Application of effective stress intensity factors to crack growth rate description

1986 ◽  
Vol 23 (4) ◽  
pp. 333-339 ◽  
Author(s):  
A. F. Liu
Keyword(s):  
Growth Rate ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Effective Stress ◽  
Stress Intensity Factors ◽  
Intensity Factors

Growth of Corner Cracks at a Hole

1982 ◽  
Vol 104 (2) ◽  
pp. 107-114 ◽  
Author(s):  
A. F. Liu ◽  
H. P. Kan
Keyword(s):  
Growth Rate ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Stress Intensity Factors ◽  
Crack Size ◽  
Crack Growth Behavior ◽  
Intensity Factors ◽  
Open Hole ◽  
Corner Cracks

The two-dimensional growth characteristics of corner cracks emanating from an open hole were demonstrated by conducting constant amplitude cyclic crack growth tests on a set of 51 specimens. The specimens were machined from 2024-T851 aluminum alloy in three thicknesses (6.35, 12.7, and 19.30 mm) and three hole diameters (6.35, 12.7, and 19.05 mm). The precrack sizes are very small (typically 0.5 to 1.0 mm in either length or depth dimensions) having many arbitrary initiated length-to-depth ratios. Empirical stress intensity factors for various crack size, crack shape, and specimen geometry combinations were calibrated by back-tracking of the crack growth rate behavior in these specimens and the material baseline crack growth rate data (also in three thicknesses of the same heat) developed from compact specimens. Superposition principles were applied to separate the lumped stress intensity factors into a parametric functional form. It has been demonstrated that these empirically derived stress intensity expressions are capable of predicting the crack growth behavior in both the length (on specimen surface) and depth (on the hole wall) directions.

scholarly journals Creep crack growth assessment in terms of continuum damage mechanics

2018 ◽  
Vol 165 ◽  
pp. 19003
Author(s):  
Valery Shlyannikov ◽  
Andrey Tumanov
Keyword(s):  
Growth Rate ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Process Zone ◽  
Creep Crack Growth ◽  
Intensity Factors ◽  
Stress Strain ◽  
Creep Crack ◽  
Creep Stress

The stress, strain rate, and process zone with respect to the creep-crack growth in compacttension C(T) specimen is analyzed by employing damage-evolution equations. The damage model for the fracture of the process zone is represented using a stress based formulation. Both damage free and defective creeping solids have been studied. The variations in the creep stress/strain and crack-tip governing parameter in terms of the creep stress intensity factors with respect to time and the evolution of creep damage are analyzed using an FE model for C(T) specimen. The creep-fatigue crack growth rate tests were performed on special designed program test-cycle. The interpretation of the experimental creep crack growth rate data was given in terms of introduced creep stress intensity factors based on undamaged and damaged stress/strain fields.

Fatigue Crack Growth of Alloy 7050-T7451 Plate in L-S Orientation

2012 ◽  
Vol 525-526 ◽  
pp. 221-224
Author(s):  
Rui Bao ◽  
Xiao Chen Zhao ◽  
Ting Zhang ◽  
Jian Yu Zhang
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Growth Characteristics ◽  
Stress Intensity Factor Range ◽  
Constant Amplitude ◽  
Stress Ratios

Experiments have been conducted to investigate the crack growth characteristics of 7050-T7451 aluminium plate in L-S orientation. Two loading conditions are selected, i.e. constant amplitude and constant stress intensity factor range (ΔK). The effects of ΔK-levels and stress ratios (R) on crack splitting are studied. Test data shows that crack splitting could result in the reverse of crack growth rate trend with the increasing R ratio at high ΔK-level. The appearance of crack splitting depends on both ΔK and R.

Nickel Alloy Crack Growth Correlations in BWR Environment and Application to Core Support Structure Welds Evaluation

2008 ◽  
Author(s):  
Raj Pathania ◽  
Robert G. Carter
Keyword(s):  
Growth Rate ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Growth Model ◽  
Thickness Direction ◽  
Support Structure ◽  
Nickel Base ◽  
Crack Growth Model ◽  
Crack Growth Rates

An intergranular stress corrosion cracking (IGSCC) growth model for unirradiated nickel-base alloys (Alloys 82, 182 and 600) in boiling water reactor (BWR) environments has been developed by EPRI. This model has been used for assessment of the crack growth rates in BWR nickel base austenitic alloys with particular application to the BWR shroud support structure materials and welds, including attachments to the reactor pressure vessel fabricated from these alloys. However, the crack growth model can be used for other components with like materials in BWR environments provided that specific parameters such as stresses and stress intensity factor (KI) distributions are determined. The methodology involves development of crack growth disposition curves that can account for the variability of important IGSCC parameters to provide a conservative, yet realistic assessment of crack growth rate in BWR environments. An extensive nickel base alloy crack growth rate database was developed from data generated through the peer review process and includes both experimental data points and in-plant crack arrest verification system data. Most of the data in the database have reasonable definition of environmental conditions and other important crack growth parameters thus permitting a more realistic generic crack growth model to be developed. Although most of the data is for Alloy 182, it bounds the crack growth rate of Alloy 82 and Alloy 600. The database was used to derive crack growth disposition curves under normal water chemistry (NWC) and hydrogen water chemistry (HWC) conditions. The disposition curves have two stress intensity regimes; one for KI < 25 ksi√in where the crack growth is KI-dependent and one for KI > 25 ksi√in where the crack growth is KI-independent. The crack growth disposition curves were used together with a crack growth estimation methodology to determine the crack propagation of the BWR shroud support structure welds which are fabricated from Alloy 82/182. The steps involved in the development of the methodology include determination of residual stresses and operating stresses, development of stress intensity factor (KI) solutions for crack propagation in the through-thickness direction and estimation of crack growth rates. This methodology was applied specifically for crack growth in the through-thickness direction. Application of this crack growth model to BWR shroud support structure welds H8 and H9 indicates that there is an adequate time period between inspections before initial cracks of ≤10% through-wall thickness reaches the allowable flaw sizes, particularly for HWC conditions.

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