INRIA, Institut National de Recherche en Informatique et en Automatique

For many years fatigue has been a significant and difficult problem for engineers, especially for those who design structures such as aircraft, bridges, pressure vessels, and cranes. Fatigue of engineering materials is commonly regarded as an important deterioration process and a principal mode of failure for various structural and mechanical systems. This book presents a unified approach to stochastic modeling of the fatigue phenomenon, particularly the fatigue crack growth process. The main approaches to construction of these stochastic models are presented to show their methodological consistency and potential usefulness in engineering practice. The analyses contained in this work should also inspire the development of new approaches for designing and performing fatigue experiments.

The topology optimization method solves the basic enginee- ring problem of distributing a limited amount of material in a design space. The first edition of this book has become the standard text on optimal design which is concerned with the optimization of structural topology, shape and material. This edition, has been substantially revised and updated to reflect progress made in modelling and computational procedures. It also encompasses a comprehensive and unified description of the state-of-the-art of the so-called material distribution method, based on the use of mathematical programming and finite elements. Applications treated include not only structures but also materials and MEMS.

Uncertainties about analytical models, fluctuations in loads, and variability of material properties contribute to the small but real probability of structure failures. This advanced engineering text describes methods developed to deal with stochastic aspects of structural behavior, providing a framework for evaluating, comparing, and combining stochastic effects. Starting with the general problem of consistent evaluation of the reliability of structures, the text proceeds to examination of the second-moment reliability index methods that describe failure in terms of one or more limit states. It presents first-order reliability methods for computation of failure probabilities for individual limit states and for systems; and it illustrates identification of the design parameters most affecting reliability. Additional subjects include a self-contained presentation of extreme-value theory and stochastic processes; stationary, evolutionary, and nonlinear aspects of stochastic response of structures; a stochastic approach to material fatigue damage and crack propagation; and stochastic models for several natural and manufactured loads.

In recent years, the Finite Element Methods FEM were more and more employed in development and design departments as very fast working tools in order to determine stresses, deformations, eigenfrequencies etc. for all kinds of constructions under complex loading conditions. Meanwhile. very effective software systems have been developed by various research teams although some mathematical problems (e. g. convergence) have not been solved satisfac torily yet. In order to make further advances and to find a common language between mathe maticians and mechanicians the "Society for Applied Mathematics and Mechanics" (GAMM) agreed on the foundation of a special Committee: "Discretization Methods in Solid Mechanics" focussing on the following problems: - Structuring of various methods (displacement functions, hybrid and mixed approaches, etc. >, - Survey of approach functions (Lagrange-/Hermite-polynominals, Spline-functions), - Description of singularities, - Convergence and stability, - Practical and theoretical optimality to all mentioned issues (single and interacting). One of the basic aims of the GAMM-Committee is the interdisciplinary cooperation between mechanicians, mathematicians, and users which shall be intensified. Thus, on September 22, 1985 the committee decided to hold a seminar on "Structural Optimization" in order to allow an exchange of experiences and thoughts between the experts of finite element methods and those of structural optimization. A GAMM-seminar entitled "Discretization Methods and Structural Optimization - Procedures and Applications" was hold on October 5-7, 1988 at the Unversity of Siegen.

Topology optimization of structures and composite materials is a new and rapidly expanding field of mechanics which now plays an ever-increasing role in most branches of technology, such as aerospace, mechanical, structural, civil and ma terials engineering, with important implications for energy production as well as building and environmental sciences. It is a truly "high-tech" field which requires advanced computer facilities and computational methods, whilst involving unusual theoretical considerations in pure mathematics. Topology optimization deals with some of the most difficult problems of mechanical sciences, but it is also of consid erable practical interest because it can achieve much greater savings than conven tional (sizing or shape) optimization. Extensive research into topology optimization is being carried out in most of the developed countries of the world. The workshop addressed the state of the art of the field, bringing together re searchers from a diversity of backgrounds (mathematicians, information scientists, aerospace, automotive, mechanical, structural and civil engineers) to span the full breadth and depth of the field and to outline future developments in research and avenues of cooperation between NATO and Partner countries. The program cov ered • theoretical (mathematical) developments, • computer algorithms, software development and computational difficulties, and • practical applications in various fields of technology. A novel feature of the workshop was that, in addition to shorter discussions after each lecture, a 30 minutes panel discussion took place in each sesssion, which made this ARW highly interactive and more informal.