Effect of Friction on Residual Stress Distribution Induced by Split Sleeve Cold Expansion Process

2021 ◽  
Author(s):  
Mithun Kumar Dey ◽  
Dave Kim ◽  
Hua Tan
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stress Distribution ◽  
Expansion Process ◽  
Cold Expansion

Effect of Friction on Residual Stress Distribution Induced by Split Sleeve Cold Expansion Process

2020 ◽  
Author(s):  
Mithun K. Dey ◽  
Dave Kim ◽  
Hua Tan
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Compressive Residual Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Residual Stress Distribution ◽  
Expansion Process ◽  
Cold Expansion ◽  
Three Dimensional Finite Element

Abstract Residual Stress distribution and parametric influence of friction are studied for the split sleeve cold expanded holes in Al 2024 T351 alloy, by developing a three-dimensional finite element model of the process. Fastener holes in the alloy are necessary for the manufacturing process, but they create a potential area for stress concentration, which eventually leads to fatigue under cyclic loading. Beneficial compressive residual stress distribution as a result of the split sleeve cold expansion process provides retardation against crack initiation and propagation at the critical zones near hole edges. In this parametric study, the influence of friction between contact surfaces of the split sleeve and mandrel is numerically investigated. Hole reaming process after split sleeve cold expansion is often not discussed. Without this post-processing procedure, split sleeve cold expansion is incomplete in practice, and its purpose of providing better fatigue performance is invalidated. This study presents results and an overview of the significance of friction with the consideration of the postprocessing of split sleeve cold expansion. The numerical results show that with increasing friction coefficient, compressive residual stress reduces significantly at the mandrel entry side, which makes the hole edge more vulnerable to fatigue. The different aspects of finite element modeling approaches are also discussed to present the accuracy of the prediction. Experimental residual stress observation or visual validation is expensive and time-consuming. So better numerical prediction with the transparency of the analysis design can provide critical information on the process.

Measurement of the three-dimensional residual stress distribution around split-sleeve cold-expanded holes

1996 ◽  
Vol 31 (6) ◽  
pp. 413-421 ◽  
Author(s):  
A T Özdemir ◽  
L Edwards
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Plate Thickness ◽  
Three Dimensional ◽  
Residual Stress Distribution ◽  
Expansion Process ◽  
Cold Expansion ◽  
Civil Aircraft ◽  
Hoop Stresses ◽  
Fatigue Endurance

Cold expansion of fastener holes is an increasingly common way of improving the fatigue endurance of airframes. Although a number of methods of cold expansion are possible, the split-sleeve cold-expansion process is the most widely accepted and is widely used in the repair and manufacture stages of both military and civil aircraft. In the present work, the residual stress distribution around split-sleeve cold-expanded holes has been measured as a function of both position through the plate thickness and around the hole through novel use of the Sachs method. It is found that the residual hoop stresses being generated at the mid-thickness of the plate at orientation 90° from the position of the split in the expansion sleeve. It is suggested that this variation must be taken into account both in the implementation of the technology and in any potential model used for the prediction of fatigue life of cold-expanded holes.

scholarly journals Effect of cold expansion on fatigue life of double lap structure

2021 ◽  
Vol 39 (1) ◽  
pp. 189-196
Author(s):  
Hang Peng ◽  
Jianbo Qin ◽  
Tianjiao Zhao
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Simulation Analysis ◽  
Element Model ◽  
Residual Stress Distribution ◽  
Cold Expansion ◽  
Before And After ◽  
Hole Making

The finite element simulation analysis was used to determine the weak parts of the fatigue life of a double lap structure, for which the cold expansion finite element model was established. The effect of the cold expansion of slotted bushings on the residual stress distribution around the hole of the double lap structure under different interferences was deeply studied, and the optimal interference amount was determined to be 2.5%. The effect of reaming on the residual stress distribution around the hole was studied. The residual stress distribution around the edge of the hole under actual loading conditions before and after cold expansion was compared to provide a theoretical analysis basis for extending the fatigue life of the specimen after cold expansion. The China-made and free- forged 7A85 aluminum alloy specimen was used to obtain the fatigue life and DFR value of the double lap structure after ordinary hole making and the cold expansion of slotted bushing. The results show that the fatigue life under 95% confidence and 95% reliability after cold expansion strengthening increases by about 49% and that the tested DFR value increases by about 9.8%.

The Effect of Cold Expansion on the Fatigue Life of the Chamfered Holes

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Jae-Soon Jang ◽  
Dave Kim ◽  
Myoung-Rae Cho
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Compressive Residual Stress ◽  
Cold Work ◽  
Fatigue Crack Initiation ◽  
Experimental Studies ◽  
Residual Stress Distribution ◽  
Element Analysis ◽  
Cold Expansion

The cold expansion method is one of the most popular techniques in the fatigue enhancement processes, and it has been widely used as a means of improving the fatigue resistance for aircraft structures with holes. Cold expanded holes have lower compressive residual stresses on the entry surface rather than the middle and exit surfaces. Due to the nonuniform residual stress distribution, fatigue crack initiation often occurs on the entry surface. This study proposes a new approach to increase the compressive residual stress magnitude at the entry of the hole. The new method is to apply chamfers into holes before the cold expansion process. Split mandrel process was used to cold work the hole with and without chamfers. Both numerical and experimental studies were done to verify the effects of hole chamfers on the residual stress distribution of the cold expanded holes. Finite element analysis (FEA) was conducted in order to see the effects of the chamfer geometries on the residual stress distributions. The FEA results showed an improvement of compressive residual stress magnitudes at the entry position of the cold expanded hole. The numerical results were compared with X-ray diffraction measurements. Fatigue tests were done to compare the fatigue life of the holes with various chamfer sizes and angles. The cold expansion chamfered holes showed a clear improvement in fatigue life over cold expanded holes without chamfers.

Influence of the Welded Joint on the Mechanical Behavior of Steel Piles during Static and Dynamic Deformation

2007 ◽  
Vol 345-346 ◽  
pp. 1469-1472
Author(s):  
Gab Chul Jang ◽  
Kyong Ho Chang ◽  
Chin Hyung Lee
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Mechanical Behavior ◽  
Welded Joint ◽  
Dynamic Deformation ◽  
Three Dimensional ◽  
Steel Structures ◽  
Residual Stress Distribution ◽  
Dynamic Mechanical Behavior ◽  
Steel Piles

During manufacturing the welded joint of steel structures, residual stress is produced and weld metal is used inevitably. And residual stress and weld metal influence on the static and dynamic mechanical behavior of steel structures. Therefore, to predict the mechanical behavior of steel pile with a welded joint during static and dynamic deformation, the research on the influence of the welded joints on the static and dynamic behavior of steel pile is clarified. In this paper, the residual stress distribution in a welded joint of steel piles was investigated by using three-dimensional welding analysis. The static and dynamic mechanical behavior of steel piles with a welded joint is investigated by three-dimensional elastic-plastic finite element analysis using a proposed dynamic hysteresis model. Numerical analyses of the steel pile with a welded joint were compared to that without a welded joint with respect to load carrying capacity and residual stress distribution. The influence of the welded joint on the mechanical behavior of steel piles during static and dynamic deformation was clarified by comparing analytical results

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