A Unified Statistical Methodology for Modeling Fatigue Damage

This book is an attempt to provide a uni?ed methodology to derive models for fatigue life. This includes S-N, ?-N and crack propagation models. This is not a conventional book aimed at describing the fatigue fundamentals, but rather a book in which the basic models of the three main fatigue approaches, the stress-based, the strain-based and the fracture mechanics approaches, are contemplated from a novel and integrated point of view. On the other hand, as an alternative to the preferential attention paid to deterministic models based on the physical, phenomenological and empirical description of fatigue, their probabilistic nature is emphasized in this book, in which stochastic fatigue and crack growth models are presented. This book is the result of a long period of close collaborationbetween its two authors who, although of di?erent backgrounds, mathematical and mechanical, both have a strong sense of engineering with respect to the fatigue problem. When the authors of this book ?rst approached the fatigue ?eld in 1982 (twenty six years ago), they found the following scenario: 1. Linear, bilinear or trilinear models were frequently proposed by relevant laboratoriesandacademiccenterstoreproducetheW¨ ohler?eld. Thiswas the case of well known institutions, which justi?ed these models based on clientrequirementsorpreferences. Thisledtotheinclusionofsuchmodels and methods as, for example, the up-and-down, in standards and o?cial practical directives (ASTM, Euronorm, etc.), which have proved to be unfortunate.

brings together state of the art in the field, and presents a unified approach of the subject Includes supplementary material: sn.pub/extras

Klappentext

This book aims to provide a unified methodology to derive models for fatigue life prediction. This includes S-N, e-N and crack propagation models. This book is unique in that it contemplates the three main fatigue approaches (stress-based, strain-based and fracture mechanics) from a novel and integrated point of view. As an alternative to the preferential attention paid to deterministic models based on the physical, phenomenological and empirical description of fatigue, their probabilistic nature is emphasized in this book, in which stochastic fatigue and crack growth models are presented.

After an introductory chapter in which an overview of the book is provided, the following chapters are devoted to derive models for the S-N fields for fixed and varying stress level, the e-N fields, the relations between the two, and an analysis of the size effect in fatigue problems. Next, crack grow models are derived based on fracture mechanics, statistical and common sense considerations, which lead to functional equations providing non-arbitrary models. Two different approaches are given, leading to two classes of models, the intersection class of which is derived through compatibility analysis. Then the compatibility of the S-N curves model and the crack growth model, which are two aspects of the same fatigue problem, are used to obtain a model which allows both approaches to be connected. Finally, the problem of selection damage measures is analyzed, and some damage measures are proposed as the most convenient, including the probability of failure and a normalized measure related to the percentile curve. This leads to very simple and useful damage accumulation models, which are illustrated with some examples.

The book ends with an appendix with a short description of some classical and some more recent fatigue models of those existing in the literature.

Inhalt
and Motivation of the Fatigue Problem.- Presentation of the Book. An Integrated Overview of the Fatigue Problem.- Models Used in the Stress Based Approach.- S-N or Wöhler Field Models.- Length Effect.- Models Used in the Strain Based Approach.- Log-Weibull ?-N Model.- Models Used in the Fracture Mechanics Approach.- Crack Growth Models.- Damage and Damage Accumulation Models.- Damage Measures.- Damage Accumulation.