Effects of Stress Ratio and Hold-Time on Fatigue Crack Growth in Alloy 718 PDF Download

Author: P. Shahinian
Publisher:
ISBN:
Category :
Languages : en
Pages : 7

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Author: Naval Research Laboratory (U.S.)
Publisher:
ISBN:
Category : Naval research
Languages : en
Pages : 628

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Author: T. Nicholas
Publisher:
ISBN:
Category : Crack growth
Languages : en
Pages : 11

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Crack-growth-rate experiments were conducted on compact tension (CT) specimens of Inconel 718 in air at 649°C. The loading spectrum consisted of a single 1 Hz cycle at R = 0.1, where R is the ratio of minimum to maximum stress-intensity factors, and a hold time which was applied at various levels of the fatigue cycle. The ratio of the hold-time amplitude to the maximum amplitude of the fatigue cycle, Rin, was kept at 1.0, 0.9, 0.8, or 0.5. Hold times were varied from 0 to 200 s. Tests were performed under computer-controlled constant-K conditions using values of the maximum of the fatigue cycle of 40 and 50 MPa m1/2. Data show that for Rin = 1.0, a linear summation model works well, while at Rin = 0.9 there is a measurable retardation effect on the crack growth during the hold time. For values of Rin less than or equal to 0.8, the sustained-load crack growth is almost completely retarded. A simple retardation model is proposed which can fit the experimental data and is based on the concept of an overload plastic zone being produced by the fatigue cycles. It is concluded that hold times do not contribute to crack growth in this material unless their amplitude is at or near the maximum amplitude of the adjacent fatigue cycles.

Author: Michael R. Mitchell
Publisher: ASTM International
ISBN: 0803114230
Category : Fracture mechanics
Languages : en
Pages : 495

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Twenty-seven papers from fatigue researchers and practitioners review in detail recent progress in the development of methods to predict fatigue performance of materials and structures and to assess the extent to which these new methods are finding their way into practice. The papers, from the ASTM

Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 960

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Author: C. Moura Branco
Publisher: Springer Science & Business Media
ISBN: 9780792341130
Category : Science
Languages : en
Pages : 758

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This volume contains the edited version of lectures and selected research contributions presented at the NATO ADVANCED STUDY INSTITUTE on MECHANICAL BEHA VI OUR OF MATERIALS AT HIGH TEMPERATURE, held in Sesimbra, Portugal, 12th-22nd September 1995, and organized by 1ST-Lisbon Institute of Technology, PortugaL The Institute was attended by 88 participants, including 15 lecturers from 17 countries including five CP countries. The lecturers were leading scientists and technologists from universities, research institutions and industry. The students were mainly young PhD students and junior academic or research staff with postgraduate qualifications (MSc or PhD). Fourteen students were from the five CP countries. The students presented research papers or posters during the Institute reporting the current progress of their research projects. A total of thirty three lectures, ten research papers and fifty posters were presented. This book does not contain the poster presentations and seven research papers were selected for publication. All the sessions were very active and quite extensive discussions on scientific aspects took place during the Institute. The Advanced Study Institute provided a forum for interaction among scientists and engineers from different areas of research, and young researchers.

Author: T. Nicholas
Publisher:
ISBN:
Category : Creep/fatigue interactions
Languages : en
Pages : 14

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An experimental investigation was conducted to evaluate the effects of hold times on the fatigue crack growth rate of Inconel 718 at 649°C using compact tension specimens. Tests were run under computer-controlled constant K conditions using compliance to determine crack length. Hold times ranging from 5 to 50 s were applied at maximum, minimum, and intermediate load levels. The data show that the hold times at maximum load were the most damaging in terms of crack growth rate. Hold times greater than 5 s led to purely time-dependent crack growth behavior which was predictable from sustained load data using K as a correlating parameter. Hold times at minimum or intermediate load levels had little or no effect on crack growth rate. A linear cumulative damage model based solely on fatigue and sustained load data was found to be adequate for spectrum loading so long as the hold times were at maximum load.

Author: M.P. Wnuk
Publisher: Springer
ISBN: 3709127580
Category : Technology & Engineering
Languages : en
Pages : 452

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Author:
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 774

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Author: The Minerals, Metals & Materials Society (TMS)
Publisher: John Wiley & Sons
ISBN: 1119016886
Category : Technology & Engineering
Languages : en
Pages : 951

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