Corrosion Prevention Compound on the Fatigue Life of 2024-T3 Aluminum Alloy

Materials ◽  
2005 ◽  
Author(s):  
M. A. Wahab ◽  
J. H. Park ◽  
S. S. Pang
Keyword(s):  
Aluminum Alloy ◽  
Water Vapor ◽  
Fatigue Life ◽  
Crack Growth ◽  
Fatigue Loading ◽  
Corrosive Environment ◽  
Constant Amplitude ◽  
Corrosion Prevention ◽  
Electron Microscopic ◽  
Stress Ratios

Corrosion-Prevention-Compounds (CPC) are commonly used to prevent corrosion in the aircraft industry. The presence of corrosive environment on aircraft structures has detrimental effects on the aircraft components which reduces the fatigue life and may also accelerate the crack growth rate in the structures. This is an experimental study on 2024-T3 aluminum alloy to investigate the effect of fatigue crack growth (life from threshold crack growth to final failure) using CPC on fatigue life. The corrosion fatigue with the presence of water-vapor reduces the total fatigue life. The fatigue life with the CPC treatment is shown to increase the fatigue life due to the protection from the corrosive environment containing water-vapor. Test results are obtained for various stress ratios and frequencies with and without the CPC treatment under constant amplitude fatigue loading in water vapor. The second aspect of this work is to investigate the effect of periodic overloads and the limitation in their spacing cycles on the fatigue life under constant amplitude fatigue loading. The results confirm the earlier work that the fatigue life increases due to the periodic overloads in 2024-T3 aluminum alloy. The interactions between overloads that are controlled by the spacing cycles between overloads are also examined. From scanning electron microscopic work the transition from the ductile to brittle mode is observed clearly in this experimental work.

The Effects of Periodic High Loads on Fretting Fatigue

1981 ◽  
Vol 103 (3) ◽  
pp. 223-228 ◽  
Author(s):  
A. Kantimathi ◽  
J. A. Alic
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Growth Retardation ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Constant Amplitude ◽  
Axial Loads ◽  
Prolonged Fatigue ◽  
Stress Ratios ◽  
Crack Growth Retardation

Fretting fatigue tests have been conducted on 7075-T7351 aluminum alloy coupons with fretting pads of the same material. Three different stress ratios were used, the otherwise constant amplitude axial loads being interrupted every 1000 cycles by either tensile overloads to 400 MPa or compressive underloads to −200 MPa. Tensile overloads greatly prolonged fatigue life for low stresses where the overload ratios were 1.6 and above; compressive underloads had comparatively little effect. The results are discussed in terms of crack growth retardation phenomena.

Fatigue Crack Growth of Alloy 7050-T7451 Plate in L-S Orientation

2012 ◽  
Vol 525-526 ◽  
pp. 221-224
Author(s):  
Rui Bao ◽  
Xiao Chen Zhao ◽  
Ting Zhang ◽  
Jian Yu Zhang
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Growth Characteristics ◽  
Stress Intensity Factor Range ◽  
Constant Amplitude ◽  
Stress Ratios

Experiments have been conducted to investigate the crack growth characteristics of 7050-T7451 aluminium plate in L-S orientation. Two loading conditions are selected, i.e. constant amplitude and constant stress intensity factor range (ΔK). The effects of ΔK-levels and stress ratios (R) on crack splitting are studied. Test data shows that crack splitting could result in the reverse of crack growth rate trend with the increasing R ratio at high ΔK-level. The appearance of crack splitting depends on both ΔK and R.

scholarly journals Effects of Actual Marine Atmospheric Pre-Corrosion and Pre-Fatigue on the Fatigue Property of 7085 Aluminum Alloy

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 81
Author(s):  
Laixin Shi ◽  
Lin Xiang ◽  
Jianquan Tao ◽  
Jun Liu ◽  
Qiang Chen ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Pitting Corrosion ◽  
Atmospheric Corrosion ◽  
Fatigue Property ◽  
Outdoor Exposure ◽  
Fatigue Tests ◽  
Constant Amplitude ◽  
Fatigue Fractography ◽  
Corrosion Mode

Effects of actual marine atmospheric precorrosion and prefatigue on the fatigue property of 7085-T7452 aluminum alloy were investigated by using the methods of marine atmospheric outdoor exposure tests and constant amplitude axial fatigue tests. Marine atmospheric corrosion morphologies, fatigue life, and fatigue fractography were analyzed. After three months of outdoor exposure, both pitting corrosion and intergranular corrosion (IGC) occurred, while the latter was the dominant marine atmospheric corrosion mode. Marine atmospheric precorrosion could result in a dramatical decrease in the fatigue life of the as-received 7085-T7452 aluminum alloy, while selective prefatigue can improve the total fatigue life of the precorroded specimen. The mechanism of the actual marine atmospheric corrosion and its effects on the fatigue life of the 7085-T7452 aluminum alloy were also discussed.

scholarly journals Application of Life-Dependent Material Parameters to Fatigue Life Prediction under Multiaxial and Non-Zero Mean Loading

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1587 ◽  
Author(s):  
Krzysztof Kluger ◽  
Aleksander Karolczuk ◽  
Szymon Derda
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Fatigue Loading ◽  
Mean Value ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
Test Results ◽  
Material Parameters ◽  
Fixed Material ◽  
Stress Ratios

This study presents the life-dependent material parameters concept as applied to several well-known fatigue models for the purpose of life prediction under multiaxial and non-zero mean loading. The necessity of replacing the fixed material parameters with life-dependent parameters is demonstrated. The aim of the research here is verification of the life-dependent material parameters concept when applied to multiaxial fatigue loading with non-zero mean stress. The verification is performed with new experimental fatigue test results on a 7075-T651 aluminium alloy and S355 steel subjected to multiaxial cyclic bending and torsion loading under stress ratios equal to R = −0.5 and 0.0, respectively. The received results exhibit the significant effect of the non-zero mean value of shear stress on the fatigue life of S355 steel. The prediction of fatigue life was improved when using the life-dependent material parameters compared to the fixed material parameters.

The Effect of Crack Growth Retardation when Comparing Constant Amplitude to Variable Amplitude Loading in an Aluminium Alloy

2014 ◽  
Vol 891-892 ◽  
pp. 948-954 ◽  
Author(s):  
Madeleine Burchill ◽  
Simon A. Barter ◽  
Michael Jones
Keyword(s):  
Growth Rate ◽  
Fatigue Life ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Growth Retardation ◽  
Crack Front ◽  
Constant Amplitude ◽  
Variable Amplitude ◽  
Growth Increments ◽  
Crack Growth Retardation

It has often been observed that the growth of short fatigue cracks under variable amplitude (VA) cyclic loading is not well predicted when utilising standard constant amplitude (CA) crack growth rate/stress intensity data (da/dN v DK). This paper outlines a coupon fatigue test program and analyses, investigating a possible cause of crack growth retardation from CA-only testing. Various test loading spectra were developed with sub-blocks of VA and CA cycles, then using quantitative fractography (QF) the sub-block crack growth increments were measured. Comparison of these results found that, after establishing a consistent uniform crack front using a VA load sequence, the average crack growth rate then progressively slowed down with the number of subsequent CA load cycles applied. Further fractographic investigation of the fracture surface at the end of each CA and VA sub-block crack growth, identified significant crack front morphology differences. Thus it is postulated that a variation or deviation from an efficient crack path is a driver of local retardation in short crack growth during CA loading. This may be a source of error in analytical predictions of crack growth under VA spectra loading that may need to be considered in addition to other potential effects such asless closure whilst cracks are small. For aircraft designers, using solely CA data for fatigue life predictions this may result in non-conservative estimates of total crack fatigue life, producing unexpected failures or an increased maintenance burden.

Use of Fatigue Fuses for Prediction of Fatigue Life of Steel Bridges

1996 ◽  
Vol 1544 (1) ◽  
pp. 71-78
Author(s):  
Everett McEwen ◽  
George Tsiatas
Keyword(s):  
Fatigue Life ◽  
Highway Bridges ◽  
Fatigue Loading ◽  
Highway Bridge ◽  
Constant Amplitude ◽  
Bridge Inspection ◽  
Structural Details ◽  
Critical Issues ◽  
The Mean ◽  
Cycles To Failure

The fatigue fuse is a device for predicting the fatigue life of steel highway bridge members when the bridge is subject to variable loads. The fuse is calibrated so that the cracking of each of its four legs can be related to damage in the structure. In a preliminary laboratory study, fatigue fuses are attached to eight steel girders, selected to represent three types of structural details found in existing highway bridges. The fuses are cemented to the girders and the girders subjected to a constant-amplitude fatigue loading. Cracking of the fatigue fuses is monitored by checking electrical continuity across each fuse leg. Tests are continued until girder failure or until all fuse legs are broken and the mean fatigue life of the girder as predicted by AASHTO is reached. The breaking of the fuse legs is used to predict the fatigue life of each girder, which is then compared with the actual cycles to failure of the girder and the AASHTO mean life. The prediction gives satisfactory agreement with the AASHTO mean life in four of the tests. In two tests, the predictions vary significantly from the AASHTO mean life. Although several critical issues remain (such as adapting the fatigue fuse to the environment of a real bridge and conducting tests on a statistically valid sample), the results of this feasibility study indicate that the fuse could be a valuable tool for highway bridge inspection.

Reliability Analysis of Corrosion Fatigue Crack Growth for 2024-T3 Aluminum Alloy

2008 ◽  
Vol 44-46 ◽  
pp. 105-110
Author(s):  
Sen Ge ◽  
Zhong Li ◽  
J.G. Zhang ◽  
Y.C. Xiao ◽  
G.Q. Liu ◽  
...  
Keyword(s):  
Growth Rate ◽  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Reliability Analysis ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Loading Frequency ◽  
Corrosive Environment

Fatigue crack growth rate experiments of center-cracked tension (CCT) specimens of the 2024-T3 aluminum alloy under constant-amplitude load in corrosive environment are carried out with 3 kinds of loading frequency. The fatigue crack growth rates in 3.5% NaCl solution are obtained by using seven-point incremental polynomial method. A probabilistic approach is presented for fatigue crack growth rate in corrosive environment with log-normal random variable model. The reliability analysis of crack propagation is conducted based on the experimental data. The crack exceedance probability at given service time and the distribution of the service time at given crack size are obtained by using the reliability analysis approach. The effect of loading frequency on crack propagation is studied. It is shown that the fatigue crack growth rate is increasing with loading frequency decreasing in corrosive environment. The predicted results by the presented method match the experimental results very well.

scholarly journals IMPROVEMENT OF FATIGUE LIFE OF A HOLED SPECIMEN OF ALUMINUM-ALLOY 2024-T3 BY INDENTATION AND HOLE EXPANSION

2012 ◽  
Vol 06 ◽  
pp. 336-342 ◽  
Author(s):  
MD. SHAFIUL FERDOUS ◽  
CHOBIN MAKABE ◽  
TATSUJIRO MIYAZAKI ◽  
NOBUSUKE HATTORI
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Crack Growth ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Local Plastic ◽  
Aluminum Alloy 2024 ◽  
Pull Tests

A method of improving the fatigue life and crack growth behavior of a center holed specimen was investigated. Local plastic deformation was applied around the hole by indentation to achieve the purpose. A series of fatigue tests was conducted on aluminum-alloy 2024-T3. Push-pull tests were performed under a stress ratio of R= -1 and a frequency of 10Hz. The observations of the crack initiation and growth were performed with a microscope, and hardness around the hole was measured by Vickers hardness testing machine. In the present study, the longest fatigue life was observed in the case of an indentation specimen with the highest load. The indentation was performed on both sides of the hole edges. The crack growth rate was decreased by indentation or expansion of the material around the hole. From the experimental results, it is found that the fatigue life and crack growth behavior of a holed or notched specimen can be improved by a simple technical method that is related to the local plastic working.

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