scholarly journals Fatigue Crack Growth Rate and Stress-Intensity Factor Corrections for Out-of-Plane Crack Growth

2005 ◽  
Vol 2 (1) ◽  
pp. 12026 ◽  
Author(s):  
SC Forth ◽  
DJ Herman ◽  
MA James ◽  
WM Johnston
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Out Of Plane

Background of Addition of Fatigue Crack Growth Rate Factors for Intermediate Strength Ferritic Steels in KD-4 of ASME Section VIII Division 3

2021 ◽  
Author(s):  
Susumu Terada ◽  
Toshio Yoshida
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Threshold Value

Abstract In Table KD-430 and KD-430M of ASME Section VIII Division 3 (hereinafter called ASME Div. 3), there were no fatigue crack growth rate factors and threshold value of stress intensity factor range for carbon and low alloy steels with yield strength less than or equal to 620 MPa. These fatigue crack growth rate factors and threshold value of stress intensity factor range for ferritic steels with intermediate strength were also necessary for designing ASME Div. 3 vessels. We investigated the fatigue crack growth rates given in various standards. Especially Bloom’s paper related to ASME Sec. XI was investigated in detail. The test results on fatigue crack growth rate under various stress intensity range ratio in Bloom’s paper were compared with test results in other references. An equation for fatigue crack growth corrected by the stress intensity factor ratio was developed based on our investigation. The equation developed for fatigue crack growth was confirmed to agree with the test data in Bloom’s paper for negative and positive R ratios. Hence this equation, which was appropriate for a wide range of positive and negative R ratios, was proposed for ASME Div. 3. The addition of the threshold value of the stress intensity factor range for intermediate strength ferritic steels was also proposed. The fatigue crack growth rate factors at room temperature were provided in Table KD-430 and KD-430M of ASME Div. 3. As the operating temperature is higher than room temperature, the temperature correction is necessary for calculating fatigue crack growth. The temperature correction method in KD-4 of ASME Div. 3 was also proposed. These proposed changes except minimum threshold value were approved by Board in 2018 and they were reflected in 2019 Edition. The minimum threshold value was approved by the Board in 2021. It will be reflected in 2021 Edition. The background of these proposed changes is shown in this paper.

The Role of Three-Dimensional Effects in Constant Amplitude Fatigue Crack Growth Testing

1980 ◽  
Vol 102 (4) ◽  
pp. 341-346 ◽  
Author(s):  
J. J. McGowan ◽  
H. W. Liu
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Mean Stress

An accurate knowledge of the dependence of the fatigue crack growth rate (da/dN) on the stress intensity factor range (ΔK) is necessary to perform a safety analysis of any structure. Fatigue crack growth tests are normally performed on simple, two-dimensional finite thickness specimens to determine this dependence. Certain anomalies in this dependence have been observed when specimen thickness and mean stress have been varied. The thickness effect and the mean stress effect on the fatigue crack growth rate are related to the variation in crack closure and the local stress intensity factor along the crack front. A simple model incorporating both of these two effects is proposed. The model is applied to fatigue crack growth data for a nickel-base super alloy (IN-100) with very good success.

Negative R Fatigue Crack Growth Rate Testing on Austenitic Stainless Steel in Air and Simulated Primary Water Environments

2018 ◽  
Author(s):  
Norman Platts ◽  
Ben Coult ◽  
Wenzhong Zhang ◽  
Peter Gill
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
High Temperature ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Growth Laws

Light water reactor coolant environments are known to significantly enhance the fatigue crack growth rate of austenitic stainless steels. However, most available data in these high temperature pressurized water environments have been derived using specimens tested at positive load ratios, whilst most plant transients involve significant compressive as well as tensile stresses. The extent to which the compressive loading impacts on the environmental enhancement of fatigue crack growth, and, more importantly, on the processes leading to retardation of those enhanced rates is therefore unclear, potentially leading to excessive conservatism in current assessment methodologies. A test methodology using corner cracked tensile specimens, and based on finite element analysis of the specimens to generate effective stress intensity factors, Keff, for specimens loaded in fully reverse loading has been previously presented. The current paper further develops this approach, enabling it to be utilized to study a range of positive and negative load ratios from R = −2 to R = 0.5 loading, and provides a greater understanding of the development of stress intensity factor within a loading cycle. Test data has been generated in both air and high temperature water environments over a range of loading ratios. Comparison of these data to material specific crack growth data from conventional compact tension specimens and environmental crack growth laws (such as Code Case N-809) enables the impact of crack closure on the effective stress intensity factor to be assessed in both air and water environments. The significance of indicated differences in the apparent level of closure between air and water environments is discussed in the light of accepted growth laws and material specific data.

A Probabilistic Approach to Fatigue Crack Growth Rate

1980 ◽  
Vol 102 (3) ◽  
pp. 300-302 ◽  
Author(s):  
Akira Tsurui ◽  
Akito Igarashi
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Probabilistic Model ◽  
Probabilistic Approach

A probabilistic model for fatigue crack growth proposed by K. P. Oh is modified in some respects. Under more natural assumptions than Oh’s it is derived that the rate of fatigue crack growth is proportional to some power of the range of the stress intensity factor. It is also shown that the exponent ranges from 2 to 4.

Mechanisms of Fatigue Crack Growth in WC-Co Cemented Carbides

2005 ◽  
Vol 297-300 ◽  
pp. 1120-1125 ◽  
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.

Long Fatigue Cracks — Microstructural Effects and Crack Closure

MRS Bulletin ◽  
1989 ◽  
Vol 14 (8) ◽  
pp. 25-36 ◽  
Author(s):  
P.K. Liaw
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Load Ratio ◽  
Stress Intensity Range ◽  
Intensity Range

Fracture mechanics technology is an effective tool for characterizing the rates of fatigue crack propagation. Generally, fatigue crack growth rate (da/dN) in each loading cycle can be presented as a function of stress intensity range (ΔK), where ΔK = Kmax — Kmin, Kmax and Kmin are the maximum and the minimum stress intensities, respectively. A typical fatigue crack growth rate curve of da/dN versus ΔK can be divided into three regimes, i.e., Stage I (near-threshold), Stage II (Paris), and Stage III (fast) crack growth regions, as shown in Figure 1.Depending on the region of crack growth, fatigue crack growth behavior can be sensitive to microstructure, environment, and loading conditions [e.g., R (load) ratio = Kmin / Kmax]. In the nearthreshold region, fatigue crack growth rates are very slow, ranging from approximately 10−10 to 10−8 m/cycle. In this region, the fatigue crack growth rate curve eventually reaches a threshold stress intensity range, ΔKth, below which the crack would not grow or grow at an extremely slow rate. Typically, the value of ΔKth is operationally defined as the stress intensity range which gives a corresponding crack growth rate of 10−10 m/cycle. In the nearthreshold region, the influence of microstructure, environment, and load ratio on the rates of crack propagation is very significant.

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