Fatigue Crack Growth in Large Specimens With Various Stress Ratios

1984 ◽  
Vol 106 (3) ◽  
pp. 255-260 ◽  
Author(s):  
F. Ellyin ◽  
H.-P. Li
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stress Ratio ◽  
Type Equation ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Stress Ratios

An experimental investigation has been carried out on large plates made of pressure vessel steel A516 Gr.70, to determine the fatigue crack growth rate. The specimen size was 914.4 × 304.8 × 12.7 mm (36 × 12 × 0.5 in.) with an initial central through crack of about 92 mm (3.6 in.). The stress ratio, R, applied to the specimens varied from zero to 0.4. This ratio was maintained constant during a test, but the stress amplitude, Δσ, at times was increased in order to obtain data under a large range of stress intensity factor, ΔK. The crack growth rate, da/dN, is expressed in terms of stress intensities, ΔK and Kmax, through a power-law-type equation. The variation of material constants with the applied stress ratio is discussed. From the data analysis, a general equation for the crack propagation rate is suggested in the form of da/dN = C (Kmax)n where C and n are functions of ΔK, Kmax and material parameters. The results are also compared with the recommended ASME Code formula and are found to be in fairly good agreement.

The Effect of Specimen Thickness Upon the Fatigue Crack Growth Rate of A516-60 Pressure Vessel Steel

1977 ◽  
Vol 99 (2) ◽  
pp. 248-252 ◽  
Author(s):  
A. M. Sullivan ◽  
T. W. Crooker
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Pressure Vessel ◽  
Specimen Thickness ◽  
Pressure Vessel Steel ◽  
Vessel Steel

Fatigue crack growth rate studies on A516-60 pressure vessel steel indicate no effect of specimen thickness in stress-relieved specimens ranging in thickness from 0.25 to 2.0 in. (6.35 to 50.8 mm). A regression curve equation for all thicknesses relating cyclic crack growth rate (da/dN) to crack-tip stress-intensity factor range (ΔK) is obtained. The significance of these results is discussed in the light of current engineering practice and previous studies on size effects in fatigue crack propagation.

Studies on Strain Fatigue Crack Growth Rate Controlled by Displacement or Load of 16MnR Steel

2011 ◽  
Vol 243-249 ◽  
pp. 5680-5685
Author(s):  
Yan Yan ◽  
An Zhong Liu ◽  
Dao Xiang Zhou
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Plastic Energy ◽  
Weighted Means

In order to understand the strain fatigue crack growth rate of pressure vessel steel controlled by displacement or load, we did experiments on strain fatigue of 16MnR steel and describe the fatigue with the energy method. We have obtained delayed cycle curve of strain fatigue controlled by displacement or load and calculated the J-integral at crack tip. In order to compare strain fatigue crack growth rates of 16MnR steel on two conditions，we compute weighted means of the strain fatigue controlled by displacement or load. Comparing two kinds of fatigue growth rate, it is obvious that the crack growth rate of fatigue controlled by displacement is greater than that controlled by load. All experiments show that compress plastic energy is higher, the fatigue growth rate of 16MnR is lower.

Effect of Environment on Fatigue Crack Propagation Behavior of an Al-Cu-Mg Aluminum Alloy

2014 ◽  
Vol 1004-1005 ◽  
pp. 142-147
Author(s):  
Ming Liu ◽  
Kun Zhang ◽  
Sheng Long Dai ◽  
Guo Ai Li ◽  
Min Hao ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Fatigue Crack Growth Rate ◽  
Fatigue Crack Propagation Behavior ◽  
Stress Ratios

The fatigue crack propagation behaviors of an Al-Cu-Mg alloy are investigated in different environments and with varying stress ratios. Fatigue experiments are carried out via a fatigue crack growth rate test in laboratory air, a 3.5% (mass fraction) NaCl solution and a tank seeper. The results show that a corrosion environment has an obvious influence on the fatigue crack growth rate, and the degrees of influence of the two different corrosive environments are basically identical. When the stress ratio is R = 0.5 and 0.06 with a decrease of the stress intensity factor, the difference in the crack propagation rates for the corrosion and air environments gradually increases. However, the corrosion acceleration in each stage of crack propagation is obvious while R=−1.

Fatigue Crack Growth Rate Curve for Nickel Based Alloys in PWR Environment

2007 ◽  
Author(s):  
Yuichiro Nomura ◽  
Katsumi Sakaguchi ◽  
Hiroshi Kanasaki
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stainless Steels ◽  
Stress Ratio ◽  
Austenitic Stainless Steels ◽  
Rising Time

Japanese reference fatigue crack growth rate (FCGR) curves for ferrite and austenitic stainless steels in light water reactor environments are prescribed in JSME S NA1-2004. However, similar reference FCGR curve for nickel-based alloys for pressurized water reactors (PWR) are not prescribed. In order to propose reference FCGR curve for nickel-based alloys, under high stress ratio and low rising time, the effect of the welding method, the effect of specimen orientation and low stress intensity range fatigue crack propagation tests of nickel-based alloys 600, 132 and 82 weld metals were conducted as part of the Environmental Fatigue Test (EFT) projects of Japan Nuclear Energy Safety Organization (JNES). The results show that the effect of heat, welding methods, specimen orientations and environmental water conditions on the FCGR was not significant for Alloys 600, 132 and 82. The FCGR increased with increase of stress ratio, and cyclic loading frequency. According to the procedure for determining the reference FCGR curve of austenitic stainless steels in PWR environment of nickel-based alloys is proposed based on the reference data and the results of this study. The reference FCGR curve for nickel-based alloys in PWR environment are determined as a function of stress intensity factor range, temperature, load rising time and stress ratio.

Fatigue Crack Growth Rate of 16mnr Steel with Effect of Stress Ratio

2010 ◽  
Vol 118-120 ◽  
pp. 278-282
Author(s):  
Dong Hui Yin ◽  
Xiao Gui Wang ◽  
Bao Xiang Qiu ◽  
Zeng Liang Gao
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stress Ratio ◽  
Unified Model ◽  
Multiaxial Fatigue ◽  
Cyclic Plasticity ◽  
Finite Element Software

Fatigue crack growth was simulated by using a newly developed unified model on the fatigue initiation and crack growth based on an incremental multiaxial fatigue criterion. The cyclic elastic-plastic stress-strain field was analyzed using the general-purpose finite element software (ABAQUS) with the implementation of a robust cyclic plasticity theory. The fatigue crack growth rates with respect to three different stress ratios were selected as the benchmark to check the unified model. The predicted results agreed with the experimental data very well. The insensitivity of the crack growth rate to the stress ratio is due to the fast mean stress relaxation.

Fatigue Crack Growth Curve for Austenitic Stainless Steels in BWR Environment

2000 ◽  
Vol 123 (2) ◽  
pp. 166-172 ◽  
Author(s):  
M. Itatani ◽  
M. Asano ◽  
M. Kikuchi ◽  
S. Suzuki ◽  
K. Iida,
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Stainless Steels ◽  
Stress Ratio ◽  
Austenitic Stainless Steels ◽  
Reference Curve

Fatigue crack growth data obtained in the simulated BWR water environment were analyzed to establish a formula for reference fatigue crack growth rate (FCGR) of austenitic stainless steels in BWR water. The effects of material, mechanical and environmental factors were taken into the reference curve, which was expressed as: da/dN=8.17×10−12s˙Tr0.5s˙ΔK3.0/1−R2.121≦ΔK≦50 MPam where da/dN is fatigue crack growth rate in m/cycle, Tr is load rising time in seconds, ΔK is range (double amplitude) of K–value in MPam, and R is stress ratio. Tr=1 s if Tr<1 s, and Tr=1000 s if Tr cannot be defined. ΔK=Kmax−Kmin if R≧0.ΔK=Kmax if R<0.R=Kmin/Kmax. The proposed formula provides conservative FCGR at low stress ratio. Although only a few data show higher FCGR than that by proposed formula at high R, these data are located in a wide scatter range of FCGR and are regarded to be invalid. The proposed formula is going to be introduced in the Japanese Plant Operation and Maintenance Standard.

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