Elsevier Science Internet Homepage http://www.elsevier.nl (Europe) http://www.elsevier.com (America) http://www.elsevier.co.jp (Asia) Full catalogue information on all books, journals and electronic products. Elsevier Titles of Related Interest Mathematics of Finite Elements & Applications Ed. John Whiteman ISBN: 0080435688 (Forthcoming) APCOM'99- 4th Asia Pacific Conference on Computational Mechanics Ed. K.H. Lee ISBN: 0080432093 (Forthcoming) Deformation and Progressive Failure in Geomechanics Ed. A. Asaoka, T. Adachi, F. Oka ISBN: 008042838X CREAM- Cognitive Reliability and Error Analysis Method Erik Hollnagel ISBN: 0080428487 Engineering Rock Mechanics: An Introduction to Principles John A.Hudson & John P. 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This book has been reproduced in its entirety directly from the original manuscripts of the authors. First edition 1999 Library of Congress Cataloging in Publication Data A catalog record from the Library of Congress has been applied for. British Library Cataloguing in Publication Data A catalogue record from the British Library has been applied for. ISBN: 0 08 043570 X HC @ The paper used in this publication meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper). Printed in The Netherlands. NOTE FROM THE EDITORS The first EPMESC Conference took place in 1985. As explained several times since then, the idea of the Conference was due to Prof Tadahiko Kawai, then Professor of the University of Tokyo, and to the first Editor of these proceedings. The late Prof Luo Songfa, from the South China Institute of Technology, became our Chinese colleague in the Organising Committee. It will never be too much remembering his enthusiastic contribution for the organisation of the first EPMESC Conference, and for making it a significant scientific event in the Region. The Government of Macao agreed in sponsoring right from the beginning. Dr. Jorge Rangel, then Secretary for Education (he became later President of the Macao Foundation and, still later, again member of the Government of Macao), was the highly qualified representative of the Territory Administration with whom the Committee dialogued since the very beginning. The first EPMESC Conference could take place, therefore, in the summer of 1985. It was during the Conference, and recognising the success it had been, that the promoters decided to organise other EPMESC conferences, giving birth to a new series of international meetings devoted to computational methods in engineering. The second Conference was held in the South China Institute of Technology (now called the South China University of Technology-SCUT), in Guangzhou, the fourth in the Dalian University of Technology, under the chairmanship of Prof. Zhong Wanxie, and the sixth in the South China University of Technology, under the chairmanship of Prof. Han Dajian. The University of Macao, the venue chosen for the first, the third and the fifth, will host also the seventh. The interest of the Chinese scientific community in these meetings explains in part their remarkable success. Special acknowledgements are due, however, to the authorities of Macao, namely His Excellency the Governor, General Vasco da Rocha Vieira, himself a civil engineer, who was already the Governor when the 5th EPMESC was held, and the Secretary for Education, Dr. Jorge Rangel, a humanist who perfectly understands the role of Science and Technology in the development of societies. The Macao Foundation, presided by Antonio Rodrigues Junior, was the main local funding agency. A word of acknowledgement is due also to the Territory academic, scientific and cultural institutions, as well as to other kind of sponsors whose complete list is to be made public during the Conference. The University of Macao and the Laboratory of Civil Engineering of Macao are the two best examples to be quoted, for the active support provided to the Organisation from the beginning. It is amazing how much the Macao scientific and higher education community and system have progressed since fifteen years ago, when the first EPMESC Conference took place. Many other changes took place, however. On one hand, China, the main actor of the EPMESC Conferences, together with Europe, became one of the great scientific powers of the World. The economical crisis of the Region, which seems to have spared such a gigantic nation, did not stop its scientific growth. On the other hand, the global scientific reality, as well as that of the Asia-Pacific Region, have also changed. For this reason, the acronym EPMESC has now evolved to a more universal meaning. The variety of subjects covered by the papers submitted to the 7th Conference demonstrates how much computational methods expanded and became richer in their applications to Science and Technology. New paradigms are being cultivated as non-numerical applications started to compete with the more traditional numerical ones. The scientific and technological communities to which the EPMESC Conferences use to be addressed themselves have changed. The two-volume Proceedings that we achieved to gather represent many of the interesting developments that are taking place, not only in the Asia Pacific Region, but also in some other ν vi scientifically advanced parts of the World, and cover a vast list of subjects grouped under the following headings: Applied Mathematics Physics and Materials Science Solid Mechanics Finite Element and Boundary Element Methods Structural Analysis Structural Dynamics and Earthquake Engineering Structural Engineering Reinforced Concrete Knowledge-Based Systems Artificial Neural Networks and Genetic Algorithms Computer-Aided Instruction Computer-Aided Design and Computer-Aided Engineering Geographic Information Systems Environmental Applications Road Engineering Geotechnics Soil Mechanics Fluid Mechanics and Hydraulics 251 summaries were accepted, many of them with comments and restrictions, by the Programme Committee. From these, 153 papers resulted, many of them from Portuguese and Chinese origin, that were submitted to the revision of an international panel of referees from Australia, Belgium, Brazil, China, Italy, Macao, Portugal, Switzerland, United Kingdom and United States, to which we gladly acknowledge our gratitude and appreciation. We are happy to say that the reviewing process, although having to be done within the short time frame available, was quite successful and contributed a lot to the high quality that the Organising Committee aimed to attain. Some papers were deeply changed by their authors, according to the referees' comments. Some others had, unfortunately, to be rejected. In what concerns the keynote lecturers, whose choice certainly is one of the most important factors of success in any scientific conference, a great care was put in inviting them. Invitations were addressed to eminent professors, from China, Europe, the United States, Australia and Japan. It is for us a great honour and pleasure that almost all of them accepted to co-operate. Their presence in Macao will ensure that the aims of the Organising Committee will be met. E. Arantes e Oliveira Joâo Bento Eduardo Pereira PREFACE In his famous work entitled The Decline of the West, published shortly after the 1st World War, Oswald Spengler included, as one of its main ideas, a refusal to see modern science as a continuation or perfectionning of ancient science. The latter was, according to Spengler, a creation of a different nature, as, for example, modern art is different from ancient art. Each one reached, like art itself, its ideal point of perfection. In other words, modern European science was a creation of the Renaissance and so, although using medieval philosophy as an intellectual crutch, a late creation by Western culture. Thus, why would other civilisations adopt as theirs this kind of science and transform it into an adjectiveless Science, instead of using their own scientific systems ? Wouldn't it have been because such a kind of knowledge could have technological consequences which, when used, could make it possible the solution of problems which were or became, in all these societies, similar to the West's ? The need for social-economic development depends, obviously, on the structure of the societies, their aims, their spiritual values, their human and natural resources and the problems they intend to solve. In some cases, Western scientific knowledge was used by other civilisations having as their aims such goals that had nothing to do with the ideals which had given the inspiration for its development. However, the impact which resulted from the encounters, not always peaceful, of the different civilisations with Western civilisation, the fact that Europe became politically dominant, for a while, in a huge proportion of the Globe, the seduction of success when achieved, and the fact that the amount of communication established between the different parts of the Globe brought to the surface new and analogous problems throughout the Earth, had the result, for every society, of producing a need for those technologies which only the West possessed. In more recent times, the tendency to use these technologies was brought about, in certain non- Western countries, mainly in Eastern Asia, by the need to compete and position themselves in other continent's markets. There could have been few cases, thus, in which Technology wasn't the vehicle used for the Western scientific system to merge into the heart of the remaining civilisations. However, the majority of times, the West gave its techniques without giving its knowledge, at least to permit those in the receiving to develop it. The promoters of the EPMESC series of conferences, both from the Asia Pacific Region and from the West, were aware of these facts. The EPMESC project was thus aimed to promote scientific methods in the Asia Pacific Region. And the EPMESC meetings were successful enough to become, at least in the broad area of computational methods in engineering, the longest series of international conferences in the Region. The EPMESC Conferences were initially devoted to the Education, Practice and Promotion of Computational Methods in Engineering Using Small Computers. These objectives, which were deemed adequate in 1985, when the series started, have later been extended to accommodate the evolution of technology and the generalisation of the use of computational tools to a broader range of scientific fields. The emphasis became thus associated, under the same acronym, to the Enhancement and Promotion of Computational Methods in Engineering and Science. * The first EPMESC Conference was held in Macao in 1985. Since then, the Conferences have been held alternatively in Macao and in mainland China. It was in 1557 that the Portuguese settled in Macao. China was then the most important country in the World and the Europeans came to China with feelings of respect and admiration. vii viii The Territory of Macao was thus not taken by force. It was graciously granted by the great Central Empire to serve as a base for merchants and missionary/scientists whose activity was regarded with great interest by China. Portugal, the strange and semi-barbarian (as seen by Chinese) Ta Si Yan Kuo, the Country of the Western Ocean, was useful to China, and the Chinese pragmatism prevailed upon any other feeling or consideration. The Portuguese, pragmatic as well, remained in Macao, wisely avoiding understand too clearly which was the statute assigned to them. The best definition of the traditional statute of Macao is perhaps the one given by the 1976 Portuguese Constitution: a Chinese Territory under Portuguese Administration. Under the long lasting Portuguese administration, Macao, which was once compared to Venice as a kind of city-state, knew highly prosperous periods, particularly when it served as a link between China and Japan. The city was strongly affected by the isolation of Japan under the Tokugawa. Subsequently, the rise of Hong Kong drove the Territory to an increasing oblivion, transforming it almost into an interesting historical relic. But, about twenty years ago, following the example of most countries in the Region, Macao initiated a new cycle of economic prosperity and became again what had been before: a door between China and the Western World. * The appearance of computers in the middle of the 20th Century caused in Science and Engineering what can be called the second revolution (the first being launched by the use of Science in Engineering). The new possibilities, enabling engineers to make more extensive use of existing scientific tools, allowed them also to access to fields that had previously been considered to lie outside their sphere of interest. On the other hand, computers brought with them another possibility: that of computing automation. Making it necessary the modelling and programming of analysis, computing-automation raised problems, however, that simply did not exist before the advent of computers. In an article published in 1964, Charles Miller, then Head of the Civil Engineering Department of the MIT, made an analysis - now historic - of the perverse effects that the use of computers was then having on civil engineering. His accurate criticisms were partly overcome by the extraordinary development of the machines, particularly in what concerned capacity and speed. From their side, computer scientists answered the challenge by developing non-numerical computational techniques that are being spread among engineers and scientists. The modelling of knowledge-based processes and, in particular, its modelling within an engineering environment, may be said to correspond to a recent endeavour, largely resulting from the extension of early attempts to enhance computer-aided engineering tasks confusingly gathered under the CAE acronym. EPMESC Conferences series is long enough to make it clear how this evolution has taken place, and the organisers of the present Conference are proud that a large number of papers on non-numerical computational methods have been included in the present proceedings. * In December 1999, shortly after the Vllth EPMESC Conference, Macao will cease to be a Chinese Territory under Portuguese Administration to become a Chinese Territory under Chinese Administration. Such major political change may represent a stimulus for Macao to reinforce its role as a traditional meeting point between Eastern and Western cultures. ix With its calm atmosphere, its young University and modern scientific institutions, the specificity of its culture, its excellent infrastructures, Macao may namely become one of the favourite places in China for hosting international scientific meetings. The Chairman of the EPMESC VII Organising Committee Eduardo R. de Arantes e Oliveira To Contact the Publisher Elsevier Science welcomes enquiries concerning publishing proposals; books, journals special issues, conference proceedings etc. All formats and media can be accommodated. Should you have a publishing proposal you wish to discuss, please contact, without obligation, the publisher responsible for Elsevier's civil and structural engineering publishing programme; Dr. Jim Hough Publishing Editor Materials Science and Engineering Elsevier Science Ltd The Boulevard, Langford Lane Phone: +44 (0)1865 843879 Kidlington, Oxford Fax: +44(0)1865 843920 0X5 1GB, UK E-mail: [email protected] General enquiries including placing orders, should be directed to Elsevier's Regional Sales Offices- please access the Elsevier homepage for full contact details. FINITE ELEMEN T MODELLIN G OF CONTINUOU S CASTIN G S. Cescotto 1, A.M . Habraken1, F . Pascon1, F . Labory2 and M. Bourdouxhe2 1 University of Liège, MS M Department, Belgium 2 ARBE D Research and Development, Luxembourg ABSTRACT The surfac e and internal quality of continuous cast semis depends very much on the behaviour of th e strand in the mould. The mould taper is one of the most important parameters likely to influence it. In order to understand and to predict this behaviour, we have developed a finite element mode l that should lead us to determine the thermal shrinkage of the strand and the stress an d strain fields in the solidified shell. This paper presents our assumptions and the different tool s that we have developed especially for this model. The final results are not already achieve d with this complete model, but a simpler model has already provided results. These firs t results allowed us to define the taper of the mould so that the thermal exchange conditions ar e improved. KEYWORDS continuous casting , mould taper, modelling, finite element INTRODUCTION It is well known that, among the parameters likely to influence the breakouts or the surface and th e internal quality of the continuous cast semis, the mould taper takes a prominent part. Up t o now, physical phenomena involved in the continuous casters are not totally known or understood, i n spite of all the past and current researches on the topic. However, th e steel producer has to determine as accurately as possible the taper of his moulds for the continuous casting of his semis. This determination is usually carried out empirically or b y using a mathematical model. 3 4 For the totally convex cross sections like blooms or billets, the taper is positive on the whole outline. In this case, the consequences of a taper that is too low are a loss of contact and a gap between the strand and the mould. The thermal exchange and the shell growth decrease dramatically, the section can get out of shape and the product can be affected by surface or subsurface defects or even breakouts. The consequence of a taper that is too high is friction between the strand and the mould, inducing stresses and strains in the solidifying shell. Like in above case, the consequences can be surface or subsurface defects or breakouts. For more complex cross sections showing a partly concave outline, like a beam blank for instance, the taper can be negative on a part of the outline. For a negative taper, a value that is too low leads to friction between the strand and the mould, inducing stresses and strains in the solidifying shell, and a value that is too high leads to a loss of contact and an insufficient thermal exchange and shell growth. In both cases, the consequences can be defects or breakouts. The goal of this study is to model the solidification of a 125 mm χ 125 mm billet in a mould the taper of which is equal to 0.65625 mm/m (see Figure 1). 125 mm A Ζ 700 mm 600 mm LIQUID STEEL SECONDARY COOLING (WATER SPRAY) MUSHY ZONE SOLIDIFIED SHELL Figure 1 : Strand in the mould We only deal with the first part of the cast (primary cooling), when the strand is still in the mould. The next part (secondary cooling by water spray), after the exit of the mould, needs another model that is not the topic of this paper. GENERAL MODEL DESCRIPTION The models are based on a finite element method and more specifically on the non linear code LAG AMINE developed in University of Lièg e by the team of professor S. Cescotto since 1982. Able to simulate various forming processes, this code takes into account non linear phenomena a s large strains, large displacements or rotations, various non linear constitutive laws, contact and friction. Staggered or fully coupled thermo-mechanical analysis are