Finite Element Analysis Of Plasticity Induced Fatigue Crack Closure In Three Dimensional Cracked Geometries
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Finite Element Analysis Of Plasticity Induced Fatigue Crack Closure In Three Dimensional Cracked Geometries
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Author :
language : en
Publisher:
Release Date : 2001
Finite Element Analysis Of Plasticity Induced Fatigue Crack Closure In Three Dimensional Cracked Geometries written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
Elastic-plastic finite element analyses were performed to predict the crack opening level profiles in semi-elliptical surface cracks. A script was written to use the commercial finite element code ANSYS to predict opening levels in cracked geometries. The functionality of the scripts was verified by comparing predicted opening levels in two and three-dimensional center-cracked geometries to experimental results. In addition, a parameter study was performed in which various aspects of the modeling routine were modified. This included a mesh refinement study as well as a study into the effect of a strain hardening material. The main focus of the current research, however, is to compare finite element predicted opening levels with published opening levels determined experimentally. Due to the complexities and long run-times involved with these models, no attempt was made at growing the cracks from initial length to final length. Instead, discrete crack lengths at which experimental opening levels were published were instead used. Also, no attempt was made to predict the crack aspect ratio evolution. The finite element predicted opening levels were in all cases significantly lower than those reported experimentally, however, similar trends in both crack opening level profile along the crack front, and opening level variations with crack growth were shown.
Finite Element Analysis Of Plasticity Induced Fatigue Crack Closure In Three Dimensional Cracked Geometries
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Author : Jeffrey David Skinner
language : en
Publisher:
Release Date : 2001
Finite Element Analysis Of Plasticity Induced Fatigue Crack Closure In Three Dimensional Cracked Geometries written by Jeffrey David Skinner and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Finite element method categories.
[3] The finite element predicted opening levels were in all cases significantly lower than those reported experimentally, however, similar trends in both crack opening level profile along the crack front, and opening level variations with crack growth were shown.
Two And Three Dimensional Finite Element Analysis Of Plasticity Induced Fatigue Crack Closure A Comprehensive Parametric Study
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Author :
language : en
Publisher:
Release Date : 2002
Two And Three Dimensional Finite Element Analysis Of Plasticity Induced Fatigue Crack Closure A Comprehensive Parametric Study written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.
Finite element analyses are frequently used to model growing fatigue cracks and the associated plasticity-induced crack closure. Two-dimensional, elastic-perfectly plastic finite element analyses of middle-crack tension (M(T)), bend (SEB), and compact tension (C(T)) geometries were conducted to study fatigue crack closure and to calculate the crack opening values under plane-strain and plane-stress conditions. The loading was selected to give the same maximum stress intensity factor in both geometries, and thus similar initial forward plastic zone sizes. Mesh refinement studies were performed on all geometries with various element types. For the C(T) geometry, negligible crack opening loads under plane-strain conditions were observed. In contrast, for the M(T) specimen, the plane-strain crack opening stresses were found to be significantly larger. This difference was shown to be a consequence of in-plane constraint. Under plane-stress conditions, it was found that the in-plane constraint has negligible effect, such that the opening values are approximately the same for the C(T), SEB, and M(T) specimens. Next, the crack opening values of the C(T), SEB and M(T) specimens were compared under various stress levels and load ratios. The effect of a highly refined mesh on crack opening values was noted and significantly lower crack opening values than those reported in literature were found. A new methodology is presented to calculate crack opening values in planar geometries using the crack surface nodal force distribution under minimum loading as determined from finite element analyses. The calculated crack opening values are compared with values obtained using finite element analysis and more conventional crack opening assessment methodologies. It is shown that the new method is independent of loading increment, integration method (normal and reduced integration), and crack opening assessment location. The compared opening values were in good agreement with strip-yield.
Finite Element Analysis Of Plasticity Induced Fatigue Crack Closure
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Author : Mehmet Gkhan Gken
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2010-05
Finite Element Analysis Of Plasticity Induced Fatigue Crack Closure written by Mehmet Gkhan Gken and has been published by LAP Lambert Academic Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-05 with categories.
In spite of the fact that the use of contact elements in modeling crack surface contact, and thus in modeling of crack closure is inherently natural, almost no effort to incorporate it in the finite element analysis of fatigue crack growth has been reported in the literature. The traditional method is based on placing truss elements on the crack surface nodes In this research contact elements are used to model crack surface contact and similar to mentioned method the determination of crack opening stress is accomplished by monitoring the state of contact elements during incrementally applied loading. Instead of determining crack opening stress of every load cycle, an algorithm that makes it possible to find crack opening stress at predetermined load cycle intervals is developed. With the developed algorithm it was possible to analyze crack closure behavior during a larger number of load cycles with less execution time. Due to simulation of relatively high number of load cycles, final stabilization of crack opening stress values after a subsequent decay in the initially "stabilized" opening stress values is observed.
Modeling Of Three Dimensional Effects On Fatigue Crack Closure Processes In Small Scale Yielding
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Author : RH. Dodds
language : en
Publisher:
Release Date : 2005
Modeling Of Three Dimensional Effects On Fatigue Crack Closure Processes In Small Scale Yielding written by RH. Dodds and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Contact categories.
In ductile metals, plasticity-induced closure of fatigue cracks often retards significantly measured crack growth rates in the Paris regime and contributes strongly to the observed R-ratio effect in experimental data. This work describes a similarity scaling relationship based on the 3D small-scale yielding framework wherein the thickness, B, defines the only geometric length-scale of the model. Dimensional analysis suggests a scaling relationship for the crack opening loads relative to the maximum cyclic loads (Kop/Kmax) governed by the non-dimensional load parameter ̄K=Kmax/?0 ?B, i.e., a measure of the in-plane plastic zone size normalized by the thickness. Both Kop and Kmax refer to remotely applied values of the mode I stress-intensity factor. Large-scale, 3D finite element analyses described here demonstrate that Kop/Kmax values vary strongly across the crack front in thin sheets but remain unchanged when Kmax, B, and ?0 vary to maintain ̄K = constant. The paper also includes results to demonstrate that the scaling relationship holds for non-zero values of the T-stress (which affect the Kop/Kmax values) and for an overload interspersed in the otherwise constant amplitude cycles. The present results focus on R = Kmin/Kmax = 0 loading, although the scaling relationship has been demonstrated to hold for other R > 0 loadings as well. The new similarity scaling relationship makes possible more realistic estimates of crack closure loads for a very wide range of practical conditions from just a few analyses of the type described here.
Finite Element Simulations Of Three Dimensional Microstructurally Small Fatigue Crack Growth In 7075 Aluminum Alloy Using Crystal Plasticity Theory
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Author :
language : en
Publisher:
Release Date : 2005
Finite Element Simulations Of Three Dimensional Microstructurally Small Fatigue Crack Growth In 7075 Aluminum Alloy Using Crystal Plasticity Theory written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
This thesis discusses plasticity-induced crack closure based finite element simulations of small fatigue cracks in three dimensions utilizing crystal plasticity theory. Previously, modeling has been performed in two dimensions using a double-slip crystal plasticity material model. The goal of this work is to extend that research using a full three-dimensional FCC crystal plasticity material model implementation that accounts for all twelve FCC slip systems. Discussions of Python scripts that were written to perform analyses with the commercial finite element code ABAQUS are given. A detailed description of the modeling methodology is presented along with results for single crystals and bicrystals. The results are compared with finite element and experimental results from the literature. A discussion of preliminary work for the analysis of crack growth around an intermetallic particle is also presented.
Mechanics Of Fatigue Crack Closure
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Author : Wolf Elber
language : en
Publisher: ASTM International
Release Date : 1988
Mechanics Of Fatigue Crack Closure written by Wolf Elber and has been published by ASTM International this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with Fracture mechanics categories.
Fatique And Fracture Mechanics
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Author : Gary R. Halford
language : en
Publisher: ASTM International
Release Date : 2000
Fatique And Fracture Mechanics written by Gary R. Halford and has been published by ASTM International this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with Fatigue categories.
Simulating Fatigue Crack Growth In Spiral Bevel Pinion
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Author :
language : en
Publisher:
Release Date : 2003
Simulating Fatigue Crack Growth In Spiral Bevel Pinion written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with categories.
New results for predicting crack trajectory and fatigue life for a spiral bevel pinion using the Finite Element Method (FEM) are reported. The predictions presented are based on linear elastic fracture mechanics combined with the FEM, incorporating plasticity induced fatigue crack closure and moving gear tooth loads. The analyses were carried out using a parallel FEM solver, which calculates stress intensity factors using equivalent domain J-integral method. Fatigue life predictions were made based on a modified Paris model incorporating crack closure. To obtain a more detailed understanding of the contact between a cracked pinion tooth in mesh with an uncracked gear tooth, three-dimensional contact analyses were performed on a spiral bevel gear set incorporating a crack. The goal in carrying out these analyses was to capture the redistribution of contact loads due to crack growth. Results of these analyses showed the expected trend of decreasing tooth loads carried by the cracked tooth with increasing crack length. It was also showed that this decrease in contact loads bad an impact on the stress intensity factor values and therefore would also affect the crack trajectory and fatigue life predictions.
Finite Element Simulations Of Three Dimensional Microstructurally Small Fatigue Crack Growth In 7075 Aluminum Alloy Using Crystal Plasticity Theory
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Author : Stephen Riley Johnston
language : en
Publisher:
Release Date : 2005
Finite Element Simulations Of Three Dimensional Microstructurally Small Fatigue Crack Growth In 7075 Aluminum Alloy Using Crystal Plasticity Theory written by Stephen Riley Johnston and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Aluminum alloys categories.
This thesis discusses plasticity-induced crack closure based finite element simulations of small fatigue cracks in three dimensions utilizing crystal plasticity theory. Previously, modeling has been performed in two dimensions using a double-slip crystal plasticity material model. The goal of this work is to extend that research using a full three-dimensional FCC crystal plasticity material model implementation that accounts for all twelve FCC slip systems. Discussions of Python scripts that were written to perform analyses with the commercial finite element code ABAQUS are given. A detailed description of the modeling methodology is presented along with results for single crystals and bicrystals. The results are compared with finite element and experimental results from the literature. A discussion of preliminary work for the analysis of crack growth around an intermetallic particle is also presented.