A multi-stage confining pressure cylindrical shell structure

Abstract

This invention discloses a multi-stage confining pressure cylindrical shell structure, belonging to the field of pressure-resistant structures for underwater vehicles. The structure includes end flanges, a skin, cap-shaped main stiffeners, helical secondary stiffeners, and powder discharge holes. The end flanges transition axial stress; the skin is the main load-bearing structure; the cap-shaped main stiffeners are evenly distributed, providing circumferential stiffness and effectively improving the overall buckling load of the structure; the helical secondary stiffeners are evenly distributed between the skin and the cap-shaped main stiffeners, reducing the concentrated stress distribution near the cap-shaped main stiffeners, resisting local bulging, and suppressing strength failure. The multi-stage confining pressure cylindrical shell structure of this invention exhibits uniform stress distribution and high confining pressure bearing efficiency, overcoming the shortcomings of traditional metal confining pressure configurations such as insufficient load-bearing capacity at large diving depths, and is beneficial for the design and application of pressure-resistant structures for deep-diving underwater vehicles.

Description

Technical Field

[0001] This invention belongs to the technical field of pressure-resistant structures for underwater vehicles, specifically relating to a multi-stage confining pressure cylindrical shell structure. Background Technology

[0002] As a core component of submersibles, the confining hull is typically a steel ring-ribbed cylindrical shell, accounting for approximately one-quarter to one-half of the total structural weight. It provides a reliable and safe space for instruments, equipment, and personnel. Its design, in addition to meeting basic mechanical requirements, is subject to strict weight constraints to accommodate the loads of instruments and equipment. The development of deep-sea exploration capabilities demands that submersibles possess deep-diving and multi-load capabilities. Under traditional confining hull structures, the contradiction between the pressure resistance requirements for deep-diving and the limited structural weight requirements is becoming increasingly prominent. How to meet the load-bearing requirements for deep-diving without significantly increasing the structural weight is a current challenge in confining hull design. 3D printing technology can overcome the limitations of traditional welding processes on the structural form of confining hulls, enabling the manufacture of more complex and higher-efficiency multi-stage confining hull structures.

[0003] Multi-level structural design is inspired by biomimicry, such as bamboo joints and bones, whose microstructures consist of multiple structures, each serving different functions during evolution. Multi-level stiffening ribs are designed to resist different forms of buckling. Primary stiffeners increase overall bending stiffness and buckling load, while secondary stiffeners reduce stress concentration and localized buckling caused by uneven stress distribution. Due to the complexity of multi-level structures, traditional manufacturing processes are difficult and costly; currently, there are no designs for multi-level stiffened metal rib structures in pressure shell design. Summary of the Invention

[0004] This invention provides a multi-stage confining pressure cylindrical shell structure, which can improve the low efficiency of traditional pressure-resistant structures and achieve high-efficiency load-bearing performance for complex structures.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A multi-stage confined pressure cylindrical shell structure includes end flanges, a skin, cap-shaped main stiffeners, spiral secondary stiffeners, and powder discharge holes. The cap-shaped main stiffeners are evenly distributed on the inner side of the skin, and their spacing is obtained through structural load efficiency optimization. The spiral secondary stiffeners are evenly distributed between the cap-shaped main stiffeners and the skin, closely attached to the inner side of the skin. The overlapping portion of the spiral secondary stiffeners and the cap-shaped main stiffeners is interrupted. The end flanges are located at both ends of the structure and are thickened from the skin inward. The ends of the end flanges and the ends of the cap-shaped main stiffeners are transitioned by a slope to ensure that the stress is evenly transferred to the main load-bearing structure. The powder discharge holes are arranged at a 90° offset on both sides of the cap-shaped main stiffeners.

[0007] The multi-stage confining cylindrical shell structure has a length l, thickness t, radius R, and the number of cap-shaped main reinforcing ribs is N. s Evenly distributed on the inner side of the skin, with a spacing of l s =l / N s The corners of the main stiffening ribs in the cap shape are chamfered to reduce stress concentration, reduce the risk of damage caused by uneven stress transmission, and facilitate manufacturing.

[0008] The main stiffening rib of the cap shape is designed in three parts: bottom brim, sloping web, and top flange. The bottom brim is directly connected to the skin, and the sloping web is connected to the brim by a chamfer transition. Finally, the sloping web is connected to the top flange to form the main stiffening rib of the cap shape. The bottom brim transmits the stress of the skin and equalizes the stress distribution. The sloping web provides bending stiffness, and the top flange enhances the bending stiffness, constrains the deformation of the sloping web, and ensures the continuity of 3D printing.

[0009] The angle α between the main reinforcing rib of the hat shape and the skin design is 40° to 45°; the thickness t of the hat-shaped reinforcing rib is... s =0.5t~1.5t, bottom cap brim length is l b =max(0.1l b ~0.15l b , t s / sinα), length of the oblique web l f =0.25l s ~0.7l s Top flange length l t =0.05l s ~0.12l s 0.35l s <(l t +2l f cosα) < 0.4l s To improve material load efficiency while meeting process requirements, the corners of the main stiffening ribs in the cap shape are chamfered to reduce stress concentration effects.

[0010] The angle β of the spiral secondary stiffener is ±60°~75°, and the number of spiral stiffeners N p =30~70, the edges of the spiral secondary stiffening ribs are chamfered for easy manufacturing.

[0011] Each cap-shaped main reinforcing rib has 4 powder discharge holes, and the powder discharge holes between different reinforcing ribs are arranged at equal intervals.

[0012] The aforementioned multi-level confined cylindrical shell structure is manufactured using 3D printing technology. Before 3D printing, the structure is chamfered, and the shell is printed vertically without any external support.

[0013] Beneficial Effects: This invention provides a multi-stage confining pressure cylindrical shell structure, which differs from traditional single-stage stiffened rib pressure-resistant structures. This invention employs a multi-stage stiffening rib design, with end flanges transitioning axial stress, ensuring a uniform transition of axial stress to the main load-bearing structure and reducing the risk of end failure. The skin is the main load-bearing structure; the cap-shaped main stiffening ribs are evenly distributed, providing circumferential stiffness and effectively improving the overall buckling load of the structure and enhancing material load efficiency; spiral secondary stiffening ribs are evenly distributed between the skin and the cap-shaped main stiffening ribs, reducing concentrated stress distribution near the cap-shaped main stiffening ribs. The introduction of spiral secondary stiffening ribs enhances the structure's buckling resistance, effectively broadening the structural optimization form, resulting in higher structural load-bearing efficiency, resisting local bulging, and suppressing strength failure; furthermore, the design of the powder discharge holes solves the problem of powder accumulation within the closed structure. The discrete distribution of the powder discharge holes avoids stress concentration, resulting in more uniform stress distribution and providing a foundation for subsequent heat treatment. The present invention features a rationally optimized structure, uniform stress distribution, high pressure resistance, good product stability, and fast manufacturing time. The multi-stage confining pressure cylindrical shell structure of the present invention exhibits uniform stress distribution and high confining pressure bearing efficiency, solving the shortcomings of traditional metal confining pressure configurations such as insufficient bearing capacity at large depths, and is beneficial to the design and application of pressure-resistant structures for deep-diving submersibles. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a multi-level confined pressure cylindrical shell structure manufactured by 3D printing technology in an embodiment of the present invention;

[0015] Figure 2 This is a 1 / 4 cross-sectional view of the multi-level confined pressure cylindrical shell structure manufactured by 3D printing technology in an embodiment of the present invention;

[0016] Figure 3 This is a front view of the main stiffening rib of the cap-shaped multi-level confined pressure cylindrical shell structure manufactured by 3D printing technology in an embodiment of the present invention;

[0017] Figure 4 This is a front view of a single cap-shaped main stiffening rib of a multi-level confined pressure cylindrical shell structure manufactured by 3D printing technology in an embodiment of the present invention.

[0018] Figure 5 This is a top view of a single cap-shaped main stiffening rib of a multi-level confined pressure cylindrical shell structure manufactured by 3D printing technology in an embodiment of the present invention.

[0019] Figure 6 This is a front view of the powder discharge hole of the multi-stage confined pressure cylindrical shell structure manufactured by 3D printing technology in an embodiment of the present invention;

[0020] Figure 7 This is a top view of the powder discharge hole of a multi-stage confined pressure cylindrical shell structure manufactured by 3D printing technology in an embodiment of the present invention;

[0021] Figure 8This is a cross-sectional view of a multi-stage confined pressure cylindrical shell structure flange manufactured using 3D printing technology in an embodiment of the present invention;

[0022] Figure 9 This is a schematic diagram of the main reinforcing ribs of the cap shape in an embodiment of the present invention;

[0023] Figure 10 This is a schematic diagram of the spiral secondary stiffening rib in an embodiment of the present invention;

[0024] Figure 11 This is a diagram showing the arrangement of the powder discharge ports in an embodiment of the present invention;

[0025] In the figure, 1-end flange, 2-spiral secondary stiffener, 3-cap-shaped main stiffener, 4-powder discharge hole, 5-skin. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments:

[0027] like Figure 1 As shown, a multi-stage confined cylindrical shell structure includes end flanges, a skin, cap-shaped main stiffeners, spiral secondary stiffeners, and powder discharge holes. The cap-shaped main stiffeners are evenly distributed on the inner side of the skin, and their spacing is obtained through structural load efficiency optimization. The spiral secondary stiffeners are evenly distributed between the cap-shaped main stiffeners and the skin, closely adhering to the inner side of the skin. The overlapping portion of the spiral secondary stiffeners and the cap-shaped main stiffeners is interrupted. The end flanges are located at both ends of the structure and are thickened from the skin inwards. The ends of the end flanges and the end cap-shaped main stiffeners are connected by... The sloping transition ensures a uniform stress transfer to the main load-bearing structure; the powder discharge holes are staggered by 90° on both sides of the cap-shaped main stiffener; the end flanges can uniformly transfer stress to the main structure when subjected to axial loads; the skin is the main load-bearing structure; the cap-shaped main stiffener primarily improves the overall bending stiffness to resist overall deformation; the spiral secondary stiffener primarily reduces the stress concentration effect between the skin and the cap-shaped main stiffener and resists local buckling; the powder discharge holes on both sides of the main stiffener remove powder from the inside of the main stiffener and avoid sintering problems caused by subsequent heat treatment.

[0028] The number of the main reinforcing ribs in the cap shape is N. s Evenly distributed on the inner side of the skin, with a spacing of l s =l / N s The corners of the main stiffening ribs in the cap shape are chamfered to reduce stress concentration, reduce the risk of damage caused by uneven stress transmission, and facilitate manufacturing.

[0029] The main stiffening rib of the hat shape is designed in three parts: the bottom brim, the sloping web, and the top flange. The bottom brim transmits the skin stress and homogenizes the stress distribution; the sloping web provides bending stiffness; and the top flange enhances bending stiffness, constrains the deformation of the sloping web, and ensures the continuity of 3D printing. Based on the structural optimization results and structural rationality requirements, the angle α between the main stiffening rib and the skin is designed to be 40° to 45°; the thickness t of the hat-shaped stiffening rib is... s =0.5t~1.5t, where t is the skin thickness; the length of the bottom cap brim is l b =max(0.1) b ~0.15l b , t s / sinα); Length of the oblique web l f =0.25l s ~0.7l s Top flange length l t =0.05l s ~0.12l s 0.35l s <(l t +2l f cosα) < 0.4l s To improve material load efficiency while meeting process requirements, the corners of the main stiffening ribs in the cap shape are chamfered to reduce stress concentration effects.

[0030] The angle β of the spiral secondary stiffener is ±60°~75°, and the number of spiral stiffeners N p =30~70, the edges of the spiral secondary stiffening ribs are chamfered for easy manufacturing.

[0031] Each cap-shaped main reinforcing rib has 4 powder discharge holes, and the powder discharge holes between different reinforcing ribs are arranged at equal intervals.

[0032] The aforementioned multi-level confined cylindrical shell structure was manufactured using 316L powder and selective laser melting technology. The structure was integrally formed and then heat-treated to remove residual stress from the printing process. The design parameters of the metal cap-shaped multi-level stiffened cylindrical shell are shown in Table 1. Finally, dimensional scanning and model reconstruction were performed for subsequent analysis. The final finite element test result was 9.5 MPa. In actual underwater testing at 7 MPa, the structure showed no significant deformation, and the overall structure locally entered a critical plastic state with no signs of leakage.

[0033] Table 1. Design Parameters for Metal Hat-Shaped Multi-Stiffened Cylindrical Shells

[0034]

[0035] The above are merely preferred embodiments of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A multi-stage confining pressure cylindrical shell structure, characterized in that, It includes end flanges, skin, cap-shaped main stiffeners, and secondary stiffeners; the main stiffeners are evenly distributed on the inner side of the skin; the secondary stiffeners are evenly distributed between the main stiffeners and the skin, closely attached to the inner side of the skin, and the secondary stiffeners are interrupted in the overlapping part with the main stiffeners; the end flanges are located at both ends of the structure and are thickened from the skin inwards, and the ends of the end flanges and the end main stiffeners are transitioned by a slope; The main reinforcing rib of the cap shape includes a bottom cap brim, a sloping web plate, and a top flange. The bottom cap brim is directly connected to the skin. The sloping web plate is connected to the bottom cap brim by a chamfer transition. The sloping web plate is connected to the top flange.

2. The multi-stage confining pressure cylindrical shell structure according to claim 1, characterized in that, The spacing between the main reinforcing ribs of the cap shape is: l is the length of the multi-stage confining pressure cylindrical shell structure. The number of main reinforcing ribs.

3. The multi-stage confining pressure cylindrical shell structure according to claim 1, characterized in that, The angle between the main reinforcing rib of the cap and the skin .

4. The multi-stage confining pressure cylindrical shell structure according to claim 1 or 3, characterized in that, The thickness of the main reinforcing rib of the cap shape The length of the bottom cap brim is Length of oblique web Top flange length ,in .

5. The multi-stage confining pressure cylindrical shell structure according to claim 1 or 3, characterized in that, The corners of the main reinforcing ribs in the cap shape are chamfered for transition.

6. The multi-stage confining pressure cylindrical shell structure according to claim 1, characterized in that, The secondary stiffener is a spiral rectangular secondary stiffener, and the number of spiral rectangular secondary stiffeners is... .

7. The multi-stage confining pressure cylindrical shell structure according to claim 6, characterized in that, The angle of the spiral rectangular secondary stiffening rib The edges of the spiral rectangular secondary stiffening ribs are chamfered.

8. The multi-stage confining pressure cylindrical shell structure according to claim 1 or 2, characterized in that, The main reinforcing rib of the cap shape is provided with powder discharge holes, which are offset on both sides of the main reinforcing rib. Arrangement; the powder discharge holes between different reinforcing ribs are arranged at equal intervals.

9. The multi-stage confining pressure cylindrical shell structure according to claim 1, characterized in that, The multi-stage confining cylindrical shell structure is manufactured using 3D printing technology. Before 3D printing, the structure is chamfered, and the shell is printed vertically without any external support.

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