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.

scholarly journals Fatigue Life Behavior of Laser Shock Peened Duplex Stainless Steel with Different Samples Geometry

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
César A. Vázquez Jiménez ◽  
Vignaud Granados Alejo ◽  
Carlos Rubio González ◽  
Gilberto Gómez Rosas ◽  
Sergio Llamas Zamorano
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Duplex Stainless Steel ◽  
Fatigue Crack Initiation ◽  
Stress Raiser ◽  
Residual Stress Distribution ◽  
Laser Shock

Two different stress raiser geometries (fillets and notched) were treated by laser shock peening (LSP) in order to analyze the effect of sample geometry on fatigue behavior of 2205 duplex stainless steel (DSS). The LSP treatment was carried through Nd : YAG pulsed laser with 1064 nm wavelength, 10 Hz frequency, and 0.85 J/pulse. Experimental and MEF simulation results of residual stress distribution after LSP were assessed by hole drilling method and ABAQUS/EXPLICIT software, respectively. The fatigue tests (tensile-tensile axial stress) were realized with stress ratio of R = 0.1 and 20 Hz. A good comparison of residual stress simulation and experimental data was observed. The results reveal that the fatigue life is increased by LSP treatment in the notched samples, while it decreases in the fillet samples. This is related to the residual stress distribution after LSP that is generated in each geometry type. In addition, the fatigue crack growth direction is changed according to geometry type. Both the propagation direction of fatigue crack and the anisotropy of this steel results detrimental in fillet samples, decreasing the number of cycles to the fatigue crack initiation. It is demonstrated that the LSP effect on fatigue performance is influenced by the specimen geometry.

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.

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%.

Finite element analysis of the residual stress of automotive wheel made of long glass fiber-reinforced thermoplastic composite

2018 ◽  
Vol 233 (10) ◽  
pp. 3592-3602 ◽  
Author(s):  
Weihao Chai ◽  
Xiandong Liu ◽  
Yinchun Shan ◽  
Xiaofei Wan ◽  
Er Jiang
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Simulation Method ◽  
Residual Stress Distribution ◽  
Thermoplastic Composite ◽  
Element Analysis ◽  
Simulation Accuracy ◽  
Glass Fiber Reinforced ◽  
Long Glass Fiber ◽  
Bending Fatigue Test

To increase the simulation accuracy, a finite element analysis method for the prediction of the residual stress distribution in the injection molded wheel made of the long glass fiber-reinforced thermoplastic composite (LGFT) is studied, and a simulation method of the wheel bending fatigue test considering the residual stress distribution is investigated in this paper. First, the in-cavity residual stress is calculated using the molding simulation method. Then the residual stress relaxation process is analyzed and the final residual stress distribution is obtained. With the residual stress as the initial stress, the structural simulation of the LGFT wheel under the bending load is performed. To evaluate the influence of the residual stress on the LGFT wheel, an additional simulation without considering the residual stress is conducted. The result shows that the interior stress considering residual stress is much higher than that without considering residual stress. To verify the simulation accuracy of these two cases, the high-stress area locations in the simulation results are compared with the damage locations in physical bending fatigue test. The result illustrates that the simulation result considering the residual stress accords with the experimental result better. Therefore, the simulation result of the residual stress is reasonable, and it is necessary to consider residual stress in the simulation of the LGFT wheel.

scholarly journals Residual Stress Distribution in Feal Weld Overlay on Steel

1994 ◽  
Vol 364 ◽  
Author(s):  
X.-L. Wang ◽  
S. Spooner ◽  
C. R. Hubbard ◽  
P. J. Maziasz ◽  
G. M. Goodwin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Post Weld Heat Treatment ◽  
Residual Stress Distribution ◽  
Element Analysis ◽  
Weld Overlay

AbstractNeutron diffraction was used to measure the residual stress distribution in an FeAl weld overlay on steel. It was found that the residual stresses accumulated during welding were essentially removed by the post-weld heat treatment that was applied to the specimen; most residual stresses in the specimen developed during cooling following the post-weld heat treatment. The experimental data were compared with a plasto-elastic finite element analysis. While some disagreement exists in absolute strain values, there is satisfactory agreement in strain spatial distribution between the experimental data and the finite element analysis.

Heterogeneous Microstructure Effect on Residual Stress and Fatigue Crack Resistance in Dual-Phase Materials

2009 ◽  
Author(s):  
Masahito Mochizuki ◽  
Yoshiki Mikami
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Stress Distribution ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Compressive Residual Stress ◽  
Fatigue Tests ◽  
Residual Stress Distribution ◽  
Experimental Result ◽  
Microstructure Effect

The effect of transformation-induced microscopic residual stress on fatigue crack propagation behaviour of ferrite-martensite lamellar steel was discussed. Fatigue tests of prestrained and non-prestrained specimens were performed. Inflections and branches at ferrite-martensite boundaries were observed in the non-prestrained specimens. On the other hand, less inflections and branches were found in the prestrained specimens. The experimental results showed that the transformation induced microscopic residual stress has influence on the fatigue crack propagation behaviour. To estimate the microscopic residual stress distribution, a numerical simulation of microscopic residual stress induced by martensitic transformation was performed. The simulation showed that compressive residual stress was generated in martensite layer, and the result agree with the experimental result that inflections and branches were observed at ferrite-martensite boundaries. In addition, the change in the microscopic residual stress distribution by prestraining was also calculated to show the compressive residual stress changed to tensile by prestraining. This also agree with the experimental result of the observation of fatigue crack path.

A Study on the Residual Stress and Fracture Behavior of Pipeline Girth Welds Joining Pipes of Different Strength

2010 ◽  
Author(s):  
Woo-sik Kim ◽  
Jong-hyun Baek ◽  
Choel-man Kim ◽  
Young-pyo Kim
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Material Property ◽  
Fracture Behavior ◽  
Residual Stress Distribution ◽  
Element Analysis ◽  
Weld Region ◽  
Similar Materials ◽  
Base Strength ◽  
Girth Welds

The following cases of girth welded region between pipelines having different base strength were considered. The pipeline shows different fracture behavior from girth welded pipeline between similar materials due to strength mismatch and residual stress distribution. Investigation about the residual stress distribution and fracture behavior of pipeline having girth welds of the differnet base metals (X70/X65 and X70/X42) with different material property has performed using finite element analysis. The effect of mismatched material property on girth weld region is negligible when shape of pipeline is similar. The assessment for occurance of crack on girth weld region with pipes with material property mismatched can be replaced by that of the similar pipes with low strength on the point view of conservation.

Influence of Residual Stress due to Prior Overloading on the Fatigue Life of a Notched Plate

2016 ◽  
Author(s):  
Kumarswamy Karpanan
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Internal Pressure ◽  
Compressive Residual Stress ◽  
Fatigue Crack Initiation ◽  
Pressure Vessels ◽  
Stress And Strain ◽  
Maximum Shear Strain

During autofrettage, pressure vessels are subjected to high internal pressure, causing the internal wall to yield plastically. When the internal pressure is released, the inner wall of the vessel develops compressive residual stress. Similarly, when a subsea component is hydrotested, some of the highly stressed regions yield during hydrotesting and, when the pressure is released, these regions develop compressive residual stress. Fatigue life is greatly influenced by local stress on the component surface. Fatigue crack initiation primarily depends on the cyclic stress or strain and the residual stress state. Tensile residual stress decreases fatigue life and the compressive residual stress significantly increases fatigue life. This is true for both fatigue crack initiation and propagation. In this paper, effects of residual stress on a notched plate are studied by subjecting it to an initial overload cycle and subsequent low loading cycles. Tensile and compressive overloads on the notched plate induce compressive and tensile residual stresses, respectively. An elastic-plastic finite element analysis (FEA) was performed to simulate the overload and low loading cycles on the notched plate. The stress and strain from the FEA is used to perform strain-based fatigue analysis. ASME VIII-3, Brown-Miller (B-M), Maximum shear strain, Socie-Bannantine, and Fatemi-Socie methods are used for calculating the fatigue life of the notched plate. Fatigue life predicted by both stress and strain methods matches well with the test fatigue data.

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