Evaluation of three current methods for including the mean stress effect in fatigue crack growth rate prediction

In general, aluminum alloy is a commonly used for liquefied natural gas (LNG) storage systems. In this regard, it is important to know exact mechanical properties at cryogenic temperature. There are many researches to assess mechanical properties of aluminum alloy, such as tensile strength, fatigue performance and fracture toughness. Fatigue crack growth rate (FCGR) is important to predict the service life. In particular, mean stress effect can significantly affect the fatigue life. In this regard, this study carried out by a series of FCGR test at five different stress ratios (R=0.1, 0.3, 0.5, 0.7 and 0.85). The major objective of this paper is to suggest a new model that can consider the mean stress effect on FCGR of aluminum alloy in a unified manner. A mean stress equation is incorporated into Paris’ law. In order to validate the model, FCGR test data of aluminum alloy is compared with Walker’s relationship. Compared to the other existing model, the new model is found to exhibit more accurate result compared to Walker model.

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Effect of Hardness and Tensile Mean Stress on Fatigue Crack Growth in Beryllium Copper

Journal of Mechanical Engineering Science ◽

10.1243/jmes_jour_1969_011_041_02 ◽

1969 ◽

Vol 11 (3) ◽

pp. 343-349 ◽

Cited By ~ 2

Author(s):

L. P. Pook

Keyword(s):

Growth Rate ◽

Fatigue Crack ◽

Crack Growth Rate ◽

Fatigue Crack Growth ◽

Residual Stresses ◽

Crack Growth ◽

Fatigue Crack Growth Rate ◽

Mean Stress ◽

Growth Data ◽

Beryllium Copper

Some fatigue crack growth data have been obtained for age-hardened beryllium copper. The fatigue crack growth rate was found to be very dependent on the hardness and tensile mean stress. This dependence is believed to be associated with the intense residual stresses surrounding Preston-Guinier zones.

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Energy response of S355 and 41Cr4 steel during fatigue crack growth process

The Journal of Strain Analysis for Engineering Design ◽

10.1177/0309324718798234 ◽

2018 ◽

Vol 53 (8) ◽

pp. 663-675 ◽

Cited By ~ 15

Author(s):

Grzegorz Lesiuk ◽

Mieczysław Szata ◽

Dariusz Rozumek ◽

Zbigniew Marciniak ◽

José Correia ◽

...

Keyword(s):

Experimental Data ◽

Fatigue Crack ◽

Fatigue Crack Growth ◽

Crack Propagation ◽

Crack Growth ◽

Stress Effect ◽

Mean Stress ◽

Mean Stress Effect ◽

R Ratio ◽

The Mean

In this research, a novel approach of the fatigue crack growth rate description has been proposed. Based on theoretical and experimental approach, the mean stress effect expressed by R-ratio is present in classical da/dN–Δ K diagram. According to energy approach – based on the irrevocably dissipated energy accumulated in material (hysteresis loop) during fatigue process – the mean stress effect can be minimalized. Experimental validation of the proposed model was performed using results of fatigue crack propagation data for S355 and 41Cr4 steels in terms of strain energy density parameter Δ S or cyclic J-integral range –Δ J. In contrast to the force approach based on Kmax (or Δ K), the energy parameters Δ S or Δ J represent unambiguously the fatigue crack propagation rate, without influence of mean stress effect – R-ratio. However, in near threshold range of kinetic fatigue fracture diagram, the energy parameter displays a slight dispersion of the experimental data. According to the crack closure theory and its U-Elber parameter, the dispersion of experimental data is decreased. Therefore, the crack closure effects have a high significance in energy model – similar to the ‘force approach’ based on Δ K concept.

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A New Model of Fatigue Crack Growth Rate Considering Mean Stress Effects Due to Locked-In Stress

International Journal of Steel Structures ◽

10.1007/s13296-018-0190-z ◽

2018 ◽

Vol 19 (4) ◽

pp. 1099-1111 ◽

Cited By ~ 1

Author(s):

Yoo Choi ◽

Dong Jin Oh ◽

Jae Myung Lee ◽

Kyoung Seok Lee ◽

Myung Hyun Kim

Keyword(s):

Growth Rate ◽

Fatigue Crack ◽

Crack Growth Rate ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Fatigue Crack Growth Rate ◽

Mean Stress ◽

New Model ◽

Stress Effects

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

Journal of Engineering Materials and Technology ◽

10.1115/1.3224821 ◽

1980 ◽

Vol 102 (4) ◽

pp. 341-346 ◽

Cited By ~ 8

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.

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