Numerical investigation of the effect of hole reaming on fatigue life by cold expansion

2022 ◽  
Author(s):  
Kuanyu Liu ◽  
Xinsheng Yang ◽  
Li Zhou ◽  
Ming Li ◽  
Weijin Zhu
Keyword(s):  
Fatigue Life ◽  
Fatigue Tests ◽  
Stress Fields ◽  
Analysis Software ◽  
Fe Method ◽  
Alloy Plate ◽  
Cold Expansion ◽  
Hole Edge ◽  
Aluminum Alloy Plate ◽  
The Relationship

The reaming process of the 6061 aluminum alloy plate after cold expansion with split sleeve was simulated by finite element (FE) method based on Abaqus/CAE, the relationship between the reaming depths and the distribution of residual stress fields is obtained by analysis. The fatigue lives of the plate under different reaming depths were calculated by using the fatigue analysis software FE-SAFE, and verified by fatigue tests. The results show that reaming after expansion will increase the residual compressive stress at the hole edge on the entrance surface. In addition, the fatigue life of the specimens increases with the increase of the reaming depth, and the best fatigue gain of the specimen is obtained when the reaming depth of 0.5 mm.

Effect of Split-Sleeve Cold Expansion on the Fatigue Life of 7050-T7451 Aluminum Alloy

2014 ◽  
Vol 1082 ◽  
pp. 403-407 ◽  
Author(s):  
Hong Huang ◽  
Qing Yun Zhao ◽  
Feng Lei Liu
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Transgranular Fracture ◽  
Alloy Plate ◽  
Cold Expansion ◽  
Compressive Stresses ◽  
Aluminum Alloy Plate ◽  
Relationship Of ◽  
The Relationship

Split-sleeve cold expansion processing was employed on the 7050-T7451 aluminum alloy plate. Fatigue lives were compared according different expansion, then the relationship of fatigue life and expansion was analyzed. Residual stresses were measured with different expansion, and the fatigue fractograph was analyzed by SEM. The results show that the split-sleeve cold expansion can obtain longer life compared with the non-strengthen hole. When over the optimum expansion, fatigue life began to decrease. The maximum fatigue life increased to 2.92 times with 4.1% expansion. The maximum values of radial residual stresses grew with expansion. The depths of residual compressive stresses were more than 6mm with 2.6% and 4.1% expansion. The fatigue fractograph shows mixed transgranular fracture.

scholarly journals Effects of Pre-Tensile Deformation on the Fatigue Fracture Behavior of Annealed 7005 Aluminum Alloy Plate

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 623
Author(s):  
Ni Tian ◽  
Zhen Feng ◽  
Xu Shi ◽  
Wenze Wang ◽  
Kun Liu ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Fracture ◽  
Tensile Deformation ◽  
Thin Strip ◽  
Second Phase ◽  
Alloy Matrix ◽  
Alloy Plate ◽  
Dislocation Distribution ◽  
Aluminum Alloy Plate

In the present study, the fatigue life and fatigue fracture characteristics of annealed 7005 aluminum alloy plates subjected to different pre-tensile deformations were investigated. The results obtained upon increasing the pre-tensile deformation of the alloy plate to 20% revealed that the second-phase particles did not show any obvious changes, and that the thickness of the thin strip grain slightly decreased. The dislocation distribution in the alloy matrix varied significantly among the grains or within each grain as the dislocation density gradually increased with increasing pre-tensile deformation. Moreover, the fatigue performance of the annealed 7005 aluminum alloy plate was significantly improved by the pre-tensile deformation, and the alloy plate subjected to 20% pre-tensile deformation exhibited an optimal fatigue life of ~1.06 × 106 cycles, which was 5.7 times and 5.3 times that of the undeformed and 3% pre-stretched alloy plates, respectively. Two fatigue life plateaus were observed in the pre-tensile deformation ranges of 3–5% and 8–12%, which corresponded to heterogeneous dislocation distribution among various grains and within each grain, respectively. Moreover, two large leaps in the plot of the fatigue-life–pre-tensile-deformation curve were observed, corresponding to the pre-tensile deformation ranges of 5–8% and 16–20%, respectively.

Relationship Between Fatigue Life Distribution, Notch Configuration, and S-N Curve of a 2024-T4 Aluminum Alloy

1985 ◽  
Vol 107 (3) ◽  
pp. 214-220 ◽  
Author(s):  
T. Shimokawa ◽  
Y. Hamaguchi
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Stress Amplitude ◽  
Fatigue Tests ◽  
Test Results ◽  
Notched Specimens ◽  
Wide Range ◽  
Life Distributions ◽  
The Relationship ◽  
Test Stress

The objective of this study is to identify the most closely related variable to the distribution of fatigue life in unnotched and three kinds of notched 2024-T4 aluminum alloy specimens. Carefully designed fatigue tests under a constant temperature and humidity condition provided fatigue life distributions over a wide range of stress amplitude. This study used about 1000 specimens. On the basis of the test results, the dependence of the scatter in fatigue life on notch configuration, the period to crack initiation, the level of stress amplitude, the median fatigue life, and the slope of the median S-N curve is investigated, and the relationship between the distributional form of fatigue life and the shape of the median S-N curve is discussed. It is concluded that the slope and shape of the median S-N curve in the vicinity of the test stress level are closely related to the scatter and distributional form of fatigue life respectively. This is common to the unnotched and three kinds of notched specimens. A variability hypothesis to correlate the median S-N curve with fatigue life distributions is examined.

The Influence of Corrosion Pits and Cold Expanded Fastener Holes on the Fatigue Life Aluminium 7075-T651

2014 ◽  
Vol 891-892 ◽  
pp. 87-92 ◽  
Author(s):  
Benjamin Withy ◽  
Stephen Campbell ◽  
Glenn Stephen
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Air Force ◽  
Fatigue Tests ◽  
Expansion Process ◽  
Cold Expansion ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Corrosion Pits

The Royal New Zealand Air Force (RNZAF) utilised the split sleeve cold expansion process to increase the fatigue life of fastener holes in the wings of the C130 transport fleet. As part of the validation of the fatigue improvements offered by the process the Defence Technology Agency conducted a series of fatigue tests on cold expanded fastener holes in aluminium 7075-T651, including specimens with corrosion induced after the cold expansion process had been performed. This research conducted an analysis of fatigue crack origins and modelled the stress concentration factors generated as a result of the corrosion pits. These results were used to explain the differing fatigue life and s-n curves produced by corroded and non-corroded fatigue specimens and the location of crack initiation sites around corroded cold expanded fastener holes.

scholarly journals Cold Working Process on Hard Metal Stacked Assembly

2021 ◽  
pp. 41-47
Author(s):  
Guillaume Pichon ◽  
Alain Daidie ◽  
Adeline Fau ◽  
Clément Chirol ◽  
Audrey Benaben
Keyword(s):  
Fatigue Life ◽  
Hard Metal ◽  
Fatigue Tests ◽  
Cold Expansion ◽  
Double Shear ◽  
Shear Fatigue ◽  
First Results ◽  
Negative Effect ◽  
Mechanical Performances ◽  
Metallic Parts

AbstractDesigned for aeronautical and automotive applications, the split sleeve cold expansion process is used to improve the fatigue life of bolted metallic parts. Although its application has been well tested on aluminum assemblies, hard metal applications are still being studied. This paper presents experimental results of double bolt joint assemblies under double shear fatigue tests after stacked split sleeve cold expansion. The behaviors of two sizes of assemblies with different degrees of expansion are investigated. S-N curves are the main indicators of this study but thermal aspects are also investigated to observe fretting in the specimens as bolts are preloaded. Bolt tension is a major parameter in assembly regarding fatigue life. Interference between those two phenomena is at the heart of this paper. The first results show that stacked cold expansion has a negative effect on mechanical performances, as it deteriorates the fatigue life of the assembly. However, an examination of these results provides a coherent explanation for the loss of performance that occurs.

scholarly journals Effects of chamfering, cold expansion, bolt clamping, and their combinations on fatigue life of aluminum–lithium alloy single plate

2018 ◽  
Vol 10 (1) ◽  
pp. 168781401775068
Author(s):  
Yongjie Huang ◽  
Zhidong Guan ◽  
Haitao Li ◽  
Xu Yang ◽  
Zengshan Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Three Dimensional ◽  
Fatigue Tests ◽  
Cold Expansion ◽  
Lithium Alloy ◽  
Single Plate ◽  
Aluminum Lithium Alloy ◽  
Aluminum Lithium ◽  
Three Dimensional Finite Element

The objective of this study was to establish the effects of cold expansion, chamfering, bolt clamping, and their combinations on the fatigue life of an aluminum–lithium alloy single plate. Fatigue tests were conducted to quantify the anti-fatigue effects of the different techniques. A scanning electron microscope was used to perform fracture analyses of the used specimens, and the residual stresses were measured using an X-ray diffraction device. In addition, three-dimensional finite element models of the specimens were established and used to characterize their stress states, and the Smith–Watson–Topper method was used to predict the fatigue lives of the specimens. The fatigue test results showed that all the considered processes improved the fatigue life of the pristine specimen. The most effective was a combination of 3.2% cold expansion, 1-mm chamfering, and bolt clamping using a 6.4-N m torque, which improved the fatigue life of the pristine specimen by a factor of 15.5. The finite element method results also revealed that this combination decreased the maximum stress and confirmed its superiority in relation to the other fatigue-life enhancement techniques in terms of the anti-fatigue effect. The Smith–Watson–Topper method underestimated the specimen fatigue life, but the accuracy satisfied engineering requirements.

Vertical Wall on an Aluminum Alloy Plate Fabricated by Friction Stir Forming

2017 ◽  
Vol 748 ◽  
pp. 202-206 ◽  
Author(s):  
Takahiro Ohashi ◽  
Hamed Mofidi Tabatabaei ◽  
Tadashi Nishihara
Keyword(s):  
Aluminum Alloy ◽  
Aspect Ratio ◽  
Vertical Wall ◽  
Thick Wall ◽  
Back Surface ◽  
Alloy Plate ◽  
Friction Stir ◽  
Key Factor ◽  
Aluminum Alloy Plate ◽  
The Relationship

This paper describes utilization of friction-stir forming (FSF) to generate a single wall on an aluminum alloy plate. The proposed process is as follows. The authors placed a material plate on a die having a variable-width groove and conducted friction stirring on its back surface. The material filled the cavity due to high pressure and heat caused by friction stirring. This process can be applied to generate thermal plate-fins and rib structures. The present study investigates the forming conditions and the corresponding results including the height limit of walls to obtain reference data for applications. In the experiment, a 3mm-thick JIS A5083P-O aluminum plate was utilized as the substrate. With a grove of less than 0.2mm-width, the wall was difficult to generate. The maxim height of the 0.2mm-thick wall formed by FSF was 2.8mm, and its aspect ratio was 14, which was difficult to form using conventional forging. Overall, the relationship between groove width of the die cavity and aspect ratio of maximum wall height to wall thickness followed the fractional curvature. This results implies that the deformable material volume generated by friction stirring is a key factor for wall height.

scholarly journals Flexural Fatigue Behaviors of Silicon Carbide Recycled Concrete in Corrosive Environments

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jinzhi Zhou ◽  
Tiantian Fu ◽  
Chuheng Zhong ◽  
Kun Peng ◽  
Ziyang Shuang
Keyword(s):  
Silicon Carbide ◽  
Fatigue Life ◽  
Failure Probability ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Recycled Concrete ◽  
Flexural Fatigue ◽  
Corrosive Environments ◽  
The Relationship

An experimental study on the flexural fatigue behaviors of recycled concrete (RC) and silicon carbide recycled concrete (SiCRC) was conducted. The immersion time was 0 d, 30 d, 60 d, and 90 d in 5% NaCl solution for these two kinds of recycled concrete specimens, respectively, and then, four-point flexural fatigue tests were performed by MTS fatigue testing machine. The fatigue life for varying stress levels ranging from 0.9 to 0.6 was obtained. The fatigue life was given considering the failure probability according to the fatigue life and stress level of the specimen via the logarithmic normal distribution and Weibull distribution, respectively. The relationship between fatigue life and failure probability was also obtained. The fatigue life with failure probability of 1% and 50% was further predicted. The results showed that the fatigue life of RC and SiCRC increased in corrosive environments. The fatigue life of SiCRC is higher than that of RC, and the incorporation of SiCRC can improve the fatigue life of recycled concrete.

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