AN ANALYSIS OF MODE I FATIGUE CRACK GROWTH UNDER BIAXIAL STRESS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3824-3829
Author(s):  
M. ENDO ◽  
H. SAKAI ◽  
A. J. MCEVILY
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth ◽  
Biaxial Stress ◽  
Mode I ◽  
Plastic Behavior ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
The Difference ◽  
Stress States

A modified linear-elastic method of analysis was proposed for the estimation of fatigue lifetimes of biaxially loaded components containing cracks. A constitutive relation of the crack growth rate, d a/ d N, was used as a basis for the analysis. The modifications included a correction for elastic-plastic behavior, consideration of Kitagawa effect, and consideration of the development of crack closure in the wake of a newly formed crack. A unified evaluation for the d a/ d N data measured by Brown and Miller in different biaxial stress states was made by use of the proposed method. It was found that the difference in elastic-plastic behavior accounted for the effect of biaxial stress on d a/ d N.

Simulation of Fatigue Initiation and Non-Self-Similar Fatigue Crack Growth under Mixed Mode I/II Loading

2012 ◽  
Vol 224 ◽  
pp. 303-306
Author(s):  
Chen Chen Ma ◽  
Xiao Gui Wang
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Mixed Mode ◽  
Mode I ◽  
Fatigue Initiation ◽  
Self Similar ◽  
Crack Growth Model

The fatigue initiation and non-self-similar fatigue crack growth behavior of three notched compact tension and shear specimens of 16MnR steel under mixed mode I/II loading were investigated. The plane-stress finite element model with the implemented Armstrong-Frederick type cyclic plasticity model was used to calculate the elastic-plastic stress-strain responses. A recently developed dynamic crack growth model was used to simulate the effects of loading history on the successive crack growth. With the outputted numerical results, a multiaxial fatigue damage criterion based on the critical plane was used to determine the location of fatigue initiation. A formula of fatigue crack growth rate, which is based on the postulation that the fatigue initiation and crack growth have the same damage mechanism, was then used to calculate the transient crack growth rate and determine the non-self-similar crack growth path. The predicted fatigue initiation position, crack path and crack growth rate are in excellent agreement with the experimental data.

Simulation of Fatigue Crack Growth Using XFEM

2020 ◽  
Author(s):  
Durlabh Bartaula ◽  
Yong Li ◽  
Smitha Koduru ◽  
Samer Adeeb
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Elastic Material ◽  
Low Cycle Fatigue ◽  
Material Behavior ◽  
Plastic Behavior ◽  
Linear Elastic Material ◽  
Linear Elastic ◽  
Cyclic Approach

Abstract Pipelines carrying oil and gas are susceptible to fatigue failure (i.e., unstable fatigue crack propagation) due to fluctuating loading such as varying internal pressure and other external loadings. Fatigue crack growth (FCG) prediction through full-scale pipe tests can be expensive and time consuming, and experimental data is limited particularly in the face of large uncertainty involved. In contrast, numerical simulation techniques (e.g., XFEM) can be alternative to study the FCG, given that numerical models can be theoretically and/or experimentally validated with reasonable accuracy. In this study, capabilities and limitations of existing fatigue analysis code (e.g., direct cyclic approach with XFEM) in Abaqus for low cycle fatigue simulation are explored for compact-tension (CT) specimens and pipelines assuming linear elastic material behavior. The simulated FCG curve for a CT specimen is compared with that obtained from the analytical method using the stress intensity factor prescribed in ASTM E647. However, for real pipelines with elastic-plastic behavior, direct cyclic approach is not suitable, and an indirect cyclic approach is used based on the fracture energy parameters (e.g., J integral) calculated using XFEM in Abaqus. FCG law (e.g., power law relationship like Paris law) is used to generate the fatigue crack growth curve. For comparison, the FCG curve obtained through direct cyclic approach for pipelines assuming linear elastic material is also presented. The comparative studies here indicate that XFEM-based FCG simulation using appropriate techniques can be applied to pipelines for fatigue life prediction.

Experimental Study of the Fatigue Crack Propagation and Overloading Retardation in TA2 Plate

2015 ◽  
Vol 1120-1121 ◽  
pp. 1008-1013
Author(s):  
Hui Fang Li ◽  
Yuan Hong ◽  
Cai Fu Qian
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Crack Tip ◽  
Stress Intensity Factor Range ◽  
Crack Growth Behavior ◽  
Mode I ◽  
Crack Growth Path ◽  
Inclined Angle

In this paper, I+II mixed mode notch-crack fatigue propagation in titanium alloy steel TA2 was tested with the emphasis on the crack mode transition and retardation under constant amplitude loading or overloading. Finite element method was employed to calculate the stress distribution at the crack tip in order to explain the crack growth behavior. It is found that after initiation from the crack tip, the new formed crack propagates in a mode I form, regardless of the magnitudes of the inclined angle of the crack and the overloading applied. The relationship between the fatigue crack growth rate and mode I stress intensity factor range was calculated. After overloading, crack initiation and propagation will be significantly slowed, or in other words, there exists overloading retardation. Calculation shows that after overloading, a plastic zone with residual compressive stress is formed which is responsible for the retardation of the crack growth rate. Micro-morphologies of the crack growth path and the crack fracture surface were also observed and analyzed.

Comparison of Theoretical Estimates and Experimental Measurements of Fatigue Crack Growth Under Severe Thermal Shock Conditions—Part I: Experimental Observations

1986 ◽  
Vol 108 (4) ◽  
pp. 501-506 ◽  
Author(s):  
D. Marsh ◽  
D. Green ◽  
R. Parker
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Thermal Cycle ◽  
Experimental Measurements ◽  
Linear Elastic ◽  
Elastic Fracture

This paper reports the results of an experiment in which a severe thermal cycle comprising of alternate upshocks and downshocks has been applied to an axisymmetric feature with an internal, partial penetration weld and crevice. The direction of cracking and crack growth rate were observed experimentally and detailed records made of the thermal cycle. A second part of the paper, reported separately, compares a linear elastic fracture mechanics assessment of the cracking to the experimental observations.

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