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ASM Inteational_
Materials Park, Ohio 44073-0002
Copyright 2006 by ASM Inteational
First printing, March 2006
Library of Congress Cataloging-in-Publication Data
ISBN: 0-87170-825-6
Metal fatigue has long been associated with variations of stress and strain. In Wo?hler’s time, about 150 years ago, it was his identification of this fact that led him to the development of the rotating bending machine that has been used so effectively throughout the years to gain an understanding of the fatigue phenomenon and to characterize the fatigue resistance of many materials. In more recent years, as interest has grown in the study of high-strain, low-cycle fatigue, it has been recognized that the rotating bending test imposes limitations in the ability to measure and control stresses and strains, especially when plastic strains are present. Bending also subjects a specimen to a wide variation of stress-strain conditions through its cross section, and even if these conditions can be properly analyzed, only a small volume of material undergoes the maximum stress and strain. By using axially strained specimens, wherein the entire test section volume is under the same conditions, greater volumes of material can be fatigued. Furthermore, using axial straining allows stress and strain to be measured and controlled more accurately. New testing equipment has been highly developed for controlling stress, strain, or any combination of parameters, so as to give special meaning to the control variables. In this chapter, we concentrate our discussion of material behavior under uniaxial stress and strain cycling.
ASM Inteational_
Materials Park, Ohio 44073-0002
Copyright 2006 by ASM Inteational
First printing, March 2006
Library of Congress Cataloging-in-Publication Data
ISBN: 0-87170-825-6
Metal fatigue has long been associated with variations of stress and strain. In Wo?hler’s time, about 150 years ago, it was his identification of this fact that led him to the development of the rotating bending machine that has been used so effectively throughout the years to gain an understanding of the fatigue phenomenon and to characterize the fatigue resistance of many materials. In more recent years, as interest has grown in the study of high-strain, low-cycle fatigue, it has been recognized that the rotating bending test imposes limitations in the ability to measure and control stresses and strains, especially when plastic strains are present. Bending also subjects a specimen to a wide variation of stress-strain conditions through its cross section, and even if these conditions can be properly analyzed, only a small volume of material undergoes the maximum stress and strain. By using axially strained specimens, wherein the entire test section volume is under the same conditions, greater volumes of material can be fatigued. Furthermore, using axial straining allows stress and strain to be measured and controlled more accurately. New testing equipment has been highly developed for controlling stress, strain, or any combination of parameters, so as to give special meaning to the control variables. In this chapter, we concentrate our discussion of material behavior under uniaxial stress and strain cycling.