Large-angle winding positive Gaussian curvature metal lining composite pressure-resistant shell and machining method thereof

Abstract

The invention discloses a large-angle winding positive Gaussian curvature metal lining composite pressure-resistant shell which comprises a metal lining and a carbon fiber layer wrapping the metal lining, the metal lining is provided with a plurality of holes with outward openings, round nails are fixed in part of or all the holes, and the round nails penetrate out of the carbon fiber layer from the metal lining. The round nails are arranged on the surface of the metal lining with the positive Gaussian curvature, so that the problem that the fiber band slides in the large-angle winding process is solved, the fiber band is guided to be laid along the preset track, the winding angle is accurately controlled, and the winding quality is improved.

Description

Technical Field

[0001] The invention relates to pressure-resistant equipment, in particular to a large-angle wound positive Gaussian curvature metal-lined composite pressure-resistant shell and a processing method thereof. Background Art

[0002] The pressure hull is the core component and buoyancy unit of deep-sea submersibles, and plays an important role in protecting the normal operation of non-pressure equipment, the health and safety of occupants, and providing positive buoyancy. The rotating shell with positive Gaussian curvature is a common structure of the pressure hull, including spherical shells, longan shells, ellipsoidal shells and eggshells. There are many problems with general metal positive Gaussian curvature pressure hulls. For example, large volume-to-weight ratio, high defect sensitivity, low material utilization rate and other problems. With the development of composite material science, composite materials are used in pressure-resistant structures due to their many excellent properties. It effectively improves the load-bearing capacity of the pressure hull and reduces the weight of the pressure hull and deep-sea submersible, thereby obtaining a larger load and a longer range.

[0003] In the prior art, for example, Chinese patent application with application number 202210335856.9 discloses a continuous carbon fiber reinforced aluminum-based composite pressure hull for deep-sea submersibles, but it is only designed for spherical shells, covers a single object and has a vague specific preparation process. Another example is Chinese patent application with application number 201910554969.6, which discloses a ply optimization design method for a composite pressure hull, which includes angles such as ±30° and ±45°. However, for the positive Gaussian curvature composite pressure hull formed by wet winding, due to its unique structural shape, fiber slippage will occur during the winding process at large angles. Therefore, it is difficult to achieve winding at the above angles. In summary, it is ultimately summarized into the following two problems:

[0004] 1. Traditional metal pressure hulls have a relatively large bulk density, low material utilization, and are difficult to process. They are prone to buckling under hydrostatic pressure.

[0005] 2. The positive Gaussian curvature metal-lined composite pressure-resistant shell that is wound by wet winding will experience fiber slippage during the large-angle winding process, making it impossible to achieve large-angle winding, limiting its ultimate bearing capacity and being unable to meet the requirements of deep-sea operations at great depths. Summary of the invention

[0006] Purpose of the invention: In view of the above shortcomings, the present invention provides a carbon fiber layer with high winding quality and large-angle winding positive Gaussian curvature metal lined composite pressure hull.

[0007] The present invention also provides a method for large-angle winding of the metal-lined composite pressure-resistant shell with positive Gaussian curvature.

[0008] Technical solution: To solve the above problems, the present invention adopts a large-angle wound positive Gaussian curvature metal-lined composite pressure-resistant shell, including a metal lining and a carbon fiber layer wrapped around the metal lining. The metal lining is provided with a plurality of holes opening outward, and round nails are fixed in some or all of the holes, and the round nails pass through the carbon fiber layer from the metal lining.

[0009] Furthermore, the other end of the hole of the metal liner is sealed and extends out from the metal liner, and the depth h of the hole is:

[0010] h=k1t s , k1∈[1.5,2]

[0011] Among them, t s is the thickness of the metal lining.

[0012] Furthermore, the outer contour of the metal liner is a rotational surface with positive Gaussian curvature, including an egg-shaped contour, an ellipsoidal contour and a spherical contour.

[0013] Furthermore, the outer contour of the metal lining is an egg-shaped contour, and the contour equation R(x) is:

[0014]

[0015] Wherein, L is the major axis of the metal liner, B is the minor axis of the metal liner, and SI is the egg-shaped coefficient of the metal liner.

[0016] Furthermore, the total number of holes provided in the metal lining is ∑(I-1)*j i , where the arc length of the generatrix of the metal lining is divided into I parts, resulting in I-1 circular rings. Then there are I-1 holes in the generatrix direction of the metal lining, and the number of holes in the i-th circular ring of the metal lining is j i ,have:

[0017]

[0018] Among them, R(x i ) is the annular radius of the ith ring of the metal liner, and d is the bandwidth of the wet-wound fiber bundle.

[0019] Furthermore, the length l of the round nail is:

[0020]

[0021] Among them, t c is the thickness of the carbon fiber layer, and Φ2 is the diameter of the round nail.

[0022] Furthermore, the pressure hull also includes an upper head and a lower head fixed to both ends of the metal liner, and the upper head and the lower head are sealed with the carbon fiber layer by epoxy resin glue respectively.

[0023] The present invention also adopts a processing method for the above-mentioned large-angle winding positive Gaussian curvature metal lined composite pressure hull, comprising the following steps:

[0024] Step 1: Determine the shape and size of the metal lining and process it;

[0025] Step 2: Determine the winding angle and thickness of the carbon fiber layer;

[0026] Step 3: Determine the position for inserting the round nail on the metal liner: Preliminarily determine the position for inserting the round nail on the metal liner based on the friction force of the friction surface between the metal liner and the carbon fiber layer. After inserting the round nail, perform fiber bundle winding simulation through a winding machine based on the data of the metal liner and the carbon fiber layer, observe the slippage of the fiber bundle in real time, mark the slippage position, and take the circular ring with the hole closest to the slippage position on the metal liner as the slippage area. After removing the metal liner, install the round nail in the slippage area, and continue to wind the fiber bundle until the fiber layer reaches the preset thickness, and then obtain the position for inserting the round nail on the metal liner;

[0027] Step 4: inserting round nails into the processed metal lining according to the determined position for inserting round nails on the metal lining;

[0028] Step 5: Clamp the metal liner after the round nails are inserted on the winding machine, and wind the fiber bundle according to the shape and size of the metal liner and the winding angle and thickness of the carbon fiber layer until the fiber layer reaches a preset thickness;

[0029] Step 6: After the model is wrapped, heat curing is performed;

[0030] Step 7: After removing the excess structure, polish and apply a waterproof layer;

[0031] Step 8: Install the upper and lower heads and seal with epoxy.

[0032] Furthermore, in step 1, after the shape and size of the metal lining are determined, the metal lining is obtained by 3D printing.

[0033] Furthermore, in the step 3, in the fiber bundle winding simulation performed by the winding machine, after the fiber bundle completely wraps the metal lining for the first time, when the fiber bundle slips on the surface of the carbon fiber layer, the winding is stopped, the slip position is marked, the carbon fiber layer is removed, and the circular ring with holes closest to the slip position on the metal lining is used as the slip area, and the fiber bundle is rewound after round nails are installed in the slip area.

[0034] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0035] 1. The composite pressure hull with a large-angle wound positive Gaussian curvature metal lining has good geometric stability and can evenly distribute the applied pressure under high pressure to avoid local stress concentration. It also combines the advantages of composite materials in terms of lightweight, fatigue resistance and corrosion resistance with the high toughness and impact resistance of metal materials.

[0036] 2. By arranging round nails on the surface of the metal lining with positive Gaussian curvature, the problem of fiber tape slippage during large-angle winding is prevented, and the fiber tape is guided to be laid along a predetermined trajectory, thereby ensuring precise control of the winding angle and improving the winding quality.

[0037] 3. Using round nails to penetrate the composite material can provide cross-layer connection, significantly improving the fracture toughness and shear strength between the layers of the composite material, reducing the risk of interlayer delamination and failure, thereby improving the overall compressive performance and service life of the structure.

[0038] 4. The round nails on the metal lining and the holes without round nails can increase the bonding area between the metal lining and the composite material, forming a strong mechanical connection that can maintain stability in a long-term high-pressure environment, avoiding the aging and falling off of the traditional bonding layer under extreme conditions, thereby extending the service life of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a front view and a cross-sectional view of the eggshell-shaped pressure-resistant shell in the present invention.

[0040] Figure 2 It is a schematic diagram of the contour equation curve of the eggshell-shaped metal liner in the present invention.

[0041] Figure 3 It is the front view and the cross-sectional view of the eggshell-shaped metal liner in the present invention.

[0042] Figure 4 It is a schematic diagram of the connection of the metal lining, the fiber layer and the round nails in the present invention.

[0043] Figure 5 It is a structural schematic diagram of the round nail in the present invention.

[0044] Figure 6 It is a schematic diagram of the force applied to the fiber bundle on the metal lining in the present invention.

[0045] Figure 7 It is a schematic diagram of the winding angle and limit load of the fiber bundle in the egg-shaped pressure-resistant shell of the present invention.

[0046] Figure 8 It is a schematic diagram of the winding trajectory of the fiber bundle wound around the metal liner in the present invention.

[0047] Fig. 9 It is a structural schematic diagram of the head in the present invention.

[0048] Fig.10 It is a schematic diagram of the processing flow in the present invention.

[0049] Fig.11 It is a front view and a cross-sectional view of the ellipsoidal pressure hull of the present invention.

[0050] Fig.12 It is a schematic diagram of the contour equation curve of the ellipsoidal metal liner in the present invention.

[0051] Fig.13 It is the front view and the cross-sectional view of the ellipsoidal metal liner in the present invention.

[0052] Fig.14 It is a front view and a cross-sectional view of the spherical pressure shell in the present invention.

[0053] Fig.15 It is a schematic diagram of the contour equation curve of the spherical metal liner in the present invention.

[0054] Fig.16 It is the front view and the cross-sectional view of the spherical metal liner in the present invention. DETAILED DESCRIPTION

[0055] Example 1

[0056] like Figure 1 As shown, the large-angle wound positive Gaussian curvature metal lined composite pressure hull of the present invention is composed of a metal liner 4, a carbon fiber layer 3, round nails 5, an upper head 1, a lower head 6 and epoxy resin glue 2. The outer contour of the metal liner is a rotational surface of positive Gaussian curvature. In this embodiment, an egg-shaped contour is taken as an example, and a wet-wound fiber bundle is used to wind the metal liner at a large angle to form a carbon fiber layer.

[0057] like Figure 2 The figure shows the schematic diagram of the contour equation of the composite egg-shaped metal lining. The contour equation of the egg-shaped metal lining is designed using the egg-shaped curve equation NR equation based on the Cartesian coordinate system proposed by two scholars Narushin VG and Romanov MN. The generatrix contour equation is shown in formula (1):

[0058]

[0059] Wherein R(x) is the contour equation of the egg-shaped metal lining, L is the major axis of the egg-shaped metal lining, B is the minor axis of the egg-shaped metal lining, and SI is the egg-shaped coefficient of the egg-shaped metal lining.

[0060] After determining the contour curve of the egg-shaped metal lining, the hole positions of the round nails 5 on the egg-shaped metal lining 4 are designed. Figure 3 The schematic diagram of the egg-shaped metal liner structure is shown. The arc length of the generatrix of the egg-shaped metal liner 4 is taken as S, and the arc length S is shown in formula (2):

[0061]

[0062] There are connecting rods at both ends of the egg-shaped metal liner, and a and b represent the starting and ending abscissas of the actual egg-shaped metal liner shell;

[0063] The arc length of the generatrix of the egg-shaped metal liner 4 is divided into I parts on average, and there are I-1 holes in the generatrix direction of the egg-shaped metal liner 4. The arc length between two adjacent holes is S I , arc length S I As shown in formula (3):

[0064]

[0065] After determining the number of holes in the generatrix direction of the egg-shaped metal liner 4, the number of holes in the circumferential direction of the egg-shaped metal liner 4 is designed. The width of the wet-wound fiber bundle is d, and the circumferential radius of the egg-shaped metal liner 4 is R (x i ), the circumference C of the egg-shaped metal liner 4 i As shown in formula (4), the number of holes in the circumferential direction j i As shown in formula (5):

[0066] C i =2πR(x i ) (4)

[0067]

[0068] like Figure 4 , 5 is a partial schematic diagram of the composite egg-shaped pressure hull and a schematic diagram of the round nail. The depth and diameter of each hole on the egg-shaped metal liner 4 are h and Φ1 respectively, and the thickness of the egg-shaped metal liner 4 is t s , the thickness of the carbon fiber layer 3 is t c The length and diameter of the round nail are l and Φ2 respectively. Here, the hole depth h is equal to the thickness t of the egg-shaped metal lining 4. s The relationship is shown in formula (6):

[0069] h=k1t s , k1∈[1.5,2] (6)

[0070] The relationship between the length l of the round nail 5 and the thickness of the egg-shaped metal liner 4 and the carbon fiber layer 3 is shown in formula (7):

[0071]

[0072] The diameter Φ2 of the round nail 5 is slightly smaller than the diameter Φ1 of the hole, as shown in formula (8):

[0073] Φ2=k2Φ1,k2∈[0.8,1) (8)

[0074] The force analysis of the fiber bundle wound on the egg-shaped metal liner 4 is carried out, as shown in FIG. Figure 6 As shown, where F is the fiber tension, f n is the normal force on the fiber, f μ is the lateral force on the fiber, R n is the normal radius of curvature (perpendicular to the surface), R g is the geodesic curvature radius (parallel to the surface). Fiber normal force f n and fiber lateral force f μ As shown in formula (9) and (10) respectively:

[0075]

[0076]

[0077] When the fiber normal force f n and fiber lateral force f μ When the relationship of equation (11) or (12) is not satisfied, it means that the fiber bundle will slip on the egg-shaped surface.

[0078]

[0079]

[0080] In the above formula, μ1 and μ2 are the surface friction coefficients of the egg-shaped metal liner 4 and the carbon fiber layer 3 respectively.

[0081] like Figure 7 As shown in the figure, after considering geometric nonlinearity and material nonlinearity, when the winding angle of the composite egg-shaped pressure hull is between ±50 and ±60°, its ultimate load is much greater than the ultimate load at other winding angles. ±50 to ±60° is also the winding angle range selected in this embodiment. Based on the preferred large-angle winding angle for increasing the ultimate load, the fiber bundle will slip on the egg-shaped curved surface. In order to meet the ultimate load and the reliability of the wound fiber layer, round nails need to be installed in the slip area to assist the fiber winding.

[0082] like Figure 8 As shown, the geometric dimensions and shape of the egg-shaped metal liner 4 are input into the winding software, and after the winding parameters are set, the winding trajectory of the fiber bundle on the egg-shaped metal liner 4 can be directly generated.

[0083] like Fig. 9 As shown, sealing heads at both ends are designed according to the size of the egg-shaped composite pressure shell after winding.

[0084] The above-mentioned method for processing the large-angle winding positive Gaussian curvature metal lined composite pressure hull comprises the following steps:

[0085] Step 1: Determine the contour equation of the metal lining 4 according to the design requirements.

[0086] Step 2: Design a three-dimensional model of the metal lining 4 according to the contour equation of the metal lining 4 determined in step 1.

[0087] Step 3: Use 3D printing technology to manufacture the metal lining 4.

[0088] Step 4: Determine the winding angle and thickness of the carbon fiber layer 3 according to design requirements.

[0089] Step 5: Preliminarily calculate the fiber bundle slip position according to formulas (9)-(12), and install round nails 5 at the slip position. The round nails 5 are fixed in the holes of the metal liner 4 with glue, and then simulated winding is performed to determine the position of the round nails inserted on the metal liner. The specific process is: the geometric parameters of the metal liner 4 and the design parameters of the carbon fiber layer 3 are input into the winding software, and the winding software generates the fiber winding trajectory and winding program.

[0090] The metal liner 4 is clamped on the winding machine, and the winding program is input into the winding machine. The winding machine is started. It is determined by observation whether the fiber bundle slips at the position on the metal liner 4 where the round nails 5 are not arranged.

[0091] When slippage occurs, stop winding, mark the slippage position, and take the circular ring with the hole closest to the slippage position on the metal liner as the slippage area. Remove the metal liner 4, and continue to install the round nail 5 in the slippage area, and fix the round nail 5 in the hole of the metal liner 4 with glue.

[0092] Re-clamp the metal liner 4 and start the winding machine to continue winding. Repeat winding-removal-insertion of round nails until the fiber bundle completely wraps the metal liner 4 for the first time.

[0093] After the fiber bundle completely wraps the metal liner 4, the winding surface changes from the surface of the metal liner 4 to the surface of the carbon fiber layer 3. The change of the winding surface will cause a change in the friction coefficient. In the subsequent winding process, it is still necessary to observe whether the fiber bundle slips on the surface of the carbon fiber layer 3.

[0094] When the fiber bundle slips on the surface of the carbon fiber layer 3, stop winding and mark the slip position. Disassemble the model and remove the carbon fiber layer 3 at the same time, and use the circular ring with the hole closest to the slip position on the metal liner as the slip area. Install round nails 5 in the slip area, and fix the round nails 5 in the holes of the metal liner 4 with glue. Rewind the fiber bundle until the fiber bundle does not slip on the surface of the metal liner 4 and the carbon fiber layer 3.

[0095] Step 6: inserting round nails into the processed metal lining according to the determined position for inserting round nails on the metal lining;

[0096] Step 7: Clamp the metal liner after the round nails are inserted on the winding machine, and wind the fiber bundle according to the shape and size of the metal liner and the winding angle and thickness of the carbon fiber layer until the fiber layer reaches a preset thickness;

[0097] Step 8: After the model is wrapped, place the model in an autoclave for heat curing.

[0098] Step 9: After thermal curing is completed, the connecting rods at both ends of the metal liner 4 are cut off.

[0099] Step 10: Use sandpaper to polish the surface of the positive Gaussian curvature composite pressure hull and apply a waterproof layer.

[0100] Step 11: Install the upper head 1 and the lower head 6 respectively, and seal them with epoxy resin glue 2.

[0101] Embodiment 2:

[0102] like Fig.11 , 12, 13, in this embodiment, a large-angle wound positive Gaussian curvature metal lined composite pressure shell is composed of a metal lining 4, a carbon fiber layer 3, round nails 5, an upper head 1, a lower head 6 and an epoxy resin glue 2.

[0103] The design and processing methods used in Example 2 are consistent with those in Example 1. Only the contour equation of the metal liner 4 is changed. Fig.12 The figure shows the schematic diagram of the contour equation of the composite material ellipsoidal metal lining. The contour equation of the ellipsoidal metal lining is shown in formula (13):

[0104]

[0105] Embodiment 3:

[0106] like Fig.14 , 15, 16, in this embodiment, a large-angle wound positive Gaussian curvature metal lined composite pressure-resistant shell is composed of a metal lining 4, a carbon fiber layer 3, round nails 5, an upper head 1, a lower head 6 and an epoxy resin glue 2.

[0107] The design and processing methods used in Example 3 are consistent with those in Example 1. Only the contour equation of the metal liner 4 is changed. Fig.15 The figure shows a schematic diagram of the contour equation of a composite material spherical metal liner. The contour equation of a spherical metal liner is shown in formula (14):

Claims

1. A large-angle wound positive Gaussian curvature metal-lined composite pressure hull, characterized in that: The invention comprises a metal lining (4) and a carbon fiber layer (3) wrapped outside the metal lining (4); the metal lining (4) is provided with a plurality of holes opening outwards; round nails (5) are fixed in some or all of the holes; the round nails (5) penetrate the carbon fiber layer (3) from the metal lining (4).

2. The large-angle wound positive Gaussian curvature metal lined composite pressure hull according to claim 1 is characterized in that: The other end of the hole of the metal liner (4) is sealed and extends out from the metal liner (4), and the depth h of the hole is: h=k1t s ,k1∈[1.5,2] Among them, t s is the thickness of the metal lining.

3. The large-angle wound positive Gaussian curvature metal lined composite pressure hull according to claim 1 is characterized in that: The outer contour of the metal liner is a rotational curved surface with positive Gaussian curvature, including an egg-shaped contour, an ellipsoidal contour and a spherical contour.

4. The large-angle wound positive Gaussian curvature metal lined composite pressure hull according to claim 3 is characterized in that: The outer contour of the metal lining is an egg-shaped contour, and the contour equation R(x) is: n=1.057(L / B) 2.372 , Wherein, L is the major axis of the metal liner, B is the minor axis of the metal liner, and SI is the egg-shaped coefficient of the metal liner.

5. The large-angle wound positive Gaussian curvature metal lined composite pressure hull according to claim 4 is characterized in that: The total number of holes provided in the metal lining is ∑(I-1)*j i , where the arc length of the generatrix of the metal lining is divided into I parts, resulting in I-1 circular rings. Then there are I-1 holes in the generatrix direction of the metal lining, and the number of holes in the i-th circular ring of the metal lining is j i ,have: Among them, R(x i ) is the annular radius of the ith ring of the metal liner, and d is the bandwidth of the wet-wound fiber bundle.

6. The large-angle wound positive Gaussian curvature metal lined composite pressure hull according to claim 2 is characterized in that: The length l of the round nail is: Among them, t c is the thickness of the carbon fiber layer, and Φ2 is the diameter of the round nail.

7. The large-angle wound positive Gaussian curvature metal lined composite pressure hull according to claim 1 is characterized in that: It also comprises an upper head (1) and a lower head (6) fixed at both ends of the metal liner (4); the upper head (1) and the lower head (6) are sealed with the carbon fiber layer (3) respectively by epoxy resin glue (2).

8. A method for processing a large-angle wound positive Gaussian curvature metal-lined composite pressure hull according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Determine the shape and size of the metal lining and process it; Step 2: Determine the winding angle and thickness of the carbon fiber layer; Step 3: Determine the position for inserting the round nail on the metal liner: Preliminarily determine the position for inserting the round nail on the metal liner based on the friction force of the friction surface between the metal liner and the carbon fiber layer. After inserting the round nail, perform fiber bundle winding simulation through a winding machine based on the data of the metal liner and the carbon fiber layer, observe the slippage of the fiber bundle in real time, mark the slippage position, and take the circular ring with the hole closest to the slippage position on the metal liner as the slippage area. After removing the metal liner, install the round nail in the slippage area, and continue to wind the fiber bundle until the fiber layer reaches the preset thickness, and then obtain the position for inserting the round nail on the metal liner; Step 4: inserting round nails into the processed metal lining according to the determined position for inserting round nails on the metal lining; Step 5: Clamp the metal liner after the round nails are inserted on the winding machine, and wind the fiber bundle according to the shape and size of the metal liner and the winding angle and thickness of the carbon fiber layer until the fiber layer reaches a preset thickness; Step 6: After the model is wrapped, heat curing is performed; Step 7: After removing the excess structure, polish and apply a waterproof layer; Step 8: Install the upper and lower heads and seal with epoxy.

9. The processing method according to claim 8, characterized in that: In the step 1, after the shape and size of the metal lining are determined, the metal lining is obtained by 3D printing.

10. The processing method according to claim 8, characterized in that: In the step 3, in the fiber bundle winding simulation performed by the winding machine, after the fiber bundle completely wraps the metal liner for the first time, when the fiber bundle slips on the surface of the carbon fiber layer, the winding is stopped, the slip position is marked, the carbon fiber layer is removed, and the circular ring with holes closest to the slip position on the metal liner is used as the slip area. After installing round nails in the slip area, the fiber bundle is rewound.

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