New method and tool for increasing fatigue life of a large number of small fastener holes in 2024-T3 Al alloy

2019 ◽  
Vol 41 (4) ◽  
Author(s):  
J. T. Maximov ◽  
G. V. Duncheva ◽  
A. P. Anchev ◽  
I. M. Amudjev
Keyword(s):  
Fatigue Life ◽  
New Method ◽  
Al Alloy

Hole Expansion by Using Al-Alloy Specimen and 0.45% Carbon Steel Specimen

2010 ◽  
Vol 452-453 ◽  
pp. 601-604
Author(s):  
Muhammed Sohel Rana ◽  
Md. Shafiul Ferdous ◽  
Chobin Makabe ◽  
Masaki Fujikawa
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Carbon Steel ◽  
Cold Work ◽  
Fatigue Crack Initiation ◽  
Steel Specimen ◽  
Expansion Method ◽  
Al Alloy ◽  
2024 Aluminum Alloy ◽  
Cold Worked

The enhancement method of fatigue life and the crack initiate and growth behavior of a holed specimen was investigated by using the 2024 Aluminum alloy and 0.45% Carbon steel. The purpose of present study is to propose a simple technical method for enhancement of fatigue life in a notched specimen. Also, the effect of local plastic deformation by cold work on fatigue crack initiation behavior was examined. This paper presents a basic experimental kinematic cold expansion method by inserting and removing a pin through the specimen hole. The shape of cross-section of pin was a circle or an ellipse. It was shown that the fatigue life of the specimen with the cold-worked hole was longer than that of the specimen with non-cold-worked hole for the case of same stress level in aluminum alloy and carbon steel. Also, the fatigue strength was higher in the case of the cold expanded hole. In this study, a methodology of lengthening of fatigue life of holed specimen is shown. Also, the improvement conditions of fatigue life were significantly affected by shape of pin, local hardening and residual stress conditions. The fatigue life improvement of the damaged component of structures was studied.

High Cycle Fatigue Damage Evaluation of Steel Pipelines Based on Microhardness Changes During Cyclic Loads: Part II

2018 ◽  
Author(s):  
Geovana Drumond ◽  
Bianca Pinheiro ◽  
Ilson Pasqualino ◽  
Francine Roudet ◽  
Didier Chicot
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
High Cycle Fatigue ◽  
Steel Structures ◽  
New Method ◽  
Microplastic Deformation ◽  
Surface Phenomenon ◽  
Cyclic Loads ◽  
Cycle Fatigue ◽  
Indentation Tests

The hardness of a material shows its ability to resist to microplastic deformation caused by indentation or penetration and is closely related to the plastic slip capacity of the material. Therefore, it could be significant to study the resistance to microplastic deformations based on microhardness changes on the surface, and the associated accumulation of fatigue damage. The present work is part of a research study being carried out with the aim of proposing a new method based on microstructural changes, represented by a fatigue damage indicator, to predict fatigue life of steel structures submitted to cyclic loads, before macroscopic cracking. Here, Berkovich indentation tests were carried out in the samples previously submitted to high cycle fatigue (HCF) tests. It was observed that the major changes in the microhardness values occurred at the surface of the material below 3 μm of indentation depth, and around 20% of the fatigue life of the material, proving that microcracking is a surface phenomenon. So, the results obtained for the surface of the specimen and at the beginning of the fatigue life of the material will be considered in the proposal of a new method to estimate the fatigue life of metal structures.

scholarly journals Influence of Pre-Stress Magnitude on Fatigue Crack Growth Behavior of Al-Alloy

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1267
Author(s):  
Chunguo Zhang ◽  
Weizhen Song ◽  
Qitao Wang ◽  
Wen Liu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Shot Peening ◽  
Fatigue Property ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Al Alloy ◽  
Fatigue Crack Growth Behavior

From tensile overload to shot peening, there have been many attempts to extend the fatigue properties of metals. A key challenge with the cold work processes is that it is hard to avoid generation of harmful effects (e.g., the increase of surface roughness caused by shot peening). Pre-stress has a positive effect on improving the fatigue property of metals, and it is expected to strength Al-alloy without introducing adverse factors. Four pre-stresses ranged from 120 to 183 MPa were incorporated in four cracked extended-compact tension specimens by application of different load based on the measured stress–strain curve. Fatigue crack growth behavior and fractured characteristic of the pre-stressed specimens were investigated systematically and were compared with those of an as-received specimen. The results show that the pre-stress ranged from 120 to 183 MPa significantly improved the fatigue resistance of Al-alloy by comparison with that of the as-received specimen. With increasing pre-stress, the fatigue life first increases, then decrease, and the specimen with pre-stress of 158 MPa has the longest fatigue life. For the manner of pre-stress, no adverse factor was observed for increasing fatigue property, and the induced pre-stress reduced gradually till to disappear during subsequent fatigue cycling.

Influence of Different Surface Treatments on Fatigue Life of 7050 Al Alloy

2019 ◽  
Vol 944 ◽  
pp. 142-148 ◽  
Author(s):  
Nan Li ◽  
Hai Tao Li ◽  
Jing Yi Zhou ◽  
Hong Tao Liu ◽  
Chang Kui Liu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Fracture Surface ◽  
Surface Morphology ◽  
Surface Analysis ◽  
Shot Peening ◽  
Surface Treatments ◽  
Al Alloy ◽  
Stress Measurements ◽  
Fracture Surface Analysis

The fatigue life of 7050 Al alloy samples after different surface treatments, i.e., as-machined, anodizing, shot peening, and shot peening followed by anodizing, had been tested. The shot peening treatment specimens presented the longest average fatigue life. The fatigue life of anodizing treatment specimens decreased by 69.3% and 78.8% at 215 MPa and 260 MPa stress levels than as-machined ones. Introducing the shot peening treatment before anodizing can increase the fatigue life by 220% / 296.9% at 215 MPa/260 Mpa than that only treated by anodizing. The effect of the surface treatments on the fatigue life were studied by performing surface morphology investigation, residual stress measurements and fracture surface analysis.

A new method for fatigue life estimation of steels

2000 ◽  
Vol 5 (1-2) ◽  
pp. 9-14
Author(s):  
Akira Kato ◽  
Mitsue Hayashi
Keyword(s):  
Fatigue Life ◽  
New Method ◽  
Life Estimation ◽  
Fatigue Life Estimation

New method for low temperature fabrication of Ni–Al alloy powder for molten carbonate fuel cell applications

2014 ◽  
Vol 39 (23) ◽  
pp. 12259-12265 ◽  
Author(s):  
Seong-Cheol Jang ◽  
Byung Yong Lee ◽  
Suk Woo Nam ◽  
Hyung Chul Ham ◽  
Jonghee Han ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Low Temperature ◽  
Alloy Powder ◽  
New Method ◽  
Molten Carbonate Fuel Cell ◽  
Al Alloy ◽  
Molten Carbonate ◽  
Carbonate Fuel Cell

Thermo-Mechanical Fatigue Life Estimation of Al Alloy Using Plastic-Creep Separate Method

2019 ◽  
Vol 2019 (0) ◽  
pp. J04228
Author(s):  
Kohei FUKUCHI ◽  
Ken-ichi OHGUCHI ◽  
Yorimasa TSUBOTA ◽  
Takuro MITA ◽  
Wataru NAGAI ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Al Alloy ◽  
Life Estimation ◽  
Mechanical Fatigue ◽  
Fatigue Life Estimation ◽  
Plastic Creep
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