Download or read book Analysis of Fatigue Crack Closure During Simulated Threshold Testing written by RC. McClung and published by . This book was released on 2000 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Load shedding procedures during fatigue crack growth threshold testing can, under some conditions, induce significant changes in fatigue crack closure levels, which can in turn artificially influence the apparent threshold level. In this paper, mechanics analyses of growing fatigue cracks that account for plasticity-induced closure are used to study load shed effects on crack opening levels during simulated threshold testing. Both finite element and FASTRAN strip yield models are employed, and the two approaches are compared. The current ASTM standard test method for determining thresholds is evaluated. Analyses explore the effects of initial stress, initial stress intensity factor, specimen size, material flow strength, and load shed rates on crack closure.
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 Analyses of Fatigue Crack Growth and Closure Near Threshold Conditions for Large Crack Behavior written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-29 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: A plasticity-induced crack-closure model was used to study fatigue crack growth and closure in thin 2024-T3 aluminum alloy under constant-R and constant-K(sub max) threshold testing procedures. Two methods of calculating crack-opening stresses were compared. One method was based on a contact-K analyses and the other on crack-opening-displacement (COD) analyses. These methods gave nearly identical results under constant-amplitude loading, but under threshold simulations the contact-K analyses gave lower opening stresses than the contact COD method. Crack-growth predictions tend to support the use of contact-K analyses. Crack-growth simulations showed that remote closure can cause a rapid rise in opening stresses in the near threshold regime for low-constraint and high applied stress levels. Under low applied stress levels and high constraint, a rise in opening stresses was not observed near threshold conditions. But crack-tip-opening displacement (CTOD) were of the order of measured oxide thicknesses in the 2024 alloy under constant-R simulations. In contrast, under constant-K(sub max) testing the CTOD near threshold conditions were an order-of-magnitude larger than measured oxide thicknesses. Residual-plastic deformations under both constant-R and constant-K(sub max) threshold simulations were several times larger than the expected oxide thicknesses. Thus, residual-plastic deformations, in addition to oxide and roughness, play an integral part in threshold development.Newman, J. C., Jr.Langley Research CenterCRACK PROPAGATION; DISPLACEMENT; FATIGUE (MATERIALS); ALUMINUM ALLOYS; CRACK TIPS; SURFACE ROUGHNESS; SIMULATION; OXIDES
Download or read book Analyses of Fatigue Crack Growth and Closure Near Threshold Conditions for Large crack Behavior written by J. C. Newman and published by . This book was released on 1999 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: A plasticity-induced crack-closure model was used to study fatigue crack growth and closure in thin 2024-T3 aluminum alloy under constant-R and constant-Kmax threshold testing procedures. Two methods of calculating crack-opening stresses were compared. One method was based on a contact-K analyses and the other on crack-opening-displacement (COD) analyses. These methods gave nearly identical results under constant-amplitude loading, but under threshold simulations the contact-K analyses gave lower opening stresses than the contact COD method. Crack-growth predictions tend to support the use of contact-K analyses. Crack-growth simulations showed that remote closure can cause a rapid rise in opening stresses in the near threshold regime for low-constraint and high applied stress levels. Under low applied stress levels and high constraint, a rise in opening stresses was not observed near threshold conditions. But crack-tip-opening displacement (CTOD) were of the order of measured oxide thicknesses in the 2024 alloy under constant-R simulations. In contrast, under constant-Kmax testing the CTOD near threshold conditions were an order-of-magnitude larger than measured oxide thicknesses. Residual-plastic deformations under both constant-R and constant-Kmax threshold simulations were several times larger than the expected oxide thicknesses. Thus, residual-plastic deformations, in addition to oxide and roughness, play an integral part in threshold development.
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 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 Crack Growth Thresholds Endurance Limits and Design written by J. C. Newman and published by ASTM International. This book was released on 2000 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Contains 24 papers from the November, 1998 symposium of the same name, sponsored by the ASTM Committee E8 on Fatigue and Fracture, and presented by Newman and Piascik (both of the NASA Langley Research Center). The papers focus on such areas as fatigue-crack growth threshold mechanisms, loading and specimen-type effects, analyses of fatigue-crack-growth-threshold behavior, and applications of threshold concepts and endurance limits to aerospace and structural materials. Annotation copyrighted by Book News, Inc., Portland, OR.
Download or read book A Re evaluation of Fatigue Threshold Test Procedures and the Simulation and Prediction of Fatigue Crack Growth Under Conditions of Low Crack Closure written by William Alexander Herman and published by . This book was released on 1988 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analytical and Experimental Study of Near Threshold Interactions Between Crack Closure Mechanisms written by John A. Newman and published by . This book was released on 2003 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Automation in Fatigue and Fracture written by C. Amzallag and published by ASTM International. This book was released on 1994 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Testing and Analysis Under Variable Amplitude Loading Conditions written by Peter C. McKeighan and published by ASTM International. This book was released on 2005 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applications of Automation Technology in Fatigue and Fracture Testing and Analysis written by Arthur A. Braun and published by ASTM International. This book was released on 2002 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Virtual Crack Closure Technique History Approach and Applications written by Ronald Krueger and published by . This book was released on 2002 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: An overview of the virtual crack closure technique is presented. The approach used is discussed, the history summarized, and insight into its applications provided. Equations for two-dimensional quadrilateral elements with linear and quadratic shape functions are given. Formula for applying the technique in conjuction with three-dimensional solid elements as well as plate/shell elements are also provided. Necessary modifications for the use of the method with geometrically nonlinear finite element analysis and corrections required for elements at the crack tip with different lengths and widths are discussed. The problems associated with cracks or delaminations propagating between different materials are mentioned briefly, as well as a strategy to minimize these problems. Due to an increased interest in using a fracture mechanics based approach to assess the damage tolerance of composite structures in the design phase and during certification, the engineering problems selected as examples and given as references focus on the application of the technique to components made of composite materials.
Download or read book Analysis of Fatigue Crack Closure and Thresholds written by K. Sadananda and published by . This book was released on 1995 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: A critical examination of fatigue crack closure concepts indicates that (a) procedures commonly followed in estimating crack closure are in error, (b) complete premature crack closure occurs only when cracks are completely filled with oxides or corrosion products, (d) such closure manifests as an infinite slope in the load-displacement (crack mouth opening) curves; rarely observed in experiments, (e) asperities cause only local closure, (f) their contribution is less significant than is assumed and (g) plasticity does not contribute to closure. New concepts are developed to explain fatigue phenomena hitherto attributed to crack closure. Implications of these concepts to understand fatigue crack growth are discussed.
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 Evaluation of the Effect of Crack Closure on Fatigue Crack Growth of Simulated Short Cracks written by and published by . This book was released on 1984 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
