scholarly journals A MODEL RELATING LOW CYCLE FATIGUE PROPERTIES AND MICROSTRUCTURE TO FATIGUE CRACK PROPAGATION RATES

1979 ◽  
Vol 2 (3) ◽  
pp. 331-344 ◽  
Author(s):  
SAGHANA B. CHAKRABORTTY
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue

scholarly journals About the Role of Interfaces on the Fatigue Crack Propagation in Laminated Metallic Composites

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2564
Author(s):  
Philip Manuel Pohl ◽  
Frank Kümmel ◽  
Christopher Schunk ◽  
Itziar Serrano-Munoz ◽  
Henning Markötter ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Yield Stress ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Crack Deflection ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Metallic Composites

The influence of gradients in hardness and elastic properties at interfaces of dissimilar materials in laminated metallic composites (LMCs) on fatigue crack propagation is investigated experimentally for three different LMC systems: Al/Al-LMCs with dissimilar yield stress and Al/Steel-LMCs as well as Al/Ti/Steel-LMCs with dissimilar yield stress and Young’s modulus, respectively. The damage tolerant fatigue behavior in Al/Al-LMCs with an alternating layer structure is enhanced significantly compared to constituent monolithic materials. The prevalent toughening mechanisms at the interfaces are identified by microscopical methods and synchrotron X-ray computed tomography. For the soft/hard transition, crack deflection mechanisms at the vicinity of the interface are observed, whereas crack bifurcation mechanisms can be seen for the hard/soft transition. The crack propagation in Al/Steel-LMCs was studied conducting in-situ scanning electron microscope (SEM) experiments in the respective low cycle fatigue (LCF) and high cycle fatigue (HCF) regimes of the laminate. The enhanced resistance against crack propagation in the LCF regime is attributed to the prevalent stress redistribution, crack deflection, and crack bridging mechanisms. The fatigue properties of different Al/Ti/Steel-LMC systems show the potential of LMCs in terms of an appropriate selection of constituents in combination with an optimized architecture. The results are also discussed under the aspect of tailored lightweight applications subjected to cyclic loading.

scholarly journals Description of short fatigue crack propagation under low cycle fatigue regime

2016 ◽  
Vol 2 ◽  
pp. 3010-3017 ◽  
Author(s):  
Pavel Hutař ◽  
Jan Poduška ◽  
Alice Chlupová ◽  
Miroslav Šmíd ◽  
Tomáš Kruml ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Short Fatigue Crack

LOW CYCLE FATIGUE BEHAVIOR OF Zn-22Al ALLOY IN SUPERPLASTIC REGION AND NON-SUPERPLASTIC REGION

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5477-5482 ◽  
Author(s):  
ATSUMICHI KUSHIBE ◽  
TSUTOMU TANAKA ◽  
YORINOBU TAKIGAWA ◽  
KENJI HIGASHI
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Crack Tip ◽  
The Other ◽  
Al Alloy ◽  
Cycle Fatigue ◽  
Secondary Cracks

The crack propagation properties for ultrafine-grained Zn -22 wt % Al alloy during low cycle fatigue (LCF) in the superplastic region and the non-superplastic region were investigated and compared with the corresponding results for several other materials. With the Zn - 22 wt % Al alloy, it was possible to conduct LCF tests even at high strain amplitudes of more than ±5%, and the alloy appeared to exhibit a longer LCF lifetime than the other materials examined. The fatigue life is higher in the superplastic region than in the non-superplastic region. The rate of fatigue crack propagation in the superplastic region is lower than that in the other materials in the high J-integral range. In addition, the formation of cavities and crack branching were observed around a crack tip in the supereplastic region. We therefore conclude that the formation of cavities and secondary cracks as a result of the relaxation of stress concentration around the crack tip results in a reduction in the rate of fatigue crack propagation and results in a longer fatigue lifetime.

The Fatigue and Fracture Analysis of Steam Turbine Rotor Shafts Containing Defects

2019 ◽  
Vol 795 ◽  
pp. 254-261
Author(s):  
Shang Wang ◽  
Wei Qiang Wang ◽  
Ming Da Song ◽  
Hao Zhang
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Steam Turbine ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Turbine Rotor ◽  
Initial Surface ◽  
Cycle Fatigue ◽  
Steam Turbine Rotor ◽  
Fatigue Crack Propagation Life

In this study, the assessment and calculation methods for the crack propagation life of steam turbine rotor shafts containing defects are presented. The analytic methods for estimating the average stress and the alternating stress amplitude of the steam turbine rotor shafts are introduced. The defects on/in the rotor shafts were regularized by the method of fracture mechanics, and the high cycle fatigue crack propagation life and low cycle fatigue crack propagation life of the rotor shafts are estimated from Paris formula. Taking the 60MW turbine rotor shafts containing an initial surface defect and an initial internal defect as the examples respectively, the crack propagation life of them were calculated. The results indicated that the assessment method for the crack propagation life can preliminarily be both used to estimate the safety-operating life and to analyze the fracture reason of a steam turbine rotor shaft containing defects. This paper can provide reference for periodic maintenance and safety evaluation of turbine rotor shafts.

Fatigue Crack Modeling and Simulation Based on Continuum Damage Mechanics

2006 ◽  
Vol 129 (1) ◽  
pp. 96-102 ◽  
Author(s):  
Masakazu Takagaki ◽  
Toshiya Nakamura
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Present Theory ◽  
Continuum Damage ◽  
Cycle Fatigue

Numerical simulation of fatigue crack propagation based on fracture mechanics and the conventional finite element method requires a huge amount of computational resources when the cracked structure shows a complicated condition such as the multiple site damage or thermal fatigue. The objective of the present study is to develop a simulation technique for fatigue crack propagation that can be applied to complex situations by employing the continuum damage mechanics (CDM). An anisotropic damage tensor is defined to model a macroscopic fatigue crack. The validity of the present theory is examined by comparing the elastic stress distributions around the crack tip with those obtained by a conventional method. Combined with a nonlinear elasto-plastic constitutive equation, numerical simulations are conducted for low cycle fatigue crack propagation in a plate with one or two cracks. The results show good agreement with the experiments. Finally, propagations of multiply distributed cracks under low cycle fatigue loading are simulated to demonstrate the potential application of the present method.

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