The homogeneous problem

2014 ◽  
pp. 177-190
Author(s):  
Mark Kot
Keyword(s):  
Homogeneous Problem

An Effective Numerical Approach for Multiple Void-Crack Interaction

2005 ◽  
Vol 73 (4) ◽  
pp. 525-535 ◽  
Author(s):  
Xiangqiao Yan
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Elastic Plate ◽  
Homogeneous Problem ◽  
Crack Problem ◽  
General System ◽  
Numerical Approach ◽  
Displacement Discontinuity ◽  
Crack Problems ◽  
Element Method

This paper presents a numerical approach to modeling a general system containing multiple interacting cracks and voids in an infinite elastic plate under remote uniform stresses. By extending Bueckner’s principle suited for a crack to a general system containing multiple interacting cracks and voids, the original problem is divided into a homogeneous problem (the one without cracks and voids) subjected to remote loads and a multiple void-crack problem in an unloaded body with applied tractions on the surfaces of cracks and voids. Thus the results in terms of the stress intensity factors (SIFs) can be obtained by considering the latter problem, which is analyzed easily by means of the displacement discontinuity method with crack-tip elements (a boundary element method) proposed recently by the author. Test examples are included to illustrate that the numerical approach is very simple and effective for analyzing multiple crack/void problems in an infinite elastic plate. Specifically, the numerical approach is used to study the microdefect-finite main crack linear elastic interaction. In addition, complex crack problems in infinite/finite plate are examined to test further the accuracy and robustness of the boundary element method.

scholarly journals Some Time Stepping Methods for Fractional Diffusion Problems with Nonsmooth Data

2018 ◽  
Vol 18 (1) ◽  
pp. 129-146 ◽  
Author(s):  
Yan Yang ◽  
Yubin Yan ◽  
Neville J. Ford
Keyword(s):  
Initial Data ◽  
Convergence Rate ◽  
Homogeneous Problem ◽  
Fractional Diffusion ◽  
Nonsmooth Data ◽  
Time Stepping ◽  
Time Discretisation ◽  
Nonsmooth Initial Data ◽  
Densely Defined ◽  
Diffusion Problems

AbstractWe consider error estimates for some time stepping methods for solving fractional diffusion problems with nonsmooth data in both homogeneous and inhomogeneous cases. McLean and Mustapha [18] established an {O(k)} convergence rate for the piecewise constant discontinuous Galerkin method with nonsmooth initial data for the homogeneous problem when the linear operator A is assumed to be self-adjoint, positive semidefinite and densely defined in a suitable Hilbert space, where k denotes the time step size. In this paper, we approximate the Riemann–Liouville fractional derivative by Diethelm’s method (or L1 scheme) and obtain the same time discretisation scheme as in McLean and Mustapha [18]. We first prove that this scheme has also convergence rate {O(k)} with nonsmooth initial data for the homogeneous problem when A is a closed, densely defined linear operator satisfying some certain resolvent estimates. We then introduce a new time discretisation scheme for the homogeneous problem based on the convolution quadrature and prove that the convergence rate of this new scheme is {O(k^{1+\alpha})}, {0<\alpha<1}, with the nonsmooth initial data. Using this new time discretisation scheme for the homogeneous problem, we define a time stepping method for the inhomogeneous problem and prove that the convergence rate of this method is {O(k^{1+\alpha})}, {0<\alpha<1}, with the nonsmooth data. Numerical examples are given to show that the numerical results are consistent with the theoretical results.

Heat Transfer Analysis of Local Evaporative Turbulent Falling Liquid Films

1992 ◽  
Vol 114 (3) ◽  
pp. 688-694 ◽  
Author(s):  
N. M. Al-Najem ◽  
K. Y. Ezuddin ◽  
M. A. Darwish
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Homogeneous Problem ◽  
Interfacial Shear Stress ◽  
Liquid Films ◽  
Heat Transfer Analysis ◽  
Tube Length ◽  
Prandtl Numbers ◽  
Falling Liquid Films

A theoretical study has been conducted for evaporative heating of turbulent free-falling liquid films inside long vertical tubes. The methodology of the present work is based on splitting the energy equation into homogeneous and nonhomogeneous problems. Solving these simple problems yields a rapidly converging solution, which is convenient for computational purposes. The eigenvalues associated with the homogeneous problem can be computed efficiently, without missing any one of them, by the sign-count algorithm. A new correlation for the local evaporative heat transfer coefficient along the tube length is developed over wide ranges of Reynolds and Prandtl numbers. Furthermore, the average heat transfer coefficient is correlated as a function of Reynolds and Prandtl numbers as well as the interfacial shear stress. A correlation for the heat transfer coefficient in the fully developed region is also presented in terms of Reynolds and Prandtl numbers. Typical numerical results showed excellent agreement of the present approach with the available data in the literature. Moreover, a parametric study is made to illustrate the general effects of various variables on the velocity and temperature profiles.

On Multiple Inhomogeneities in Plane Elasticity

2019 ◽  
Author(s):  
Elie Honein ◽  
Tony Honein ◽  
Michel Najjar ◽  
Habib Rai
Keyword(s):  
Homogeneous Problem ◽  
Analytical Techniques ◽  
Plane Elasticity ◽  
Plane Case ◽  
Schwarz Alternating Method ◽  
Innovative Methods ◽  
Arbitrary Loading ◽  
The Matrix ◽  
Homogeneous Matrix ◽  
Made In

Abstract In this paper we present some new analytical techniques which have been recently developed to solve for problems of circular elastic inhomogeneities in anti-plane and plane elasticity. The inhomogeneities may be composed of different materials and have different radii. The matrix may be subjected to arbitrary loadings or singularities. The solution to this heterogeneous problem is sought as a transformation performed on the solution of the corresponding homogeneous problem, i.e., the problem when all the inhomogeneities are removed and the homogeneous matrix is subjected to the same loading/singularities, a procedure which has been dubbed ‘heterogenization’. In previous works, a single inhomogeneity or hole has been considered and the transformation has been shown to be purely algebraic in the antiplane case and involves differentiation of the Kolosov-Mushkelishvili complex potentials in the plane case. Universal formulas, i.e., formulas which are independent of the loading/singularities, that express the stresses at the inter-face of the inhomogeneity in terms of the stresses that would have existed at the same interface had the inhomogeneity been absent, have been be derived. The solution for a single inhomogeneity bonded to a matrix which is subjected to arbitrary loading/singularities can then in principle be used systematically in a Schwarz alternating method to obtain the solution for multiple inhomogeneities to any degree of accuracy. However alternative and innovative methods have been sought which lead to a much faster convergence and in some cases to exact expressions in terms of infinite series. The aim of this paper is to present some of the progress that has been made in this direction.

scholarly journals Solving higher order Fuchs type differential systems avoiding the increase of the problem dimension

1994 ◽  
Vol 17 (1) ◽  
pp. 91-102
Author(s):  
E. Navarro ◽  
L. Jódar ◽  
R. Company
Keyword(s):  
Homogeneous Problem ◽  
Higher Order ◽  
Closed Form Expression ◽  
Power Series Solution ◽  
Matrix Equations ◽  
Form Expression ◽  
Initial Value ◽  
Generalized Power Series ◽  
The Matrix ◽  
Problem Dimension

In this paper, we develop a Frobenius matrix method for solving higher order systems of differential equations of the Fuchs type. Generalized power series solution of the problem are constructed without increasing the problem dimension. Solving appropriate algebraic matrix equations a closed form expression for the matrix coefficient of the series are found. By means of the concept of ak-fundamental set of solutions of the homogeneous problem an explicit solution of initial value problems are given.

Periodic solutions of forced Liénard equations with jumping nonlinearities under nonuniform conditions

1988 ◽  
Vol 110 (3-4) ◽  
pp. 183-198 ◽  
Author(s):  
R. Iannacci ◽  
M.N. Nkashama ◽  
P. Omari ◽  
F. Zanolin
Keyword(s):  
Differential Equation ◽  
Asymptotic Behaviour ◽  
Periodic Solutions ◽  
Homogeneous Problem ◽  
A Priori ◽  
Critical Values ◽  
Liénard Equations ◽  
Jumping Nonlinearities ◽  
Existence Of Periodic Solutions ◽  
Image Position

SynopsisThis paper is devoted to the existence of periodic solutions for the scalar forced Lienard differential equationThe key assumptions relate the asymptotic behaviour as x →± ∞of g(t; x)/x to the “critical values” of the positively 1-homogeneous problemNo condition on f, except continuity, is assumed. Our approach is based on Leray–Schauder degree techniques and a priori estimates.

Structural Health Monitoring of Cracked Beam by the Dual Reciprocity Boundary Element Method

2012 ◽  
Vol 538-541 ◽  
pp. 1634-1639 ◽  
Author(s):  
Andrea Alaimo ◽  
Alberto Milazzo ◽  
Calogero Orlando
Keyword(s):  
Structural Health Monitoring ◽  
Boundary Element ◽  
Health Monitoring ◽  
Electrical Response ◽  
Mass Matrix ◽  
Homogeneous Problem ◽  
Element Model ◽  
Cracked Beam ◽  
Structural Health ◽  
Element Technique

In this paper a 2D boundary element model is used to characterize the transient response of a piezoelectric based structural health monitoring system for cracked beam. The BE model is written for piezoelectric non-homogeneous problem employing generalized displacements. The dual reciprocity method is used to write the mass matrix in terms of boundary parameters only. The multidomain boundary element technique is implemented to model non-homogeneous and cracked configuration, unilateral interface conditions are also considered to prevent the physical inconsistence of the overlapping between interface nodes belonging to the crack surfaces. To assess the reliability and the effectiveness of the model numerical analyses are carried out on the modal and dynamic response of undamaged beam and results are compared with finite element calculations. Electrical response of piezoelectric sensors are then reported for different crack configurations in comparison with the undamaged case.

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