Fatigue Analyses Under Constant And Variable Amplitude Loading Using Small Crack Theory PDF Download
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Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 28 |
Release | : 2018-05-31 |
Genre | : |
ISBN | : 9781720523055 |
Download Fatigue Analyses Under Constant- And Variable-Amplitude Loading Using Small-Crack Theory Book in PDF, ePub and Kindle
Studies on the growth of small cracks have led to the observation that fatigue life of many engineering materials is primarily "crack growth" from micro-structural features, such as inclusion particles, voids, slip-bands or from manufacturing defects. This paper reviews the capabilities of a plasticity-induced crack-closure model to predict fatigue lives of metallic materials using "small-crack theory" under various loading conditions. Constraint factors, to account for three-dimensional effects, were selected to correlate large-crack growth rate data as a function of the effective stress-intensity factor range (delta-Keff) under constant-amplitude loading. Modifications to the delta-Keff-rate relations in the near-threshold regime were needed to fit measured small-crack growth rate behavior. The model was then used to calculate small-and large-crack growth rates, and to predict total fatigue lives, for notched and un-notched specimens under constant-amplitude and spectrum loading. Fatigue lives were predicted using crack-growth relations and micro-structural features like those that initiated cracks in the fatigue specimens for most of the materials analyzed. Results from the tests and analyses agreed well.Newman, J. C., Jr. and Phillips, E. P. and Everett, R. A., Jr.Langley Research CenterCRACK PROPAGATION; FATIGUE LIFE; MICROCRACKS; STRESS INTENSITY FACTORS; DYNAMIC LOADS; FRACTURE MECHANICS; VARIABLE AMPLITUDE LOADING; MICROSTRUCTURE; VOIDS; EDGE DISLOCATIONS; DEFECTS; NOTCHES; CRACK CLOSURE; PLASTIC PROPERTIES
Author | : J. C. Newman (Jr) |
Publisher | : |
Total Pages | : 30 |
Release | : 1999 |
Genre | : |
ISBN | : |
Download Fatigue Analyses Under Constant- and Variable-Amplitude Loading Using Small-Crack Theory Book in PDF, ePub and Kindle
Author | : J. C. Newman |
Publisher | : |
Total Pages | : 22 |
Release | : 1999 |
Genre | : Fracture mechanics |
ISBN | : |
Download Fatigue Analyses Under Constant- and Variable-amplitude Loading Using Small-crack Theory Book in PDF, ePub and Kindle
Studies on the growth of small cracks have led to the observation that fatigue life of many engineering materials is primarily "crack growth" from micro-structural features, such as inclusion particles, voids, slip-bands or from manufacturing defects. This paper reviews the capabilities of a plasticity-induced crack-closure model to predict fatigue lives of metallic materials using "small-crack theory" under various loading conditions. Constraint factors, to account for three-dimensional effects, were selected to correlate large-crack growth rate data as a function of the effective stress-intensity factor range ([delta]Keff) under constraint-amplitude loading. Modifications to the [delta]Keff-rate relations in the near-threshold regime were needed to fit measured small-crack growth rate behavior. The model was then used to calculate small- and large-crack growth rates, and to predict total fatigue specimens for most of the materials analyzed. Results from the tests and analyses agreed well.
Author | : J. Schijve |
Publisher | : Springer Science & Business Media |
Total Pages | : 627 |
Release | : 2008-12-16 |
Genre | : Science |
ISBN | : 1402068085 |
Download Fatigue of Structures and Materials Book in PDF, ePub and Kindle
Fatigue of structures and materials covers a wide scope of different topics. The purpose of the present book is to explain these topics, to indicate how they can be analyzed, and how this can contribute to the designing of fatigue resistant structures and to prevent structural fatigue problems in service. Chapter 1 gives a general survey of the topic with brief comments on the signi?cance of the aspects involved. This serves as a kind of a program for the following chapters. The central issues in this book are predictions of fatigue properties and designing against fatigue. These objectives cannot be realized without a physical and mechanical understanding of all relevant conditions. In Chapter 2 the book starts with basic concepts of what happens in the material of a structure under cyclic loads. It illustrates the large number of variables which can affect fatigue properties and it provides the essential background knowledge for subsequent chapters. Different subjects are presented in the following main parts: • Basic chapters on fatigue properties and predictions (Chapters 2–8) • Load spectra and fatigue under variable-amplitude loading (Chapters 9–11) • Fatigue tests and scatter (Chapters 12 and 13) • Special fatigue conditions (Chapters 14–17) • Fatigue of joints and structures (Chapters 18–20) • Fiber-metal laminates (Chapter 21) Each chapter presents a discussion of a speci?c subject.
Author | : |
Publisher | : |
Total Pages | : 34 |
Release | : 1997 |
Genre | : |
ISBN | : |
Download Fatigue-Life Prediction Methodology Using Small-Crack Theory Book in PDF, ePub and Kindle
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 32 |
Release | : 2018-07-03 |
Genre | : |
ISBN | : 9781722231705 |
Download Fatigue-Life Prediction Methodology Using Small-Crack Theory Book in PDF, ePub and Kindle
This paper reviews the capabilities of a plasticity-induced crack-closure model to predict fatigue lives of metallic materials using 'small-crack theory' for various materials and loading conditions. Crack-tip constraint factors, to account for three-dimensional state-of-stress effects, were selected to correlate large-crack growth rate data as a function of the effective-stress-intensity factor range (delta K(eff)) under constant-amplitude loading. Some modifications to the delta k(eff)-rate relations were needed in the near-threshold regime to fit measured small-crack growth rate behavior and fatigue endurance limits. The model was then used to calculate small- and large-crack growth rates, and to predict total fatigue lives, for notched and un-notched specimens made of two aluminum alloys and a steel under constant-amplitude and spectrum loading. Fatigue lives were calculated using the crack-growth relations and microstructural features like those that initiated cracks for the aluminum alloys and steel for edge-notched specimens. An equivalent-initial-flaw-size concept was used to calculate fatigue lives in other cases. Results from the tests and analyses agreed well. Newmann, James C., Jr. and Phillips, Edward P. and Swain, M. H. Langley Research Center RTOP 538-02-10-01...
Author | : J. Petit |
Publisher | : Springer |
Total Pages | : 422 |
Release | : 1988-12-31 |
Genre | : Technology & Engineering |
ISBN | : |
Download Fatigue Crack Growth Under Variable Amplitude Loading Book in PDF, ePub and Kindle
Author | : Maria El Zeghayar |
Publisher | : |
Total Pages | : 158 |
Release | : 2010 |
Genre | : |
ISBN | : |
Download The Introduction of Crack Opening Stress Modeling Into Strain-life and Small Crack Growth Fatigue Analysis Book in PDF, ePub and Kindle
The work in this thesis is concerned with the mechanics of the initiation and growth of small fatigue cracks from notches under service load histories. Fatigue life estimates for components subjected to variable amplitude service loading are usually based on the same constant amplitude strain-life data used for constant amplitude fatigue life predictions. The resulting fatigue life estimates although they are accurate for constant amplitude fatigue, are always non conservative for variable amplitude load histories. Similarly fatigue life predictions based on small crack growth calculations for cracks growing from flaws in notches are non conservative when constant amplitude crack growth data are used. These non conservative predictions have, in both cases, been shown to be due to severe reductions in fatigue crack closure arising from large (overload or underload) cycles in a typical service load history. Smaller load cycles following a large near yield stress overload or underload cycle experience a much lower crack opening stress than that experienced by the same cycles in the reference constant amplitude fatigue tests used to produce design data. This reduced crack opening stress results in the crack remaining open for a larger fraction of the stress-strain cycle and thus an increase in the effective portion of the stress-strain cycle. The effective strain range is increased and the fatigue damage for the small cycles is greater than that calculated resulting in a non conservative fatigue life prediction. Previous work at Waterloo introduced parameters based on effective strain-life fatigue data and effective stress intensity versus crack growth rate data. Fatigue life calculations using these parameters combined with experimentally derived crack opening stress estimates give accurate fatigue life predictions for notched components subjected to variable amplitude service load histories. Information concerning steady state crack closure stresses, effective strain-life data, and effective stress intensity versus small crack growth rate data, are all obtained from relatively simple and inexpensive fatigue tests of smooth specimens in which periodic underloads are inserted into an otherwise constant amplitude load history. The data required to calibrate a variable amplitude fatigue crack closure model however, come from time consuming measurements of the return of crack closure levels for small cracks to a steady state level following an underload (large cracks for which crack closure measurements are easier to make cannot be used because at the high stress levels in notches under service loads a test specimen used would fracture).
Author | : Dieter Radaj |
Publisher | : Springer Science & Business Media |
Total Pages | : 507 |
Release | : 2013-05-13 |
Genre | : Technology & Engineering |
ISBN | : 364230740X |
Download Advanced Methods of Fatigue Assessment Book in PDF, ePub and Kindle
In five chapters, this volume presents recent developments in fatigue assessment. In the first chapter, a generalized Neuber concept of fictitious notch rounding is presented where the microstructural support factors depend on the notch opening angle besides the loading mode. The second chapter specifies the notch stress factor including the strain energy density and J-integral concept while the SED approach is applied to common fillet welded joints and to thin-sheet lap welded joints in the third chapter. The forth chapter analyses elastic-plastic deformations in the near crack tip zone and discusses driving force parameters. The last chapter discusses thermomechanical fatigue, stress, and strain ranges.
Author | : Ralph Ivan Stephens |
Publisher | : ASTM International |
Total Pages | : 345 |
Release | : 1976 |
Genre | : Alloys |
ISBN | : |
Download Fatigue Crack Growth Under Spectrum Loads Book in PDF, ePub and Kindle