Fuzzy arithmetic and solving of the static governing equations of fuzzy finite element method

2002 ◽  
Vol 23 (9) ◽  
pp. 1054-1061 ◽  
Author(s):  
Guo Shu-xiang ◽  
Lü Zhen-zhou ◽  
Feng Li-fu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fuzzy Arithmetic ◽  
Governing Equations ◽  
Fuzzy Finite Element ◽  
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.

Coupled Thermoelasticity Analysis of Annular Laminate Disk Using Laplace Transform and Galerkin Finite Element Method

2014 ◽  
Vol 656 ◽  
pp. 298-304 ◽  
Author(s):  
S.M. Nowruzpour Mehrian ◽  
Amin Nazari ◽  
Mohammad Hasan Naei
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Thermal Shock ◽  
Outer Edge ◽  
Galerkin Finite Element Method ◽  
Governing Equations ◽  
Space Domain ◽  
Annular Disk ◽  
Galerkin Finite Element ◽  
Element Method

In this paper, a dynamic analysis of annular laminate disk under radial thermal shock is carried out by employing a Galerkin Finite Element (GFE) approach. The governing equations, including the equation of the motion and energy equation are obtained based on Lord-Shulman theory. These two equations are solved simultaneously to obtain the displacement components and temperature distributions. A simply support boundary condition through outer edge is assumed for the annular disk. The inner radius is subjected to thermal shock and free of any traction. The outer edge is keeping at a constant temperature. Using Laplace transfer technique to transfer the governing equations into the space domain, where the Galerkin Finite Element Method is employed to obtain the solution in space domain. The inverse of Laplace transfer is performed numerically to achieve the final solution in the real time domain. The results are validated with the known data reported in the literature.

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.

A Least-Squares/Galerkin Finite Element Method for Incompressible Navier-Stokes Equations

2008 ◽  
Author(s):  
Rajeev Kumar ◽  
Brian H. Dennis
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Least Squares ◽  
Basis Functions ◽  
Galerkin Finite Element Method ◽  
Governing Equations ◽  
Galerkin Finite Element ◽  
First Order ◽  
Convection Dominated ◽  
Element Method

The least-squares finite element method (LSFEM), which is based on minimizing the l2-norm of the residual, has many attractive advantages over Galerkin finite element method (GFEM). It is now well established as a proper approach to deal with the convection dominated fluid dynamic equations. The least-squares finite element method has a number of attractive characteristics such as the lack of an inf-sup condition and the resulting symmetric positive system of algebraic equations unlike GFEM. However, the higher continuity requirements for second-order terms in the governing equations force the introduction of additional unknowns through the use of an equivalent first-order system of equations or the use of C1 continuous basis functions. These additional unknowns lead to increased memory and computing time requirements that have prevented the application of LSFEM to large-scale practical problems, such as three-dimensional compressible viscous flows. A simple finite element method is proposed that employs a least-squares method for first-order derivatives and a Galerkin method for second order derivatives, thereby avoiding the need for additional unknowns required by pure a LSFEM approach. When the unsteady form of the governing equations is used, a streamline upwinding term is introduced naturally by the leastsquares method. Resulting system matrix is always symmetric and positive definite and can be solved by iterative solvers like pre-conditioned conjugate gradient method. The method is stable for convection-dominated flows and allows for equalorder basis functions for both pressure and velocity. The stability and accuracy of the method are demonstrated with preliminary results of several benchmark problems solved using low-order C0 continuous elements.

Uncertain Static and Dynamic Analysis of Imprecisely Defined Structural Systems

2014 ◽  
pp. 357-382
Author(s):  
S. Chakraverty ◽  
Diptiranjan Behera
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Fuzzy System ◽  
Eigenvalue Problems ◽  
Linear Equations ◽  
System Of Linear Equations ◽  
Static And Dynamic Analysis ◽  
Fuzzy Finite Element ◽  
Element Method

This chapter presents the static and dynamic analysis of structures with uncertain parameters using fuzzy finite element method. Uncertainties presents in the parameters are modelled through convex normalised fuzzy sets. Fuzzy finite element method converts the structures into fuzzy system of linear equations and fuzzy eigenvalue problem for static and dynamic problems respectively. As such method to solve fuzzy system of linear equations, fully fuzzy system of linear equations and fuzzy eigenvalue problems are presented. These methods are applied to various structural problems to find out the fuzzy static and dynamic responses of the structures. Also the chapter analyses the numerical solution of uncertain fractionally damped spring-mass system. Uncertainties considered in the initial condition of the system.

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