Theoretical and experimental study of the free hydroforming of egg-shaped shell

Zhang, Jian; Dai, Mingqiang; Wang, Fang; Tang, Wenxian; Zhao, Xilu; Zhu, Yumei

doi:10.1080/17445302.2020.1827637

Cited by 22 publications

(18 citation statements)

References 44 publications

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“…Then, experimental and numerical study of non-linear hydroforming and mechanical properties was done. The experimental results are shown to be in good agreement with the analytical results [1][2].…”

Section: Introductionsupporting

confidence: 78%

Experimental Bulging and Buckling of Bi-segmented Cylinders

Wang

Zhang

Zuo

et al. 2022

J. Phys.: Conf. Ser.

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This paper studies the experimental free bulging and buckling of bi-segmented cylinders. Two cylindrical shells are manufactured using argon-arc welding and analyzed for manufacturing errors. Next, free bulging tests and hydrostatic pressure tests are conducted to verify the feasibility of the free bulging technique and to confirm the destruction form of the bulged bi-segmented barrel. At the same time, the reasonableness of the circular thick plate is examined, which is determined according to the deformation consistency. The results show that the bi-segmented cylindrical preforms exhibit good welding quality by TIG welding technology. It has the same critical pressure load as a single cylindrical preform. Nevertheless, the bi-segmented cylindrical preforms have larger internal volume and better buoyancy capability than the single cylindrical preform. The free bulging bi-segmented shell has good symmetry along the axial direction. It has larger internal volume and higher critical buckle capacities than the non-bulging one.

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Section: Introductionsupporting

confidence: 78%

Experimental Bulging and Buckling of Bi-segmented Cylinders

Wang

Zhang

Zuo

et al. 2022

J. Phys.: Conf. Ser.

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“…The selection of egg shape coefficient 𝐵/𝐿 has an important impact on the performance of egg-shaped structures. Zhang Jian et al [1] proposed that when the egg shape coefficient is 0.69, the egg-shaped pressure shell has good comprehensive performance. The characteristic parameters of eggshell shape are mainly determined by the long axis dimension 𝐿 and the short axis dimension 𝐵.…”

Section: Bionic Egg Structure Modelmentioning

confidence: 99%

“…For deep-sea submersibles, a pressure hull is a vital component, which can provide buoyancy and protect internal devices from pressure and failure [1]. The design of pressure shells needs to take into account space utilization, hydrodynamic characteristics, buoyancy coefficient and other elements, so the shape design is the top priority.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it is feasible to develop a bionic egg-shaped pressure shell by using granular medium bulging as a new method. However, considering that the egg-shaped shell is a multi-focus and rotary shell structure that meets the positive Gauss curve [1], in order to obtain an egg-shaped shell with a homogeneous structure and stable service performance, it is necessary to improve the stress distribution on the shell surface, so higher requirements are put forward for the forming process and loading path.…”

Section: Introductionmentioning

confidence: 99%

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Research on deformation mechanism of egg-shaped shell in granular medium bulging

Huang¹,

Sun

Shi³

et al. 2022

Preprint

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The design of pressure hull structure plays an essential role in the research and development of underwater operation equipment such as deep-sea submersibles. As a bionic structure, egg-shaped shell has apparent advantages in the application of an underwater pressure hull. Still, the egg-shaped shell is a positive Gauss surface, so it is difficult to control the manufacturing accuracy and quality. In this paper, the technology of solid particle flexible medium forming and the principle of high pressure bulging in tubes are proposed to manufacture high-precision egg-shaped shell parts. By optimizing the shape of the punch structure, optimizing the process parameters, improving the stress and strain distribution of the egg-shaped shell, analyzing the deformation mechanism in the bulging process, and mastering the deformation and quality control methods of the granular medium flexible bulging of non-equal curvature tubular structures.

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“…Zhang et al [18][19][20][21] studied the buckling strength of the pressure spherical shell formed by the butt-welded method but did not consider the influence welding residual stress and hydrogen diffusion would have on their results. Zhang [22] and Zhang et al [23][24][25] studied the hydrogen permeation behavior of welded joints of X80 pipeline steel with a wall thickness of 18.4 mm using a high-pressure gaseous hydrogen permeation test device.…”

Section: Introductionmentioning

confidence: 99%

Effect of Residual Stress on Hydrogen Diffusion in Thick Butt-Welded High-Strength Steel Plates

Jiang¹,

Zeng

2022

Metals

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Thick high-strength steel plates are increasingly being used for ship structures. Moreover, hydrogen enters the process of manufacturing and service, and large residual tensile stress occurs near the weld. Such stress can facilitate the diffusion and accumulation of hydrogen in the material, leading to hydrogen embrittlement fracture of the shell. Therefore, residual-stress-induced diffusion and accumulation of hydrogen in the stress concentration region of thick butt-welded high-strength steel plate structures need to be studied. In this study, manual metal arc welding was realized by numerical simulation of residual stress in a thick butt-welded high-strength steel plate model using the thermoelastic–plastic theory and a double ellipsoidal heat source model. To analyze residual stress, a set of numerical simulation methods was obtained through comparative analysis of the test results of relevant literature. Residual and hydrostatic stress distributions were determined based on these methods. Then, hydrogen diffusion parameters in each region of the model were obtained through experimental tests. Finally, the results of the residual stress field were used as the predefined field of hydrogen diffusion to conduct a numerical simulation analysis. The distribution of hydrogen diffusion under the influence of residual stress was obtained based on the theory of stress-induced hydrogen diffusion. The weak area of the welding joint was found to be near the weld toe, which exhibited high hydrostatic stress and hydrogen concentration. Further, the maximum hydrogen concentration value of the vertical weld path was approximately 6.1 ppm, and the maximum value of the path parallel to the weld centerline and 31 mm away from the weld centerline was approximately 6.22 ppm. Finally, the hydrostatic tensile stress in the vertical weld path was maximized (~345 MPa), degrading the material properties and causing hydrogen-related cracking. Hence, a reliable method for the analysis of hydrogen diffusion according to residual stress in thick high-strength steel plates was obtained. This work could provide a research basis for controlling and eliminating the adverse effects of hydrogen on the mechanical properties of ship structures and ensuring the safe service of marine equipment.

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Theoretical and experimental study of the free hydroforming of egg-shaped shell

Cited by 22 publications

References 44 publications

Experimental Bulging and Buckling of Bi-segmented Cylinders

Experimental Bulging and Buckling of Bi-segmented Cylinders

Research on deformation mechanism of egg-shaped shell in granular medium bulging

Effect of Residual Stress on Hydrogen Diffusion in Thick Butt-Welded High-Strength Steel Plates

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