Underwater curved surface cabin door based on three-period minimal curved surface structure
Through the three-period minimal surface structure design, the sealing and lightweight problems of underwater curved hatches in deep-sea high-pressure environments are solved, achieving the effects of high-strength, lightweight and low-noise navigation.
Patent Information
- Application Number
- CN202511014060.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-23
- Publication Date
- 2025-09-19
AI Technical Summary
Existing underwater curved hatches are difficult to ensure sealing and structural integrity in the deep-sea high-pressure environment, and there is also the problem of being too heavy.
It adopts a three-periodic minimal surface structure design, including an upper panel, a lower panel and a three-periodic minimal surface structure core layer. The three-periodic minimal surface structure in a cylindrical coordinate system is constructed through one-piece molding technology, combined with composite material filling to improve strength and lightweight.
It achieves the goal of maintaining sealing and structural integrity in a high-pressure environment, while significantly reducing weight, improving the door's load-bearing capacity and sailing speed, and reducing noise and vibration.
Smart Images
Figure CN120664056A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of underwater curved hatches, and in particular to an underwater curved hatch based on a three-periodic minimal surface structure. Background Art
[0002] Faced with the gradual depletion of terrestrial resources, the exploration and exploitation of deep-sea mineral resources is becoming a new global strategic focus. To meet the critical needs of deep-sea resource exploration, industrial development, and scientific research, high-performance underwater vehicles with lightweight structures, deep diving capabilities, long endurance, high speeds, and excellent vibration and acoustic attenuation have become the key driving force and foundational platform for strategic ocean exploration.
[0003] The design of underwater curved hatches is an important component in ensuring the safety and functionality of submersibles. They must not only maintain sealing and structural integrity under extreme deep-sea pressures, but also ensure the safe entry and exit of personnel and the effective operation of equipment. Therefore, underwater curved hatches face multiple technical challenges: (1) The high-pressure environment problem of underwater curved surface opening and closing hatches. The deep-sea pressure is huge, and the hatches must be able to withstand atmospheric pressure and meet the requirements of underwater strength, rigidity, and stability to ensure that the hatches can be opened and closed normally under high pressure.
[0004] (2) The lightweighting of underwater curved hatches: while ensuring the structural strength, the weight of the hatches should be reduced as much as possible. Summary of the Invention
[0005] The purpose of the present invention is to solve the shortcomings of the existing technology and propose an underwater curved hatch based on a three-period minimal surface structure. The present invention can not only meet the load-bearing requirements of the underwater curved hatch under high-pressure environment, but also achieve the problem of lightweighting the underwater curved hatch, thanks to the excellent characteristics of the three-period minimal surface structure.
[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A design of an underwater curved hatch door based on a three-period minimal curved surface structure includes an upper panel, a three-period minimal curved surface structure, and a lower panel. Composite materials can be filled into the core layer of the three-period minimal curved surface structure as needed to further improve the structural strength of the underwater curved hatch door and achieve lightweighting. The underwater curved hatch includes an upper panel, a lower panel and a three-periodic minimal surface structure core layer located inside the upper and lower panels, wherein the core layer adopts an integrated molding technology to construct a three-periodic minimal surface structure in a cylindrical coordinate system.
[0007] The upper panel and the lower panel are in a spline curve structure and have equal thickness.
[0008] The three-periodic minimal surface structure is a smooth curved surface structure with three-dimensional periodic repeating units, located between the upper and lower panels. The core layer of the three-periodic minimal surface structure is embedded in the upper and lower panels, and the core layer and the upper and lower panels are fixed in relative position.
[0009] Furthermore, according to the present invention, the core layer of the triply periodic minimal surface structure is composed of a triply periodic minimal surface. A triply periodic minimal surface (TPMS) is a periodic, smooth, implicit surface with zero mean curvature. Compared with other types of porous structures, TPMS has two significant advantages: (1) The TPMS structure has an extremely high porosity and a large specific surface area. The internal channels are fully connected, the surface is smooth and has no edges or corners, and there are various topological structures (such as G-type, D-type, P-type, etc.). The geometric shape can be precisely controlled through parametric design; (2) While maintaining high porosity, it exhibits good strength and toughness. At the same time, its unique structure enables it to effectively disperse and absorb energy when impacted, and its structural stability is high.
[0010] The three-periodic minimal surface can be generated by the series set approximation equation defined and derived by Fourier series:
[0011] Where k is the reciprocal vector, is the phase shift, the structure factor is the amplitude associated with a given vector k.
[0012] Truncating the series to its leading term yields a function consisting of a combination of trigonometric functions. , and satisfy the equation .function defines a surface evaluated at the constant value (i.e., level set constant) c.
[0013] The three-periodic minimal surfaces include but are not limited to the following surfaces: Schwarz-Primitive(P)
[0014] Schoen-Gyroid(G)
[0015] Schwarz–Diamond(D)
[0016] Schwarz–Diamond1(D1)
[0017] Schoen-IWP(IWP)
[0018] Neovius(N)
[0019] Where, , , , 、 、 are the unit cell sizes in the X, Y, and Z coordinate directions respectively, and its basic periodic unit is ,TPMS unit cell structure can be The relative density can be expressed by the constant Control. The relative density can be expressed as , is the volume of the TPMS unit cell structure, It is the volume of the cube occupied by the TPMS unit cell structure.
[0020] Furthermore, the physical coordinates (x, y, z) of the TPMS structure are linearly mapped to the B-spline parameter space , ensure that the parameter space boundaries are strictly aligned with the physical space period unit boundaries: Step 1: Ternary B-spline surface is a three-dimensional parameter The vector function is composed of the tensor product of the control points and the B-spline basis functions in each direction. Its mathematical expression is:
[0021] in: Is a 3D control vertex ; are the p-, q-, and r-order B-spline basis functions in the u-, v-, and w-directions, respectively; Control the number of vertices for each direction .
[0022] Furthermore, for any parameter direction (such as u direction), a periodic node vector is constructed The steps are as follows: Step 1: Assume that the number of splines in the u direction is p and the number of control vertices is ; Step 2: The number of internal nodes of the periodic node vector must satisfy the number of internal nodes = , the internal nodes are The intervals are evenly distributed, with an interval of ; Step 3: To ensure periodicity, the first and last nodes need to be repeated p+1 times. The final periodic node vector in the u direction is:
[0023] The v and w direction node vectors of the ternary B-spline Constructed in the same way, the final three-dimensional node vector is .
[0024] Step 4: To ensure that the surface is continuous at the parameter boundary, it is necessary to impose cyclic constraints on the control vertices so that the boundary control vertices coincide in the periodic direction.
[0025] Set constraints for the u, v, and w directions separately: U direction constraint: for any ,have: ; V direction constraint: for any ,have: ; W direction constraint: for any ,have: ; Step 5: The initial control vertices must satisfy the above constraints and be evenly distributed within the physical period unit of the TPMS. Internal uniform sampling points, corresponding to the parameters , which is converted into physical coordinates through a linear mapping.
[0026] The TPMS surface structure obtained through the above process can adjust the number of periods in each direction of the core unit cell of the three-periodic minimal surface structure in the panel by adjusting the unit cell size, inner radius, and outer radius. The shape of the spline curve can be adjusted by controlling the number of points. In addition, the thickness of the core layer of the three-periodic minimal surface structure can also be adjusted according to the relative density. When the unit cell size and relative density of two adjacent periods are different, the three-periodic minimal surface structure becomes a gradient structure, and the volume density is no longer uniform in space.
[0027] Furthermore, the present invention can be installed in combination, wherein the upper panel, the three-period minimal surface structure core layer, and the lower panel are nested and installed, and the contact parts of the structure can be connected by welding or other methods.
[0028] To optimize the above technical solutions, specific measures taken also include: (1) The above-mentioned panel is made of rigid material, and the core layer of the three-periodic minimal surface structure can be made of the same material as the panel. The three-periodic minimal surface structure can also be made of different materials as needed.
[0029] (2) Since the core layer of the three-period minimal surface structure is a porous structure, after being combined with the upper and lower panels, the core layer can be filled with composite materials to improve the mechanical properties of the hatch.
[0030] Compared with the existing technology, the beneficial effects of the present invention are as follows: the three-period minimal surface structure has periodic and porous characteristics, which can significantly reduce the amount of material used while maintaining high strength, thereby achieving a lightweight design. Its zero-mean curvature characteristic helps to disperse and transfer loads, reduce stress concentration, and improve the load-bearing capacity of the hatch. When the hatch encounters collisions and impacts, the three-period minimal surface structure can absorb a large amount of energy through plastic deformation, protecting the safety of the hatch and internal equipment. The smooth curved surface and streamlined design of the three-period minimal surface structure help to reduce the resistance of the water flow to the hatch, improve the navigation speed and efficiency of the submersible, and can also disperse and guide the water flow, reduce the generation of vortices, and reduce noise and vibration during navigation. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] In order to more specifically and intuitively illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.
[0032] Figure 1 This is a schematic diagram of an underwater vehicle with its hatch closed, where 1 is the hatch and 2 is the cabin; Figure 2 This is a schematic diagram of an underwater submersible with its hatch open, where 1 is the hatch and 2 is the cabin; Figure 3 The diagram of the hatch is shown in Figure 3, where 3 is the upper panel, 5 is the lower panel, and 4 is the three-periodic minimal surface core layer. The three-periodic minimal surface core layers include: a is G type; b is D1 type; c is IWP type; d is D type; e is P type; Figure 4 It is a schematic diagram of mapping a three-periodic minimal surface to a spline curve; Figure 5 It is a performance diagram of a three-periodic minimal surface; Figure 6 It is a schematic diagram of sound insulation of a three-periodic minimal surface.
[0033] In the figure: hatch 1, cabin body 2, upper panel 3, three-periodic minimal surface core layer 4, lower panel 5. DETAILED DESCRIPTION
[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.
[0035] Example 1 This embodiment is based on the design of an underwater vehicle hatch with a three-periodic minimal surface structure, such as Figure 1-6 As shown, it includes an upper panel 1, a core layer 2 of a three-periodic minimal surface structure, and a lower panel 3. The upper and lower panels are welded together with the three-periodic minimal surface structure; the core layer structure is determined by the mathematical formula defining the three-periodic minimal surface, the mathematical formula defining the fan-shaped mapping of the sandwich structure, and the relative density of the structure.
[0036] Taking the P-type three-periodic minimal surface as an example, the mathematical formula for defining the three-periodic minimal surface is:
[0037] Where, , , , 、 、 They are the unit cell sizes in the X, Y, and Z coordinate directions respectively. The P-type three-periodic minimal surface unit cell structure can be obtained by The relative density can be controlled by the constant c. The relative density can be expressed as , is the volume of the P-type three-periodic minimal surface unit cell structure, is the volume of the cube occupied by the P-type three-periodic minimal surface unit cell structure. In this example, the relative density is defined as 20%, and the period size is .
[0038] The coordinate points selected in this example are: (0,0,100), (109,300,100), (197,600,100), (270,900,100), (331,1200,100), (381,1500,100), (419,1800,100), (446,2100,100), (469,2400,100).
[0039] Furthermore, the physical coordinates (x, y, z) of the TPMS structure are linearly mapped to the B-spline parameter space , ensure that the parameter space boundary is strictly aligned with the physical space period unit boundary. In this example, the TPMS structure physical coordinates (x, y, 100) are linearly mapped to the B-spline parameter space , .
[0040] Step 1: Ternary B-spline surface is a three-dimensional parameter The vector function is composed of the tensor product of the control points and the B-spline basis functions in each direction. Its mathematical expression is:
[0041] in: Is a 3D control vertex ; are the p-, q-, and r-order B-spline basis functions in the u-, v-, and w-directions, respectively; Control the number of vertices for each direction .
[0042] Furthermore, for any parameter direction (such as u direction), a periodic node vector is constructed The steps are as follows: Step 1: Assume that the number of splines in the u direction is p and the number of control vertices is In this example, p is 3, which controls the number of vertices. , the number of control vertices is 5×5.
[0043] Step 2: The number of internal nodes of the periodic node vector must satisfy the number of internal nodes = , the internal nodes are The intervals are evenly distributed, with an interval of ; Step 3: To ensure periodicity, the first and last nodes need to be repeated p+1 times. The final periodic node vector in the u direction is:
[0044] The v and w direction node vectors of the ternary B-spline Constructed in the same way, the final three-dimensional node vector is In this example, .
[0045] Step 4: To ensure that the surface is continuous at the parameter boundary, it is necessary to impose cyclic constraints on the control vertices so that the boundary control vertices coincide in the periodic direction.
[0046] Set constraints for the u, v, and w directions separately: U direction constraint: for any ,have: In this example, .
[0047] V direction constraint: for any ,have: In this example, .
[0048] W direction constraint: for any ,have: ; Step 5: The initial control vertices must satisfy the above constraints and be evenly distributed within the physical period unit of the TPMS. Internal uniform sampling points, corresponding to the parameters , which is converted into physical coordinates through a linear mapping.
[0049] Step 6: Substitution and ,have to , then the equation is , the B-spline curve is The coordinates at the input point are equal , the objective function is: , the objective function can be used to ensure that the control vertices satisfy the constraints.
[0050] The principle of the above-mentioned underwater curved hatch design based on a three-period minimal surface structure is as follows: the three-period minimal surface structure has periodic and porous characteristics, which can significantly reduce the amount of material used while maintaining high strength, thereby achieving a lightweight design. Its zero-mean curvature characteristic helps to disperse and transfer loads, reduce stress concentration, and improve the load-bearing capacity of the hatch. When the hatch encounters collisions and impacts, the three-period minimal surface structure can absorb a large amount of energy through plastic deformation, protecting the safety of the hatch and internal equipment. The smooth curved surface and streamlined design of the three-period minimal surface structure help reduce the resistance of the water flow to the hatch, improve the navigation speed and efficiency of the submersible, and can also disperse and guide the water flow, reduce the generation of vortices, and reduce noise and vibration during navigation.
[0051] Example 2 The structure and method of the underwater curved hatch design based on the three-periodic minimal surface structure provided in the embodiment of the present invention are the same as those in Example 1, with the only difference being that the three-periodic minimal surface structure in the embodiment of the present invention is a G-type three-periodic minimal surface, and its expression is: .
[0052] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.
Claims
1. An underwater curved hatch based on a three-periodic minimal surface structure, comprising a cabin (2) and a hatch (1), characterized in that: The hatch (1) comprises an upper panel (3) and a lower panel (5), wherein a three-periodic minimal curved surface core layer (4) is provided between the upper panel (3) and the lower panel (5), wherein the three-periodic minimal curved surface core layer (4) is an integrally formed structure, and the three-periodic minimal curved surface core layer (4) is a periodic smooth implicit curved surface with an average curvature of zero.
2. The underwater curved hatch based on a three-periodic minimal surface structure according to claim 1, characterized in that: The upper panel (3) and the lower panel (5) are in a spline curve structure and both have equal thickness.
3. The underwater curved hatch based on a three-periodic minimal surface structure according to claim 2, characterized in that: The surface of the three-periodic minimal surface core (4) is generated by the Fourier series defined and derived series set approximation equation: ； Where k is the reciprocal vector, is the phase shift, and the structure factor is the amplitude associated with a given vector k; Truncating the series to its leading term yields a function consisting of a combination of trigonometric functions satisfying the equation φ(x,y,z)=c, which defines a surface evaluated at the isovalue (i.e., the level set constant) c.
4. The underwater curved hatch based on a three-periodic minimal surface structure according to claim 3, characterized in that: The three-periodic minimal surfaces include but are not limited to the following surfaces: Schwarz-Primitive(P): ； Schoen-Gyroid(G): ； Schwarz–Diamond(D): ； Schwarz–Diamond1(D1): ； Schoen-IWP(IWP): ； Neovius(N): ； Where, , , , Lx, Ly, and Lz are the unit cell sizes in the X, Y, and Z coordinate directions respectively, and its basic periodic unit is ,TPMS unit cell structure can be Realized, its relative density can be controlled by the constant c; The relative density can be expressed as , V TPMS is the volume of the TPMS unit cell structure, V cube It is the volume of the cube occupied by the TPMS unit cell structure.
5. The underwater curved hatch based on a three-periodic minimal surface structure according to claim 4, characterized in that: Linearly map the TPMS structure physical coordinates (x, y, z) to the B-spline parameter space ,Ensure that the parameter space boundary is strictly aligned with the physical space period unit boundary. The specific steps include: Step 1: Ternary B-spline surface is a three-dimensional parameter The vector function is composed of the tensor product of the control points and the B-spline basis functions in each direction. Its mathematical expression is: ； in: Is a 3D control vertex ; are the p-, q-, and r-order B-spline basis functions in the u-, v-, and w-directions, respectively; Control the number of vertices for each direction .
6. The underwater curved hatch based on a three-periodic minimal surface structure according to claim 5, characterized in that: For any parameter direction in u, v, w, construct a periodic node vector The steps are as follows: Step 1: Assume that the number of splines in the u direction is p and the number of control vertices is ; Step 2: The number of internal nodes of the periodic node vector must satisfy the number of internal nodes = , the internal nodes are The intervals are evenly distributed, with an interval of ; Step 3: To ensure periodicity, the first and last nodes need to be repeated p+1 times. The final periodic node vector in the u direction is: ； The v and w direction node vectors of the ternary B-spline Constructed in the same way, the final three-dimensional node vector is ; Step 4: To ensure the surface is continuous at the parameter boundary, it is necessary to impose cyclic constraints on the control vertices so that the boundary control vertices coincide in the periodic direction; Set constraints for the u, v, and w directions separately: U direction constraint: for any ,have: ; V direction constraint: for any ,have: ; W direction constraint: for any ,have: ; Step 5: The initial control vertices must satisfy the above constraints and be evenly distributed within the physical period unit of the TPMS. Internal uniform sampling points, corresponding to the parameters , which is converted into physical coordinates through a linear mapping.
7. The underwater curved hatch based on a three-periodic minimal surface structure according to claim 6, characterized in that: The upper panel (3), the lower panel (5) and the three-period minimal curved surface core layer (4) are assembled and connected by welding at the contact parts.
8. The underwater curved hatch based on a three-periodic minimal surface structure according to claim 7, characterized in that: The three-periodic minimal surface core layer (4) is filled with composite material.