A numerical solution for axially symmetrical elasticity problems

An integral equation method is presented for the solution of axially symmetrical elasticity problems. The obtained integral equations are of second kind with regular (Fredholm) and singular kernel. The method is suited to the treament of both simply and multiply connected regions with irregular boundary shapes and any boundary load distribution which satisfies the equilibrium conditions. Numerical results are included.     

The solution of elasticity problems for the half-space by the method of Green and Collins

The paper reviews the method of complex potential functions developed by Green and Collins as applied to axisymmetric mixed boundary value problems in elasticity for the half-space. It is shown how the method can be applied to problems in several coupled potential functions such as adhesive and frictional contact problems, to problems involving annular regions and to problems in thermoelasticity. Attention is given to the question of choosing a formulation which leads to a well-behaved numerical solution. Tables are given of the most commonly needed inversion formulae and of expressions for total load and stress intensity factor.     

A mixed finite volume formulation for the solution of gradient elasticity problems

The present works aims at solving the equations of dipolar gradient elasticity via the finite volume method. Initially, a general, mixed, finite volume formulation is stated. As a first approach, the equations of 1D and 2D gradient elasticity are solved via the proposed method. Numerical implementation shows that the suggested model is in excellent agreement with analytic solutions. The approach seems to be promising for extension to 3D problems also.     

A numerical method for separation of stresses in photo-orthotropic elasticity

A numerical method is suggested for separation of stresses in photo-orthotropic elasticity using the numerical solution of compatibility equation for orthotropic case. The compatibility equation is written in terms of a stress parameter S analogous to the sum of principal stresses in two-dimensional isotropic case. The solution of this equation provides a relation between the normal stresses. The photoelastic data give the shear stress and another relation between the two normal stresses. The accuracy of the numerical method and its application to practical problems are illustrated with examples.     

A numerical study on the solution of the Cauchy problem in elasticity

This work deals with the Cauchy problem in two-dimensional linear elasticity. The equations of the problem are discretized through a standard FEM approach and the resulting ill-conditioned discrete problem is solved within the frame of the Tikhonov approach, the choice of the required regularization parameter is accomplished through the Generalized Cross Validation criterion. On this basis a numerical experimentation has been performed and the calculated solutions have been used to highlight the sensitivity to the amount of known data, the noise always present in the data, the regularity of boundary conditions and the choice of the regularization parameter. The aim of the numerical study is to implicitly device some guidelines to be used in the solution of this kind of problems.     

A new method for the Lebedev-Ufliand integral equation for contact problems of elasticity

Let a circular flat punch penetrate a finitely thick slab resting on a rigid foundation. Lebedev and Ufliand showed that the determination of the stresses and displacements can be reduced to solving the Fredholm integral equation{ie181-1}We show how to reduce this integral equation to a Cauchy system in which plays the role of the time-like variable. Numerical experiments show the computational efficacy.

---

Zusammenfassung Man lasse einen flachen, kreisrunden Durchschlag in eine auf einer steifen Unterlage ruhenden Platte von endlicher Dicke eindringen. Lebedeff und Ufliand haben gezeigt wie das Bestimmen der Drücke und Verschiebungen zurückgeführt werden kann auf die Losung der Integralgleichung von Fredholm,{ie181-1}Wir zeigen, wie man dieses Problem auf ein Cauchysystem reduziert, worin der Parameter t die Rolle der Zeit spielt. Ein numerisches Beispiel illustriert die digitale Lösbarkeit.

     

A general solution to some plane problems of micropolar elasticity

We obtain a general solution to the field equations of plane micropolar elasticity for materials characterized by a hexagonal or equilateral triangular structure. These materials exhibit 3-fold symmetry in the plane and the elastic response is isotropic. Utilizing two displacement potential functions, the solution is obtained in terms of two analytic functions and a third function satisfying the modified homogeneous Helmholtz equation. Expressions for the two-dimensional components of displacement, stress, and couple stress, along with the resultant force on a contour, are presented. We observe that micropolar effects are most significant in material regions subjected to large deformation gradients. Specific results are presented for the classical crack problem, the half plane loaded uniformly on the surface, Flamant's problem, and the circular cylinder compressed by equal and opposite concentrated forces.     

Applications of the extrapolation method to the numerical solution of singular perturbation problems

In this paper we consider applications of extrapolation method to the numerical solution of singular perturbation problem for elliptic—parabolic equation in order to manifesting accuracy of approximations and estimate the order of accuracy. Concerning the uniform convergence in ref. [1], its proof is given in the appendix.     

A rate type method for large deformation problems of nonlinear elasticity

ＡＲＡＴＥＴＹＰＥＭＥＴＨＯＤＦＯＲＬＡＲＧＥＤＥＦＯＲＭＡＴＩＯＮＰＲＯＢＬＥＭＳＯＦＮＯＮＬＩＮＥＡＲＥＬＡＳＴＩＣＩＴＹＬｉａｎｇＦｅｉ（梁非）,ＺｈａｎｇＳｈａｎ－ｙｕａｎ（张善元）（ＴａｉｙｕａｎＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈｎｏｌｏｇｙ...     

A general method for the incremental solution of elastic-plastic problems

Summary A general iterative method for the incremental solution of elastic-plastic problems is described. The convergence of the procedure on the rigorous solution is demonstrated.

---

Sommario Si espone un procedimento iterativo generale per la soluzione incrementale dei problemi elasto-plastici. Si dimostra la convergenza del procedimento verso la soluzione effettiva.

---

---

The results presented in this paper were obtained in the course of research sponsored by the C.N.R., Gruppo Plasticità     

A discontinuous Galerkin scheme for the numerical solution of flow problems with discontinuities

In this paper, a new discontinuous Galerkin finite element method for the numerical solution of flow problems with discontinuities is presented. The method is based on the limitation in every cell of the difference between the extrema values and the mean value of the numerical solution. The algorithm and technical details for the implementation of the method are presented in one‐and two‐dimensional problems. Numerical experiments for classical test problems are solved on unstructured triangulations to demonstrate the performance of the proposed method. Copyright © 2011 John Wiley & Sons, Ltd.     

A Petrov-Galerkin method for the numerical solution of the Bradshaw-Ferriss-Atwell turbulence model

The Bradshaw-Ferriss-Atwell model for 2D constant property turbulent boundary layers is shown to be ill-posed with respect to numerical solution. It is shown that a simple modification to the model equations results in a well-posed system which is hyperbolic in nature. For this modified system a numerical algorithm is constructed by discretizing in space using the Petrov-Galerkin technique (of which the standard Galerkin method is a special case) and stepping in the timelike direction with the trapezoidal (Crank-Nicolson) rule. The algorithm is applied to a selection of test problems. It is found that the solutions produced by the standard Galerkin method exhibit oscillations. It is further shown that these oscillations may be eliminated by employing the Petrov-Galerkin method with the free parameters set to simple functions of the eigenvalues of the modified system.