Download or read book An Experimental Study of Crack Initiation and Growth from Coldworked Holes written by Nopporn Chandawanich and published by . This book was released on 1977 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Studies of Coldworked Fastener Holes written by William N Sharpe (Jr) and published by . This book was released on 1978 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes the accomplishments of this research and catalogs its resulting papers and reports. When an oversized mandrel is pulled through a hole, the material near the hole edge is coldworked. After the mandrel is removed, the elastic restoring forces of material away from the hole generate compressive stresses at the edge. Subsequent tensile loading must overcome the compressive edge stresses, so a considerable improvement in the ultimate or fatigue loading capability of a structure can be achieved. The research was performed in four phases: Phase I-Measurement of the residual strains around coldworked holes. Phase II-Measurement of the location of the boundary between the elastic and plastic regions around the hole. Phase III-A study of fatigue crack initiation and growth from coldworked and noncoldworked holes. Phase IV-A study, similar to Phase III, of holes that had existing cracks and were then coldworked. (Author).
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Study of Fatigue Crack Growth from Fastener Holes Repaired by Coldworking written by Walter Joseph Cesarz and published by . This book was released on 1978 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 An Experimental Study of Three dimensional Strain Around Coldworked Holes and in Thick Compact Tension Specimens written by Somnuek Paleebut and published by . This book was released on 1982 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 An Experimental Study of Large Compressive Loads Upon Residual Strain Fields and the Interaction Between Surface Strain Fields Created by Coldworking Fastener Holes written by Gary L. Cloud and published by . This book was released on 1980 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research investigated three related problems, namely: (1) the evaluation of the residual strain redistribution around an initially coldworked fastener hole in a semi-infinite plate subjected to large in-plane compressive loads; (2) the determination of the effects of a near edge of a row of coldworked holes parallel to such an edge, and the possible creation of a strain climate at the straight edge which could lead to stress corrosion problems; and, (3) the interactions of surface strain fields between rivet holes which are being coldworked. The strain distributions were obtained by a moire technique, with the aid of coherent optical processing and digital data reduction. Many useful conclusions about the residual strain fields near coldworked holes were established.
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 Studies on Crack Initiation and Stable Crack Growth written by C. F. Shih and published by . This book was released on 1978 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multiphysics Modelling and Simulation for Systems Design and Monitoring written by Mohamed Haddar and published by Springer. This book was released on 2015-01-03 with total page 551 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports on the state of the art in the field of multiphysics systems. It consists of accurately reviewed contributions to the MMSSD’2014 conference, which was held from December 17 to 19, 2004 in Hammamet, Tunisia. The different chapters, covering new theories, methods and a number of case studies, provide readers with an up-to-date picture of multiphysics modeling and simulation. They highlight the role played by high-performance computing and newly available software in promoting the study of multiphysics coupling effects, and show how these technologies can be practically implemented to bring about significant improvements in the field of design, control and monitoring of machines. In addition to providing a detailed description of the methods and their applications, the book also identifies new research issues, challenges and opportunities, thus providing researchers and practitioners with both technical information to support their daily work and a new source of inspiration for their future research.
Download or read book Residual Stress Effects on Fatigue and Fracture Testing and Incorporation of Results Into Design written by Michael R. Mitchell and published by ASTM International. This book was released on 2007 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Eleven peer-reviewed papers, written by experts in their field, provide an understanding of residual stresses, fatigue crack growth, fatigue lifetime predictions, and their effect on structural integrity. Residual stresses can be present due to processing and manufacturing of materials and structures, so it is imperative to understand how and why they can influence the test data that we used in structural design methodologies. Residual stresses may also be intentionally engineered into structures in attempts to improve fatigue life, and it is equally important that designers understand how to account for these potential effects on fatigue life."--Publisher's website.
Download or read book Investigate the Effectiveness of Stop Drill Hole in Delaying Crack from Crack Initiation written by Syafiq Hashim and published by . This book was released on 2012 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many failures in engineering applications or machine components have been caused by a crack initiated from points at which stress was concentrated. As the stress concentration level is higher than a critical value, continuous crack-growth results in failure in the machine components. Crack initiation behavior has been evaluated to prevent an early failure of machine equipment. Delaying the crack initiation is important for the maintenance of machine elements as well as for the detection of crack initiation. Hence, the main objective of this study is to investigate the delay of crack using stop drilled holes. The investigation was based on the diameter of the stop drilled holes, the location of stop drilled hole and the ancillary stop hole drilled. The experiment and selected experiment on finite element analysis were done in order to validate the result. The experiment was carried out by using tensile test to obtain maximum applied load to the specimen while the finite element analysis was analyzed by using ALGOR software to obtain the stress of the specimen.The experimental results and the finite element analysis results show that the crack initiation life of the specimen was longer when the diameter of the stop drilled holes increased. The further the location of the stop drilled holes with the slits location, the longer crack initiation life of the specimen. The influence of extra stop-hole drill increase more time for delaying the crack on the specimen. From the experiment the longest time on delaying crack propagation is 92.32% increase compare before install stop-hole drill gained from Experiment 3. Thus, the influence of the stop drilled holes on the crack initiation life has been proved.
Download or read book The Experimental Characterisation of Residual Stresses and Fatigue Crack Growth in the Vicinity of Cold Worked Holes in Al 2024 T351 written by Maria Priest and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ICAF 97 Lecture papers written by R. Cook and published by . This book was released on 1997 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The First Joint DoD FAA NASA Conference on Aging Aircraft written by and published by . This book was released on 1998 with total page 904 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Study of the Interaction of Strain Fields Between Coldworked Fastener Holes written by Mark T. Tipton and published by . This book was released on 1980 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
