Experimental Determination of Non-Ideal Structural Boundary Conditions Based on Spectral Element Model

2006 ◽  
Vol 326-328 ◽  
pp. 1625-1628
Author(s):  
Joo Yong Cho ◽  
Usik Lee
Keyword(s):  
Boundary Conditions ◽  
Element Model ◽  
Spectral Element ◽  
Ideal Boundary ◽  
Beam Structures ◽  
Effective Boundary ◽  
Vibration Responses ◽  
Structural Boundary ◽  
Spring Constants

In this paper, experiments are conducted to determine the non-ideal boundary conditions (BCs) of example beam structures. The spectral element (SE)-model is used for the beam structures, and the non-ideal BCs are represented by the frequency-dependent effective boundary springs. The boundary spring constants are then determined from the measured FRF-data. It is shown that the vibration responses analytically predicted by using experimentally identified BCs are very close to the measurements.

scholarly journals Stiffness Estimation and Equivalence of Boundary Conditions in FEM Models

2021 ◽  
Vol 11 (4) ◽  
pp. 1482
Author(s):  
Róbert Huňady ◽  
Pavol Lengvarský ◽  
Peter Pavelka ◽  
Adam Kaľavský ◽  
Jakub Mlotek
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Boundary Conditions ◽  
Model Updating ◽  
Element Model ◽  
Computational Time ◽  
Stiffness Coefficients ◽  
First Case ◽  
Numerical Approaches

The paper deals with methods of equivalence of boundary conditions in finite element models that are based on finite element model updating technique. The proposed methods are based on the determination of the stiffness parameters in the section plate or region, where the boundary condition or the removed part of the model is replaced by the bushing connector. Two methods for determining its elastic properties are described. In the first case, the stiffness coefficients are determined by a series of static finite element analyses that are used to obtain the response of the removed part to the six basic types of loads. The second method is a combination of experimental and numerical approaches. The natural frequencies obtained by the measurement are used in finite element (FE) optimization, in which the response of the model is tuned by changing the stiffness coefficients of the bushing. Both methods provide a good estimate of the stiffness at the region where the model is replaced by an equivalent boundary condition. This increases the accuracy of the numerical model and also saves computational time and capacity due to element reduction.

scholarly journals Frequency Domain Spectral Element Model for the Vibration Analysis of a Thin Plate with Arbitrary Boundary Conditions

2016 ◽  
Vol 2016 ◽  
pp. 1-20 ◽  
Author(s):  
Ilwook Park ◽  
Taehyun Kim ◽  
Usik Lee
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Rectangular Plate ◽  
Element Model ◽  
Spectral Element ◽  
Plate Element ◽  
Arbitrary Boundary ◽  
Arbitrary Boundary Conditions ◽  
Plate Elements ◽  
Rectangular Plate Element

We propose a new spectral element model for finite rectangular plate elements with arbitrary boundary conditions. The new spectral element model is developed by modifying the boundary splitting method used in our previous study so that the four corner nodes of a finite rectangular plate element become active. Thus, the new spectral element model can be applied to any finite rectangular plate element with arbitrary boundary conditions, while the spectral element model introduced in the our previous study is valid only for finite rectangular plate elements with four fixed corner nodes. The new spectral element model can be used as a generic finite element model because it can be assembled in any plate direction. The accuracy and computational efficiency of the new spectral element model are validated by a comparison with exact solutions, solutions obtained by the standard finite element method, and solutions from the commercial finite element analysis package ANSYS.

scholarly journals On the Modeling of Beam Reinforced Thin Plates Using the Spectral Element Method

2008 ◽  
Vol 15 (3-4) ◽  
pp. 425-434 ◽  
Author(s):  
N.B.F. Campos ◽  
J.R.F. Arruda
Keyword(s):  
Boundary Conditions ◽  
Spectral Element Method ◽  
Low Frequency ◽  
Element Model ◽  
Spectral Element ◽  
Computational Effort ◽  
Boundary Element Methods ◽  
Thin Plates ◽  
Arbitrary Boundary ◽  
Element Method

Modeling beam reinforced thin plates at mid and high frequencies through the most commonly used methods such as finite and boundary element methods frequently leads to unsatisfactory results, since the accuracy of these methods depends on the relation between the dimensions of the elements in which the structure was discretized and the wavelength. Due to this characteristic, the modeling using these techniques will require that the size of the elements becomes smaller as the frequency increases, while its number needs to be increased. For structures that are usual in some areas, like the aerospace industry, this will be possible only with an unreasonable computational effort, which is responsible for restricting the use of these methods practically to low-frequency applications. Semi-analytical methods such as the spectral element method do not need mesh refinement at higher frequencies, but they were very limited in the geometries and boundary conditions that can be treated. This paper presents a spectral element for rectangular thin plates reinforced symmetrically along the sides with Euler beams, which can be used to model plates with arbitrary boundary conditions. The method was verified by comparing its results with those obtained from a Finite Element model.

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