Scalar finite-element evaluation of cut-off wavelength in glass wave guides and comparison with experiment

1990 ◽  
Vol 68 (11) ◽  
pp. 1251-1256 ◽  
Author(s):  
Guy Lamouche ◽  
S. Iraj Najafi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Single Mode ◽  
First Order ◽  
Comparison With Experiment ◽  
Wave Guides ◽  
Channel Waveguides ◽  
Element Method

The scalar finite-element method is used to analyze ion-exchanged glass channel waveguides. Cut-off wavelengths for fundamental and first-order modes are calculated and the single-mode region is determined. The results are compared with the experimentally measured values.

scholarly journals Stress Analysis of Polarization Maintaining Optical Fibers by the Finite Element Method

1970 ◽  
Vol 1 (1) ◽  
Author(s):  
M. H. Aly A. S. Farahat, M. S. Helmi and M. Farhoud
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Optical Fibers ◽  
Radial Distance ◽  
Single Mode ◽  
The Finite Element Method ◽  
Modal Birefringence ◽  
Polarization Maintaining ◽  
External Forces ◽  
Element Method

Stress-induced birefringence in single mode polarization maintaining optical fibers has been investigated using the finite element method. The modal birefringence caused by external forces in the Panda and the Side Tunnel fibers are calculated. It is found that the modal birefringence is directly proportional to the radial distance from the fiber center. As expected, the modal birefringence vanishes with the variation in the magnitude of the applied external loads.Key Words: Birefringence, Polarization, Panda Fiber, Side-Pit Fiber, Finite Element Method.

Simulation and Analysis of Cantilever-Membrane Structure for Piezoresistive Micro-Accelerometers

2012 ◽  
Vol 503 ◽  
pp. 87-90 ◽  
Author(s):  
Yan Liu ◽  
Yu Long Zhao ◽  
Lu Sun
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Natural Frequency ◽  
Frequency Band ◽  
Membrane Structure ◽  
Measurement Sensitivity ◽  
First Order ◽  
Working Frequency ◽  
Element Method

Dynamic and static performances are the most important parameters for accelerometers. The natural frequency decides the sensor’s working frequency band, and the accompanying stress represents the measurement sensitivity. In this paper, a novel sensing structure, cantilever-membrane structure, for piezoresistive accelerometers is studied, in order to detect the structural dimension’s effect on the sensor. With the help of FEM (Finite element method) software, the first order natural frequency of the cantilever-membrane based accelerometer is investigated with the different combinations of membrane’s dimensions. The accompanying stress of the sensing structure is also simulated in this paper. The results show that the membrane’s dimensions affect the frequency and stress more tempestuously when the membrane is short, but the tendency become gentle when the width of the membrane increases.

Eigenvector and eigenvalue analysis of thick plates resting on elastic foundation with first order finite element

2018 ◽  
Vol 4 (2) ◽  
pp. 61
Author(s):  
Yaprak Itır Özdemir
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Aspect Ratio ◽  
Free Vibration ◽  
Vibration Analysis ◽  
Free Vibration Analysis ◽  
Winkler Foundation ◽  
Thick Plates ◽  
First Order ◽  
Element Method

The purpose of this paper is to study free vibration analysis of thick plates resting on Winkler foundation using Mindlin’s theory with first order finite element, to determine the effects of the thickness/span ratio, the aspect ratio, subgrade reaction modulus and the boundary conditions on the frequency parameters of thick plates subjected to free vibration. In the analysis, finite element method is used for spatial integration. Finite element formulation of the equations of the thick plate theory is derived by using first order displacement shape functions. A computer program using finite element method is coded in C++ to analyze the plates free, clamped or simply supported along all four edges. In the analysis, 4-noded finite element is used. Graphs are presented that should help engineers in the design of thick plates subjected to earthquake excitations. It is concluded that 4-noded finite element can be effectively used in the free vibration analysis of thick plates. It is also concluded that, in general, the changes in the thickness/span ratio are more effective on the maximum responses considered in this study than the changes in the aspect ratio.

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.

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