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.

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.

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.

Effect of Interference-Fit on Fatigue Life for Composite Lap Joints

2014 ◽  
Vol 939 ◽  
pp. 39-46 ◽  
Author(s):  
Hong Qian Xue ◽  
Qian Tao ◽  
Emin Bayraktar
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Tests ◽  
Lap Joints ◽  
Finite Element Simulations ◽  
Cyclic Loads ◽  
Lap Joint ◽  
Interference Fit ◽  
3D Finite Element ◽  
Double Shear

The aim of this study is to examine the effect of the clearance and interference-fit on the fatigue life of composite lap joints in double shear, 3D finite element simulations have been performed to obtain stress (or strain) distributions around the hole due to interference fit using FEM package, Non-linear contact analyses are performed to examine the effects of the clearance and interference for titanium and composite lap joint. Fatigue tests were conducted for the titanium and composite lap joints with clearance fit and interference fit with 0.5, 1, and 1.5% nominal interference fit levels at different cyclic loads. The results shows that interference fit increases fatigue life compared to clearance fit specimens, the titanium and composite lap joint with 1% interference fit level has the better fatigue life.

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.

Effect of bolt tightening on the fatigue behavior of GLARE double shear lap joints

2021 ◽  
pp. 002199832110033
Author(s):  
B Abazadeh ◽  
HR Maleki
Keyword(s):  
Fatigue Life ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Lap Joints ◽  
Clamping Force ◽  
Test Results ◽  
Load Range ◽  
Double Shear ◽  
Aluminum Sheets ◽  
Aluminum Alloy 2024

In this paper, the effect of bolt torque tightening has been investigated on the fatigue behavior of GLARE in double shear lap configuration. To do so, experimental fatigue tests were conducted using GLARE3-5/4-0.4 specimens with applied torques of 0 (finger tightened), 2 and 4 Nm at different cyclic longitudinal load ranges to achieve the stress-life (S-N) curves. The results revealed that applying and increasing the clamping force enhances the fatigue life of the GLARE specimens. Furthermore, comparison of fatigue test results of GLARE and available monolithic aluminum alloy 2024-T3 plates indicated when the applied load range is low, the effect of clamping force is more noticeable in GLARE specimens due to longer fatigue crack growth life of GLARE. Also, the occurrence of fretting fatigue didn’t reduce the fatigue life of GLARE specimens considerably in contrary to aluminum sheets because of the laminated structure of GLARE. The obtained results can provide insights in designing bolted GLARE joints with superior fatigue in-service performance.

Local Fatigue Properties of Al-Zn-Mg Alloy Welded Joint

2012 ◽  
Vol 468-471 ◽  
pp. 2010-2013
Author(s):  
Liang Zhang ◽  
Xue Song Liu ◽  
Lin Sen Wang ◽  
Zi Qi Ma ◽  
Hong Yuan Fang
Keyword(s):  
Fatigue Life ◽  
Yield Strength ◽  
Aluminium Alloy ◽  
Welded Joint ◽  
Fatigue Tests ◽  
Mg Alloy ◽  
Fatigue Properties ◽  
Notched Specimens ◽  
The Difference ◽  
Mechanical Performances

Local tensile properties and fatigue properties of Al-Zn-Mg alloy welded joint were investigated. Experiment results show that A7N01 aluminium alloy welded joint is highly inhomogenous both in microstructure and mechanical performances. Ultimate tensile strength and yield strength of base metal are superior compared to HAZ and weld metal. U-shape notched specimens were used in fatigue tests to study local fatigue properties of the joint. Fatigue tests results demonstrate that the difference of local fatigue life is conspicuous in the three regions. The difference of yield strength is believed to result from the diversity of fatigue life for each region in A7N01 aluminium alloy welded joint.

scholarly journals Fatigue Performance of Wet and Dry Pulverized Wood Flour Reinforced PP Composites

2019 ◽  
Vol 3 (1) ◽  
pp. 20 ◽  
Author(s):  
Md Haque ◽  
Koichi Goda ◽  
Hirokazu Ito ◽  
Shinji Ogoe ◽  
Masaki Okamoto ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Wood Flour ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Test Results ◽  
Polypropylene Composites ◽  
Different Types ◽  
Pine Trees ◽  
Negative Effect ◽  
Positive Effect

In this paper, we exclusively studied the effects of dry and wet pulverization of different wood flours on the fatigue performance of polypropylene (PP)/wood flour (WF) composites. Wood flours obtained from cypress and Scots pine trees were pulverized in both dry and wet conditions at two different mill-plate gaps, 200 µm and 350 µm, and were used as reinforcement in PP matrices. Master batches of PP with different types of pulverized WF were compounded before processing in an extruder. The PP/WF composites of initial WF were also prepared for comparison. The prepared composites were analyzed by tensile and fatigue tests. It was found that the tensile properties of wood/polypropylene composites were affected by the pulverization of WF. Fatigue test results displayed that wet pulverization of short cypress flour had a negative effect on the fatigue life of PP/WF composites, while wet pulverization of long cypress flour and pine flour had a positive effect on the fatigue life of PP/WF composites.

scholarly journals Experimental study on fatigue performance of Q420qD high-performance steel cross joint in complex environment

2021 ◽  
Author(s):  
Haigen Cheng ◽  
Cong Hu ◽  
Yong Jiang
Keyword(s):  
Fatigue Life ◽  
High Performance ◽  
Steel Structure ◽  
Steel Structures ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Corrosive Media ◽  
Joint Connection ◽  
High Performance Steel ◽  
The Cross

AbstractThe steel structure under the action of alternating load for a long time is prone to fatigue failure and affects the safety of the engineering structure. For steel structures in complex environments such as corrosive media and fires, the remaining fatigue life is more difficult to predict theoretically. To this end, the article carried out fatigue tests on Q420qD high-performance steel cross joints under three different working conditions, established a 95% survival rate $$S{ - }N$$ S - N curves, and analyzed the effects of corrosive media and high fire temperatures on its fatigue performance. And refer to the current specifications to evaluate its fatigue performance. The results show that the fatigue performance of the cross joint connection is reduced under the influence of corrosive medium, and the fatigue performance of the cross joint connection is improved under the high temperature of fire. When the number of cycles is more than 200,000 times, the design curves of EN code, GBJ code, and GB code can better predict the fatigue life of cross joints without treatment, only corrosion treatment, and corrosion and fire treatment, and all have sufficient safety reserve.

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