A Unified Statistical Methodology for Modeling Fatigue Damage

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.