A method for forming a composite folded core curved shell panel structure for a ship

Abstract

The application relates to a forming method of a marine composite corrugated sandwich curved shell frame structure, which comprises the following steps: preparing a supporting mold and foam corrugated strips A and foam corrugated strips B; pre-assembling the foam corrugated strips A and the foam corrugated strips B; laying glass fiber mats on the foam corrugated strips A to form an overall negative mold capable of being adjusted in shape; laying a first fiber cloth, the negative mold, a corrugated core layer and the foam corrugated strips B in sequence, laying glass fiber mats and a second fiber cloth on the foam corrugated strips B, and completing a preformed body; and finally, performing glue injection treatment to obtain a curved shell frame. The application is simple and convenient to operate, realizes controllable preparation of a corrugated-foam hybrid core material in a curved shell structure, solves the technical problems of forming precision, interface combination and form control of a complex structure, and fills the technical blank of the curved forming process of the type of plate frame structure.

Description

Technical Field

[0001] This application relates to the field of ship composite plate technology, and in particular to a molding method for a marine composite pleated sandwich curved shell plate frame structure. Background Technology

[0002] Plate frame structures are one of the main structural forms of ship hulls, and their optimized design is an important direction for reducing ship weight and improving overall structural efficiency. Currently, steel plate frames still dominate ship structural design, mainly bearing pressure and bending moment. By rationally optimizing the material layout, more material can be distributed away from the structure's neutral axis, effectively improving its load-bearing efficiency. However, with the increasing speed requirements of unmanned surface vessels (USVs), higher demands are placed on hull structures, especially on the mechanical properties of local hull areas. For example, high-speed vessels such as USVs often face wave impact pressures of hundreds of kilopascals at their bows when sailing at high speeds in harsh sea conditions. Composite sandwich structures are used in ship hull structures due to their advantages such as absorbing impact energy, high specific strength / stiffness, and stable platform loads.

[0003] Conventional forming methods for pleated sandwich structures (such as continuous rolling, stamping folding, and molding processes) have limitations, especially for curved shell structures with curvature characteristics. For example, when forming curved surfaces, directly gluing the lower panel and then stacking the sandwich pleats and upper panel can easily result in unevenness on the top and bottom surfaces of the formed frame structure, as well as problems such as low forming accuracy and poor bonding between adjacent interfaces. Furthermore, due to the different shapes of curved surfaces, existing pleated sandwich structures often have uncontrollable problems in interface bonding and shape control in curved shell structures, making them unsuitable for mass production.

[0004] Therefore, we propose a molding method for a marine composite pleated sandwich curved shell frame structure. Summary of the Invention

[0005] To address the shortcomings of existing production technologies, the applicant provides a molding method for a marine composite pleated sandwich curved shell plate frame structure, which is simple and convenient to operate and achieves pleating... The controllable preparation of foam hybrid core materials in curved shell structures solves the technological challenges of molding accuracy, interface bonding and morphological control in complex structures. It fills the technological gap in curved molding processes for this type of plate frame structure and provides a feasible manufacturing approach for its practical application in lightweight ship hulls.

[0006] The technical solution adopted in this application is as follows: A method for forming a marine composite pleated sandwich curved shell frame structure includes the following steps: S1, Prepare the support mold with an arc-shaped structure; Cut the foam corrugated board into foam corrugated strip A and foam corrugated strip B by CNC water jet. The cross-section of foam corrugated strip A and foam corrugated strip B is a triangular structure and the two sides are corrugated surface structures. S2, multiple foam corrugated strips B are laid side by side on the support mold, and then multiple foam corrugated strips A are placed between adjacent foam corrugated strips B in sequence, so that the corrugated surface on the foam corrugated strip A matches the corrugated surface on the foam corrugated strip B; single-sided adhesive fiberglass mat is laid on the multiple foam corrugated strips A, with the adhesive side facing down, so that the multiple foam corrugated strips A form a female mold that can be adjusted according to the shape. S3, clear the support mold, and then lay the first fiber cloth, the negative mold, the pleated core layer, the foam corrugated strip B, the single-sided adhesive glass fiber mat, and the second fiber cloth on the support mold in sequence to complete the preform of the composite pleated sandwich curved shell frame structure. S4 uses a vacuum injection molding process to inject adhesive into the preform to obtain a marine composite pleated sandwich curved shell frame structure.

[0007] Its further features are: In step S1, metal or non-metal hard curved surface support molds are processed using processes such as stamping, rolling, forging, casting, machining, injection molding, and 3D printing. Then, the inner surface of the support mold is sanded to eliminate local protrusions and unevenness. After processing, a single-sided adhesive release cloth is pasted on the inner surface of the support mold to ensure that the inner surface of the support mold is flat and wrinkle-free.

[0008] In step S1, the corrugations on both sides of foam corrugated strip A and foam corrugated strip B are processed by CNC waterjet cutting.

[0009] In step S1, after processing foam corrugated strip A and foam corrugated strip B, they are placed in an oven at 50℃-70℃ for drying for 1-3 hours.

[0010] The foam corrugated strips A and B have "S"-shaped corrugations arranged along their length on both sides, and they are staggered from each other; each corrugation is inclined towards the middle.

[0011] The formula for calculating the tilt angle θA of the foam corrugated strip A is: θA=θB φ The formula for calculating the tilt angle θB of the foam corrugated strip B is: θB=arctan2hR hφ Where h is the thickness of the composite pleated sandwich curved shell frame structure used in this ship; R is the maximum radius of the sandwich curved shell; φ is the central angle between adjacent corrugated foam strips A of the female mold, and its calculation formula is: φ= n in, The total central angle is the composite pleated sandwich curved shell frame structure used in this ship, and n is the logarithm of the circumferential array of foam corrugated strips A.

[0012] The first fiber cloth, the second fiber cloth, and the pleated core layer can all be woven from commonly used fibers such as carbon fiber, glass fiber, aramid fiber, and basalt fiber.

[0013] In step S3, the pleated core layer is first laid on the foam corrugated strip A, and the foam corrugated strip B is laid on the pleated core layer using a row-by-row molding process. This process can suppress the rebound and displacement of the pleated core layer during the laying process until all the foam corrugated strips B are laid.

[0014] The vacuum injection molding process includes the following steps: S4-1, Lay out the guide pipe and seal it: Double-layer guide netting is laid on the upper and lower surfaces of the preform, linear injection pipes and dispensing pipes are laid, and sealing tape is used to vacuum seal the whole; Connect the dispensing tube to the vacuum pump, close the dispensing port, start the vacuum equipment to test the airtightness, mix the resin and curing agent at a ratio of 100:30, and degas the mixed resin by vacuuming. S4-2, Injection and Impregnation: Immerse the injection port into the degassed resin container and use the internal and external pressure difference to inject the resin into the preform. After the preform is completely impregnated, close the injection port and the outlet port in sequence to terminate the vacuuming process. S4-3, Curing and Demolding: The preform after impregnation is first cured at room temperature under continuous vacuum, then heated to 70-90℃ and maintained for 6-10 hours to complete curing. Finally, after demolding, a marine composite pleated sandwich curved shell frame structure is obtained.

[0015] In step S4-1, the injection tube is located on one side of the preform, and the line is perpendicular to the length direction of the foam corrugated strip A; the dispensing tube is located on the other side of the preform, opposite to the injection tube. The resin inlet of the injection tube is located at the axial end of the curved shell and close to both circumferential sides.

[0016] The beneficial effects of this application are as follows: This application features a compact and reasonable structure, and is easy to operate. Multiple foam corrugated strips A and B are pre-assembled on an arc-shaped support mold, followed by the laying of single-sided adhesive-coated fiberglass mat. This allows the foam corrugated strips A to form an integral female mold that can be adjusted to conform to the shape. This avoids the unevenness at the top and bottom caused by traditional direct laying, and the integral female mold, as the bottom layer of the pleated core, can be adjusted accordingly, making it suitable for different curved surface structures. A row-by-row molding process is used to complete the segmental shaping of the pleated core layer, and vacuum injection molding completes the fabrication of the sandwich curved shell frame structure. The method is simple and convenient, enabling controllable fabrication of pleated-foam hybrid core materials in curved shell structures. It solves the technological challenges of molding accuracy, interface bonding, and morphological control in complex structures, filling the technological gap in curved molding processes for this type of plate frame structure and providing a feasible manufacturing approach for its practical application in lightweight ship hulls. In addition, the corrugated structure is processed by CNC waterjet cutting followed by drying to ensure the integrity of the corresponding foam corrugated component structure, avoiding local collapse and resulting in a smooth surface of the pleated sandwich panel after molding.

[0017] In addition, this application also has the following advantages: (1) After the preparation of the corresponding preform is completed, based on the process simulation analysis results, the resin injection uses the arc-shaped inclined surface formed after the foam corrugated strips A and B are assembled as the resin flow channel. Since the width of the curved shell structure is small, in order to simplify the process operation, a double-layer flow guide net is used for flow guidance and end-to-end injection, as well as a combination of linear injection and dispensing. By controlling the distance between the boundary of the flow guide net and the surrounding area of ​​the structure, the resin is guided to achieve stable and controllable directional flow, which can improve the injection efficiency and prevent encapsulation and dry spot defects caused by backflow due to premature injection.

[0018] (2) The corrugations on both sides of foam corrugated strip A and foam corrugated strip B are processed by CNC water jet cutting. After processing, foam corrugated strip A and foam corrugated strip B are placed in an oven at 50℃-70℃ for drying treatment, and the drying time is 1-3 hours. When multiple foam corrugated strips A and foam corrugated strip B are molded together, the upper and lower surfaces and the inclined surfaces can be completely bonded. The structure of foam corrugated strip A and foam corrugated strip B is complete and there is no local collapse. The surface of the pleated sandwich panel formed after molding has good flatness.

[0019] (3) The single-sided adhesive glass fiber mat shaping process is adopted. This bonding method not only maintains a high bonding strength between the face and core, but also the overall negative mold formed can meet the folding and laying requirements of single and double-layer pleated core layers, and better solves the problem of fixing discrete foam corrugated strips. Attached Figure Description

[0020] Figure 1 This is a flowchart of this application.

[0021] Figure 2 This is a schematic diagram of the row-by-row mold closing process used in step S3 of this application.

[0022] Figure 3 This is a schematic diagram showing the inclined angle of the foam corrugated strip A and foam corrugated strip B in this application.

[0023] Figure 4 This is a diagram showing the effect of using traditional CNC precision engraving to process ripples.

[0024] Figure 5 This is a diagram showing the effect of CNC waterjet cutting for corrugation processing in this application.

[0025] Figure 6 This is a top view of the arrangement of the dispensing tube and the dispensing tube in this application.

[0026] Figure 7 This is a schematic diagram of the preparation of a marine composite pleated sandwich curved shell frame structure according to this application. Detailed Implementation

[0027] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0028] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0029] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0032] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0033] like Figure 1 , Figure 2 As shown, a method for forming a marine composite pleated sandwich curved shell frame structure includes the following steps: S1, Prepare the support mold with an arc-shaped structure; Cut the foam corrugated board into foam corrugated strip A and foam corrugated strip B by CNC water jet. The cross-section of foam corrugated strip A and foam corrugated strip B is a triangular structure and the two sides are corrugated surface structures. S2, multiple foam corrugated strips B are laid side by side on the support mold, and then multiple foam corrugated strips A are placed between adjacent foam corrugated strips B in sequence, so that the corrugated surface on the foam corrugated strip A matches the corrugated surface on the foam corrugated strip B; single-sided adhesive fiberglass mat is laid on the multiple foam corrugated strips A, with the adhesive side facing down, so that the multiple foam corrugated strips A form a female mold that can be adjusted according to the shape. S3, clear the support mold, and then lay the first fiber cloth, the negative mold, the pleated core layer, the foam corrugated strip B, the single-sided adhesive glass fiber mat, and the second fiber cloth on the support mold in sequence to complete the preform of the composite pleated sandwich curved shell frame structure. S4 uses a vacuum injection molding process to inject adhesive into the preform to obtain a marine composite pleated sandwich curved shell frame structure.

[0034] Specifically, in step S1, according to the designed curved surface structure, metal or non-metal hard curved surface support molds are processed using processes such as stamping, rolling, forging, casting, machining, injection molding, and 3D printing. Then, the inner surface of the support mold is sanded to eliminate local protrusions and unevenness. After processing, a single-sided adhesive release cloth is pasted on the inner surface of the support mold to ensure that the inner surface of the support mold is flat and wrinkle-free.

[0035] In the preparation process of foam corrugated strip A and foam corrugated strip B, the foam corrugated board is first selected according to the design thickness. In step S2, under the condition that the support mold is not covered with carbon fiber cloth, multiple foam corrugated strips A and foam corrugated strips B are pre-assembled in sequence, with foam corrugated strip A located between adjacent foam corrugated strips B. Considering that a pleated core layer needs to be laid between foam corrugated strip A and foam corrugated strip B, and that the pleated core layer has a certain thickness, in the case of pre-assembly, an appropriate gap is reserved between adjacent foam corrugated strip A and foam corrugated strip B to provide tolerance space for subsequent folding and molding operations; After pre-assembly, a single-sided adhesive fiberglass mat is applied to the upper surface of multiple foam corrugated strips A, connecting the discrete foam corrugated strips A into a conformal mold. This conformal function refers to the multiple foam corrugated strips A forming a variable arc-shaped mold that can match the supporting mold. In actual installation, the traditional method of fixing the foam corrugated strips with a setting adhesive is suitable for cases with a small number (thickness) of pleated core layers. When the number (thickness) of pleated core layers is large, the bonding strength of the setting adhesive is insufficient to reliably fix the foam corrugated strips. During waterjet cutting tests, the sandwich curved shell frame structure formed by this method showed panel detachment. This is because a small amount of sprayed adhesive cannot provide sufficient fixing force, while excessive use of adhesive will affect the mechanical properties of the face-core interface. In this application, a single-sided adhesive fiberglass mat shaping process is used. This bonding method not only maintains high face-core interface bonding strength, but the resulting integral mold can meet the folding and laying requirements of single and double-layer pleated core layers, effectively solving the problem of fixing discrete foam corrugated strips. In step S3, the first fiber cloth, the second fiber cloth, and the pleated core layer can all be made of commonly used fiber woven fabrics such as carbon fiber, glass fiber, aramid fiber, and basalt fiber; foam corrugated strips A and B act as the male and female molds of the carbon fiber woven fabric during the molding process. The carbon fiber woven fabric is transformed from a two-dimensional to a three-dimensional structure to form a curved pleated core layer. A special auxiliary mold can be prepared using 3D printing technology. By applying controllable pressure to the carbon fiber weaving, it is folded to form a high-precision curved pleated core layer. The pleated core layer can match the corrugated surfaces of foam corrugated strips A and B. First, the pleated core layer is laid on the foam corrugated strip A. Then, the foam corrugated strip B is laid on the pleated core layer using a row-by-row molding process. This process can suppress the rebound and displacement of the pleated core layer during the laying process until all the foam corrugated strips B are laid. Finally, single-sided adhesive glass fiber mat and second fiber cloth are laid sequentially on the shaped structure to complete the layering assembly of the entire preform. The length direction of the foam corrugated strip A of the female mold is parallel to the axis of the supporting mold.

[0036] It can also be applied to various Miura folds and their deformables, including V-type and M-type, providing a feasible manufacturing method for their practical application in lightweight ship hulls; like Figure 2 As shown, in some examples of this application, the foam corrugated strips A and B have “S”-shaped corrugations arranged along their length on both sides and are staggered from each other. Each ripple slopes towards the center; like Figure 3 As shown, in some examples of this application, the tilt angle of the foam corrugated strip A is... The calculation formula is:

[0037] Inclination angle of foam corrugated strip B The calculation formula is:

[0038] Where h is the thickness of the composite pleated sandwich curved shell frame structure used in this ship; R is the maximum radius of the sandwich curved shell; The formula for calculating the central angle between adjacent female mold foam corrugated strips A is as follows:

[0039] in, The total central angle of the composite pleated sandwich curved shell plate frame structure used in this ship is n, which is the logarithm of the circumferential array of foam corrugated strips A. Specifically, multiple foam corrugated strips A and B are evenly distributed around the circumference. During pre-assembly, foam corrugated strip A, as the female mold, and foam corrugated strip B, as the male mold, are designed with different tilt angles to ensure their fitting accuracy with the curved substrate.

[0040] In some examples of this application, the corrugations on both sides of foam corrugated strip A and foam corrugated strip B are machined using CNC waterjet cutting; After processing, place foam corrugated strip A and foam corrugated strip B in an oven at 50℃-70℃ for drying for 1-3 hours. Specifically, the traditional method of processing corrugations is to use CNC precision engraving. This involves first selecting the appropriate foam corrugated board material according to the design thickness, then fixing it on the processing table of a precision engraving machine (four-axis CNC precision engraving machine), then importing the three-dimensional design model of the corresponding corrugations into the main control system to complete the processing path planning, and finally using the appropriate tool to engrave the foam board. However, the corrugated surface is generally rough during the above processing, and there is incomplete cutting near the processing table area, such as... Figure 4 As shown, the curved slope processed by the carving process actually presents a complex curved surface shape, which causes a significant crescent-shaped gap to be formed at the joint of the slope after multiple foam corrugated strips A and B are joined together in an alternating manner. like Figure 5 As shown, compared with the CNC engraving sample, the water-cutting process used to process the foam corrugated board results in a smoother corrugated surface, with complete cuts and no residue in the beveled areas. When multiple foam corrugated strips A and B are molded together, the upper and lower surfaces and the beveled areas can fit together completely. The structure of foam corrugated strips A and B is intact, with no local collapse. The surface of the pleated sandwich panel formed after molding has good flatness. After the CNC waterjet process is completed, the corresponding foam corrugated board will inevitably be affected by water immersion. In order to ensure its applicability in the molding process of composite sandwich panel frame structure, the processed foam corrugated strip needs to be dried. Preferably, the PVC foam corrugated strip is placed in a 60℃ oven and dried for 2 hours.

[0041] In step S4, as Figure 6 As shown, in the vacuum injection molding process, the injection tube is located linearly on one side of the preform, and this linearity is perpendicular to the length direction of the foam corrugated strip A; The dispensing tube is located linearly on the other side of the preform, opposite to the injection tube; The resin inlet of the injection tube is located at the axial end of the curved shell and close to both circumferential sides. Specifically, after the corresponding preform preparation is completed, based on the process simulation analysis results, the resin injection uses the arc-shaped inclined surface formed after the foam corrugated strips A and B are assembled as the resin flow channel. Since the width of the curved shell structure is small, in order to simplify the process operation, a double-layer flow guide net and end-to-end resin injection are adopted, as well as a combination of linear resin injection and dispensing. By controlling the spacing between the boundary of the flow guide net and the surrounding area of ​​the structure, the resin is guided to achieve stable and controllable directional flow, which can improve the resin injection efficiency and prevent encapsulation and dry spot defects caused by backflow due to premature resin injection. The vacuum infusion molding process includes the following steps: S4-1, Lay out the guide pipe and seal it: Double-layer guide netting is laid on the upper and lower surfaces of the preform, linear injection pipes and dispensing pipes are laid, and sealing tape is used to vacuum seal the whole; Connect the dispensing tube to the vacuum pump, close the dispensing port, start the vacuum equipment to test the airtightness, mix the resin and curing agent at a ratio of 100:30, and degas the mixed resin by vacuuming. S4-2, Injection and Impregnation: Immerse the injection port into the degassed resin container and use the internal and external pressure difference to inject the resin into the preform. After the preform is completely impregnated, close the injection port and the outlet port in sequence to terminate the vacuuming process. S4-3, Curing and Demolding: The preform after impregnation is first cured at room temperature, then heated to 70-90℃ and maintained for 6-10 hours to complete curing. Finally, after demolding, a marine composite pleated sandwich curved shell frame structure is obtained.

[0042] During the curing process, it is preferable to first cure at room temperature for 24 hours, then raise the temperature to 80°C and maintain it for 8 hours to complete the curing. Finally, after demolding, the marine composite pleated sandwich panel frame structure can be obtained.

[0043] The T700 grade carbon fiber woven fabric has the following basic parameters: fiber linear density of 199 g / km, fiber density of 1.81 g / cm3, fiber tensile modulus of 248 GPa, fiber tensile strength of 5404 MPa, fiber tensile strength Cv of 3%, fiber breaking elongation of 2.2%, and sizing agent content of 0.71%, as shown in Figure 1. Table 1 Basic physical properties of carbon fiber woven fabric

[0044] A / BS type room temperature curing epoxy resin was used for injection treatment. The resin system consists of special epoxy resin main agent 2511-1A and curing agent 2511-1BS. It has the characteristics of low viscosity, moderate gelation time, good mechanical properties, high heat distortion temperature and good wettability of carbon fiber, as shown in Table 2. Table 2 Basic physical properties of epoxy resin

[0045] PVC V80 foam material was used as foam corrugated strip A and foam corrugated strip B, as shown in Table 3; Table 3 Basic physical properties of PVC V80 foam material

[0046] Compression and tensile tests were conducted on the PVC foam in the X, Y, and Z directions. The results showed that the material exhibited low dispersion and good repeatability in the compression mechanical properties data in the three directions. The compression modulus and strength were significantly lower than those in the Z direction, indicating obvious anisotropy. The tensile properties also showed low dispersion and good repeatability, exhibiting significant anisotropy. The density and main mechanical properties of the foam material showed low dispersion, meeting the requirements for material consistency and reliability in engineering applications. A CNC five-axis ultra-high pressure waterjet cutting machine is used to process PVC foam to obtain foam corrugated strips A and B. The cutting machine has a five-axis linkage function (including three-axis translation in X, Y, and Z, ±70° oscillation of the A-axis, and ±360° rotation of the C-axis). The angle control accuracy reaches 0.01°. That is, according to the inclined angle designed for the corrugated surface, the A-axis of the cutter is adjusted to the left by the corresponding angle to control the waterjet to make the first cut in the XY plane along an S-shaped trajectory. After completing this process, the A-axis is adjusted to the right by the same angle to make a second cut along the S-shaped trajectory. After cutting, the foam corrugated strips A and B were placed in a 60℃ oven and dried for 2 hours. The mechanical properties of the foam material were compared under three conditions: no water immersion, water immersion and drying, and water immersion and no drying. The compressive mechanical properties in the three directions did not change significantly. Therefore, the water jet cutting process not only has high processing efficiency and precision, but also has no significant impact on the mechanical properties of the material, and can well meet the processing quality requirements of PVC foam corrugated strips. A stainless steel support mold with an inner diameter of 2000mm is used with a bending plate process. The processing error is controlled within 5mm. To suppress the impact of bending plate springback deformation on the molding quality, steel frames are welded to both sides of the support mold for reinforcement. Then, the inner surface of the support mold is sanded to eliminate local protrusions and unevenness. After the treatment is completed, a single-sided adhesive release cloth is pasted on the inner surface of the support mold to ensure that it is flat and wrinkle-free. Foam corrugated strip A and foam corrugated strip B are pre-assembled, and then single-sided adhesive fiberglass mat is used to cover foam corrugated strip A to form an integral female mold with conformal function. The first fiber cloth and the negative mold are laid on the support mold in sequence. The pleated core layer is laid on the negative mold by row-by-row mold closing process. Multiple foam corrugated strips B are laid on the pleated core layer in sequence so that the corrugations of the foam corrugated strips B match the foam corrugated strips A, and the pleated core layer is shaped segment by segment. The preform was then subjected to resin injection, a process that took approximately 7 minutes to complete on the inner surface of the curved shell. Initially, the resin flow was relatively uniform, but as the resin front reached the folded area of ​​the vacuum bag, the flow velocity in this area was significantly faster than in other areas, resulting in uneven diffusion of the overall flow. Notably, the fibers in the arc-shaped top area were also fully impregnated, indicating that gravity did not have a significant impact on the resin injection process of this curved shell.

[0047] The final result is a composite pleated sandwich curved shell frame structure for this ship, such as... Figure 7 As shown, the sandwich curved shell frame structure has good inner and outer surface quality, with no forming defects such as arc grooves or convex lines. This demonstrates the feasibility of this type of carbon fiber composite sandwich structure in curved surface applications and shows good industrial application potential.

[0048] The above description is an explanation of this application and not a limitation thereof. The scope of this application is defined by the claims. Within the scope of protection of this application, any form of modification may be made.

Claims

1. A method for forming a marine composite pleated sandwich curved shell frame structure, characterized in that, Includes the following steps: S1, Prepare the support mold with an arc-shaped structure; Cut the foam corrugated board into foam corrugated strip A and foam corrugated strip B by CNC water jet. The cross-section of foam corrugated strip A and foam corrugated strip B is a triangular structure and the two sides are corrugated surface structures. S2, multiple foam corrugated strips B are laid side by side on the support mold, and then multiple foam corrugated strips A are placed between adjacent foam corrugated strips B in sequence, so that the corrugated surface on the foam corrugated strip A matches the corrugated surface on the foam corrugated strip B; single-sided adhesive fiberglass mat is laid on the multiple foam corrugated strips A, with the adhesive side facing down, so that the multiple foam corrugated strips A form a female mold that can be adjusted according to the shape. S3, clear the support mold, and then lay the first fiber cloth, the negative mold, the pleated core layer, the foam corrugated strip B, the single-sided adhesive glass fiber mat, and the second fiber cloth on the support mold in sequence to complete the preform of the composite pleated sandwich curved shell frame structure. S4 uses a vacuum injection molding process to inject adhesive into the preform to obtain a marine composite pleated sandwich curved shell frame structure.

2. The molding method of a marine composite pleated sandwich curved shell plate frame structure as described in claim 1, characterized in that: In step S1, metal or non-metal hard curved surface support molds are processed using processes such as stamping, rolling, forging, casting, machining, injection molding, and 3D printing. Then, the inner surface of the support mold is sanded to eliminate local protrusions and unevenness. After processing, a single-sided adhesive release cloth is pasted on the inner surface of the support mold to ensure that the inner surface of the support mold is flat and wrinkle-free.

3. The molding method of a marine composite pleated sandwich curved shell plate frame structure as described in claim 1, characterized in that: In step S1, the corrugations on both sides of foam corrugated strip A and foam corrugated strip B are processed by CNC waterjet cutting.

4. The molding method of a marine composite pleated sandwich curved shell plate frame structure as described in claim 3, characterized in that: In step S1, after processing foam corrugated strip A and foam corrugated strip B, they are placed in an oven at 50℃-70℃ for drying for 1-3 hours.

5. The molding method of a marine composite pleated sandwich curved shell plate frame structure as described in claim 1, characterized in that: The foam corrugated strips A and B have "S"-shaped corrugations arranged along their length on both sides, and they are staggered from each other; each corrugation is inclined towards the middle.

6. The molding method of a marine composite pleated sandwich curved shell plate frame structure as described in claim 5, characterized in that: Inclination angle of foam corrugated strip A The calculation formula is: Inclination angle of foam corrugated strip B The calculation formula is: Where h is the thickness of the composite pleated sandwich curved shell frame structure used in this ship; R is the maximum radius of the sandwich curved shell; The formula for calculating the central angle between adjacent female mold foam corrugated strips A is as follows: in, The total central angle is the composite pleated sandwich curved shell plate frame structure used in this ship, and n is the logarithm of the circumferential array of foam corrugated strips A.

7. The molding method of a marine composite pleated sandwich curved shell plate frame structure as described in claim 1, characterized in that: The first fiber cloth, the second fiber cloth, and the pleated core layer can all be woven from commonly used fibers such as carbon fiber, glass fiber, aramid fiber, and basalt fiber.

8. The molding method of a marine composite pleated sandwich curved shell plate frame structure as described in claim 1, characterized in that: In step S3, the pleated core layer is first laid on the foam corrugated strip A, and the foam corrugated strip B is laid on the pleated core layer using a row-by-row molding process. This process can suppress the rebound and displacement of the pleated core layer during the laying process until all the foam corrugated strips B are laid.

9. The molding method of a marine composite pleated sandwich curved shell plate frame structure as described in claim 1, characterized in that, The vacuum injection molding process includes the following steps: S4-1, Lay out the guide pipe and seal it: Double-layer guide netting is laid on the upper and lower surfaces of the preform, linear injection pipes and dispensing pipes are laid, and sealing tape is used to vacuum seal the whole; Connect the dispensing tube to the vacuum pump, close the dispensing port, start the vacuum equipment to test the airtightness, mix the resin and curing agent at a ratio of 100:30, and degas the mixed resin by vacuuming. S4-2, Injection and Impregnation: Immerse the injection port into the degassed resin container and use the internal and external pressure difference to inject the resin into the preform. After the preform is completely impregnated, close the injection port and the outlet port in sequence to terminate the vacuuming process. S4-3, Curing and Demolding: The preform after impregnation is first cured at room temperature, then heated to 70-90℃ and maintained for 6-10 hours to complete curing. Finally, after demolding, a marine composite pleated sandwich curved shell frame structure is obtained.

10. The molding method of a marine composite pleated sandwich curved shell plate frame structure as described in claim 9, characterized in that: In step S4-1, the injection tube is located on one side of the preform, and the line is perpendicular to the length direction of the foam corrugated strip A; the dispensing tube is located on the other side of the preform, opposite to the injection tube. The resin inlet of the injection tube is located at the axial end of the curved shell and close to both circumferential sides.

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