A non-metallic connecting device and method for thermoplastic FRP parallel plates and cables.

Abstract

This invention discloses a non-metallic connection device and method for thermoplastic FRP parallel plates and cables, belonging to the field of fiber-reinforced composite material connection technology. The connection device includes a first thermoplastic FRP plate and cable, a second thermoplastic FRP plate and cable, a non-metallic upper pressure plate, a non-metallic lower pressure plate, and a fiber pretensioning band. The connecting sections of the first and second thermoplastic FRP plate and cables are thermoplastically molded to form corrugated connecting sections, which are alternately layered along the thickness direction. An adhesive medium is provided between adjacent corrugated connecting sections, forming a corrugated interlocking structure with corrugated peaks and troughs. The inner surfaces of the non-metallic upper and lower pressure plates are provided with corrugated grooves matching the corrugated connecting sections. The fiber pretensioning band is wound around the outside of the pressure plates and cured to form a continuous fiber-reinforced composite sleeve. This solution eliminates the need for metal bolts and through-hole fastening, reducing stress concentration, interface peeling, and corrosion risks, and improving the reliability of FRP parallel plate and cable connections.

Description

Technical Field

[0001] This invention belongs to the field of fiber-reinforced composite material joining technology, and specifically relates to a non-metallic joining device and joining method for thermoplastic FRP parallel plates and cables. Background Technology

[0002] Fiber-reinforced composite materials, or FRP for short, possess advantages such as lightweight, high strength, corrosion resistance, and fatigue resistance, and have been increasingly applied in fields such as bridge cables, long-span spatial structures, marine engineering mooring systems, and soil and rock anchoring. Compared with traditional metal cables, FRP materials exhibit better durability in corrosive environments, and when using non-metallic reinforcing fibers and insulating resin systems, they can reduce the risk of magnetic interference and electrochemical corrosion caused by metal components. Therefore, they are suitable for engineering environments where metal components are highly sensitive, such as geomagnetic observatories, radar stations, and nuclear magnetic resonance facilities.

[0003] However, FRP materials exhibit significant anisotropy, possessing high tensile strength along the fiber direction but relatively weak transverse shear strength, compressive strength, and interlaminar peel resistance. In the FRP parallel plate-cable connection region, improper connection structure design can easily lead to localized stress concentration, interface debonding, plate-cable slippage, interlaminar peeling, or fragmentation failure. Therefore, achieving reliable connections without damaging the continuous FRP fibers is a crucial technical challenge restricting the engineering application of FRP parallel plate-cable systems.

[0004] Existing FRP cable connection or anchoring methods mainly include adhesive connections, clamped connections, and bolt-plate clamped connections. Adhesive connections typically involve filling a metal sleeve with epoxy resin, reactive powder concrete, or other high-strength adhesive media, embedding the FRP reinforcement or cable / plate within it, and relying on interfacial shear force to transfer the load. This type of connection has a relatively simple structure, but under high stress, shear stress peaks are prone to occur near the loading end, leading to gradual debonding of the adhesive interface from the loading end and ultimately slippage failure. Furthermore, adhesive connections usually require a long connection length, resulting in a large connection device size, and the metal sleeve is susceptible to corrosion in humid, marine, or corrosive environments.

[0005] Clamping connections primarily draw upon the traditional steel cable wedge anchoring principle, applying clamping force to the FRP cable via clamps, pressure plates, or fixtures, and relying on friction and mechanical interlocking to transfer the load. However, FRP materials have relatively weak lateral load-bearing capacity; excessive local clamping force can easily cause crushing, splitting, or interlayer damage; while insufficient clamping force is insufficient to prevent cable slippage. Therefore, this type of connection is highly sensitive to the shape of the fixture, clamping pressure, and manufacturing precision, and its connection performance may degrade due to loosening of the clamping force during long-term service.

[0006] Bolted plate clamping connections typically use upper and lower pressure plates to clamp FRP (fiberglass reinforced plastic) sheets and cables, with multiple rows of bolts providing fastening force. While this structure is easy to assemble, it requires bolt holes in the FRP sheet / cable or pressure plate connection area. For FRP sheets and cables, these holes cut through continuous fibers, causing stress concentration at the hole edges, reducing the sheet / cable's load-bearing capacity, and easily inducing crack propagation, interlaminar delamination, and fatigue damage. Furthermore, metal bolts, metal pressure plates, or metal sleeves can introduce problems such as electrochemical corrosion, magnetic interference, and long-term relaxation.

[0007] To improve the connection performance of FRP sheets or cables, existing technologies have proposed corrugated clamping plates or corrugated tooth clamping structures, which increase the contact area and introduce a certain mechanical interlocking effect through the corrugated tooth surface. However, existing corrugated clamping plate structures still mostly rely on metal pressure plates and metal bolts to provide clamping force, failing to fundamentally solve the problems of metal component corrosion, magnetic interference, stress concentration in bolt holes, and uneven distribution of bolt preload. Furthermore, this type of structure mainly focuses on FRP sheet anchoring or end clamping, and lacks effective solutions for butt joint connections between thermoplastic FRP parallel cables, especially how to utilize the heat-curing and secondary molding characteristics of thermoplastic FRP materials to form a hole-free, metal-free, mechanically interlocked, and multi-interface collaborative force transmission connection structure. Summary of the Invention

[0008] The purpose of this invention is to provide a non-metallic connection device and connection method for thermoplastic FRP parallel plate cables, so as to solve the problems existing in the existing FRP parallel plate cable connection structure, such as dependence on metal components, stress concentration in bolt holes, cutting of continuous fibers, easy debonding and slippage of the bonding interface, uneven distribution of clamping force, and insufficient long-term connection reliability.

[0009] The present invention is achieved by the following measures: a non-metallic connecting device for thermoplastic FRP parallel plates and cables, characterized in that it includes a first thermoplastic FRP plate and cable, a second thermoplastic FRP plate and cable, a non-metallic upper pressure plate, a non-metallic lower pressure plate, and a fiber pretensioning belt; The first thermoplastic FRP sheet has a first corrugated connecting section, and the second thermoplastic FRP sheet has a second corrugated connecting section. Both the first corrugated connecting section and the second corrugated connecting section are corrugated connecting sections formed by thermoplastic deformation. The first corrugated connecting section and the second corrugated connecting section are alternately stacked along the thickness direction, and an adhesive medium is provided between adjacent corrugated connecting sections; The non-metallic upper pressure plate is disposed on the upper side of the stacked corrugated connecting section, and the non-metallic lower pressure plate is disposed on the lower side of the stacked corrugated connecting section. The inner surface of the non-metallic upper pressure plate and the inner surface of the non-metallic lower pressure plate are both provided with corrugated grooves that match the outer contour of the corresponding corrugated connecting section. The fiber pretensioning tape is wrapped around the outside of the non-metallic upper pressure plate and the non-metallic lower pressure plate to apply circumferential constraints to the non-metallic upper pressure plate, the non-metallic lower pressure plate, and the stacked corrugated connecting section.

[0010] Furthermore, both the first thermoplastic FRP sheet and the second thermoplastic FRP sheet include multiple layers of thermoplastic FRP sheets, and the thermoplastic FRP sheets of the first thermoplastic FRP sheet and the thermoplastic FRP sheets of the second thermoplastic FRP sheet are staggered along the thickness direction in the connection area.

[0011] Furthermore, both the first and second corrugated connecting sections include multiple crests and troughs continuously arranged along the axial direction of the plate cable, with adjacent crests and troughs connected by arc transition sections. Adjacent, stacked corrugated connecting sections interlock through the engagement of crests and troughs.

[0012] Furthermore, the corrugation amplitude of the first corrugated connecting section and the second corrugated connecting section gradually decreases from the middle of the connecting region to the end of the connecting region.

[0013] Furthermore, the adhesive medium is disposed between adjacent corrugated connecting sections, between the non-metallic upper pressure plate and the uppermost corrugated connecting section, and between the non-metallic lower pressure plate and the lowermost corrugated connecting section.

[0014] Furthermore, the non-metallic upper pressure plate and the non-metallic lower pressure plate are glass fiber reinforced composite material pressure plates, aramid fiber reinforced composite material pressure plates, basalt fiber reinforced composite material pressure plates, carbon fiber reinforced composite material pressure plates, PEEK-based composite material pressure plates, or PPS-based composite material pressure plates.

[0015] Furthermore, the fiber pre-tightening tape is a continuous fiber tape impregnated with a bonding medium, and the continuous fiber tape is a carbon fiber tape, glass fiber tape, aramid fiber tape, or basalt fiber tape.

[0016] Furthermore, the fiber pretensioning tape is wound circumferentially in a direction perpendicular to the axial direction of the first thermoplastic FRP sheet and the second thermoplastic FRP sheet, or wound in a cross-wound spiral manner inclined relative to the axial direction.

[0017] Furthermore, the winding pretension force of the fiber pretension tape is 50N to 200N, and the number of winding layers of the fiber pretension tape is 2 to 20 layers.

[0018] Furthermore, neither the first nor the second thermoplastic FRP sheet / cable has a fastening hole extending through the thickness of the sheet / cable in the connection area. The first and second corrugated connection sections are thermoplastic corrugated sections with uncut continuous fibers.

[0019] The present invention also provides a method for connecting thermoplastic FRP parallel plates and cables, characterized by comprising the following steps: The connecting sections of the first thermoplastic FRP sheet and the second thermoplastic FRP sheet are heated respectively to bring the connecting sections of the first thermoplastic FRP sheet and the second thermoplastic FRP sheet to a thermoplastic deformable state. The connecting section that has reached the thermoplastic deformable state is placed in a molding die with a corrugated cavity, and a mold closing pressure is applied to the connecting section to form a first corrugated connecting section of the first thermoplastic FRP sheet and cable, and to form a second corrugated connecting section of the second thermoplastic FRP sheet and cable. The first corrugated connecting section and the second corrugated connecting section are cooled and shaped. The first corrugated connecting section and the second corrugated connecting section are alternately stacked along the thickness direction, and an adhesive medium is provided between adjacent corrugated connecting sections; A non-metallic upper pressure plate is installed on the upper side of the stacked corrugated connecting section, and a non-metallic lower pressure plate is installed on the lower side of the stacked corrugated connecting section. An adhesive medium is applied to the inner surface of the corrugated grooves of the non-metallic upper pressure plate and the non-metallic lower pressure plate, as well as the surface in contact with the thermoplastic FRP sheet. The corrugated grooves of the non-metallic upper pressure plate and the non-metallic lower pressure plate are respectively matched with the outer contour of the corresponding corrugated connecting section. Fiber pretensioning tape is wound around the outside of the non-metallic upper pressure plate and the non-metallic lower pressure plate; The bonding medium is cured to form a non-metallic connection structure of thermoplastic FRP parallel plates and cables.

[0020] When heating the connecting section of the first thermoplastic FRP sheet and the connecting section of the second thermoplastic FRP sheet, the heating temperature is higher than the glass transition temperature of the corresponding thermoplastic resin matrix.

[0021] Before setting the bonding medium, the first corrugated connecting section and the second corrugated connecting section are subjected to grinding, cleaning, plasma treatment, coupling agent treatment or sandblasting roughening treatment.

[0022] When the fiber pretensioning tape is wound around the outside of the non-metallic upper pressure plate and the non-metallic lower pressure plate, the continuous fibers are impregnated in the bonding medium to form the fiber pretensioning tape, and multiple layers are wound with a pretensioning force of 50N to 200N.

[0023] When the first corrugated connecting section and the second corrugated connecting section are alternately stacked along the thickness direction, the crests of the first corrugated connecting section and the troughs of the second corrugated connecting section are matched to form a mechanical interlocking structure between the first thermoplastic FRP sheet and the second thermoplastic FRP sheet.

[0024] The fiber pretensioning band covers the outer surfaces of the non-metallic upper pressure plate and the non-metallic lower pressure plate, and extends to the exposed thermoplastic FRP sheet / cable surfaces on both sides of the non-metallic upper pressure plate and the non-metallic lower pressure plate.

[0025] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: First, the present invention utilizes the characteristic that thermoplastic FRP sheets and cables can be re-formed after heating, and processes the connecting sections of the first thermoplastic FRP sheet and cable and the second thermoplastic FRP sheet and cable into corrugated connecting sections respectively. This corrugated connecting section does not require bolt holes or cutting of continuous fibers during the forming process, thus maintaining the continuity of the reinforcing fibers within the FRP sheet and cable, and avoiding fiber breakage and stress concentration at the hole edges caused by opening holes in traditional bolted connections.

[0026] This invention involves alternating layers of the first and second corrugated connecting sections along the thickness direction, creating a corrugated interlocking structure with corrugated crests and troughs between adjacent corrugated connecting sections. This structure, based on the interfacial shear force provided by the bonding medium, further enhances the tensile strength and anti-slip capability between the two thermoplastic FRP parallel plates / cables through the corrugated interlocking, thereby reducing the risk of overall slippage failure due to gradual debonding from the loading end in simple adhesive connections.

[0027] This invention incorporates bonding media between adjacent corrugated connecting sections, between the non-metallic upper pressure plate and the outer corrugated connecting section, and between the non-metallic lower pressure plate and the outer corrugated connecting section, forming a multi-interface bonding force transmission structure. Axial loads can be distributed and transmitted among multiple bonding interfaces and multiple corrugated interlocking interfaces, avoiding load concentration at a single interface or end region. This helps reduce local stress peaks and improves the load-bearing stability of the connecting area.

[0028] In this invention, a non-metallic upper pressure plate and a non-metallic lower pressure plate are respectively disposed on the upper and lower sides of the stacked corrugated connecting section, and their inner surfaces are provided with corrugated grooves that match the outer contour of the corrugated connecting section. These corrugated grooves can increase the contact area between the pressure plate and the corrugated connecting section, and provide shape constraint and normal clamping effect to the outer corrugated connecting section, which is beneficial for suppressing the opening, peeling, and relative misalignment of the corrugated connecting section under tension.

[0029] This invention employs a fiber preload tape wrapped around the outside of a non-metallic upper pressure plate and a non-metallic lower pressure plate. After curing, the fiber preload tape forms a continuous fiber-reinforced composite sleeve. Compared with traditional discrete bolt preload, the continuous fiber-reinforced composite sleeve can provide continuous circumferential constraint and radial clamping force along the connection area, reducing the connection performance degradation caused by uneven preload distribution and bolt loosening. At the same time, it can suppress adhesive interface peeling and pressure plate opening.

[0030] The fiber pretensioning band of this invention can cover the outer surfaces of the non-metallic upper and lower pressure plates and extend to the exposed thermoplastic FRP sheet / cable surfaces on both sides of the pressure plates, thereby forming a continuous transition constraint between the connecting and non-connecting areas. This structure can reduce the risk of peeling and local stress concentration at the ends of the pressure plates, and improve the durability and fatigue resistance of the connecting area ends.

[0031] The final service connection structure of this invention may exclude metal bolts, metal pressure plates, and metal sleeves, thereby reducing the risks of electrochemical corrosion, magnetic interference, and maintenance costs caused by metal components. For applications sensitive to metal or conductive components, such as geomagnetic observatories, radar stations, and nuclear magnetic resonance facilities, low-conductivity non-metallic materials such as glass fiber, aramid fiber, or basalt fiber can be further selected as the cable reinforcement fibers, pressure plate reinforcement fibers, and fiber pretensioning strips, thereby improving the applicability of the connection structure in special engineering environments. Attached Figure Description

[0032] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings listed below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram (color illustration) of the non-metallic connecting device of thermoplastic FRP parallel plate cable in an embodiment of the present invention. Figure 2 This is a schematic diagram (color illustration) of a high-temperature plastic device used for corrugated preforming of thermoplastic FRP sheet-cable connectors in an embodiment of the present invention. Figure 3 This is a schematic diagram (color illustration) of the thermoplastic FRP sheet cable forming a corrugated connecting section after thermoplastic molding in an embodiment of the present invention. Figure 4 This is a schematic diagram (color illustration) of the non-metallic pressure plate in an embodiment of the present invention. Figure 5 This is a schematic diagram (color illustration) of the structure after the non-metallic pressure plate and thermoplastic FRP sheet are assembled in an embodiment of the present invention. Figure 6 This is a schematic diagram of the non-metallic connecting device for thermoplastic FRP parallel plates and cables in an embodiment of the present invention; Figure 7 This is a schematic diagram (line drawing) of a high-temperature plastic device used for corrugated preforming of thermoplastic FRP sheet-cable connection sections in an embodiment of the present invention. Figure 8 This is a schematic diagram (line drawing) of the thermoplastic FRP sheet cable forming a corrugated connecting section after thermoplastic molding in an embodiment of the present invention. Figure 9 This is a schematic diagram (line drawing) of the structure of the non-metallic pressure plate in an embodiment of the present invention. Figure 10 This is a schematic diagram (line drawing) of the structure after the non-metallic pressure plate and thermoplastic FRP sheet are assembled in an embodiment of the present invention.

[0034] The components represented by each number in the attached diagram are listed below: 1. Thermoplastic FRP sheet / cable; 2. Non-metallic upper pressure plate; 3. Non-metallic lower pressure plate; 4. Fiber pretensioner belt; 5. Metal lower pressure plate; 6. Lower heating plate; 7. Heating plate wire; 8. Electrical box; 9. Metal upper pressure plate; 10. Preload screw; 11. Upper heating plate; 12. Preload nut. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] Example 1: like Figures 1 to 10 As shown, this embodiment provides a non-metallic connecting device and method for thermoplastic FRP parallel plates and cables, used to achieve a butt joint connection between two sections of thermoplastic FRP parallel plates and cables. The service connection structure of this device does not include metal pressure plates, metal bolts, or metal sleeves, thus avoiding electrochemical corrosion, magnetic interference, and stress concentration problems in bolt holes caused by metal components.

[0037] In this embodiment, the non-metallic connecting device for the thermoplastic FRP parallel plates and cables includes a thermoplastic FRP plate and cable 1, a non-metallic upper pressure plate 2, a non-metallic lower pressure plate 3, and a fiber pretensioning band 4. The thermoplastic FRP plate and cable 1 includes a first thermoplastic FRP plate and cable and a second thermoplastic FRP plate and cable. Both the first thermoplastic FRP plate and cable and the second thermoplastic FRP plate and cable are formed by combining a thermoplastic resin matrix and a continuous fiber reinforcement, and have a parallel plate structure. The thermoplastic resin matrix can be polyphenylene sulfide, polyetheretherketone, polyamide, polyetherimide, or other thermoplasticizable resin materials; the continuous fiber reinforcement can be carbon fiber, glass fiber, aramid fiber, or basalt fiber.

[0038] Both the first and second thermoplastic FRP sheets / cables comprise multiple layers of thermoplastic FRP sheets. Continuous fibers within each layer of thermoplastic FRP sheet extend continuously along the axial direction of the corresponding sheet / cable. The first thermoplastic FRP sheet / cable has a first corrugated connecting section, and the second thermoplastic FRP sheet / cable has a second corrugated connecting section. Both the first and second corrugated connecting sections are formed into a corrugated profile through thermoplastic deformation, without cutting the continuous fibers during the formation of the corrugated profile. Thus, the first and second corrugated connecting sections improve the mechanical interlocking capability of the connecting sections while maintaining the integrity of the continuous fibers within the FRP sheets, preventing fiber breakage due to openings or cutting.

[0039] Both the first and second corrugated connecting sections include multiple crests and troughs continuously arranged along the axial direction of the sheet cable, with adjacent crests and troughs connected by arc transition sections. The arc transition sections are used to reduce local bending stress at the crests and troughs, preventing localized breakage of the thermoplastic FRP sheet during molding and tensioning.

[0040] Preferably, the corrugated shape of the first and second corrugated connecting sections is sinusoidal, arc-shaped, or a smooth corrugated shape formed by a combination of arc segments and straight segments. Furthermore, the corrugation amplitude can gradually decrease from the middle of the connecting area to both ends, creating a stronger mechanical interlocking capability in the middle of the connecting area, while reducing abrupt stiffness changes at the ends of the connecting area, thus reducing the peak values ​​of end peel stress and shear stress.

[0041] The multiple layers of thermoplastic FRP sheets of the first thermoplastic FRP cable and the multiple layers of thermoplastic FRP sheets of the second thermoplastic FRP cable are staggered along the thickness direction in the connecting area. Specifically, one or more corrugated thermoplastic FRP sheets of the first thermoplastic FRP cable and one or more corrugated thermoplastic FRP sheets of the second thermoplastic FRP cable are alternately stacked in a layer-on-layer manner, so that the corrugated connecting sections of adjacent layers form a corrugated interlocking structure with corrugations and troughs. An adhesive medium is provided between adjacent corrugated connecting sections, and the adhesive medium fills the interface gaps between the corrugations, troughs, and adjacent thermoplastic FRP sheets. Thus, a force transmission structure is formed between the two thermoplastic FRP cable sections by the combined action of corrugated mechanical interlocking and multi-interface bonding.

[0042] The non-metallic upper pressure plate 2 is disposed on the upper side of the stacked corrugated connecting section, and the non-metallic lower pressure plate 3 is disposed on the lower side of the stacked corrugated connecting section. Both the non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3 are rectangular plate-shaped components and are made of non-metallic composite materials. The non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3 can be glass fiber reinforced composite material pressure plates, aramid fiber reinforced composite material pressure plates, basalt fiber reinforced composite material pressure plates, carbon fiber reinforced composite material pressure plates, PPS-based composite material pressure plates, or PEEK-based composite material pressure plates. For applications requiring further reduction of conductivity or electromagnetic influence, the non-metallic upper pressure plate 2, the non-metallic lower pressure plate 3, and the fiber pretensioning belt 4 are preferably made of glass fiber, aramid fiber, or basalt fiber reinforced composite materials.

[0043] The inner surface of the non-metallic upper pressure plate 2 is provided with an upper corrugated groove that matches the outer contour of the uppermost corrugated connecting section, and the inner surface of the non-metallic lower pressure plate 3 is provided with a lower corrugated groove that matches the outer contour of the lowermost corrugated connecting section. The upper and lower corrugated grooves respectively fit into the corresponding corrugated connecting sections to increase the contact area between the pressure plate and the thermoplastic FRP sheet 1, and to provide shape constraints for the stacked corrugated connecting sections. An adhesive medium is also provided between the non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3 and the thermoplastic FRP sheet 1, so that the non-metallic upper pressure plate 2, the non-metallic lower pressure plate 3 and the outer corrugated connecting section are bonded together.

[0044] The fiber pretensioning tape 4 is a continuous fiber tape impregnated with a bonding medium. The fiber pretensioning tape 4 can be a carbon fiber tape, glass fiber tape, aramid fiber tape, or basalt fiber tape. In this embodiment, the fiber pretensioning tape 4 is circumferentially wound around the outside of the non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3 in a direction perpendicular to the axial direction of the thermoplastic FRP sheet 1. The fiber pretensioning tape 4 covers the outer surface of the non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3, and extends to the exposed surfaces of the thermoplastic FRP sheet 1 on both sides of the non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3, forming a continuous transition constraint between the connecting area and the non-connecting area. Optionally, the fiber pretensioning tape 4 can also be cross-wound in a spiral manner inclined relative to the axial direction of the thermoplastic FRP sheet 1 to enhance the peel resistance and torsional resistance of the connecting area.

[0045] When the fiber pretensioning tape 4 is wound, a preset tension is applied, which can be 50N to 200N. The number of winding layers of the fiber pretensioning tape 4 can be 2 to 20, and the specific number of layers is determined according to the design load-bearing capacity, connection length, and pressure plate size of the thermoplastic FRP sheet cable 1. After the fiber pretensioning tape 4 and its impregnated adhesive medium are cured, a continuous fiber-reinforced composite sleeve is formed. This continuous fiber-reinforced composite sleeve surrounds the non-metallic upper pressure plate 2, the non-metallic lower pressure plate 3, and the stacked corrugated connecting sections, applying continuous circumferential restraint and radial clamping force to the internal components, thereby inhibiting interlayer bonding interface peeling, pressure plate opening, and relative slippage between corrugated connecting sections.

[0046] In this embodiment, the bonding medium can be epoxy resin structural adhesive, vinyl ester structural adhesive, methacrylate structural adhesive, polyurethane structural adhesive, or a thermoplastic adhesive film adapted to the thermoplastic resin matrix of the thermoplastic FRP sheet / cable 1. The bonding medium is disposed between adjacent corrugated connecting sections, between the non-metallic upper pressure plate 2 and the uppermost corrugated connecting section, between the non-metallic lower pressure plate 3 and the lowermost corrugated connecting section, and inside the fiber pretensioning band 4. Thus, a multi-interface composite connection structure of "interlayer bonding - pressure plate bonding - fiber hoop curing" is formed in the connection area.

[0047] This embodiment also provides a non-metallic connection method for the above-mentioned thermoplastic FRP parallel plate cables, which includes the following steps.

[0048] The first step is the preparation and surface treatment of the plates and cables.

[0049] Cut the first and second thermoplastic FRP sheets to the designed length to determine the connection area between the two sections. Clean the connection area to remove surface oil, dust, and mold release residue. Preferably, before applying the adhesive medium, the connection area is subjected to grinding, sandblasting, plasma treatment, flame treatment, coupling agent treatment, or solvent cleaning to improve the interfacial bonding strength between the thermoplastic FRP sheet 1 and the adhesive medium.

[0050] The second step is thermoforming the corrugated connecting section.

[0051] The connecting sections of the first and second thermoplastic FRP sheets are respectively placed into a high-temperature plastic forming apparatus for thermoplastic molding. For example... Figure 2 As shown, the high-temperature plastic forming device includes a lower metal pressure plate 5, a lower heating plate 6, heating plate wires 7, an electrical box 8, an upper metal pressure plate 9, a preload screw 10, an upper heating plate 11, and a preload nut 12. The upper surface of the lower metal pressure plate 5 has a lower corrugated cavity, and the lower surface of the upper metal pressure plate 9 has an upper corrugated cavity that mates with the lower corrugated cavity. The lower heating plate 6 is located at the bottom or inside of the lower metal pressure plate 5, and the upper heating plate 11 is located at the top or inside of the upper metal pressure plate 9. The lower heating plate 6 and the upper heating plate 11 are electrically connected to the electrical box 8 via the heating plate wires 7. The electrical box 8 is used to supply power and control the temperature of the lower heating plate 6 and the upper heating plate 11.

[0052] The connecting section of the thermoplastic FRP sheet 1 is placed between the lower metal pressure plate 5 and the upper metal pressure plate 9, and the connecting section is positioned within the coverage area of ​​the upper and lower corrugated cavities. The electrical control box 8 is activated, and the upper heating plate 11 and lower heating plate 6 heat the thermoplastic FRP sheet 1 from the upper and lower surfaces of the connecting section, respectively, raising the temperature of the connecting section above the glass transition temperature of its thermoplastic resin matrix and achieving a thermoplastic deformable state. Depending on the thermoplastic resin matrix material, the heating temperature can be between 120℃ and 200℃, or adjusted according to the softening or melting temperature of the specific resin material.

[0053] Once the connecting section of the thermoplastic FRP sheet 1 reaches the preset softening temperature, the preload nut 12 is gradually tightened, causing the upper metal platen 9 to move towards the lower metal platen 5. Under the action of the preload screw 10 and the preload nut 12, the upper metal platen 9 and the lower metal platen 5 apply mold-closing pressure to the connecting section, causing the softened thermoplastic FRP sheet 1 to undergo thermoplastic deformation between the upper and lower corrugated cavities, gradually forming a corrugated profile corresponding to the corrugated cavities. This results in the first corrugated connecting section of the first thermoplastic FRP sheet 1 forming the first corrugated connecting section, and the second corrugated connecting section of the second thermoplastic FRP sheet 1 forming the second corrugated connecting section. During the molding process, the continuous fibers within the thermoplastic FRP sheet 1 are bent and formed together with the thermoplastic resin matrix without being cut.

[0054] The third step is to maintain pressure, cool, and shape the product.

[0055] After the connecting section of the thermoplastic FRP sheet 1 is pressed into the corrugated cavity and forms a predetermined corrugated profile, the power supply to the upper heating plate 11 and the lower heating plate 6 is cut off, and the upper metal pressure plate 9 and the lower metal pressure plate 5 are kept in the mold-closed state, allowing the connecting section to cool naturally or by forced cooling while maintaining the mold-closed pressure. After the connecting section cools to room temperature or below the glass transition temperature of its thermoplastic resin matrix, the preload nut 12 is loosened, the upper metal pressure plate 9 and the lower metal pressure plate 5 are disassembled, and the thermoplastic FRP sheet 1 with the corrugated profile is removed. Through the above steps, the first corrugated connecting section of the first thermoplastic FRP sheet and the second corrugated connecting section of the second thermoplastic FRP sheet are obtained respectively.

[0056] The fourth step involves alternating layers of corrugated connecting segments.

[0057] The first corrugated connecting section of the first thermoplastic FRP sheet and the second corrugated connecting section of the second thermoplastic FRP sheet are butt-jointed. For multilayer thermoplastic FRP sheets, the thermoplastic FRP sheets of the first and second thermoplastic FRP sheets are alternately stacked along the thickness direction in the connecting area, and the crests and troughs between adjacent corrugated connecting sections are matched to form an interlocking structure. An adhesive medium is uniformly coated on the contact surface of adjacent corrugated connecting sections, filling the interface gap between adjacent corrugated connecting sections.

[0058] Through the aforementioned alternating layering method, the first and second thermoplastic FRP sheets not only rely on the bonding medium to transmit interfacial shear force, but also rely on the interlocking of crests and troughs to form a mechanical interlock. When the connected structure is subjected to axial tensile force, the axial tensile force is mainly transmitted between the two thermoplastic FRP sheets through the bonding shear action and mechanical interlocking action between adjacent corrugated connecting sections.

[0059] Step 5: Install the non-metallic pressure plate.

[0060] A non-metallic upper pressure plate 2 is placed on the upper side of the stacked corrugated connecting section, and a non-metallic lower pressure plate 3 is placed on the lower side of the stacked corrugated connecting section. Before installation, an adhesive medium is uniformly coated on the inner surface of the corrugated grooves of the non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3, as well as the surface in contact with the thermoplastic FRP sheet 1. During installation, the corrugated grooves of the non-metallic upper pressure plate 2 are aligned with the outer contour of the uppermost corrugated connecting section, and the corrugated grooves of the non-metallic lower pressure plate 3 are aligned with the outer contour of the lowermost corrugated connecting section. Subsequently, temporary clamps, binding straps, or other temporary positioning structures are used to initially fix the non-metallic upper pressure plate 2, the non-metallic lower pressure plate 3, and the stacked corrugated connecting section to prevent relative misalignment of the components before the adhesive medium cures.

[0061] Step 6: Wrap the fiber pretensioning tape.

[0062] A continuous fiber strip is impregnated in an adhesive medium to form a fiber pretensioning strip 4. The fiber pretensioning strip 4 is wound around the outside of the non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3 with a preset tension of 50N to 200N, thus applying circumferential constraints to the non-metallic upper pressure plate, the non-metallic lower pressure plate, and the corrugated connecting section after lamination. During winding, the fiber pretensioning strip 4 is wound circumferentially in a direction perpendicular to the axial direction of the thermoplastic FRP sheet 1, or wound in a cross-spiral manner. The fiber pretensioning strip 4 covers the outer surface of the non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3, and extends to the exposed thermoplastic FRP sheet 1 surfaces on both sides of the non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3. The ends of the fiber pretensioning strip 4 are fixed by lap bonding, and the lapped area is bonded to the adjacent winding layer using an adhesive medium.

[0063] Step 7: Curing, shaping, inspection, and finishing.

[0064] The connected assembly with the fiber pretensioning tape 4 wound is placed in a curing environment at room temperature or as required by the adhesive medium for static curing. During the curing process, the fiber pretensioning tape 4 maintains circumferential constraints on the non-metallic upper pressure plate 2, the non-metallic lower pressure plate 3, and the stacked corrugated connecting section, ensuring a stable fit between the non-metallic upper pressure plate 2, the non-metallic lower pressure plate 3, and the corrugated connecting section. After the adhesive medium is completely cured, the fiber pretensioning tape 4 and its internal adhesive medium form a continuous fiber-reinforced composite sleeve, and the non-metallic upper pressure plate 2, the non-metallic lower pressure plate 3, the first corrugated connecting section, the second corrugated connecting section, and the interlayer adhesive medium cure into an integral connected structure.

[0065] After curing, visually inspect the joint area to confirm that there are no obvious delamination, detachment, bubbles, fiber lifting, or edge defects. If necessary, trim any burrs and excess cured adhesive from the joint area edges to complete the non-metallic connection of the thermoplastic FRP parallel sheet cables.

[0066] In this embodiment, neither the first nor the second thermoplastic FRP sheet / cable has a fastening hole penetrating the thickness direction within the connection area, and the service connection structure of the connection device does not include metal bolts, metal pressure plates, or metal sleeves. Therefore, the connection area will not cut the continuous fibers in the FRP sheet due to openings, thus avoiding stress concentration at bolt holes; at the same time, the final service connection structure does not contain metal fastening components, which can reduce the risk of corrosion and the risk of metal magnetic interference.

[0067] The force mechanism of this embodiment is as follows: when the first and second thermoplastic FRP sheets are subjected to axial tensile force, the bonding medium between adjacent corrugated connecting sections provides interfacial shear force transmission, and the interlocking structure between the crests and troughs provides mechanical interlocking force transmission; the non-metallic upper pressure plate 2 and the non-metallic lower pressure plate 3 provide shape constraint and normal compression through corrugated grooves that match the outer corrugated connecting sections; the continuous fiber-reinforced composite sleeve formed by the cured fiber pretensioning band 4 provides continuous circumferential constraint and radial compression to the connecting area, suppressing interlayer interface peeling, pressure plate opening, and corrugated connecting section slippage. Therefore, this connecting device can achieve a reliable connection between parallel thermoplastic FRP sheets without damaging the continuous fibers of the thermoplastic FRP sheets and without relying on metal fasteners.

[0068] Example 2: This embodiment provides a thermoplastic FRP parallel plate cable non-metallic connection device suitable for electromagnetically sensitive environments. Its basic structure and connection method are the same as those in Embodiment 1. The difference is that the first thermoplastic FRP plate cable, the second thermoplastic FRP plate cable, the non-metallic upper pressure plate, the non-metallic lower pressure plate, the fiber pretensioning tape and the external encapsulation layer are all made of low conductivity or insulating non-metallic materials.

[0069] Specifically, the first and second thermoplastic FRP sheets are glass fiber reinforced thermoplastic FRP sheets, aramid fiber reinforced thermoplastic FRP sheets, or basalt fiber reinforced thermoplastic FRP sheets. The non-metallic upper and lower pressure plates are glass fiber reinforced composite material pressure plates, aramid fiber reinforced composite material pressure plates, basalt fiber reinforced composite material pressure plates, PEEK-based glass fiber composite material pressure plates, or PPS-based glass fiber composite material pressure plates. The fiber pretensioning tape is a glass fiber pretensioning tape, aramid fiber pretensioning tape, or basalt fiber pretensioning tape.

[0070] This embodiment uses low-conductivity non-metallic reinforcing materials such as glass fiber, aramid fiber, or basalt fiber, and avoids setting metal bolts, metal pressure plates, metal clips, metal anchor cups, or metal sleeves in the service connection structure. This can reduce the risk of metal magnetic interference, conductive loop effects, and electrochemical corrosion. It is suitable for engineering environments that are sensitive to metal or conductive components, such as geomagnetic observatories, radar stations, nuclear magnetic resonance facilities, and precision electromagnetic measurement facilities. The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A non-metallic connecting device for thermoplastic FRP parallel plates and cables, characterized in that, It includes a first thermoplastic FRP sheet, a second thermoplastic FRP sheet, a non-metallic upper pressure plate, a non-metallic lower pressure plate, and a fiber pretensioning belt; The first thermoplastic FRP sheet has a first corrugated connecting section, and the second thermoplastic FRP sheet has a second corrugated connecting section. Both the first corrugated connecting section and the second corrugated connecting section are corrugated connecting sections formed by thermoplastic deformation. The first corrugated connecting section and the second corrugated connecting section are alternately stacked along the thickness direction, and an adhesive medium is provided between adjacent corrugated connecting sections; The non-metallic upper pressure plate is disposed on the upper side of the stacked corrugated connecting section, and the non-metallic lower pressure plate is disposed on the lower side of the stacked corrugated connecting section. The inner surface of the non-metallic upper pressure plate and the inner surface of the non-metallic lower pressure plate are both provided with corrugated grooves that match the outer contour of the corresponding corrugated connecting section. The fiber pretensioning tape is wrapped around the outside of the non-metallic upper pressure plate and the non-metallic lower pressure plate to apply circumferential constraints to the non-metallic upper pressure plate, the non-metallic lower pressure plate, and the stacked corrugated connecting section.

2. The non-metallic connecting device according to claim 1, characterized in that, Both the first thermoplastic FRP sheet and the second thermoplastic FRP sheet include multiple layers of thermoplastic FRP sheets, and the thermoplastic FRP sheets of the first thermoplastic FRP sheet and the thermoplastic FRP sheets of the second thermoplastic FRP sheet are staggered along the thickness direction in the connection area.

3. The non-metallic connecting device according to claim 1, characterized in that, Both the first corrugated connecting section and the second corrugated connecting section include multiple peaks and multiple troughs arranged continuously along the axial direction of the plate cable, and adjacent peaks and troughs are connected by arc transition sections.

4. The non-metallic connecting device according to claim 1, characterized in that, The adhesive medium is disposed between adjacent corrugated connecting sections, between the non-metallic upper pressure plate and the uppermost corrugated connecting section, and between the non-metallic lower pressure plate and the lowermost corrugated connecting section.

5. The non-metallic connecting device according to claim 1, characterized in that, The fiber pretensioning tape is wound circumferentially in a direction perpendicular to the axial direction of the first thermoplastic FRP sheet and the second thermoplastic FRP sheet, or wound in a cross-wound spiral manner inclined relative to the axial direction.

6. The non-metallic connecting device according to claim 1, characterized in that, The fiber pretensioning band covers the outer surfaces of the non-metallic upper pressure plate and the non-metallic lower pressure plate, and extends to the exposed thermoplastic FRP sheet / cable surfaces on both sides of the non-metallic upper pressure plate and the non-metallic lower pressure plate.

7. The non-metallic connecting device according to claim 1, characterized in that, The continuous fibers in the first corrugated connecting section and the second corrugated connecting section extend continuously along the axial direction of their respective thermoplastic FRP sheets and cables, and the first thermoplastic FRP sheets and cables and the second thermoplastic FRP sheets and cables are not provided with through fastening holes in the connecting area.

8. A method for connecting thermoplastic FRP parallel plates and cables, characterized in that, Includes the following steps: The connecting sections of the first thermoplastic FRP sheet and the second thermoplastic FRP sheet are heated respectively to bring the connecting sections of the first thermoplastic FRP sheet and the second thermoplastic FRP sheet to a thermoplastic deformable state. The connecting section that has reached the thermoplastic deformable state is placed in a molding die with a corrugated cavity, and a mold closing pressure is applied to the connecting section to form a first corrugated connecting section of the first thermoplastic FRP sheet and cable, and to form a second corrugated connecting section of the second thermoplastic FRP sheet and cable. The first corrugated connecting section and the second corrugated connecting section are cooled and shaped. The first corrugated connecting section and the second corrugated connecting section are alternately stacked along the thickness direction, and an adhesive medium is provided between adjacent corrugated connecting sections; A non-metallic upper pressure plate is installed on the upper side of the stacked corrugated connecting section, and a non-metallic lower pressure plate is installed on the lower side of the stacked corrugated connecting section, so that the corrugated grooves of the non-metallic upper pressure plate and the non-metallic lower pressure plate respectively match the outer contour of the corresponding corrugated connecting section. A fiber pretensioning tape is wound around the outside of the non-metallic upper pressure plate and the non-metallic lower pressure plate, so that the fiber pretensioning tape applies circumferential constraints to the non-metallic upper pressure plate, the non-metallic lower pressure plate and the corrugated connecting section after stacking. The bonding medium is cured to form a non-metallic connection structure of thermoplastic FRP parallel plates and cables.

9. The connection method according to claim 8, characterized in that, When heating the connecting section of the first thermoplastic FRP sheet and the connecting section of the second thermoplastic FRP sheet, the heating temperature is higher than the glass transition temperature of the corresponding thermoplastic resin matrix.

10. The connection method according to claim 8, characterized in that, When the fiber pretensioning tape is wound around the outside of the non-metallic upper pressure plate and the non-metallic lower pressure plate, the continuous fibers are impregnated in the bonding medium to form the fiber pretensioning tape, and multiple layers are wound with a pretensioning force of 50N to 200N.

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