scholarly journals A Spatial Euler-Bernoulli Beam Element for Rigid-Flexible Coupling Dynamic Analysis of Flexible Structures

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Zhigang Zhang ◽  
Zhaohui Qi ◽  
Zhigang Wu ◽  
Huiqing Fang
Keyword(s):  
Dynamic Analysis ◽  
Cross Sections ◽  
Degrees Of Freedom ◽  
Flexible Structures ◽  
Nonlinear Dynamic Analysis ◽  
Beam Element ◽  
Small Time ◽  
Time Interval ◽  
Slender Beams ◽  
New Formulation

A two-node spatial beam element with the Euler-Bernoulli assumption is developed for the nonlinear dynamic analysis of slender beams undergoing arbitrary rigid motions and large deformations. During the analysis, the global displacement and rotation vectors with six degrees of freedom are selected as the nodal coordinates. In addition, the “shear locking” problem is avoided successfully since the beam cross-sections are always perpendicular to the current neutral axes by employing a special coupled interpolation of the centroid position and the cross-section orientation. Then a scheme is presented where the original transient strains representing the nodal forces are replaced by proposed average strains over a small time interval. Thus all the high frequencies can be filtered out and a corresponding equivalent internal damping will be produced in this new formulation, which can improve the computation performance of the proposed element for solving the stiff problem and evaluate the governing equations even by using the nonstiff ordinary differential equation solver. Finally, several numerical examples are carried out to verify the validation and efficiency of this proposed formulation by comparison with the analytical solutions and other research works.

A Study on the Use of Reduced Order Models for Unsteady Fluid Dynamic Analysis of Flexible Structures

2012 ◽  
Author(s):  
L. Ebrahimnejad ◽  
H. Yadollahi Farsani ◽  
D. T. Valentine ◽  
K. D. Janoyan ◽  
P. Marzocca
Keyword(s):  
Dynamic Analysis ◽  
Cross Sections ◽  
Fluid Dynamic ◽  
Flexible Structures ◽  
Reduced Order Models ◽  
Computationally Efficient ◽  
Reduced Order ◽  
Long Span ◽  
Long Span Bridge ◽  
Unsteady Fluid

Reduced order models (ROMs) are computationally efficient techniques, which have been widely used for predicting unsteady aerodynamic response of airfoils and wings. However, they have not been applied extensively to perform unsteady fluid dynamic analysis of flexible structures in civil engineering. This paper discusses the application of reduced order computational fluid dynamics (CFD) model based on the eigensystem realization algorithm (ERA) in the aerodynamic analysis of flexible structures with arbitrary shaped cross sections. As an example of a civil structure we examine the GBB long-span bridge for which there are published experimental data. The aerodynamic impulse responses of the GBB Bridge are used to construct the ROM, and then the aerodynamic forces due to arbitrary inputs are evaluated and compared to those of the model coupled with an advanced CFD code. Results demonstrate reasonable prediction power and high computational efficiency of the technique that can serve for preliminary design, optimization and control purposes. The methodology described in this paper has wide application in many offshore engineering problems where flexible structures interact with unsteady fluid mechanical phenomena.

scholarly journals Evaluasi Kinerja Seismik Rangka Beton Pemikul Momen Khusus dengan PERFORM-3D

2019 ◽  
Vol 25 (1) ◽  
pp. 27
Author(s):  
Junaedi Utomo ◽  
Januarti Jaya Ekaputri ◽  
Antonius Antonius ◽  
Han Ay Lie
Keyword(s):  
Dynamic Analysis ◽  
Seismic Performance ◽  
Nonlinear Model ◽  
Cross Sections ◽  
Nonlinear Dynamic ◽  
Lateral Displacement ◽  
Nonlinear Dynamic Analysis ◽  
Performance Level ◽  
Reinforced Concrete Frame ◽  
Concrete Frame

Seismic performance of reinforced concrete frame Buildings which have been designed as Special Moment Resisting Frames in accordance to three Indonesian codes (SNI 1727-2013, SNI 1726-2012 and SNI 2847-2013) can be evaluated using nonlinear dynamic analysis. Criteria related to strength such as component plastic rotation capacity, lateral displacement as well as criteria related to damage of elements in the structures were used to evaluate the seismic performance of the buildings. Assessment to the moment and curvature capacities of the cross sections of beams and columns were done using XTRACT. The global seismic performance of the structures depends on the seismic performance of components in the structures. In nonlinear model of the structures, the degrading strength of the components were modeled to take into account the gradual reduction of the contributed components to the resistance of the structures. PERFORM-3D is one of the software that can be used to generate nonlinear model of structures. Seismic performance level of structures can be obtained from the results of the nonlinear dynamic analysis using PERFORM-3D. The Seismic performance level can be utilized for: (1) detecting any weaker part in the structures, and (2) evaluating the improved design of the structures for enhancing the seismic performance of structures.

Nonlinear Dynamic Analysis of Cantilever Beam Using POD Based Reduced Order Model

2015 ◽  
Vol 786 ◽  
pp. 398-403 ◽  
Author(s):  
Kulkarni Atul Shankar ◽  
Manoj Pandey
Keyword(s):  
Dynamic Analysis ◽  
Large Deformation ◽  
Cantilever Beam ◽  
Nonlinear Dynamic ◽  
Degrees Of Freedom ◽  
Numerical Technique ◽  
Nonlinear Dynamic Analysis ◽  
Reduced Order Model ◽  
Order Model ◽  
Reduced Order

In this paper, a reduced order model is obtained for nonlinear dynamic analysis of a cantilever beam. Nonlinearity in the system is basically due to large deformation. A reduced order model is an efficient method to formulate low order dynamical model which can be obtained from data obtained from numerical technique such as finite element method (FEM). Nonlinear dynamical models are complex with large number of degrees of freedom and hence, are computationally intensive. With formulation of reduced order models (i.e. Macromodels) number of degrees of freedom are reduced to fewer degrees of freedom by using projection based method like Galerkin’s projection, so as to make system computationally faster and cost effective. These macromodels are obtained by extracting global basis functions from fully meshed model runs. Macromodels are generated using technique called proper orthogonal decomposition (POD) which gives good linear fit for the nonlinear systems. Using POD based macromodel, response of system can be computed using fewer modes instead of considering all modes of system. Macromodel is generated to obtain the response of cantilever beam with large deformation and hence, simulation time is reduced by factor of 90 approximately with error of order of 10-4. Further, method of POD based reduced order model is aplied to beam with different loading conditions to check the robustness of the macromodel. POD based macromodel response gives good agreement with FEA model response for a cantilever beam.

Dynamic modelling of flexible structures using a local frame formulation

1999 ◽  
Vol 213 (7) ◽  
pp. 645-653 ◽  
Author(s):  
G A Chochia ◽  
P K Chawdhry ◽  
C R Burrows
Keyword(s):  
High Speed ◽  
Flexible Structures ◽  
Dynamic Modelling ◽  
Element Formulation ◽  
Local Frame ◽  
Incremental Method ◽  
Slender Beams ◽  
Simplifying Assumptions ◽  
New Formulation ◽  
Inertia Forces

In this paper a new finite element formulation for slender beams is suggested that is valid for large rotations and deflections. Traditional formulations such as the floating frame approach and the incremental method are limited to small deflections, which restricts the scope of their applicability to small accelerations. In the local frame formulation no simplifying assumptions are made in accounting for the inertia forces. As the formalism remains consistent with large deflections it can be used for accurate evaluation of deformations caused by inertia forces at large accelerations. The paper is concerned with multibeam plane motions. The new formulation is implemented as a computer algebra tool that generates dynamic equations of flexible multibody systems from specifications. A number of case studies related to high-speed machinery are presented.

Nonlinear Dynamic Analysis of Beck’s Problem by Using Simple Models

1983 ◽  
Vol 7 (2) ◽  
pp. 65-75
Author(s):  
H. Ohmori ◽  
Y. Hangai ◽  
H. Tanaka
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Finite Element Model ◽  
Dynamic Analysis ◽  
Nonlinear Dynamic ◽  
Degrees Of Freedom ◽  
Nonlinear Dynamic Analysis ◽  
Element Model ◽  
Mechanical Models ◽  
Lateral Displacements

This paper deals with a nonlinear, dynamic analysis of Beck’s rod, trying to explain discrepancies between analysis and experiment and taking axial and lateral displacements of the rod into account. The numerical analysis was carried out for discrete mechanical models of the rod involving four and eight degrees-of-freedom as well as for a finite element model. Results obtained were thoroughly discussed and compared with known results stemming from previous linear treatments of Beck’s rod.

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