Michal Zyczkowski – Författare

There is a tradition to organize IUTAM Symposia "Creep in Structures" every ten years: the first Symposium was organized by N.J. Hoff in Stan­ ford (1960), the second one by J. Hult in Goteborg (1970), and the third one by A.R.S. Ponter in Leicester (1980). The fourth Symposium in Cracow, September 1990, gathered 123 par­ ticipants from 21 countries and reflected rapid development of the theory, experimental research and structural applications of creep and viscoplas­ ticity, including damage and rupture. Indeed, the scope of the Sympo­ sium was broad, maybe even too broad, but it was kept according to the tradition. Probably the chairman of "Creep in Structures V" in the year 2000 (if organized at all) will be forced to confine the scope substantially. Participation in the Symposium was reserved for invited participants, suggested by members of the Scientific Committee. Total number of sug­ gestions was very large and the response - unexpectedly high. Apart from several papers rejected, as being out of scope, over 100 papers were accepted for presentation. A somewhat unconventional way of presenta­ tion was introduced to provide ample time for fruitful and well prepared discussions: besides general lectures (30 minutes each), all the remain­ ing papers were presented as short introductory lectures (10 minutes) followed by a I-hour poster discussion with the authors and then by a general discussion. Such an approach made it possible to present general ideas orally, and then to discuss all the papers through and through.

The first optimal design problem for an elastic column subject to buckling was formulated by Lagrange over 200 years ago. However, rapid development of structural optimization under stability constraints occurred only in the last twenty years. In numerous optimal structural design problems the stability phenomenon becomes one of the most important factors, particularly for slender and thin-walled elements of aerospace structures, ships, precision machines, tall buildings etc. In engineering practice stability constraints appear more often than it might be expected; even when designing a simple beam of constant width and variable depth, the width - if regarded as a design variable - is finally determined by a stability constraint (lateral stability). Mathematically, optimal structural design under stability constraints usually leads to optimization with respect to eigenvalues, but some cases fall even beyond this type of problems. A total of over 70 books has been devoted to structural optimization as yet, but none of them has treated stability constraints in a sufficiently broad and comprehensive manner. The purpose of the present book is to fill this gap. The contents include a discussion of the basic structural stability and structural optimization problems and the pertinent solution methods, followed by a systematic review of solutions obtained for columns, arches, bar systems, plates, shells and thin-walled bars. A unified approach based on Pontryagin's maximum principle is employed inasmuch as possible, at least to problems of columns, arches and plates. Parametric optimization is discussed as well.