Crack Closure Behavior on a Variety of Materials Under High Stress Ratios and Kmax Test Conditions PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Crack Closure Behavior on a Variety of Materials Under High Stress Ratios and Kmax Test Conditions PDF full book. Access full book title Crack Closure Behavior on a Variety of Materials Under High Stress Ratios and Kmax Test Conditions by Y. Yamada. Download full books in PDF and EPUB format.
Author: Y. Yamada
Publisher:
ISBN:
Category : Chronic fatigue syndrome
Languages : en
Pages : 17
Get Book Here
Book Description
Fatigue-crack-growth-rate tests on compact specimens have been made on a variety of materials (2024-T3, 2324-T39, 7050-T7451, 4340 steel, and Inconel-718) over a wide range in stress ratios from 0.1 to 0.9 (and 0.95 in some cases) and several Kmax test conditions. Test data has been generated from threshold to near fracture using the compression precracking constant amplitude or compression precracking load reduction test methods in the threshold regime; and constant-amplitude loading at higher rates. A remote back-face strain (BFS) gage was used to monitor crack growth and to measure crack-opening loads. Local strain gages were also placed along and slightly off (about one-half thickness) the anticipated crack path to measure crack-opening loads. Elber's load-against-reduced-strain method was used to determine crack-opening loads by means of visual inspection (equivalent to a 0 % compliance offset). For a particular material, the BFS and local strain gages produced essentially the same crack-opening loads at low stress ratio (R = 0.1) conditions. But at high stress ratios (R >= 0.7) and Kmax test conditions, the local gages produced significantly higher crack-opening loads than the BFS gage in the threshold and near-threshold regimes. Previous research had proposed that high stress ratios (R >= 0.7) and Kmax test conditions produce closure-free conditions based on crack-mouth-opening-displacement or BFS gages, and plasticity-induced crack-closure modeling. However, crack closure under high stress ratios (R >= 0.7) and Kmax test conditions is attributed to residual-plastic deformations, crack-surface roughness, and/or fretting-debris. From local crack-opening load measurements, the effective stress-intensity-factor range (DKeff) appears to be uniquely related to the crack-growth rate in the threshold and near-threshold regimes.
Author: Y. Yamada
Publisher:
ISBN:
Category : Chronic fatigue syndrome
Languages : en
Pages : 17
Get Book Here
Book Description
Fatigue-crack-growth-rate tests on compact specimens have been made on a variety of materials (2024-T3, 2324-T39, 7050-T7451, 4340 steel, and Inconel-718) over a wide range in stress ratios from 0.1 to 0.9 (and 0.95 in some cases) and several Kmax test conditions. Test data has been generated from threshold to near fracture using the compression precracking constant amplitude or compression precracking load reduction test methods in the threshold regime; and constant-amplitude loading at higher rates. A remote back-face strain (BFS) gage was used to monitor crack growth and to measure crack-opening loads. Local strain gages were also placed along and slightly off (about one-half thickness) the anticipated crack path to measure crack-opening loads. Elber's load-against-reduced-strain method was used to determine crack-opening loads by means of visual inspection (equivalent to a 0 % compliance offset). For a particular material, the BFS and local strain gages produced essentially the same crack-opening loads at low stress ratio (R = 0.1) conditions. But at high stress ratios (R >= 0.7) and Kmax test conditions, the local gages produced significantly higher crack-opening loads than the BFS gage in the threshold and near-threshold regimes. Previous research had proposed that high stress ratios (R >= 0.7) and Kmax test conditions produce closure-free conditions based on crack-mouth-opening-displacement or BFS gages, and plasticity-induced crack-closure modeling. However, crack closure under high stress ratios (R >= 0.7) and Kmax test conditions is attributed to residual-plastic deformations, crack-surface roughness, and/or fretting-debris. From local crack-opening load measurements, the effective stress-intensity-factor range (DKeff) appears to be uniquely related to the crack-growth rate in the threshold and near-threshold regimes.
Author: James M. Larsen
Publisher:
ISBN:
Category : Aluminum alloys
Languages : en
Pages : 286
Get Book Here
Book Description
An investigation was performed to study the effects of slip character and crack closure on the propagation of small fatigue cracks in titanium- aluminum alloys. The materials examined were solution-treated Ti-4Al and Ti-8Al, as well as aged Ti-8Al. The propagation of naturally initiated surface cracks of depths as small as 25 micrometers was compared with the behavior of large through-thickness cracks. An extensometer was used to monitor crack closure throughout the large crack tests, and the closure behavior of the small cracks was measured using a computerized laser interferometric displacement gage having a displacement resolution of 0.01 micrometer. The measurements of crack closure were used to compute an effective stress intensity factor range. In all three alloys and for all test conditions, which included a range of stress levels and stress ratios, small cracks propagated faster than large cracks subjected to an equivalent Delta K, and the small cracks propagated under conditions that were significantly below the large-crack threshold, Delta K(th). Although the character and distribution of slip in Ti-Al alloys may have a dramatic influence on fatigue crack initiation and on the propagation of large cracks, this effect was minimal for small cracks.
Author: Wolf Elber
Publisher: ASTM International
ISBN: 0803109962
Category : Fracture mechanics
Languages : en
Pages : 671
Get Book Here
Book Description
Author: James C. Newman (Jr.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 34
Get Book Here
Book Description
Author: John A. Newman
Publisher:
ISBN:
Category : Fracture mechanics
Languages : en
Pages : 34
Get Book Here
Book Description
Author: R. Craig McClung
Publisher: ASTM International
ISBN: 0803126115
Category : Fracture mechanics
Languages : en
Pages : 487
Get Book Here
Book Description
Author: Walter G. Reuter
Publisher: ASTM International
ISBN: 080311284X
Category : Fracture mechanics
Languages : en
Pages : 428
Get Book Here
Book Description
From the symposium (on title) held in Sparks, Nevada, April 1988. Twenty-two peer-reviewed papers are divided into sections on models and experiments (monotonic loading), and fatigue crack growth. Areas addressed include the differences in constraint for 2-D through-thickness cracks and 3-D surface
Author: GH. Bray
Publisher:
ISBN:
Category : Crack closure
Languages : en
Pages : 22
Get Book Here
Book Description
In a common interpretation of crack closure, the crack is visualized as "peeling" open as stress is applied. This interpretation, while useful, has led to the assumption that the driving force for crack propagation, ?Keff, exists only when the crack tip is fully open (above K-opening). However, evidence of significant crack-tip cyclic strain below the K-opening will be presented. The exclusion of this additional driving force can yield misleading values of ?Keff. This is particularly so in the near-threshold regime where opening loads are typically high. The new analysis technique for estimating ?Keff is referred to as the adjusted compliance ratio (ACR) method and is based on an interpretation of crack closure as a stress redistribution (or load transfer) on a relatively compliant crack wake. The ACR method is evaluated using the results of fatigue crack growth tests on 6013-T651, 2324-T39 and 7055-T7751 aluminum alloys using the center crack tension M(T) specimen geometry and stress ratios ranging from -1.0 to above 0.96. The experimental results of this study indicate that the fatigue crack growth rate is not determined solely by ?Keff but also depends on Kmax. It was observed that this Kmax dependence takes the form of a power law with the magnitude of the exponent being a measure of Kmax sensitivity. As a result, ?Keff curves from all test conditions could be collapsed to a unique intrinsic FCGR curve using a simple modification to the Paris Law. It is expected that continued research in this area will lead to improvements in fatigue life prediction methodology.
Author: Jira, JR.
Publisher:
ISBN:
Category : Crack closure
Languages : en
Pages : 12
Get Book Here
Book Description
Fatigue crack growth threshold tests are conducted on a high-strength titanium alloy using a surface flaw specimen geometry. A laser interferometer is used to monitor crack-mouth opening displacements, from which compliance determined crack length is computed. Four types of loading history involving both increasing-and decreasing-?K are used to reach a threshold condition. Two of the test conditions maintain constant Kmax under computer control. Crack closure is obtained from the load-displacement plots and used to determine an effective stress-intensity range, ?Keff. Results from all four test types indicate that a single value of an effective stress-intensity range is obtained which is independent of stress ratio, R, or load history. Crack growth rate data in the near-threshold regime, on the other hand, appear to have a dependence on R even when ?Keff is used as a correlating parameter.
Author: S. Seetharamu
Publisher: Springer
ISBN: 9811060029
Category : Science
Languages : en
Pages : 468
Get Book Here
Book Description
This book presents the proceedings of Fatigue Durability India 2016, which was held on September 28–30 at J N Tata Auditorium, Indian Institute of Science, Bangalore. This 2nd International Conference & Exhibition brought international industrial experts and academics together on a single platform to facilitate the exchange of ideas and advances in the field of fatigue, durability and fracture mechanics and its applications. This book comprises articles on a broad spectrum of topics from design, engineering, testing and computational evaluation of components and systems for fatigue, durability, and fracture mechanics. The topics covered include interdisciplinary discussions on working aspects related to materials testing, evaluation of damage, nondestructive testing (NDT), failure analysis, finite element modeling (FEM) analysis, fatigue and fracture, processing, performance, and reliability. The contents of this book will appeal not only to academic researchers, but also to design engineers, failure analysts, maintenance engineers, certification personnel, and R&D professionals involved in a wide variety of industries.
