A Z-axis reinforced composite sandwich panel and its manufacturing method

Abstract

This invention relates to the field of ship composite material structure technology and discloses a Z-direction reinforced composite sandwich panel, including an upper panel, a lower panel, a composite web, and a core material. The upper and lower panels are arranged in parallel, the composite web is located between the upper and lower panels and perpendicular to the upper panel, and the core material is located between the composite webs. By adding composite webs to existing composite sandwich panels, the thickness and spacing of the composite webs can be adjusted, improving the mechanical properties in the thickness direction while meeting weight requirements, reducing adhesive stress, and reducing the delamination area under heavy loads.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship composite material structure, in particular to a Z-direction reinforced composite material sandwich panel and a manufacturing method thereof. BACKGROUND

[0002] The existing composite material sandwich panel structure is a commonly used ship composite material structure, which is composed of upper and lower panels and a lightweight core material bonded with the upper and lower panels. The upper and lower panels are usually made of fiber reinforced composite materials, and the lightweight core material is usually made of foam material. The existing composite material sandwich panel structure is usually made by vacuum bag pressing molding. (See, China Classification Society, Material and Welding Specification, 2018, Beijing: People's Communications Press)

[0003] The existing composite material sandwich panel structure has poor mechanical properties in the thickness direction (i.e. perpendicular to the panel direction) due to the low compression modulus and strength of the lightweight core material. In addition, the panel and the core material are bonded together, and the panel and the core material are prone to delamination under heavy load. SUMMARY

[0004] The technical problem to be solved by the present application is that the existing composite material sandwich panel has the problems of easy delamination and poor mechanical properties in the thickness direction.

[0005] To solve the above technical problems, the technical scheme of the present application provides a Z-direction reinforced composite material sandwich panel, which comprises an upper panel, a lower panel, a composite web and a core material. The upper panel and the lower panel are arranged in parallel, the composite web is arranged between the upper panel and the lower panel and perpendicular to the upper panel, and the core material is arranged between the composite web.

[0006] By adopting the above technical scheme, the composite web is added to the existing composite material sandwich panel, the thickness and spacing of the composite web can be adjusted, the mechanical properties in the thickness direction are improved while meeting the weight requirement, the bonding stress is reduced, and the delamination area under heavy load is reduced.

[0007] Optionally, the core material is made of light wood, PVC (polyvinyl chloride) foam, PU (polyurethane) foam or PMI (polymethyl methacrylimide) foam.

[0008] A manufacturing method of a Z-direction reinforced composite material sandwich panel, comprising the following steps:

[0009] Step 1: making a core material preform

[0010] The core material is cut and perforated according to the design dimensions. Web fiber reinforcement material is wrapped around the core material to form a core material preform. Then, the web fiber reinforcement materials of two adjacent core material preforms are stacked at the web position of the composite material to form a complete composite web fiber reinforcement material.

[0011] Step 2: Fabrication of the core material preform assembly

[0012] The composite material fastening rod is passed through the through hole of the core material preform, and multiple core material preforms are strung together. The composite material fastening rod is then passed through the composite material backing plate, which is pre-placed on the outside of the core material preform. The composite material nut plate, which is placed in the countersunk hole of the composite material backing plate, is connected to the threads at both ends of the composite material fastening rod. The core material preforms are locked longitudinally by the composite material fastening rod, the composite material backing plate, and the composite material nut plate. After the composite material fastening rod is tightened, the protruding part of the composite material fastening rod is cut off, and the burrs are polished with sandpaper to keep the composite material fastening rod, the composite material backing plate, and the composite material nut plate on the same plane, thus forming the core material preform assembly.

[0013] Step 3: Laying out the manufacturing materials

[0014] The lower panel fiber reinforcement material is laid on the surface of the molding mold. The core material preform assembly is placed on the lower panel as a whole, and the upper panel fiber reinforcement material is laid on the upper surface of the core material preform assembly. A release cloth is laid on the upper surface of the upper panel to facilitate demolding after curing. Then, a pressure equalizing plate is laid on the upper surface of the core material preform assembly. At the same time, a shaper is laid at the edge of the core material preform assembly. After the pressure equalizing plate and the shaper are laid, auxiliary materials such as a flow guide net, resin pipeline, vacuum pipeline and vacuum bag film are laid on its upper surface.

[0015] Step 4: Manufacturing Z-axis reinforced composite sandwich panels

[0016] The Z-axis reinforced composite sandwich panel is manufactured by vacuum bag compression molding process; after curing, it is demolded, and the shaped tooling and pressure plate are removed to obtain the Z-axis reinforced composite sandwich panel.

[0017] Optionally, the upper panel, lower panel, composite web, composite backing plate, and composite nut plate are all made of fiber-reinforced resin-based composite material; the fiber reinforcement material is unidirectional fabric, woven fabric, four-axis fabric, chopped strand mat, or composite mat; the fiber is carbon fiber, glass fiber, or a mixture of multiple fibers; the resin is vinyl ester resin or unsaturated polyester resin.

[0018] Optionally, the composite fastening rod has threads at both ends, and its material is fiber-reinforced resin-based composite material. The molding process adopts pultrusion molding or winding molding, and the fiber reinforcement material is carbon fiber or glass fiber; the resin is vinyl ester resin or unsaturated polyester resin.

[0019] Optionally, the composite material backplate forming process adopts vacuum induction molding, compression molding or RTM molding process.

[0020] Optionally, the composite nut plate is made of fiber-reinforced resin-based composite material, and its molding process adopts vacuum injection molding, compression molding or RTM molding. The composite nut plate is provided with two positioning pin holes and one internal thread hole, and the outer diameter of the composite fastening rod matches the internal thread hole.

[0021] Optionally, the equalizing plate is made of acrylic sheet or glass; the V-shaped tooling is made of steel or aluminum.

[0022] In summary, this invention designs a Z-direction reinforced composite sandwich panel. By adding a composite web in the Z-direction (i.e., perpendicular to the panel direction) of the existing composite sandwich panel structure, the thickness and spacing of the composite web can be adjusted, improving the mechanical properties in the thickness direction while meeting weight requirements. Simultaneously, the added composite web connects the upper and lower panels of the composite sandwich panel structure, sharing some of the load originally transmitted through the core material, reducing adhesive stress, and decreasing the debonding area under heavy loads. Furthermore, the manufacturing method of the Z-direction reinforced composite sandwich panel structure in this invention, which longitudinally locks the preforms of each core material, has good feasibility, making the Z-direction reinforced composite sandwich panel a promising candidate for widespread applications. Attached Figure Description

[0023] Figure 1 A schematic diagram of an existing composite sandwich panel structure;

[0024] Figure 2 This is a schematic diagram of the Z-axis reinforced composite sandwich panel structure of the present invention;

[0025] Figure 3 This is a schematic diagram of the core material structure of the present invention;

[0026] Figure 4 This is a schematic diagram of the web fiber reinforcement material structure in step 1 of the present invention;

[0027] Figure 5 This is a schematic diagram of the fastening frame structure in step 2 of the present invention;

[0028] Figure 6 This is a schematic diagram of the locking structure of the core material preform of the present invention;

[0029] Figure 7This is a cross-sectional view of the locking structure of the core material preform of the present invention;

[0030] Figure 8 This is a schematic diagram of the composite material fastening rod structure of the present invention;

[0031] Figure 9 This is a schematic diagram of the composite material backing plate structure of the present invention;

[0032] Figure 10 This is a schematic diagram of the composite material nut plate structure of the present invention;

[0033] Figure 11 This is a schematic diagram of the structure in step 3 of the present invention;

[0034] Figure 12 This is a schematic diagram of the auxiliary material laying in step 3 of the present invention;

[0035] In the diagram: 1. Top panel; 2. Bottom panel; 3. Core material; 4. Composite web; 5. Composite fastening rod; 6. Composite backing plate; 7. Composite nut plate; 8. Fiber-reinforced web material; 9. Core material preform; 10. Fiber-reinforced top panel material; 11. Fiber-reinforced bottom panel material; 12. Molding mold; 13. Shaped tooling; 14. Pressure equalizing plate; 16. Release cloth; 17. Vacuum bag film; 18. Locating pin hole; 19. Internal threaded hole. Detailed Implementation

[0036] The following is in conjunction with the appendix Figures 1-12 The present invention will be described in further detail below.

[0037] This invention discloses a Z-axis reinforced composite sandwich panel, with reference to Figure 2 It includes an upper panel 1, a lower panel 2, a core material 3, and a composite web 4. The upper panel 1 and the lower panel 2 are arranged in parallel. The composite web 4 is located between the upper panel 1 and the lower panel 2 and is perpendicular to the upper panel 1. The core material 3 is located between the composite web 4. The material of the core material 3 is selected according to the design requirements as balsa wood, PVC (polyvinyl chloride) foam, PU (polyurethane) foam, or PMI (polymethyl methacrylate) foam.

[0038] In practical applications, the thickness and spacing of the composite web 4 can be adjusted to meet both weight and mechanical performance requirements. The thicknesses of the upper panel 1 and the lower panel 2 can be equal or unequal.

[0039] This invention also discloses a method for manufacturing a Z-axis reinforced composite sandwich panel, comprising the following steps:

[0040] Step 1: Fabrication of core material preform

[0041] Reference Figure 3 and Figure 4The core material 3 is cut and drilled according to the design dimensions. The web fiber reinforcement material 8 is wrapped around the core material 3 to form a core material preform 9. Then, the web fiber reinforcement materials 8 of two adjacent core material preforms are stacked at the web of the composite material to form a complete composite material web fiber reinforcement material.

[0042] Step 2: Fabrication of the core material preform assembly

[0043] Reference Figures 5-10 The composite material fastening rod 5 is passed through the through hole of the core material preform 9, and multiple core material preforms 9 are strung together. The composite material fastening rod 5 is then passed through the composite material backing plate 6, which is pre-placed on the outside of the core material preform 9. The composite material nut plate 7, which is placed in the countersunk hole of the composite material backing plate 6, is connected to the threads at both ends of the composite material fastening rod 5. The core material preforms 9 are locked longitudinally by the composite material fastening rod 5, the composite material backing plate 6, and the composite material nut plate 7. After the composite material fastening rod 5 is fastened, the protruding part of the composite material fastening rod 5 is cut off, and the burrs are polished with sandpaper so that the composite material fastening rod 5, the composite material backing plate 6, and the composite material nut plate 7 are kept on the same plane, and finally the core material preform assembly is formed.

[0044] Step 3: Laying out the manufacturing materials

[0045] Reference Figure 11 and 12 The lower panel fiber reinforcement material 11 is laid on the surface of the molding mold 12. The fastened core material preform assembly is placed on the lower panel 2 as a whole, and the upper panel fiber reinforcement material 10 is laid on the upper surface of the core material preform assembly. The release cloth 16 is laid on the upper surface of the upper plate 1 so that the whole can be demolded after curing. Then, the equalizing plate 14 is laid on the upper surface of the core material preform assembly. At the same time, the weft tooling 13 is laid at the edge of the core material preform assembly to prevent the web fiber reinforcement material 8 laid at the joint of the two core material preforms from bulging locally. After the equalizing plate 14 and the weft tooling 13 are laid, auxiliary materials such as the flow guide net, resin pipeline, vacuum pipeline and vacuum bag film 17 are laid on its upper surface.

[0046] Step 4: Manufacturing Z-axis reinforced composite sandwich panels

[0047] The Z-direction reinforced composite sandwich panel is manufactured by vacuum bag compression molding process; after curing, it is demolded and the shaped tooling 13 and the pressure equalizing plate 14 are removed to obtain the Z-direction reinforced composite sandwich panel.

[0048] In a further embodiment, the upper panel 1, lower panel 2, composite web 4, composite backing plate 6, and composite nut plate 7 are all made of fiber-reinforced resin-based composite material; the fiber reinforcement material is unidirectional fabric, woven fabric, four-axis fabric, chopped strand mat, or composite mat; the fiber is carbon fiber, glass fiber, or a mixture of multiple fibers; the resin is vinyl ester resin or unsaturated polyester resin; the composite fastening rod 5 has threads at both ends. In this embodiment, the threads at both ends of the composite fastening rod 5 are processed to a certain length by a CNC machine tool. In other embodiments, the thread processing method is not limited to a CNC machine tool, and its material is fiber-reinforced resin-based composite material. The molding process is pultrusion molding or winding molding, etc. The fiber reinforcement material is carbon fiber or glass fiber; the resin is vinyl ester resin or unsaturated polyester resin; the composite backing plate 6 is molded by vacuum injection molding, compression molding, or RTM molding; the equalizing plate 14 is made of transparent or semi-transparent material, such as acrylic sheet or glass; the shaped tooling 13 is made of steel or aluminum, etc., which are not easily deformed.

[0049] In a further embodiment, the composite nut plate 7 is made of fiber-reinforced resin-based composite material, and its molding process adopts vacuum injection molding, compression molding or RTM molding. The composite nut plate 7 is provided with two positioning pin holes 18 and one internal thread hole 19, and the outer diameter of the composite fastening rod 5 matches the internal thread hole 19.

[0050] In a further embodiment, the core material 3 has a through hole diameter of 10mm to 30mm and a through hole spacing of 200mm to 300mm; the composite material fastening rod 5 has a diameter of 10mm to 30mm and both ends are machined with threads of not less than 100mm by a CNC machine tool; the composite material backing plate 6 has a countersunk hole diameter of 40mm to 55mm and a through hole diameter of 10mm to 30mm; the composite material nut plate 7 has a diameter of 40mm to 55mm and the locating pin hole in the composite material nut plate is symmetrical along the centerline with a diameter of 5mm to 10mm.

[0051] Example 1

[0052] In this embodiment, a Z-direction reinforced composite sandwich panel with dimensions of 960mm × 700mm × 58mm is manufactured, wherein the fiber reinforcement material has an areal density of 800g / m². 2 A single layer of 0.5mm thick tetraaxial E-glass fiber fabric; vinyl ester resin; core material with a density of 100kg / m³. 3 The PVC foam is used; the composite fastening rod 5 is made of glass fiber, vinyl ester resin, and pultruded; the composite backing plate 6 and the composite nut plate 7 are made of glass fiber, vinyl ester resin, and molded.

[0053] In this embodiment, five composite webs 4 are provided, each with a thickness of 4 mm and a spacing of 150 mm between them; the upper panel 1 has a thickness of 4 mm and the lower panel 2 has a thickness of 4 mm.

[0054] The manufacturing method is as follows:

[0055] Step 1: Cut the glass fiber reinforced material according to the design dimensions, process 6 pieces of PVC foam to the design dimensions (660mm×150mm×50mm), and process through holes with a diameter of 10mm on the PVC foam along the length direction; process the composite fastening rod 5, composite backing plate 6, and composite nut plate 7 according to the design dimensions, and see the table below for specific data;

[0056]

[0057] Step 2: Wrap the fiber reinforcement material, cut to the design dimensions, along the width of the PVC foam in 4 layers (approximately 2mm thick). When wrapping, remove any air bubbles to ensure the fiber reinforcement material adheres tightly to the PVC foam. Wrap 6 pieces of PVC foam in this way to form a PVC core preform 9.

[0058] Step 3: Pass the composite material fastening rod 5 through the through hole of the PVC core material 3, connect the 6 PVC core material preforms 9 in series, and connect the composite material backing plate 6 to the composite material fastening rod 5 at both ends of the PVC core material preforms 9. Adjust the position of the composite material backing plate 6 so that the dimensions of the composite material backing plate 6 and the PVC core material preforms 9 are consistent.

[0059] Step 4: Connect the two protruding pins in the fastening fixture of composite material nut plate 7 to the two positioning pin holes 18 on the composite material nut plate, and rotate clockwise; when tightening, first tighten the composite material nut plate 7 on the same side to the composite material fastening rod 5, while ensuring that the relative positions of the composite material nut plate 7 on the other side to the composite material fastening rod 5 are the same; after adjusting the position of the composite material nut plate 7 and the composite material fastening rod 5 on one side, tighten the three composite material nut plates 7 on the other side to the fastening rod; during the tightening process, pay attention to the distance between the composite material backing plates 6 at both ends. At this time, the distance between the outer edges of the composite material backing plates 6 at both ends is 954mm; after tightening, cut off the protruding part of the composite material fastening rod 5 and sand it to make the composite material fastening rod 5, the composite material backing plate 6, and the composite material nut plate 7 keep on the same plane;

[0060] Step 5: Process and clean the molding mold 12 according to the design dimensions, and apply release agent 3-4 times. Let it dry completely before use.

[0061] Step 6: Cut the fiber reinforcement material 11 of the lower panel to the design size and lay it flat on the surface of the molding mold 12. There should be no wrinkles when laying it.

[0062] Step 7: Place the secured PVC core material preform 9 onto the lower panel 2 according to the design dimensions;

[0063] Step 8: Lay fiber reinforcement material on the upper surface of the PVC core material preform 9, with 4 layers (approximately 2mm thick), and lay fiber reinforcement material on all four sides of the PVC core material preform 9 to the designed thickness;

[0064] Step 9: After the fiber reinforcement material is laid, lay the release cloth 16 on the upper surface of the top plate 1;

[0065] Step 10: Lay a pressure equalizing plate 14 of about 2mm on the upper surface of the PVC core material preform 9; at the same time, lay the weft-shaped tooling 13 at the edge and press it firmly. Lay out the guide net, resin pipeline, vacuum pipeline and vacuum bag film 17 and other auxiliary materials in sequence;

[0066] Step 11: After laying, check the air tightness. After ensuring that the air tightness meets the requirements, vacuum bag compression molding is performed. The amount of vinyl resin used is about 30kg. After curing at room temperature for 24 hours, demold, remove the shaping tool 13 and the pressure plate 14, and get the Z-direction reinforced composite sandwich panel.

[0067] In summary, this invention designs a Z-direction reinforced composite sandwich panel. By adding a composite web 4 in the Z direction (i.e., perpendicular to the panel direction) of the existing composite sandwich panel structure, the thickness and spacing of the composite web 4 can be adjusted, improving the mechanical properties in the thickness direction while meeting weight requirements. At the same time, the added composite web 4 connects the upper and lower panels of the composite sandwich panel, sharing part of the load originally transmitted through the core material 3, reducing adhesive stress, and reducing the delamination area under heavy loads.

[0068] This invention discloses a manufacturing method for a Z-axis reinforced composite sandwich panel. A composite material fastening rod 5 passes through a through-hole in a core material preform 3, connecting multiple core material preforms 9. The fastening rod 5 extends from a composite material support plate 6 pre-placed outside the core material preforms 9. A composite material nut plate 7, placed in a countersunk hole in the support plate 6, is connected to the threads at both ends of the fastening rod 5. The fastening rod 5, the support plate 6, and the nut plate 7 longitudinally lock the core material preforms 9. This method has good feasibility, making the Z-axis reinforced composite sandwich panel a promising candidate for widespread application.

[0069] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method of manufacturing a Z-stiffened composite sandwich panel, characterized in that, The application relates to a method for manufacturing a Z-direction reinforced composite sandwich plate, and the Z-direction reinforced composite sandwich plate comprises an upper panel (1), a lower panel (2), a composite web (4) and a core material (3), the upper panel (1) and the lower panel (2) are arranged in parallel, the composite web (4) is arranged between the upper panel (1) and the lower panel (2) and is perpendicular to the upper panel (1), and the core material (3) is arranged between the composite web (4) and is made of balsa wood, PVC (polyvinyl chloride) foam, PU (polyurethane) foam or PMI (polymethacrylimide) foam. The method comprises the following steps: Step 1: preparing a core material preform The core material (3) is cut according to the designed size and is punched, the core material preform (9) is formed by wrapping the web fiber reinforced material (8) on the outer side of the core material (3), then the web fiber reinforced materials (8) of two adjacent core material preforms are overlapped at the position of the composite web to form complete composite web fiber reinforced material; Step 2: preparing a core material preform assembly The composite fastening rod (5) is passed through the through hole of the core material preform (9), a plurality of core material preforms (9) are strung, the composite fastening rod (5) is passed out from the composite back plate (6) which is previously arranged on the outer side of the core material preform (9), the composite nut plate (7) arranged in the counterbore of the composite back plate (6) is connected with the threads at the two ends of the composite fastening rod (5), the core material preforms (9) are locked in the longitudinal direction through the composite fastening rod (5), the composite back plate (6) and the composite nut plate (7), after the fastening of the composite fastening rod (5) is completed, the protruding part of the composite fastening rod (5) is cut off, burrs are polished by using sandpaper, the composite fastening rod (5) and the composite back plate (6) and the composite nut plate (7) are kept in the same plane, and finally the core material preform assembly is formed; Step 3: laying manufacturing materials The lower panel fiber reinforced material (11) is laid on the surface of a forming mold (12), the fastened core material preform assembly is placed on the lower panel (2) as a whole, the upper panel fiber reinforced material (10) is laid on the upper surface of the core material preform assembly, the release cloth (16) is laid on the upper surface of the upper panel (1), then the equalizing plate (14) is laid on the upper surface of the core material preform assembly, and the shape maintaining tool (13) is laid at the edge of the core material preform assembly; after the equalizing plate (14) and the shape maintaining tool (13) are laid, auxiliary materials are laid on the upper surface, the auxiliary materials comprise a flow guide net, resin pipelines, vacuum pipelines and a vacuum bag film (17); Step 4: manufacturing the Z-direction reinforced composite sandwich plate The manufacturing of the Z-direction reinforced composite sandwich plate is completed through a vacuum bag pressure forming process; after curing and forming, the Z-direction reinforced composite sandwich plate is obtained by demolding and removing the shape maintaining tool (13) and the equalizing plate (14).

2. The method of manufacturing a Z-stiffened composite sandwich panel according to claim 1, wherein, The upper panel (1), the lower panel (2), the composite web (4), the composite backrest (6) and the composite nut plate (7) are all made of fiber reinforced resin-based composite material; the fiber reinforced material is unidirectional cloth, square cloth, four-axis cloth, chopped felt or composite felt; the fiber is carbon fiber, glass fiber or a plurality of fiber hybrid; the resin is selected from vinyl resin or unsaturated polyester resin.

3. The method of manufacturing a Z-stiffened composite sandwich panel according to claim 1, wherein, The composite fastening rod (5) is provided with threads at both ends, and the material thereof is fiber reinforced resin-based composite material, the forming process adopts pultrusion or winding forming, and the fiber reinforced material is carbon fiber or glass fiber; the resin is vinyl resin or unsaturated polyester resin.

4. The method of manufacturing a Z-stiffened composite sandwich panel according to claim 1, wherein, The composite backrest (6) adopts vacuum infusion forming, mold pressing forming or RTM forming process.

5. The method of manufacturing a Z-stiffened composite sandwich panel according to claim 1, wherein, The composite nut plate (7) is made of fiber reinforced resin-based composite material, and the forming process adopts vacuum infusion forming, mold pressing forming or RTM forming; the composite nut plate (7) is provided with two positioning pin holes (18) and one internal thread hole (19), and the outer diameter of the composite fastening rod (5) matches the internal thread hole (19).

6. The method of manufacturing a Z-stiffened composite sandwich panel according to claim 1, wherein, The material of the pressure equalizing plate (14) is selected from acrylic plate or glass; and the material of the shape tooling (13) is selected from steel or aluminum.

Images