Download or read book An Evaluation of the Plasticity induced Crack closure Concept and Measurement Methods written by J. C. Newman and published by . This book was released on 1998 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: An assessment of the plasticity-induced crack-closure concept is made, in light of the questions that have been raised on the validity of the concept, and the assumptions that have been made concerning crack-tip damage below the crack-opening stress. The impact of using other crack-tip parameters, such as the cyclic crack-tip displacement, to model crack-growth rate behavior was studied. Crack-growth simulations, using a crack-closure model, showed a close relation between traditional [delta]K[sub eff] and the cyclic crack-tip displacement ([delta][Dirac delta function][sub eff]) for an aluminium alloy and a steel. Evaluations of the cyclic hysteresis energy demonstrated that the cyclic plastic damage below the crack-opening stress was negligible in the Paris crack-growth regime. Some of the standard and newly proposed remote measurement methods to determine the "effective" crack-tip driving parameter were evaluated on middle-crack tension specimens. A potential source of the K[sub max] effect on crack-growth rates was studied on an aluminum alloy. Results showed that the ratio of K[sub max] to K[sub c] had a strong effect on crack-growth rates at high stress ratios and at low stress ratios for very high stress levels. The crack-closure concept and the traditional crack-growth rate equations were able to correlate and predict crack-growth rates under these extreme conditions.
Download or read book An Evaluation of the Plasticity Induced Crack Closure Concept and Measurement Methods written by James C. Newman (Jr.) and published by . This book was released on 1998 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Evaluation Of The Plasticity Induced Crack Closure Concept And Measurement Methods NASA TM 1998 208430 Dec 3 1998 written by United States. National Aeronautics and Space Administration 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 An Evaluation of Plasticity Induced Crack Closure Concept and Measurement Methods written by JC. Newman and published by . This book was released on 1999 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: An assessment of the plasticity-induced crack closure concept is made, in light of some of the questions that have been raised on the validity of the concept, and the assumptions that have been made concerning crack-tip damage below the crack-opening stress. The impact of using other crack-tip parameters, such as the cyclic crack-tip displacement or cyclic crack-tip hysteresis energy, to model crack-growth rate behavior was studied. Crack-growth simulations using the modified Dugdale crack closure model showed a close relation between traditional ?Keff and the cyclic crack-tip displacement (??eff) for an aluminum alloy and a steel over a wide range in stress ratios. Evaluations of the cyclic hysteresis energy demonstrated that the cyclic plastic damage below the crack-opening stress was negligible in the Paris crack-growth regime. Some of the standard and newly proposed remote measurement methods to determine crack-opening stresses and the "effective" crack-tip driving parameter were evaluated from crack-growth simulations made on middle-crack tension specimens. Here, analyses were conducted under both constant-amplitude and single-spike-overload conditions. A potential source of the Kmax effect on crack-growth rates was studied at high stress ratios and at high stress levels for an aluminum alloy. Results showed that the ratio of Kmaxto Kc had a strong effect on crack-growth rates at high stress ratios and at low stress ratios for very high stress levels. The crack-closure concept and the traditional crack-growth rate equations were able to correlate and predict crack-growth rates under these extreme conditions.
Download or read book Advances in Fatigue Crack Closure Measurement and Analysis written by R. Craig McClung and published by ASTM International. This book was released on 1999 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Finite Element Modeling of Plasticity Induced Crack Closure and a Mechanics Based Study of Crack Closure Measurement Techniques written by Marcos Lugo and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: From its discovery, crack closure was recognized as a key aspect in understanding the fatigue crack growth process. Considering the condition of plane stress, a vast amount of research has been conducted experimentally, analytically, and numerically to understand the complex process of fatigue crack growth and crack closure. Nonzero crack opening stress values are routinely observed, and it seems that there is a general agreement regarding the incidence of the phenomenon under plane stress. However, investigations regarding crack closure under plane strain conditions are less abundant. Moreover, the existence of crack closure under the plane strain state of the stress has been questioned. The importance of accurate measurements of closure to predict adequately fatigue crack growth rates should not be underestimated. Models employed to predict fatigue crack growth rates rely on plasticity-induced crack closure concepts, and the validity of plasticity-induced crack closure depends on crack closure measurements. Crack closure measurements can be performed with Elber's Method, the ASTM standard (Compliance offset method), or it may be done alternatively by the compliance ratio (CR) or the adjusted compliance ratio method (ACR). In this research, a small scale yielding two-parameter modified boundary layer analysis is performed to study the occurrence of plasticity-induced fatigue crack closure under constant amplitude loading and plane strain conditions. A wide range of T-stresses and KI levels are considered in the finite element analysis with the purpose of exploring the behavior of the crack opening stress. Crack closure was observed for some values of T-stress. Other values of T-stress resulted in an absence of closure under steady state conditions. In addition, an elastic-plastic finite element model was used to simulate a growing fatigue crack with WARP3D software. The computed displacements were used to determine the effective stress intensity factor range [delta]Keff with the ASTM standard compliance offset approach, the (CR) method, and the (ACR) method. Finally, measurement location effects on ACR and the ability of ACR method to remove residuals stresses were investigated.
Download or read book Plasticity Induced Fatigue Crack Closure written by DL. Davidson and published by . This book was released on 1988 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental measurements of plasticity-induced crack closure related factors were made on the aluminum alloy 7091-T7E69 using high resolution microscopy techniques. Two stress intensity factors were examined at a stress ratio of 0.1. The length of open crack as a function of load magnitude and the load required to open the crack to its tip were measured. Crack opening displacements and strains were determined for partially and fully open cracks. From experimental measurements, the residual stresses in the crack wake were computed, using two different methods. Models and simulations of crack closure were examined in light of the experimental results. Interpretation of these results gives useful insights into crack closure phenomena but does not allow predictions of crack closure magnitude to be made.
Download or read book Fatigue and Fracture Mechanics written by Tina Louise Panontin and published by ASTM International. This book was released on 1999 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanics of Fatigue Crack Closure written by Wolf Elber and published by ASTM International. This book was released on 1988 with total page 671 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue and Fracture Mechanics written by Walter G. Reuter and published by ASTM International. This book was released on 2002-12-31 with total page 778 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering the whole of Asia and the Pacific region, this text provides both an analytic overview and specific data for each of the 60 countries. Introductory chapters cover regional issues, including: a regional review with the year's trends, developments and key events' analysis of the threat of terrorism in the region; the effects of deflation on the economy; the water crisis and its impact on the poor; and the successes and failures of micro-credit in the region.
Download or read book Fracture Mechanics written by Nestor Perez and published by Springer. This book was released on 2016-08-13 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of this textbook includes a refined presentation of concepts in each chapter, additional examples; new problems and sections, such as conformal mapping and mechanical behavior of wood; while retaining all the features of the original book. The material included in this book is based upon the development of analytical and numerical procedures pertinent to particular fields of linear elastic fracture mechanics (LEFM) and plastic fracture mechanics (PFM), including mixed-mode-loading interaction. The mathematical approach undertaken herein is coupled with a brief review of several fracture theories available in cited references, along with many color images and figures. Dynamic fracture mechanics is included through the field of fatigue and Charpy impact testing.
Download or read book Fatigue and Fracture Mechanices written by Steven R. Daniewicz and published by ASTM International. This book was released on 2005-09 with total page 591 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modelling of TMF Crack Growth in Polycrystalline Gas Turbine Alloys written by Jordi Loureiro-Homs and published by Linköping University Electronic Press. This book was released on 2020-10-07 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of the work presented in this Licentiate of Engineering thesis is to investigate and model the fatigue crack propagation behaviour of the nickel-based superalloy Inconel 792, with special attention to the industrial lifing of high-temperature components. In-phase (IP) crack propagation tests have been performed at different temperatures and loading regimes, including extended hold times. The observations from these tests have been the basis for establishing several hypotheses to describe the crack growth behaviour, which progressively have been verified experimentally and numerically. Most prominently, it has been observed that crack closure has a substantial impact on crack growth and can explain, to a large degree, the crack growth behaviour for this material under the conditions studied. This phenomenon has been observed experimentally and modelled numerically to extend further the precision of the methodology. Huvudsyftet med arbetet som presenteras i denna licentiat avhandling är att undersöka och modellera utmattnings sprickväxtbeteendet hos den nickelbaserade superlegeringen Inconel 792, med särskild uppmärksamhet riktad mot liuslängsdmodellering av högtemperaturkomponenter i en industriell kontext. I-fas (IP) sprickväxtprov har utförts vid olika temperaturer och belastningsregimer, inklusive hålltider. Observationerna från dessa tester har legat till grund för hypoteser för att förklara spricktillväxtbeteende, vilka successivt har verifierats experimentellt och numeriskt. Mest framträdande har det observerats att sprickslutning har en väsentlig inverkan på sprickväxten, och kan i stor utsträckning förklara sprickväxten för detta material under studerade förhållanden. Detta fenomen har observerats experimentellt och modellerats numeriskt för att förbättra metodens precision.
Download or read book NASA Langley Scientific and Technical Information Output 1999 written by and published by . This book was released on 2000 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analyses of Fatigue Crack Growth and Closure Near Threshold Conditions for Large Crack Behavior written by J. C. Newman (Jr) and published by . This book was released on 1999 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book FAA NASA International Symposium on Advanced Structural Integrity Methods for Airframe Durability and Damage Tolerance written by Charles E. Harris and published by . This book was released on 1994 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
