
    Co-Authors: S Tangaramvong
    Abstract:

    This paper presents a mathematical programming based approach for the analysis of elastoplastic softening frames in the presence of Geometric Nonlinearity. Arbitrarily large deformations, albeit within a small strain regime, can be accommodated, if necessary. For the sake of efficiency, and without undue loss of accuracy, the algorithm processes the nonholonomic (path-dependent) problem in a stepwise holonomic (path-independent) fashion. This analysis capability has been used to investigate what level or order of Geometric Nonlinearity needs to be adopted to obtain sufficiently accurate results for practical frames. Two examples are provided for illustrative purposes.

  • limit analysis of elastoplastic frames considering 2nd order Geometric Nonlinearity and displacement constraints
    International Journal of Mechanical Sciences, 2009
    Co-Authors: S Tangaramvong, F Tinloi
    Abstract:

    Abstract The present paper extends the classical limit analysis of plane frames to account for 2nd-order Geometric Nonlinearity. Any specified displacement limits can also be included in the proposed analysis. The effect of combined bending moment and axial force is accommodated in the adopted piecewise linearized yield condition, albeit still assumed as perfectly plastic. The main feature of the novel approach proposed is to compute simultaneously, in a single step, the maximum load and corresponding deformations of the structure under limited displacement conditions. The problem is cast as an instance of the challenging class of (nonconvex and nonsmooth) mathematical programs with equilibrium constraints (MPECs). Various nonlinear programming based algorithms are proposed to solve the MPEC. Four numerical examples are provided to illustrate application of the proposed limit analysis approach and to highlight the necessity of considering Geometric Nonlinearity for a more realistic assessment of structural behavior.

  • extended limit analysis of strain softening frames involving 2nd order Geometric Nonlinearity and limited ductility
    Cmes-computer Modeling in Engineering & Sciences, 2009
    Co-Authors: S Tangaramvong, F Tinloi
    Abstract:

    Classical limit analysis is extended to include the effects of 2nd-order Geometric and material nonlinearities, as well as the inclusion of limited ductility constraints. For the class of frame structures considered, the material constitutive model adopted can simultaneously accommodate the effects of combined axial and flexural force as well as local softening instability through the use of piecewise linearized yield surfaces. The main feature of the approach developed is to compute, in a single step, an upper bound to the maximum load. Corresponding displacements and stresses can be obtained as a by-product of the analysis. The problem is formulated as an instance of the challenging class of so-called mathematical programs with equilibrium constraints (MPECs). A number of numerical examples are provided to validate the robustness and efficiency of the current approach, and to illustrate some key mechanical features expected of realistic frames that exhibit local softening behavior and Geometric Nonlinearity.

Toshio Miyata - One of the best experts on this subject based on the ideXlab platform.

  • wind induced nonlinear lateral torsional buckling of cable stayed bridges
    Journal of Structural Engineering-asce, 1994
    Co-Authors: Virote Boonyapinyo, Hitoshi Yamada, Toshio Miyata
    Abstract:

    A finite element approach to calculate directly the critical wind velocity for the nonlinear lateral‐torsional buckling instability of long‐span cable‐stayed bridges under the displacement‐dependent wind loads is presented. An analytical modeling of wind‐induced lateral‐torsional buckling is formulated taking into account the three components of displacement‐dependent wind loads as well as Geometric Nonlinearity. A combination of the eigenvalue analysis and the updated bound algorithm for wind velocity is applied to automatically calculate the critical wind velocity. The results show that the incorporation of the three components of displacement‐dependent wind loads as well as the Geometric Nonlinearity in the analytical modeling of the lateral‐torsional buckling instability results in significant reduction in the critical wind velocity compared with both the conventional non‐linear torsional divergence and linearized lateral‐torsional buckling.

Ye Tang - One of the best experts on this subject based on the ideXlab platform.

  • nonlinear vibration analysis of double walled carbon nanotubes based on nonlocal elasticity theory
    Applied Mathematical Modelling, 2013
    Co-Authors: Bo Fang, Yaxin Zhen, Chiping Zhang, Ye Tang
    Abstract:

    Abstract The nonlinear free vibration of double-walled carbon nanotubes based on the nonlocal elasticity theory is studied in this paper. The nonlinear equations of motion of the double-walled carbon nanotubes are derived by using Euler beam theory and Hamilton principle, with considering the von Karman type Geometric Nonlinearity and the nonlinear van der Waals forces. The surrounding elastic medium is formulated as the Winkler model. The harmonic balance method and Davidon–Fletcher–Powell method are utilized for the analysis and simulation of the nonlinear vibration. The simulation results show that the nonlocal parameter, aspect ratio and surrounding elastic medium play more important roles in the nonlinear noncoaxial vibration than those in the coaxial vibration of the double-walled carbon nanotubes. The noncoaxial vibration amplitudes of only considering nonlinear van der Waals forces are larger than those of considering both Geometric Nonlinearity and nonlinear van der Waals forces.

C.y. Chen - One of the best experts on this subject based on the ideXlab platform.

  • ANALYSIS OF NONLINEAR VIBRATIONS OF DOUBLE-WALLED CARBON NANOTUBES CONVEYING FLUID
    Computational Materials Science, 2009
    Co-Authors: You-di Kuang, C.y. Chen
    Abstract:

    Abstract This paper investigates the effect of the Geometric Nonlinearity and the Nonlinearity of van der Waals (vdW) force on the transverse vibration of the double-walled carbon nanotubes conveying fluid and the interaction between two types of nonlinearities. By using the Hamilton’s principle, the nonlinear governing equations of the double-walled carbon nanotubes conveying fluid are deduced. The effects of two types of nonlinearities on the coaxial and noncoaxial vibrations of the double-walled carbon nanotubes conveying fluid are discussed in numerical examples. The results show that the effect of Geometric Nonlinearity on the amplitude–frequency properties can be neglected if two types of nonlinearities are simultaneously considered. Compared with the uncoupling, the coupling between the longitudinal and transverse vibrations has little effect on the amplitude–frequency properties with considering two types of nonlinearities simultaneously. However, the coupling has significant effect on the amplitude–frequency properties with only considering the Geometric Nonlinearity.

Jaehong Lee - One of the best experts on this subject based on the ideXlab platform.

  • Geometrically nonlinear analysis of thin-walled open-section composite beams
    Computers & Structures, 2010
    Co-Authors: Jaehong Lee
    Abstract:

    A Geometrically nonlinear model for general thin-walled open-section composite beams with arbitrary lay-ups under various types of loadings based on the classical lamination theory is presented. It accounts for all structural coupling coming from the material anisotropy and Geometric Nonlinearity. Nonlinear governing equations are derived and solved by means of an incremental Newton-Raphson method. The finite element model that accounts for the Geometric Nonlinearity in the von Karman sense is developed to solve the problem. Numerical results are obtained for thin-walled composite Z-beam and I-beam to investigate effects of Geometric Nonlinearity, fiber orientation and warping restraint on the flexural-torsional response.

  • Geometrically nonlinear analysis of thin-walled composite box beams
    Computers & Structures, 2008
    Co-Authors: Jaehong Lee
    Abstract:

    A general Geometrically nonlinear model for thin-walled composite space beams with arbitrary lay-ups under various types of loadings has been presented by using variational formulation based on the classical lamination theory. The nonlinear governing equations are derived and solved by means of an incremental Newton-Raphson method. A displacement-based one-dimensional finite element model that accounts for the Geometric Nonlinearity in the von Karman sense is developed. Numerical results are obtained for thin-walled composite box beam under vertical load to investigate the effect of Geometric Nonlinearity and address the effects of the fiber orientation, laminate stacking sequence, load parameter on axial-flexural-torsional response.