Determination of Nonideal Beam Boundary Conditions: A Spectral Element Approach

AIAA Journal ◽  
10.2514/2.958 ◽  
2000 ◽  
Vol 38 (2) ◽  
pp. 309-316 ◽  
Author(s):  
Usik Lee ◽  
Joohong Kim
Keyword(s):  
Boundary Conditions ◽  
Spectral Element ◽  
Element Approach

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.

Vectorial thin-element approximation: a semirigorous determination of Kirchhoff's boundary conditions

2007 ◽  
Vol 24 (4) ◽  
pp. 1074 ◽  
Author(s):  
Norbert Kerwien ◽  
Thomas Schuster ◽  
Stephan Rafler ◽  
Wolfgang Osten ◽  
Michael Totzeck
Keyword(s):  
Boundary Conditions ◽  
Element Approximation

Generalized plane stress in a semi-infinite strip under arbitrary end-load

1964 ◽  
Vol 281 (1385) ◽  
pp. 184-206 ◽  
Keyword(s):  
Differential Equation ◽  
Ordinary Differential Equation ◽  
Boundary Conditions ◽  
Fourth Order ◽  
Plane Stress ◽  
Stress Function ◽  
Infinite Strip ◽  
Order Ordinary Differential Equation ◽  
Orthogonal Functions

The problem involves the determination of a biharmonic generalized plane-stress function satisfying certain boundary conditions. We expand the stress function in a series of non-orthogonal eigenfunctions. Each of these is expanded in a series of orthogonal functions which satisfy a certain fourth-order ordinary differential equation and the boundary conditions implied by the fact that the sides are stress-free. By this method the coefficients involved in the biharmonic stress function corresponding to any arbitrary combination of stress on the end can be obtained directly from two numerical matrices published here The method is illustrated by four examples which cast light on the application of St Venant’s principle to the strip. In a further paper by one of the authors, the method will be applied to the problem of the finite rectangle.

Sign in / Sign up

Export Citation Format

Share Document