Modified stress intensity factor as a crack growth parameter applicable under large scale yielding conditions

Crack growth in compact specimens of type 304 stainless steel is studied at 538oC. Loading conditions include pure fatigue loading, static loading and fatigue loading with hold time. Crack growth rates are correlated with the stress intensity factor. A finite element analysis is performed to understand the crack tip field under creep-fatigue loading. It is found that fatigue loading interrupts stress relaxation around the crack tip and cause stress reinstatement, thereby accelerating crack growth compared with pure static loading. An effort is made to model crack growth rates under combined influence of creep and fatigue loading. The correlation with the stress intensity factor is found better when da/dt is used instead of da/dN. Both the linear summation rule and the dominant damage rule overestimate crack growth rates under creep-fatigue loading. A model is proposed to better correlate crack growth rates under creep-fatigue loading: 1 c f da da da dt dt dt Ψ −Ψ     =         , where Ψ is an exponent determined from damage under pure fatigue loading and pure creep loading. This model correlates crack growth rates for relatively small loads and low stress intensity factors. However, correlation becomes poor as the crack growth rate becomes large under a high level of load.

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Slow Crack Growth in Glasses and Ceramics Under Residual and Applied Stresses

Journal of Electronic Packaging ◽

10.1115/1.3226510 ◽

1989 ◽

Vol 111 (1) ◽

pp. 61-67 ◽

Cited By ~ 3

Author(s):

F. Erdogan

Keyword(s):

Stress Intensity Factor ◽

Stress Intensity ◽

Intensity Factor ◽

Residual Stresses ◽

Crack Growth ◽

Slow Crack Growth ◽

Threshold Value ◽

Crack Arrest ◽

Growing Crack ◽

Applied Stresses

The problem of slow crack growth under residual stresses and externally applied loads in plates is considered. Even though the technique developed to treat the problem is quite general, in the solution given it is assumed that the plate contains a surface crack and the residual stresses are compressive near and at the surfaces and tensile in the interior. The crack would start growing subcritically when the stress intensity factor exceeds a threshold value. Initially the crack faces near the plate surface would remain closed. A crack-contact problem would, therefore, have to be solved to calculate the stress intensity factor. Depending on the relative magnitudes of the residual and applied stresses and the threshold and critical stress intensity factors, the subcritically growing crack would either be arrested or become unstable. The problem is solved and examples showing the time to crack arrest or failure are discussed.

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Effective local stress intensity factor criterion for prediction of crack growth trajectory under mixed mode fracture conditions

Theoretical and Applied Fracture Mechanics ◽

10.1016/j.tafmec.2016.01.009 ◽

2016 ◽

Vol 85 ◽

pp. 207-216 ◽

Cited By ~ 19

Author(s):

Davood Salimi-Majd ◽

Farhad Shahabi ◽

Bijan Mohammadi

Keyword(s):

Stress Intensity Factor ◽

Stress Intensity ◽

Intensity Factor ◽

Crack Growth ◽

Mixed Mode ◽

Local Stress ◽

Growth Trajectory ◽

Mixed Mode Fracture ◽

Mode Fracture

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Effect of Temperature on Fatigue Crack Growth in CPVC

Journal of Pressure Vessel Technology ◽

10.1115/1.1523070 ◽

2003 ◽

Vol 125 (1) ◽

pp. 71-77 ◽

Cited By ~ 5

Author(s):

Muhammad Irfan-ul-Haq ◽

Nesar Merah

Keyword(s):

Stress Intensity Factor ◽

Fatigue Crack ◽

Stress Intensity ◽

Fatigue Crack Growth ◽

Intensity Factor ◽

Crack Growth ◽

Effect Of Temperature ◽

Stress Intensity Factor Range ◽

Crack Growth Behavior ◽

Different Temperatures

This study addresses the effect of temperature on fatigue crack growth (FCG) behavior of CPVC. FCG tests were conducted on CPVC SEN tensile specimens in the temperature range −10 to 70°C. These specimens were prepared from 4-in. injection-molded pipe fittings. Crack growth behavior was studied using LEFM concepts. The stress intensity factor was modified to include the crack closure and plastic zone effects. The effective stress intensity factor range ΔKeff gave satisfactory correlation of crack growth rate (da/dN) at all temperatures of interest. The crack growth resistance was found to decrease with temperature increase. The effect of temperature on da/dN was investigated by considering the variation of mechanical properties with temperature. Master curves were developed by normalizing ΔKeff by fracture strain and yield stress. All the da/dN-ΔK curves at different temperatures were collapsed on a single curve. Crazing was found to be the dominant fatigue mechanism, especially at high temperature, while shear yielding was the dominant mechanism at low temperatures.

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Mechanisms of Fatigue Crack Growth in WC-Co Cemented Carbides

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.1120 ◽

2005 ◽

Vol 297-300 ◽

pp. 1120-1125 ◽

Cited By ~ 4

Author(s):

Myung Hwan Boo ◽

Chi Yong Park

Keyword(s):

Growth Rate ◽

Stress Intensity Factor ◽

Fatigue Crack ◽

Stress Intensity ◽

Fatigue Crack Growth ◽

Intensity Factor ◽

Crack Growth ◽

Stress Ratio ◽

Cemented Carbides ◽

Stress Intensity Factor Range

In order to study the influence of stress ratio and WC grain size, the characteristics of fatigue crack growth were investigated in WC-Co cemented carbides with two different grain sizes of 3 and 6 µm. Fatigue crack growth tests were carried out over a wide range of fatigue crack growth rates covering the threshold stress intensity factor range DKth. It was found that crack growth rate da/dN against stress intensity factor range DK depended on stress ratio R. The crack growth rate plotted in terms of effective stress intensity factor range DKeff still exhibited the effect of microstructure. Fractographic examination revealed brittle fracture at R=0.1 and ductile fracture at R=0.5 in Co binder phase. The amount of Co phase transformation for stress ratio was closely related to fatigue crack growth characteristics.

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