scholarly journals Fuzzy finite element method for frequency response function analysis of uncertain structures

AIAA Journal ◽  
2002 ◽  
Vol 40 ◽  
pp. 126-136
Author(s):  
D. Moens ◽  
D. Vandepitte
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Function Analysis ◽  
Fuzzy Finite Element ◽  
Uncertain Structures ◽  
Element Method

scholarly journals Evaluate the Impact of Cold Wave on Face Slab Cracking Using Fuzzy Finite Element Method

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Dongjian Zheng ◽  
Lin Cheng ◽  
Yanxin Xu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Temperature Drop ◽  
Extension Principle ◽  
Cold Wave ◽  
Prevention Measures ◽  
Fuzzy Variables ◽  
Fuzzy Finite Element ◽  
The Impact ◽  
Element Method

We use fuzzy finite element method (FEM) to analyze the impact of cold wave on face slab cracking of a concrete-faced rockfill dam (CFRD). The static response of dam and the temperature field of face slab are calculated using deterministic FEM since some observed and test data can be obtained. Some parameters of Goodman contact element between face slabs and cushion material are selected as fuzzy variables, and the fuzzy FEM is used to calculate fuzzy stress of face slab. The fuzzy FEM is implemented using vertex method based on the extension principle. Through the analysis of two selected calculation cases of cold wave, it is shown that the calculated cracking direction and cracking zone caused by thermal stress are similar to those of the observed cracks. This proves that the cold wave that caused swift air temperature drop is an important reason for the cracking of face slab. According to these analysis results, some cracking prevention measures are then proposed.

Change of modal parameters due to crack growth in a tripod tower platform

1993 ◽  
Vol 20 (5) ◽  
pp. 801-813 ◽  
Author(s):  
Yin Chen ◽  
A. S. J. Swamidas
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Experimental Results ◽  
Modal Testing ◽  
Modal Parameters ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Strain Frequency

Strain gauges, along with an accelerometer and a linear variable displacement transducer, were used in the modal testing to detect a crack in a tripod tower platform structure model. The experimental results showed that the frequency response function of the strain gauge located near the crack had the most sensitivity to cracking. It was observed that the amplitude of the strain frequency response function at resonant points had large changes (around 60% when the crack became a through-thickness crack) when the crack grew in size. By monitoring the change of modal parameters, especially the amplitude of the strain frequency response function near the critical area, it would be very easy to detect the damage that occurs in offshore structures. A numerical computation of the frequency response functions using finite element method was also performed and compared with the experimental results. A good consistency between these two sets of results has been found. All the calculations required for the experimental modal parameters and the finite element analysis were carried out using the computer program SDRC-IDEAS. Key words: modal testing, cracking, strain–displacement–acceleration frequency response functions, frequency–damping–amplitude changes.

Structural Reliability Analysis Using Fuzzy Finite Element Method

2013 ◽  
Vol 471 ◽  
pp. 306-312 ◽  
Author(s):  
A.Y.N. Yusmye ◽  
B.Y. Goh ◽  
A.K. Ariffin
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Classical Method ◽  
Practical Method ◽  
Main Role ◽  
Structural Reliability Analysis ◽  
Fuzzy Finite Element ◽  
Element Method

The main requirement in designing a structure is to ensure the structure is reliable enough to withstand loading and the reliability study of structure. Classical and probability approach was introduced to analyse structural reliability. However, the approaches stated above are unable to take into account and counter the uncertainties arising from the natural of geometry, material properties and loading. This leads to the reduction in accuracy of the result. The goal of this study is to assess and determine the reliability of structures by taking into consideration of the epistemic uncertainties involved. Since it is crucial to develop an effective approach to model the epistemic uncertainties, the fuzzy set theory is proposed to deal with this problem. The fuzzy finite element method (FFEM) reliability analysis conducted has shown this method produces more conservative results compared to the deterministic and classical method espacially when dealing with problems which have uncertainties in input parameters. In conclusion, fuzzy reliability analysis is a more suitable and practical method when dealing with structural reliability with epistemic uncertainties in structural reliability analysis and FFEM plays a main role in determining the structural reliability in reality.

NUMERICAL METHOD FOR VOICE GENERATION PROBLEM BASED ON FINITE ELEMENT METHOD

2006 ◽  
Vol 14 (01) ◽  
pp. 45-56 ◽  
Author(s):  
TAKASHI KAKO ◽  
KENTAROU TOUDA
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Helmholtz Equation ◽  
Frequency Response ◽  
Frequency Response Function ◽  
Bounded Region ◽  
Artificial Boundary ◽  
Complex Eigenvalues ◽  
The Voice ◽  
Generation Problem

In this paper, we consider the numerical method for the voice generation problem. The basic mathematical model for the voice generation is the Helmholtz equation in an unbounded region. Introducing an artificial boundary, we divide the unbounded region into a bounded region and the rest unbounded one with a simple shape. We apply the finite element method for the equation in the bounded region imposing an artificial boundary condition given through the Dirichlet to Neumann (DtN) mapping on the artificial boundary. We then compute the frequency response function or the formant curve by which we can simulate the voice generation process for various vowels. The complex eigenvalues related to the Helmholtz equation control the peaks of the frequency response function known as formants. We give the variational formulas for the complex eigenvalues with respect to the variation of vocal tract boundary.

scholarly journals GEODYNAMICS

GEODYNAMICS ◽  
2011 ◽  
Vol 2(11)2011 (2(11)) ◽  
pp. 38-40
Author(s):  
S. T. Verbytskyi ◽  
◽  
N. Rozhok ◽  
T. B. Brych ◽  
B. Ye. Kuplovskyi ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Comparative Analysis ◽  
Frequency Response ◽  
Dynamic Characteristics ◽  
Surface Layers ◽  
Amplitude Frequency Response ◽  
Unknown Structure ◽  
Element Method

In order to confirm the possibility of using the method of Nakamura in the study of surface layers of unknown structure, the authors carried out a comparative analysis of solid amplitude-frequency response research by both of modified Nakamura’s technique and finite element method on the estimating dynamic characteristics of surface layers.

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