Multiaxial Notch Fatigue

Metal and composite components used in structural engineering not only contain geometrical features resulting in stress concentration phenomena, but they are also subjected to in-service multiaxial fatigue loading. To address the problem, structural engineers need reliable methodologies which allow for an adequate margin of safety. The book summarises methods devised by the author to design real components against multiaxial fatigue by taking full advantage not only of nominal but also of local stress-strain quantities. The book begins by reviewing definitions suitable for calculating the stress-strain quantities commonly used to perform fatigue assessment. The Modified Wöhler Curve Method is then explained in detail, by focusing attention on both the high- and the medium-cycle fatigue regime. The existing links between the multiaxial fatigue criterion and physical properties are also discussed. A procedure suitable for employing the method developed by the author to estimate fatigue damage both in notched and in welded components is explained. The Modified Manson-Coffin Curve method is investigated in depth, by reviewing those concepts playing a fundamental role in the so-called strain based approach. Lastly, the problem of performing the fatigue assessment of composite materials is addressed by considering design parameters influencing composite behaviour under complex cyclic loading paths and those criteria suitable for designing real components against multiaxial fatigue. The book also contains two appendices summarising experimental data from the technical literature. These appendices provide a unique and highly valuable resource for engineers. The appendices summarise around 100 values of the material characteristic length L, experimentally determined by testing specimens made of different engineering materials and about 4500 experimental fatigue results generated by testing plain, notched and welded specimens under constant-amplitude proportional and non-proportional multiaxial fatigue loading are listed. Summarises methods devised by the author to design real components against multiaxial fatigue Reviews definitions suitable for calculating the stress-strain quantities commonly used to perform fatigue assessment Includes an in-depth explanation of both the Modified Wöhler Curve and Modified Manson-Coffin Curve Method

This book presents the unified fatigue life prediction equation for low/medium/high cycle fatigue of metallic materials relevant to plain materials and notched components. The unified fatigue life prediction equation is the Wöhler equation, in which the "stress-based intensity parameter" is calculated based on the linear-elastic analysis. A local approach for the static fracture analysis for notched components is presented based on the notch linear-elastic stress field. In the local approach, a stress intensity parameter is taken as a stress-based intensity parameter. Experimental verifications show that the local approach is also suited for the static fracture analysis for notched components made of ductile materials. The book is also concerned with a material failure problem under the multiaxial stress states. A concept of the material intensity parameter is introduced in this book. It is a material property parameter that depends on both Mode-I fracture toughness and Mode-II (or Mode-III) fracture toughness and the multiaxial parameter to characterize the variation of the material failure resistance (notch fracture toughness) with the multiaxial stresses states. The failure condition to assess mixed-mode fracture of notched (or cracked) components is stated as the stress-based intensity parameter being equal to the material intensity parameter. With respect to the traditional S-N equation, a similar S-N equation is presented and verified to have high accuracy. This book will be of interest to professionals in the field of fatigue and fracture for both brittle and ductile materials.

This book provides practicing engineers, researchers, and students with a working knowledge of the fatigue design process and models under multiaxial states of stress and strain. Readers are introduced to the important considerations of multiaxial fatigue that differentiate it from uniaxial fatigue.

"This book presents unified fatigue life prediction equations for a low/medium/high cycle fatigue of metallic materials, relevant to plain materials and notched components. The book enables the reader to tackle the failure problem of notched components and presents a new type of S-N equation. Detailing material intensity parameters, which are dependent on both the uniaxial material strength and the stress multiaxial parameter, the book then looks at the failure condition of these materials. Covering the Wöhler Curve Method, which is most suited to low-cycle fatigue life analysis of metallic materials, the book also includes chapters on mechanical quantities, linear-elastic stress analysis and multiaxial fatigue. The book will be of interest to professionals working in the field of fatigue, fracture, stress and metallic materials"--

Papers presented at the ASTM Symposium on Multiaxial Fatigue, held in San Diego, November 1991, to communicate the most recent international advances in multiaxial cyclic deformation and fatigue research as well as applications to component analysis and design. The 24 papers are grouped into five ca

The European Structural Integrity Society (ESIS) Technical Commitee on Fatigue of Engineering Materials and Structures (TC3) decided to compile a Special Technical Publication (ESIS STP) based on the 115 papers presented at the 6th International Conference on Biaxial/Multiaxial Fatigue and Fracture. The 25 papers included in the STP have been extended and revised by the authors. The conference was held in Lisbon, Portugal, on 25-28 June 2001, and was chaired by Manual De Freitas, Instituto Superior Tecnico, Lisbon. The meeting, organised by the Instituto Superior Tecnico and sponsored by the Portuguese Minesterio da Cienca e da Tecnologia and by the European Structural Integrity Society, was attended by 151 delegates from 20 countries. The papers in the present book deal with the theoretical, numerical and experimental aspects of the Multiaxial fatigue and fracture of engineering materials and structures. They are divided in to the following six sections; Multiaxial Fatigue of Welded Structures; High cycle Multiaxial fatigue; Non proportional and Variable-Amplitude loading; Defects, Notches, Crack Growth; Low Cycle Multiaxial Fatigue; Applications and Testing Methods. As is well-known, most engineering components and structures in the mechanical, aerospace, power generation, and other industries are subjected to multiaxial loading during their service life. One of the most difficult tasks in design against fatigue and fracture is to translate the information gathered from uniaxial fatigue and fracture tests on engineering materials into applications involving complex states of cyclic stress-strain conditions. This book is the result of co-operation between many researchers from different laboratories, universities and industries in a number of countries.

The present work aims at engineers and scientists in the field of computational mechanics of materials. The objective of this work is to develop a suitable constitutive law and apply it to study effects of cyclic loading and geometry on the fatigue assessment. Firstly, a systematical investigation on the mechanic behaviors of an austenitic stainless steel is carried out. Different multiaxial fatigue life prediction models are studied to assess fatigue damage. The Karim-Ohno kinematic hardening model is extended to incorporate more complex mechanical behaviors. The proposed constitutive model is implemented into FEM code ABAQUS. Finally a computational fatigue analysis methodology is proposed for performing life prediction of notched components based on elastic-plastic computation.