Download or read book Influence of Residual Stresses on Fatigue Crack Growth at Stress coined Holes written by Lennart Josefson and published by . This book was released on 1993 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Residual Stress Effects in Fatigue written by H. S. Reemsnyder and published by ASTM International. This book was released on 1982 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Influence of Residual Stress on Fatigue Crack Growth written by James E. LaRue and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis discusses the analysis of fatigue crack growth in the presence of residual stresses to determine a suitable method for fatigue life predictions. In the research discussed herein, the prediction methodologies are compared to determine the most accurate prediction technique. Finite element analysis results are presented as well as laboratory test data. The validity of each methodology is addressed and future work is proposed.

Download or read book Residual Stress Effects in Fatigue written by and published by . This book was released on 1982 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Influence of Residual Stress on Fatigue Crack Growth written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis discusses the analysis of fatigue crack growth in the presence of residual stresses to determine a suitable method for fatigue life predictions. In the research discussed herein, the prediction methodologies are compared to determine the most accurate prediction technique. Finite element analysis results are presented as well as laboratory test data. The validity of each methodology is addressed and future work is proposed.

Download or read book Fatigue Crack Growth Under Residual Stresses Around Holes written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Compressive residual stresses induced by tensile overloads, compressive under loads, or by a cold-expansion process in specimens containing a circular hole and their influence on subsequent fatigue crack growth in aluminum alloys are studied. The finite element method is used to calculate residual stresses. The superposition method, which uses crack-tip stress intensity factors for cases involving remote loading and residual stresses, is used to calculate crack growth life for three kinds of tests from the literature: (1) fatigue of a circular hole specimen after an overload or under load, (2) single crack growing from a circular hole after a severe tensile overload, and (3) single crack growing from a circular hole after cold-working, reaming and notching. All specimens were subjected to subsequent constant amplitude loading. The superposition method worked fairly well for most cases, but tended to over predict fatigue life for small cracks and for cracks growing under residual stresses, which produce compressive (maximum and minimum) stress intensity factors.

Download or read book Fatigue Crack Growth Under Residual Stresses Around Holes written by Ramesh Nagaralu and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Compressive residual stresses induced by tensile overloads, compressive under loads, or by a cold-expansion process in specimens containing a circular hole and their influence on subsequent fatigue crack growth in aluminum alloys are studied. The finite element method is used to calculate residual stresses. The superposition method, which uses crack-tip stress intensity factors for cases involving remote loading and residual stresses, is used to calculate crack growth life for three kinds of tests from the literature: (1) fatigue of a circular hole specimen after an overload or under load, (2) single crack growing from a circular hole after a severe tensile overload, and (3) single crack growing from a circular hole after cold-working, reaming and notching. All specimens were subjected to subsequent constant amplitude loading. The superposition method worked fairly well for most cases, but tended to over predict fatigue life for small cracks and for cracks growing under residual stresses, which produce compressive (maximum and minimum) stress intensity factors.

Download or read book Extended Finite Element Predictions for Three Dimensional Modeling of Fatigue Crack Growth in Cold worked Holes written by Mohammad Salman Yasin and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cold working has been widely used for enhancing the fatigue life of open holes. The process imparts compressive residual stresses around the hole which slows down the progression of crack under cyclic loading conditions. In the present study, fatigue crack growth in open holes in R260 grade steel, a typical railroad material, has been analyzed using the Extended Finite Element Method (XFEM). Along with the experimental studies, numerical simulation emerges as a powerful tool to predict the fatigue crack growth in rail steel and may deliver important insights to consider more situations by saving time and cost. XFEM modifies the standard displacement-based approximation by adding enrichment functions in the crack region. The investigation explored the capability of the XFEM, for a plate containing plain hole (baseline), pad coined, or split-sleeve cold-worked hole using the commercial finite element package, Abaqus, as a means of fatigue crack growth under constant amplitude loading. The effect of residual stress redistribution has been added to the numerical model to accurately predict the crack evolution. Stress Intensity Factors (SIF) are obtained from the XFEM calculations and the crack growth is estimated until the SIF reaches the fracture toughness of the modeled coupon material. The obtained simulation results are in good agreement with the fatigue experimental results in terms of the fatigue crack growth rates for plain hole (baseline), pad coined, or split-sleeve cold-worked holes. Results from the performed analysis show that cold working of an open hole increases the fatigue life when compared to the one without residual stresses due to the delay of crack initiation and propagation. The results also indicated fatigue life increase almost by a factor of three during crack propagation due to split-sleeve cold expansion in correlation to the baseline and pad coined sample.

Download or read book Fatigue Crack Growth from a Circular Hole with and Without High Prior Loading written by John H. Crews and published by . This book was released on 1972 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue crack growth from a circular hole was investigated experimentally and analytically. An aluminum-alloy sheet specimen was cycled under a single level of loading with and without prior high loads. Tests showed that the crack propagation life was significantly longer when the high loads were applied initially. This longer life was attributed to compressive residual stresses produced near the hole by the initial high loads. The residual stresses near the hole were determined by an elastoplastic analysis and were then used to develop a stress-intensity solution for a crack growing through the residual stress field. This solution and a similar solution for the case of no prior loading were used to predict crack growth. The predicted crack growth agreed closely with the experimental values.

Download or read book The Influence of Surface Residual Stress on Fatigue Crack Growth written by and published by . This book was released on 2007 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analysis of Fatigue Crack Growth and Residual Stress written by Shakhrukh Ismonov and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The first part of this dissertation employs a three-dimensional elastic-plastic finite element model of straight-through crack growth to correlate four well-known methodologies characterizing fatigue crack closure. The compliance offset and the adjusted compliance ratio (ACR) are experimental methods, whereas the node displacement and the contact stress methods are numerical approaches. Evolutions of crack closure from all four methodologies are compared for a numerical model of a single edge-cracked tension specimen subjected to different levels of constant amplitude cyclic loading. In the second part, a detailed two dimensional stress analysis is conducted for a single pin-joint under plane stress conditions. This study investigates the influence of material nonlinearity, friction, and pre-existing residual stresses from cold-working process on the local radial and hoop stress levels around the pin-loaded hole. Next, the beneficial influence of cold working process is quantified by computing the Mode I stress intensity factors K[subscript I] for a single radial crack emanating from a side of a loaded hole. Two different loading configurations are considered: (a) an open hole in tension, (b) a pin-loaded hole. The stress intensity factors are computed using the J integral solutions and the weight functions specific to the crack configuration. The reductions in K[subscript I] values due to different levels of cold-working process are presented for a range of crack lengths. The final part of the research involves a numerical investigation of an on-line crack compliance technique that is used for experimental measurements of residual stress fields along the crack growth path. A finite rectangular sheet is considered with a single crack emanating from a side of a central hole. The residual stress field is introduced around the hole by cold-working simulation. As part of validation, the normalized residual stress intensity factors computed using the on-line crack compliance technique are compared with those from the J-integral approach for the case of elastic crack growth. The influence of crack tip plasticity on the performance of the on-line crack compliance technique is studied by comparing the solutions of the elastic and elastic-plastic crack growth models.

Download or read book The Effects of Processing Residual Stresses on the Fatigue Crack Growth Behavior of Structural Materials written by Christopher James Lammi and published by . This book was released on 2009 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Residual stresses are a common and often undesired result of material processing, introduced through non-linear deformation and/or phase transformation of material under mechanical or thermo-mechanical loading. These macro stresses alter mechanical properties and the intrinsic fatigue crack growth characteristics of the material. Residual stress artifacts can introduce inconsistencies and significant errors when the true material behavior is needed for material development and optimization and for structural component design. The effects of quenching residual stresses on fatigue crack propagation behavior of various materials were investigated. In parallel, residual stresses similar in magnitude and distribution with the quenching residual stresses were generated using mechanical processes to decouple the effects of residual stresses from microstructural effects. Mechanical residual stress distributions predicted by 3D elastic-plastic finite element analysis showed good agreement with the stresses measured on fatigue crack growth testing specimens using fracture mechanics approaches. Crack propagation characteristics in fields with low and high residual stresses were studied using optical and scanning electron microscopy, and the effects of residual stress on crack path behavior were assessed. An original residual stress analytical correction to fatigue crack growth data was developed, compared to existing corrective methodologies, and validated using residual stress free data. Overall, the work provides tools to understand, control, and correct the effects of processing residual stresses on fatigue crack growth for accurate fatigue critical design and life predictions.

Download or read book Predicting Fatigue Crack Growth in the Residual Stress Field of a Cold Worked Hole written by MT. Kokaly and published by . This book was released on 2005 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cold working of holes generates compressive residual stresses resulting in a significant fatigue life improvement over a non-cold worked hole. Current fatigue life prediction methods for cold worked holes are based on two-dimensional (2-D) linear superposition of stress intensity factor, K, solutions of the non-cold worked hole and the residual stresses. Such predictions have shown various levels of agreement with the overall fatigue life and have generally underpredicted the crack growth over the majority of life. An inverse process was used to generate K solutions for the residual stresses of two experimental data sets using AFGROW and the crack growth data from the experiments. The inverse K solutions were inconsistent with the residual stress distribution indicating that it contained mechanisms or features not inherent to the 2-D weight function method. The predicted fatigue life was found to be very sensitive to a ± 1% variance in the inversely generated K solution. This sensitivity of the K method is a very important issue that must be addressed in the future. A 2-D FEA model indicated that the crack remained completely closed over a range of crack lengths despite experimental crack growth indicating that the model was not an accurate physical representation of the real crack. The results of this study combined with the significantly faster crack growth observed on the side of the hole corresponding to the entry side of the mandrel and the through thickness residual hoop stress variation show that the current methodology based on a 2-D assumptions is inadequate in predicting the fatigue crack growth from cold worked holes for the range of specimen thicknesses in this study. It is suggested that further research focus on incorporating the through thickness stress variance in a solution that predicts crack growth both in the radial and through thickness directions to capture the peculiar crack growth associated with cold working.

Download or read book Predicting Fatigue Crack Growth in the Residual Stress Field of a Cold Worked Hole written by Jude H. Restis and published by . This book was released on 2007 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cold working of holes generates compressive residual stresses resulting in a significant fatigue life improvement over a non-cold worked hole. Current fatigue life prediction methods for cold worked holes are based on two-dimensional (2-D) linear superposition of stress intensity factor, K, solutions of the non-cold worked hole and the residual stresses. Such predictions have shown various levels of agreement with the overall fatigue life and have generally underpredicted the crack growth over the majority of life. An inverse process was used to generate K solutions for the residual stresses of two experimental data sets using AFGROW and the crack growth data from the experiments. The inverse K solutions were inconsistent with the residual stress distribution indicating that it contained mechanisms or features not inherent to the 2-D weight function method. The predicted fatigue life was found to be very sensitive to a ± 1 % variance in the inversely generated K solution. This sensitivity of the K method is a very important issue that must be addressed in the future. A 2-D FEA model indicated that the crack remained completely closed over a range of crack lengths despite experimental crack growth indicating that the model was not an accurate physical representation of the real crack. The results of this study combined with the significantly faster crack growth observed on the side of the hole corresponding to the entry side of the mandrel and the through thickness residual hoop stress variation show that the current methodology based on a 2-D assumptions is inadequate in predicting the fatigue crack growth from cold worked holes for the range of specimen thicknesses in this study. It is suggested that further research focus on incorporating the through thickness stress variance in a solution that predicts crack growth both in the radial and through thickness directions to capture the peculiar crack growth associated with cold working.

Download or read book Effects of Residual Stress on Fatigue Crack Growth written by Kee Siong Lian and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Residual Stress and Crack Closure on Fatigue Crack Growth written by Jonathan R. T. Lloyd and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Residual Stress Effects on Fatigue Life Via the Stress Intensity Parameter K written by Jeffrey L. Roberts and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Residual stresses are known to have a significant effect on fatigue crack propagation and thus fatigue life. These effects have generally been quantified through an empirical approach, lending little help in the quantitative prediction of such effects. The weight function method has been used as a quantitative predictor, but its use neglects residual stress redistribution, treating the residual stress as a constant during crack growth. At least three different behaviors contribute to the redistribution of residual stress. First, the residual stress behind the crack tip is reduced to a negligible level as soon as the crack tip passes. Second, the residual stress tends to redistribute away from the crack tip with crack growth, and third, crack growth results in an overall relaxation of residual stress. An alternative method for predicting the effect of a residual stress distribution on fatigue crack growth is herein developed. The stress intensity factor due to residual stress, K[subscript res], is characterized as the change in crack driving force due to the presence of the residual stress. This crack driving force, being the derivative of a potential, is found through superposition of an applied stress and a residual stress, and subsequent manipulation of finite element strain energy and nodal displacement results. Finite element modeling is carried out using a spatial distribution of non-uniform thermal expansion coefficients and a unit temperature load to simulate the desired residual stress. Crack growth is then achieved through use of a node release algorithm which sequentially removes nodal displacement constraint. The complete stress distribution, nodal displacements and internal strain energy are captured for each increment of crack growth, and from this information, knowledge of the stress intensity factor as a function of crack length is derived. Results of the K[subscript res] calculations are used in a fatigue crack growth model to predict fatigue lives. The fatigue life model involves step by step analysis of crack growth increment based on knowledge of stress intensity factors resulting from applied and residual stress. The qualitative effects of residual stress predicted by this model agree with documented empirical results which show that compressive residual stress increases fatigue life, while tensile residual stress decreases fatigue life. Two solutions for K[subscript res] are possible, depending on the choice of load-control or displacement-control modeling. Use of displacement-control, or fixed displacement loading, minimizes redistribution of residual stress and, under net tensile loading, tends to lead to more conservative fatigue life predictions. Load-control modeling, not having the same displacement constraint, allows more relaxation of the residual stress and tends to provide the more non-conservative life estimates. Three residual stress patterns, two due to welding and one to shot peening, are also investigated. K[subscript res] solutions for each residual stress are developed, and fatigue life predictions made.