Bøger af Jean Salencon

The scale that concerns the practitioner in mechanics is usually qualified as macroscopic. Indeed, applications are rarely much below the human scale, and in order to be relevant models must be constructed on a similar scale, several orders of magnitude greater than the objects that are normally attributed to the physicist's sphere of interest. The mechanicist is therefore aware of the limits of these models, no matter how elegant their mathematical formulation may be, when the time comes far experimental validation. The mechanicist has a deep concern for the microscopic phenomena at the heart of what is being modelled, exposed by the physicist's research, which can today explain a wide range of material behaviour. The aim of this book is to present the general ideas behind continuum mechanics, thermoelasticity and one-dimensional media. Our approach to constructing mechanical models and modelling forces is based upon the principle oi virtual work. There are several advantages to thismethod. To begin with, it clearly emphasises the key role played by geometrical modelling, leading to mechanically consistent presentations in a systematic way. In addition, by requiring rigorous thought and clear formulation of hypotheses, it identifies the inductive steps and emphasises the need for validation, despite its axiomatic appearance. Moreover, once mastered, it will serve as a productive tool in the reader's later research career. This duality is used in the chapter devoted to variational methods for the solution of thermoelastic problems.

The theory of viscoelasticity has been built up as a mechanical framework for modeling important aspects of the delayed behavior of a wide range of materials. This book, primarily intended for civil and mechanical engineering students, is devoted specifically to linear viscoelastic behavior within the small perturbation framework. The fundamental concepts of viscoelastic behavior are first presented from the phenomenological viewpoint of the basic creep and relaxation tests within the simple one-dimensional framework. The linearity and non-ageing hypotheses are introduced successively, with the corresponding expressions of the constitutive law in the form of Boltzmann's integral operators and Riemann's convolution products respectively. Applications to simple quasi-static processes underline the dramatic and potentially catastrophic consequences of not taking viscoelastic delayed behavior properly into account at the design stage. Within the three-dimensional continuum framework, the linear viscoelastic constitutive equation is written using compact mathematical notations and takes material symmetries into account. The general analysis of quasi-static linear viscoelastic processes enhances similarities with, and differences from, their elastic counterparts. Simple typical case studies illustrate the importance of an in-depth physical understanding of the problem at hand prior to its mathematical analysis.

This book offers complete, practical guidance to all aspects yield design. It presents the core theory as the basis for the implementation of the Ultimate Limit State Design (ULSD) philosophy, emphasizing compatibility between equilibrium and resistance in yield design analyses.