The compressive stress effect on fatigue crack growth under tension–compression loading

2010 ◽  
Vol 32 (2) ◽  
pp. 361-367 ◽  
Author(s):  
J. Zhang ◽  
X.D. He ◽  
Y. Sha ◽  
S.Y. Du
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Compressive Stress ◽  
Stress Effect ◽  
Compression Loading

An Experimental Investigation About Fatigue Crack Growth Rate of Aluminum Alloy Considering Various Mean Stress

2015 ◽  
Author(s):  
Yoo Choi ◽  
Deok-Geun Kim ◽  
Jeong-Yeol Park ◽  
Kyoung-Seok Lee ◽  
Jae-Myung Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Growth Rate ◽  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stress Effect ◽  
Mean Stress ◽  
Mean Stress Effect

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.

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

2018 ◽  
Vol 53 (8) ◽  
pp. 663-675 ◽  
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.

scholarly journals Application of a New, Energy-Based ΔS* Crack Driving Force for Fatigue Crack Growth Rate Description

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 518 ◽  
Author(s):  
Grzegorz Lesiuk
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Crack Growth ◽  
Engineering Practice ◽  
Stress Effect ◽  
New Energy

This paper presents the problem of the description of fatigue cracking development in metallic constructional materials. Fatigue crack growth models (mostly empirical) are usually constructed using a stress intensity factor ΔK in linear-elastic fracture mechanics. Contrary to the kinetic fatigue fracture diagrams (KFFDs) based on stress intensity factor K, new energy KFFDs show no sensitivity to mean stress effect expressed by the stress ratio R. However, in the literature there is a lack of analytical description and interpretation of this parameter in order to promote this approach in engineering practice. Therefore, based on a dimensional analysis approach, ΔH is replaced by elastic-plastic fracture mechanics parameter—the ΔJ-integral range. In this case, the invariance from stress is not clear. Hence, the main goal of this paper is the application of the new averaged (geometrically) strain energy density parameter ΔS* based on the relationship of the maximal value of J integral and its range ΔJ. The usefulness and invariance of this parameter have been confirmed for three different metallic materials, 10HNAP, 18G2A, and 19th century puddle iron from the Eiffel bridge.

A Study on Fatigue Crack Propagation Properties Using the X-Ray Diffraction Method

2008 ◽  
Vol 575-578 ◽  
pp. 1162-1169
Author(s):  
Md. Anowar Hossian ◽  
Man Bae Lim ◽  
Sun Chul Huh ◽  
Won Jo Park
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Diffraction Method ◽  
Stress Effect ◽  
X Ray Diffraction ◽  
X Ray

This study evaluated fatigue crack growth characteristics, Besides consider compressive residual stress effect and verified the most suitable shot peening velocity. Fatigue crack growth delay effect was compressive residual stress, but over peening did action projecting velocity that accelerate fatigue crack growth rate. X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface. Fracture mechanics parameters could be estimated by the measurement of X-ray parameters, and the fractography observation was performed using a scanning electron microscope (SEM) for fatigue fracture surface. As the shot peening velocity increases, striation width increased. The changes in X-ray material parameters described above are directly related to the process of fatigue until the initiation of fatigue crack and X-ray diffraction pattern is thought that failure prediction with stress distribution is possible.

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