Boundary Element Methods Proceedings of the Third International Seminar, Irvine, California, July 1981 Editor: C. A. Brebbia Seminar sponsored by the International Society for Computational Methods in Engineering With 232 Figures CML PUBLICATIONS Springer-Verlag Berlin Heidelberg GmbH 1981 Dr. CARLOS A. BREBBIA Computational Mechanical Centre 125 High Street Southampton England, SOl OAA ISBN 978-3-662-11272-4 ISBN 978-3-662-11270-0 (eBook) DOI 10.1007/978-3-662-11270-0 This work is subjekt to copyright. All rights are reserved, whether the whole or part of the material is oonoerned, specifically those of translation, reprinting, re-use of illustrations, broadQlS!ing. reproduction by photocopying machine or similar means, and storage in data banks. Under § 54 of the German Cqlyright Law where copies are rrnde for other than private use a fee is payable to 'Verwertungsgesellschaft Wort', Munich. © Springer-Verlag Berlin Heidelberg 1981 Originally published by Springer-Verlag Berlin Heidelberg New York in 1981 Softcover reprint of the hardcover I st edition 1981 The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free forge neral use. 2061/3020 - 543210 v CONTENTS Introductory Remarks IX C.A. Brebbia SECTION I POTENTIAL AND FLUID FLOI-1 PROBLEMS Two Methods for Computing the Capacitance of a 3 Quadrilateral G.T. Symm Boundary Element Solutions to the Eddy Current Problem 14 S.J. Salon, J.M. Sahneider and S. Uda Numerical Solution of the Diffusion Equation by a 26 Potential Method D.A.S. Curran, B.A. Lewis and M. Cross The Application of Boundary Elements to Steady and 37 Unsteady Potential Fluid Flow Problems in Two and Three Dimensions P.H.L. Groenenboom Computing Strategy in the Integral Equation Solution of 53 Limiting Gravity Waves in Water J.M. Williams SECTION II ELASTICITY PROBLEMS 69 On the Construction of the Boundary Integral 71 Representation and Connected Integral Equations for Homogeneous Problems of Plane Linear Elastostatics M. Pignole Regular Boundary Integral Equations for Stress 85 Analysis C. Patterson and M.A. Sheikh A Boundary Element Formulation of Problems in Linear 105 Isotropic Elasticity with Body Forces D.J. Danson VI A Comparative Study of Several Boundary Elements in 123 Elasticity M.F. Seabra Pereira, C.A. Mota Soares and L.M. Oliveira Faria Non-Conforming Boundary Elements for Stress Analysis 137 C. Patterson and M.A. Sheikh The Displacement Discontinuity Method in Three 153 Dimensions W. Scott Dunbar and D.L. Anderson A Unified Second Order Boundary Element Method for 174 Structures Analysis M. Dubois Method of Boundary Integral Equations for Analysis of 183 Three Dimensional Crack Problems J. Balas and J. Sladek Cyclic Symmetry and Sliding Between Structures by the 206 Boundary Integral Equation Method A. Chaudouet On Boundary Integral Equations for Circular 224 Cylindrical Shells H. Antes The Boundary Element Method applied to Two- 239 Dimensional Contact Problems with Friction T. Andersson Quasistatic Indentation of a Rubber covered Roll by a 259 Rigid Roll - The Boundary Element Solution R.C. Batra An Improved Boundary Element Method for Plate 272 Vibrations G.K.K. Wong and J.R. Hutchinson SECTION III GEOMECHANICS 291 Boundary Elements applied to Soil-Foundation 293 Interaction M. Ottenstreuer and G. Schmid The Implementation of Boundary Element Codes in 310 Geotechnical Engineering L.A. Wood Boundary Integral Method for Porous Media 325 M. Predeleanu VII SECTION IV MATERIAL PROBLEMS 335 Numerical Analysis of Cyclic Plasticity using the 337 Boundary Integral Equation Method M. Brunet New Developments in Elastoplastic Analysis 350 J.C.F. Telles and C.A. Brebbia The Boundary Element Method for the Solution of 371 No-Tension Materials W.S. Venturini and C. Brebbia SECTION V NUMERICAL TECHNIQUES AND MATHEMATICAL 397 PRINCIPLES Some Theoretical Aspects of Boundary Integral 399 Equations M.A. Jaswon On The Asymptotic Convergence of Boundary Integral 412 Methods W.L. Wendland Boundary Methods. C-Complete Systems for the 431 Biharmonic Equations H. Gourgeon and I. Herrera The Effect of Mesh Refinement in the Boundary Element 442 Solution of Laplace's Equation with Singularities H.L.G. Pina, J.L.M. Fernandes and C.A. Brebbia Boundary Element and Linear Programming Method in 457 Optimization of Partial Differential Equation Systems T. Futagami Approximate Fundamental Solutions and Alternative 472 Formulations S. Walker An Efficient Algorithm for the Numerical Evaluation 489 of Boundary Integral Equations M. Vahle and D.L. Sikarskie Solution of the Dirichlet Problem using the Reduction 504 to Fredholm Integral Equations J. Caldwell BEMSTAT -A New Type of Boundary Element Program for 518 Two-Dimensional Elasticity Problems L. Bolteus and 0. Tullberg VIII SECTION VI COUPLING OF BOUNDARY AND FINITE ELEMENT 539 METHODS Interfacing Finite Element and Boundary Element 541 Discretizations C.A. Felippa The Derivation of Stiffness Matrices from Integral 552 Equations F. Hartmann Three Dimensional Super-Element by the Boundary 567 Integral Equation Method for Elastostatics F. Volait The Coupling of Boundary and Finite Element Methods 575 for Infinite Domain Problems in Elasto-Plasticity G. Beer and J.L. Meek A Finite Element - Boundary Integral Scheme to 592 Simulate Rock-Effects on the Liner of an Underground Intersection B.A. Dendrou and S.A. Dendrou The Use of Green's Functions in the Numerical Analysis 609 of Potential, Elastic and Plate Bending Problems C. Katz IX INTRODUCTORY REMARKS C.A. Brebbia I . HISTORICAL NOTE The great interest that finite element methods have attracted in the engineering community since the beginning of 1960's has had two important consequences. I) it stimulated an impressive amount of work in computational techniques and efficient engineering software; 2) substantial research into basic physical principles such as variational techniques, weighted residuals, etc. was originated. The first of the above points came as a natural conse quence of the emergence of new and powerful computers which were able to solve engineering problems involving large amounts of numerical storage and manipulation. The development of mathematical techniques and basic principles came instead in response to the need of extending finite element modelling, assessing convergence and accuracy and understanding the relationship of finite elements to more classical variational principles and weighted residual techniques. These techniques can be traced to pre-computer times [1 ,2] and involve different ways of solving the governing equations of a problem, i.e, Galerkin, collocation, least-squares, line techniques, matrix progression or transfer, the combination of different techniques, etc. Fortunately they were not forgotten and they reappeared in the finite element literature, sometimes with different names, such as Galerkin finite elements, finite element strip-method, some time integration schemes, etc. Another important development iu approximate analysis was the investigation of mixed principles and the realization that physical problems c&< be expressed and solved in many different ways in accordance with the part or equations of the problem that we need to approximate. These approximations are of fundamental importance for the computer implementation of the different numerical techniques. Mixed methods can be traced to Reissner [3] and more specifically for finite elements to X Pian [4]. An excellent exposition of mixed methods in structural mechanics can be found in the book by Washizu [s]. [ntegral equation techniques were until recently considered to be a different type of analytical method, somewhat unrelated to approximate methods. They became popular in Westem Ettrope through the work of a series of Russian authors, such as Muskhelishvili [6], Mikhlin [7], Kupradze [8], and Smi mov [9] but were not very popular with engineers. A predecessor of some of this work was Kellogg [10] who applied integral equations for the solution of Laplace's type problems. Integral equation techniques were mainly used in fluid mechanics and general potential problems and known as the ' source' method which is an ' indirect' method of analysis; i.e. the unknowns are not the physical variables of the problem. Work on this method continued throughout the 1960s and 1970s in the pioneering work of Jaswon ITU and Symm [12], Massonet [13], Hess [14] and many others. It is difficult to point out precisely who was the first one to propose the 'direct' method of anal~sis. It is found in a different form, in Kupradze' s book IB J • It seems fair however from the engineering point of view to consider that the method originated in the work of Cruse and Rizzo [Is] in elastostatics. · Since the early 1960s a small research group started working at Southampton University, on the applications of integral e!}uations to solve stress analysis problems. Hadid's thesis [l6j partly based on Hadjin's [!7] work was published in 1964 and dealt with the use of integral equations in shell analysis. Unfortunately the presentation of the problem, the difficulty of defining the appropriate Green's functions and the parallel emergence of the finite element method all con tributed to minimize the importance of this work. This work was continued through a series of theses dealing mainly with elastostatics problems. Recent developments in finite elements had started to find their way into the formulation of boundary integral equations, specially in the idea of using general curved elements. Finally the question of how to effectively relate the boundary integral equations to other ap~roximate techniques was solved using weighted residuals [18J • The work at the Southampton University group culminated with the first book in 1978 for which the title "Boundary Elements" was used Qe]. More recently this work has been e~anded to encompass time dependent and non-linear problems L20]. Two important International Conferences were held at Southampton University in 19 78 and 1980. The edited Proceedings of these conferences - the only ones so far on this topic - are now standard references [21 ,22].