Cold Expansion Process with Multiple Balls—Numerical Simulation and Comparison with Single Ball and Tapered Mandrels

Curto-Cárdenas, David; Calaf-Chica, José; Díez, Pedro Miguel Bravo; Calzada, Mónica Preciado; Garcia-Tarrago, Maria-Jose

doi:10.3390/ma13235536

Cited by 10 publications

(5 citation statements)

References 23 publications

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“…The authors of the work [9] applied finite element modeling and fatigue testing to compare residual hoop stresses induced by the cold expansion process using multiple balls with those arising from the cold expansion using a single ball and a tapered mandrel. The results showed that the use of three incremental balls significantly reduced the magnitude of non-conforming residual hoop stresses and the extension of this detrimental zone.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Effectiveness of Combined Surface Treatment Methods for Structural Parts with Holes to Enhance Their Fatigue Life

Grebenikov,

Humennyi,

Svitlychnyi

et al. 2024

Computation

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The typical and most widespread stress concentrators in the lower wing panels of aircraft are the drain holes located on the stringer vertical ribs. These are prime sources for the initiation and development of fatigue cracks, which lead to early failure of the wing structure. Therefore, improving fatigue life in these critical areas is one of the significant issues for research. Two combined methods of surface plastic treatment in the location around drain holes are discussed in this paper. Using the finite element method and ANSYS software, we created a finite element model and obtained nonlinear solution results in the case of tension in a plate with three holes. In addition, the development of residual stress due to the surface plastic treatment of the hole-adjacent areas was taken into account. In this paper, it is shown that after surface treatment of the corresponding areas of the holes, residual stress, which exceeds the yield stress for the plate material, is induced. When combined with alternative tensile stress, these reduce the amplitude of the local stresses, thus increasing the number of stress cycles before failure. The benefits of this technology were confirmed by fatigue test results, which include the fatigue failure types of the plates. Graphs showing the impact of applicable surface treatment combined methods on the number of cycles to failure were also plotted.

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Section: Introductionmentioning

confidence: 99%

Analysis of Effectiveness of Combined Surface Treatment Methods for Structural Parts with Holes to Enhance Their Fatigue Life

Grebenikov,

Humennyi,

Svitlychnyi

et al. 2024

Computation

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“…The addition of split sleeves is generally considered a better method to protect the hole edge material from tearing and strong friction during mandrel and ball expansion [ 11 , 12 , 13 ]. Split sleeve cold expansion (SSCE) can not only avoid axial scratching of hole walls, but also has the advantages of good adaptability and high productivity, which lead to the wide application of SSCE in the aircraft assembly field [ 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Finite Element Analysis of Split Sleeve Cold Expansion Process on Multiple Hole Aluminum Alloy

et al. 2023

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Multiple cold expansion holes are widely used in connection areas of aircraft structures, in order to achieve uniform load transfer of the skin or connection parts. Split sleeve cold expansion (SSCE) is widely used to enhance the fatigue life of fastener holes by applying compressive residual stresses around the holes. In this study, the finite element method (FEM) was used to research the distribution and variation of residual stresses along the hole edges of 7075AA single-hole and multi-hole cold expansion (CE) specimens. Full-field strain measurements of single-hole and multi-hole specimens were performed using two-dimensional digital image correlation (DIC), and the residual stress and strain at the hole edge of the specimens measured by FEM and DIC were compared. FEM results shows that the maximum circumferential and radial residual stresses of three-hole specimens with three-hole spacing are increased by 5.37% and 31.53% compared with single-hole specimens. The maximum circumferential residual stress of three-hole specimens with four-hole spacing increases by 7.25% compared with a single hole, but the radial residual stress decreases by 12.98%. In addition, for three-hole specimens with hole spacing three times the hole diameter, the strengthening effect of SSCE in the order of middle hole, then left hole, and, finally, right hole is better than that of SSCE in the order of left to right hole. FEM and DIC full-field strain results are basically consistent.

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“…To enhance the fatigue life of the hole structure, the cold expansion strengthening technology of compression bushings is widely used [7][8][9][10]. It can reduce the hole edge stress under external load and effectively inhibit the crack generation at the hole edge [11][12][13]. Compression bushings have been massively applied to the fatigue strengthening of the important joints of many aircraft models at home and abroad [14,15].…”

Section: Introductionmentioning

confidence: 99%

Research on the Residual Stress Field of a Compression Bushing-Lug Plate in Cold Expansion Strengthening

Lin,

Bai,

Wang

et al. 2023

Applied Sciences

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The accurate acquisition of the residual stress field is the key to clarifying the cold expansion strengthening mechanism of compression bushings, optimizing the extrusion process parameters, and improving the structural fatigue life. In the actual cold expansion strengthening process, the resultant distribution of residual stresses is influenced by the relative extrusion amount, mandrel structure, material properties, and extrusion speed. In this article, the distribution patterns of residual stress after cold extrusion are investigated through a combination of finite element simulation and experimental measurements using a micro-region stress tester. To examine the redistribution law of the stress field of cold expansion reinforcement under external load, the compression bushing-lug-plate-reinforced structure is loaded and unloaded. The results show that large circumferential residual compressive stresses are distributed in the hole wall of the compression bushing after cold expansion. Radial residual stresses are also compressive stresses, although the values are small. In addition, the reinforced structure after cold extrusion presents a large difference in the stress redistribution rules compared with cold extrusion after the load is applied and removed.

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Cold Expansion Process with Multiple Balls—Numerical Simulation and Comparison with Single Ball and Tapered Mandrels

Cited by 10 publications

References 23 publications

Analysis of Effectiveness of Combined Surface Treatment Methods for Structural Parts with Holes to Enhance Their Fatigue Life

Analysis of Effectiveness of Combined Surface Treatment Methods for Structural Parts with Holes to Enhance Their Fatigue Life

Finite Element Analysis of Split Sleeve Cold Expansion Process on Multiple Hole Aluminum Alloy

Research on the Residual Stress Field of a Compression Bushing-Lug Plate in Cold Expansion Strengthening

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