Experimental Investigation of Typical Environmental Corrosion Influence on Fatigue Life in 2024-T3 Aluminium Alloy

2006 ◽  
Vol 324-325 ◽  
pp. 363-366
Author(s):  
Rui Bao ◽  
Jian Yu Zhang ◽  
Bin Jun Fei
Keyword(s):  
Experimental Investigation ◽  
Aluminum Alloy ◽  
Fatigue Life ◽  
Crack Initiation ◽  
High Reliability ◽  
Mean Value ◽  
Modification Factor ◽  
Life Analysis ◽  
Crack Initiation Life ◽  
Test Result

The influence of environmental corrosion on fatigue life of 2024-T3 aluminum alloy is investigated in this paper. Experiments with center-hole specimens and CC(T) specimens are conducted and reported. The test result shows that the corrosion influence is becoming serious while the environmental causticity is increasing, and the influence on crack initiation life is greater than that on crack propagation life. Analysis of the test data also indicates that the environmental causticity enlarges the dispersivity of fatigue life. Using the corrosion-modification-factor obtained by eigenvalue or mean value to prediction the fatigue life with high reliability will cause an unconservative conclusion.

Prediction of Low-Cycle Fatigue Life of Specimens With Fabrication Flaws

1968 ◽  
Vol 90 (4) ◽  
pp. 620-626 ◽  
Author(s):  
A. G. Pickett
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Small Specimen ◽  
Cycle Fatigue ◽  
Notch Stress ◽  
Weld Defect ◽  
Life Analysis ◽  
Fatigue Life Analysis ◽  
Crack Initiation Life

A modification of the notch stress procedure for fatigue-life analysis is presented. The importance of considering the mechanics of the specimen and the effects of the notch on specimen mechanics is illustrated by example. The procedure is applied to correlate the results of small specimen tests with large weld defect specimen tests. The significance of crack-initiation life and crack-propagation life and the dependence of these portions of total fatigue life on specimen geometry and loading is developed.

The Influence of Humid Environment on Fatigue Property of Pre-Corroded 7XXX Aluminum Alloy

2011 ◽  
Vol 314-316 ◽  
pp. 1406-1410 ◽  
Author(s):  
Li Hui ◽  
Song Zhou ◽  
Liang Xu ◽  
Shao Hua Ma ◽  
Yan Wang ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Influence Factor ◽  
High Reliability ◽  
Fatigue Property ◽  
Mean Value ◽  
Humid Environment

The influence of humid environment on fatigue property of pre-corroded 7XXX aluminum alloy were investigated by means of fatigue and staircase experiments (Kt=1 and Kt=3). The results showed that humid environment significantly reduces both fatigue life and strength with the influence-factor of 0.7339(Kt=1), 0.8603(Kt=3) and 0.973(Kt=1), 0.971(Kt=3), respectively. The humid environment enlarges the dispersivity of fatigue life. As a consequence, an unconservative results on prediction of the fatigue life with high reliability of 99.9% will be obtained, based on the corrosion-influence-factor reached from eigenvalue or mean value .

Numerical method for fatigue life of plane bolted joints under thermal load

2020 ◽  
Vol 234 (14) ◽  
pp. 2041-2049 ◽  
Author(s):  
Ziyun You ◽  
Yu Fang ◽  
Xintian Liu ◽  
Tie Chen ◽  
Wenjing Li ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Numerical Method ◽  
Test Temperature ◽  
Fatigue Crack Initiation ◽  
Bolted Joints ◽  
Loading Frequency ◽  
2024 Aluminum Alloy ◽  
Crack Initiation Life

In fatigue test, the fatigue life of metal components is affected by many factors, such as test temperature, stress ratio and loading frequency. In order to study the influence of temperature on fatigue life of bolted joints, thermal stress and fast coefficient are introduced. A numerical method of fatigue crack initiation life is proposed based on Manson-Coffin strain fatigue formula. The crack initiation life of 2024 aluminum alloy at different temperatures can be obtained by this method, which provides a theoretical basis for the fatigue life prediction of metals. Then, the stress severity factor SSF is introduced to calculate fatigue life of plane bolted joints. The data obtained from the model show that the crack initiation life of aluminum alloy specimen decreases significantly with test temperature rises, the same as the fatigue life of bolted joints.

Fatigue Behavior of Circumferentially Notched Round Bars of Austenitic Stainless Steel Under Torsional and Axial Loads

2010 ◽  
Author(s):  
Masao Itatani ◽  
Keisuke Tanaka ◽  
Isao Ohkawa ◽  
Takehisa Yamada ◽  
Toshiyuki Saito
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Static Tension ◽  
Cyclic Torsion ◽  
Cyclic Tension ◽  
Crack Initiation Life

Fatigue tests of smooth and notched round bars of austenitic stainless steels SUS316NG and SUS316L were conducted under cyclic tension and cyclic torsion with and without static tension. Fatigue strength under fully reversed (R=−1) cyclic tension once increased with increasing stress concentration factor up to Kt=1.5, but it decreased from Kt=1.5 to 2.5. Fatigue life increased with increasing stress concentration under pure cyclic torsion, while it decreased with increasing stress concentration under cyclic torsion with static tension. From the measurement of fatigue crack initiation and propagation lives using electric potential drop method, it was found that the crack initiation life decreased with increasing stress concentration and the crack propagation life increased with increasing stress concentration under pure cyclic torsion. Under cyclic torsion with static tension, the crack initiation life also decreased with increasing stress concentration but the crack propagation life decreased or not changed with increasing stress concentration then the total fatigue life of sharper notched specimen decreased. It was also found that the fatigue life of smooth specimen under cyclic torsion with static tension was longer than that under pure cyclic torsion. This behavior could be explained based on the cyclic strain hardening under non-proportional loading and the difference in crack path with and without static tension.

A Probabilistic Micromechanical Code for Predicting Fatigue Life Variability: Model Development and Application

2005 ◽  
Vol 128 (4) ◽  
pp. 889-895 ◽  
Author(s):  
K. S. Chan ◽  
M. P. Enright
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Initiation ◽  
Crack Growth ◽  
Model Development ◽  
Fatigue Crack Initiation ◽  
Crack Size ◽  
Crack Initiation Life ◽  
Variability Model

This paper summarizes the development of a probabilistic micromechanical code for treating fatigue life variability resulting from material variations. Dubbed MICROFAVA (micromechanical fatigue variability), the code is based on a set of physics-based fatigue models that predict fatigue crack initiation life, fatigue crack growth life, fatigue limit, fatigue crack growth threshold, crack size at initiation, and fracture toughness. Using microstructure information as material input, the code is capable of predicting the average behavior and the confidence limits of the crack initiation and crack growth lives of structural alloys under LCF or HCF loading. This paper presents a summary of the development of the code and highlights applications of the model to predicting the effects of microstructure on the fatigue crack growth response and life variability of the α+β Ti-alloy Ti-6Al-4V.

Observation of Fatigue Crack Initiation and Propagation for Carbon and Low-Alloy Steels in Oxygenated Water at Elevated Temperature

2006 ◽  
Author(s):  
Makoto Higuchi ◽  
Katsumi Sakaguchi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Elevated Temperature ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Low Alloy Steels ◽  
Test Conditions ◽  
Alloy Steels ◽  
Crack Initiation Life ◽  
Temperature Water

Low cycle fatigue life of structural materials in LWR plants decreases remarkably in elevated temperature water depending on strain rate, temperature, water chemistry and material properties. The maximum reduction rate in fatigue life for carbon and low alloy steels is over 100 in severe conditions. Fatigue life is composed of fatigue crack initiation life and consequent propagation life. It is important to know the proportion of crack initiation life to propagation life in water environment when developing a model to estimate fatigue crack initiation life. The beachmark imprinting method was used to monitor fatigue crack initiation and consequent propagation. Environmental test conditions varied widely from severely accelerated conditions of high temperature and dissolved oxygen to mild conditions of lower temperature and oxygen. Fatigue crack initiation life could be determined using the beachmark imprinting method for all test conditions. Based on obtained test results, the susceptibility of each parameter in NWC and the relationships between NWC/NW and environmental fatigue life correction factor Fen under various conditions are discussed, but a good relationship could not be detected due to widely scattered data and a model to predict fatigue crack initiation life could not be proposed.

0106 Experimental Investigation of Fretting Fatigue Crack Initiation Life based on wear process

2013 ◽  
Vol 2013.50 (0) ◽  
pp. 010601-010602
Author(s):  
Toshiki KARASAWA ◽  
Kousoku NAGATA ◽  
Yuichi OTSUKA ◽  
Yukio MIYASHITA ◽  
Yoshiharu MUTOH
Keyword(s):  
Experimental Investigation ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Fretting Fatigue ◽  
Wear Process ◽  
Crack Initiation Life
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