A composite material pipe connection structure and its preparation method

Abstract

The present invention discloses a connection structure for a composite material pipe, which includes a metal inner inserted pipe inserted into the composite material pipe, with an adhesive layer provided therebetween. The composite material pipe is provided with holes for connecting screws to pass through. An I-shaped fiber braided pipe is sleeved on the rod body of the connecting screw, and the upper and lower end faces are respectively clamped on the outer wall and the inner wall of the composite material pipe. A bionic reinforcement ring is sleeved between the upper end face of the fiber braided pipe and the connecting screw. The preparation method of this structure is: successively prepare each component in the connection structure of the composite material pipe, and then assemble, connect, cure, clean, polish and process. The present invention sets the fiber braided pipe and the bionic reinforcement ring to reinforce the opening of the composite material pipe, realizing the comprehensive and overall reinforcement effect on the inner wall and the outer wall of the composite material pipe; the present invention prepares the bionic reinforcement ring based on stress distribution simulation calculation, realizing an excellent and accurate reinforcement effect, with simple process, high production efficiency and low overall production cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of pipe connection structures, and particularly relates to a composite pipe connection structure and a preparation method thereof. Background Art

[0002] Based on different material properties, when a composite pipe is connected to a dissimilar material such as a metal pipe, one or a combination of two of bonding, riveting or bolting connection, and threaded connection is often used. The bonding connection is achieved by coating an adhesive between the composite pipe and the metal pipe, without the need to drill holes in the composite pipe, effectively ensuring its original strength and other properties. However, due to the large performance difference between the adhesive and the two pipe materials, its connection effect is limited, and the bonding layer has a risk of peeling failure during the repeated deformation process of the composite pipe, and the bonding disadvantage cannot be fundamentally solved; both riveting or bolting connection and threaded connection require drilling holes in the composite pipe and the metal pipe, resulting in discontinuous fibers in the composite pipe, seriously damaging the strength of the composite pipe and easily causing the composite pipe to crack, and the connection effect of the rivet or bolt often leads to excessive extrusion at the hole edge, resulting in extrusion failure at the drilled hole. In the prior art, the reinforcement of the composite pipe is often achieved by reinforcing the metal pipe, and mostly the outer wall of the composite pipe is reinforced, and the inner wall of the composite pipe cannot be reinforced, and the opening defect inside the pipe cannot be solved. Other reinforcement methods such as the embedded metal method are complex in the implementation process and have a relatively high overall cost; the hole-edge stitching process needs to be carried out before the composite pipe is cured, and is only applicable to flat products and cannot be applied to round pipes, with limited use. In addition, threaded connection and the combination of thread and bonding are commonly used in the connection between metal pipes, but the thread production of composite pipes is relatively difficult, and the traditional machining method has a great damage to the wall fibers of the composite pipe, resulting in a relatively low overall connection strength. Making threads through a special mold can enhance the thread strength of the composite material, but the forming process is relatively complex and the overall production cost is high. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a composite pipe connection structure in view of the deficiencies of the above prior art. The composite pipe connection structure realizes the stable connection between the composite pipe and the metal through the insertion of the composite pipe and the metal inner insert pipe, the setting of an adhesive layer in the insertion area, and the connection with connecting screws. By setting a fiber braided pipe to continuously wrap the fibers at the opening of the composite pipe, and combining with a bionic reinforcement ring, a comprehensive and overall reinforcement effect on the inner and outer walls of the composite pipe is achieved, making up for the strength reduction caused by the opening on the surface of the composite pipe.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a composite material tube connection structure, characterized in that it includes a metal inner tube, which is inserted into the composite material tube, and an adhesive layer is arranged between the outer wall of the metal inner tube at the insertion position and the inner wall of the composite material tube, a hole for the connecting screw to pass through is opened on the tube wall of the composite material tube in the insertion position, and the lower end of the connecting screw is inserted into the tube wall of the metal inner tube, an I-shaped fiber braided tube is ringed on the rod body of the connecting screw, and the upper end face of the fiber braided tube is clamped on the outer wall of the composite material tube, and the lower end face is clamped on the inner wall of the composite material tube, and a bionic reinforcement ring is ringed between the upper end face of the fiber braided tube and the nut of the connecting screw.

[0005] The above-mentioned composite material pipe connection structure is characterized in that the bottom of the nut of the connecting screw is completely fitted on the ring body of the bionic reinforcement ring, and the top of the nut is lower than the top of the bionic reinforcement ring.

[0006] In addition, the present invention also discloses a method for preparing the composite material pipe connection structure as described above, characterized in that the method comprises the following steps:

[0007] Step 1: Using metal pipes or metal sheets as raw materials, a metal pipe blank is obtained by mechanical processing; using carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber or basalt fiber as raw materials, a composite material pipe blank is obtained by winding, rolling, rolling or pultruding processes;

[0008] Step 2: A positioning hole is opened in the sleeve joint area of ​​the metal tube blank obtained in step 1 and the composite tube blank, and then an internal thread is made on the inner hole wall of the positioning hole in the metal tube blank by stamping, welding and machining to obtain a metal inner tube, and at the same time, the positioning hole in the composite tube blank is expanded by machining to obtain a composite tube;

[0009] Step 3: Using metal bars as raw materials, machining to obtain connecting screws;

[0010] Step 4: Use finite element analysis software or simulation analysis software provided by three-dimensional drawing to simulate the stress distribution at the edge of the positioning hole connection in the composite material tube in step 2, and according to the simulation calculation results of the stress distribution, use carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber or basalt fiber as raw materials, and adopt molding or winding process to prepare a bionic reinforcement ring;

[0011] Step 5: Using carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber or basalt fiber as raw materials, a fiber braided tube is prepared by a weaving and winding process;

[0012] Step 6: Sequentially sleeving the bionic reinforcement ring in Step 4 and the fiber braided tube in Step 5 on the outer surface of the connecting screw obtained in Step 3 to obtain a reinforced connection assembly;

[0013] Step 7: Apply adhesive on the outer wall of the sleeved area of the metal inner insertion tube and the inner wall of the sleeved area of the composite material tube in Step 2, then sleeve the metal inner insertion tube into the composite material tube and align their positioning holes to obtain a connecting tube assembly;

[0014] Step 8: Apply adhesive on the outer surface of the fiber braided tube in the reinforced connection assembly obtained in Step 6, and turn the top surface outwards to form an upper end surface, then insert it into the positioning hole where the composite material tube and the metal inner insertion tube in the connecting tube assembly coincide, and use the gap between the composite material tube and the metal inner insertion tube to extrude and turn the bottom surface of the fiber braided tube outwards to form a lower end surface, and the lower end surface is clamped between the composite material tube and the metal inner insertion tube, and the upper end surface is clamped on the outer surface of the composite material tube to obtain a fiber braided tube with an I-shaped structure. At the same time, screw the end of the connecting screw in the reinforced connection assembly tightly through the inner hole wall of the positioning hole in the metal inner insertion tube, and then cure the adhesive so that an adhesive layer is formed between the outer wall of the sleeved area of the metal inner insertion tube and the inner wall of the sleeved area of the composite material tube. After cleaning, grinding and processing, a composite material tube connection structure is obtained.

[0015] In the above method, it is characterized in that the process of preparing the bionic reinforcement ring in Step 4 is as follows: First, according to the simulation calculation results of stress distribution, select raw materials and design the reinforcement area area and thickness of the bionic reinforcement ring, use the designed bionic reinforcement ring to reinforce the composite material tube, and perform simulation calculation on the stress distribution at the edge of the positioning hole connection in the reinforced composite material tube again. Repeat the above design process, reinforcement process and re-simulation calculation process until the stress distribution at the positioning hole connection in the composite material tube is below the stress failure range.

[0016] In the above method, it is characterized in that the bionic reinforcement ring is composed of circumferential fiber plies composed of continuous fibers, or is composed of circumferential fiber plies with a volume content of 60%, and horizontal fiber plies with a volume content of 20% and vertical fiber plies with a volume content of 20% distributed in the circumferential fiber plies.

[0017] In the above method, it is characterized in that the fiber braided tube in Step 5 is obtained by processing tubular fabric or is wound by planar fabric, and the planar fabric is woven from raw material fibers in a cross direction or an inclined direction.

[0018] The present invention has the following advantages compared with the prior art:

[0019] 1. The composite material pipe connection structure of the present invention realizes the stable connection between the composite material pipe and the metal by inserting the composite material pipe into the metal inner insertion pipe, setting an adhesive layer in the insertion area, and using connecting screws. A fiber braided pipe and a bionic reinforcement ring are provided to reinforce the opening of the composite material pipe, forming a continuous fiber coating on the opening, realizing the comprehensive and overall reinforcement of the inner and outer walls of the composite material pipe, greatly enhancing the reinforcement effect, and making up for the strength reduction caused by the opening on the surface of the composite material pipe.

[0020] 2. The composite material pipe connection structure of the present invention improves the structural stability of the bionic reinforcement ring by setting the bottom of the nut of the connecting screw to completely fit on the ring body of the bionic reinforcement ring, and the top of the nut is lower than the top of the bionic reinforcement ring, enhances the reinforcement effect of the fiber braided pipe and the bionic reinforcement ring, and reduces the excessive extrusion at the hole edge, realizing the protective effect of the bionic reinforcement ring on the connecting screw.

[0021] 3. The composite material pipe connection structure of the present invention is simple, low in cost, easy to assemble, and has a wide range of applications.

[0022] 4. According to the simulation calculation results of the stress distribution at the edge of the positioning hole connection in the composite material pipe after inserting the metal inner insertion pipe and the composite material pipe, the present invention determines the reinforcement area area and thickness of the bionic reinforcement ring, prepares the bionic reinforcement ring, and then prepares a suitable fiber braided pipe, improving the dimensional structure accuracy of the bionic reinforcement ring and the fiber braided pipe, realizing an excellent and precise reinforcement effect, effectively avoiding the extrusion damage of the pipe structure, effectively reducing the overall structure weight. Especially in the connection of a metal pipe and a composite material pipe with a small insertion depth (unable to meet a large insertion depth due to limited overall structure space), its connection advantages are more prominent, and at the same time, material waste is avoided.

[0023] 5. The present invention improves the strength of the bionic reinforcement ring by using continuous fibers to form the circumferential fiber layer of the bionic reinforcement ring, making it suitable for higher stress loads.

[0024] 6. The present invention adopts two knitting methods, namely planar fabric winding or tubular fabric processing, to form a structurally complete fiber braided pipe for continuous fiber coating reinforcement at the opening of the composite material pipe, significantly improving the local anti-load capacity. Among them, the fiber braided pipe prepared by tubular fabric does not need to cut the fibers when folding, the fiber continuity is better, and the overall performance is superior to the fiber braided pipe formed by planar fabric winding. However, some fibers in the planar fabric winding are discontinuous, but it is easier to process and the cost is lower than that of tubular fabric.

[0025] 7. The preparation method of the present invention can directly assemble, cure, polish and clean the metal tube and the composite material tube after simple processing, without the need for assembly before the composite material tube is cured. It is easy to implement, applicable to composite material tube products of various shapes, expanding the scope of use, with simple process, high production efficiency and low overall production cost.

[0026] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the connection structure of the composite material tube based on biological bionics of the present invention.

[0028] Figure 2 It is a schematic diagram of the structure of the bionic reinforcement ring in the connection structure of the composite material tube based on biological bionics of the present invention.

[0029] Figure 3 It is a schematic diagram of the structure of the fiber braided tube in the connection structure of the composite material tube based on biological bionics of the present invention.

[0030] Figure 4 It is a schematic diagram of the structure of the reinforcement connection assembly in the present invention.

[0031] Figure 5 It is a schematic diagram of the structure of the connecting tube assembly in the present invention.

[0032] DESCRIPTION OF THE REFERENCE NUMERALS

[0033] 1 - metal inner insertion tube; 2 - composite material tube; 3 - connecting screw;

[0034] 4 - bionic reinforcement ring; 5 - fiber braided tube; 6 - adhesive layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The connection structure of the composite material tube of the present invention will be described in detail through Embodiment 1.

[0036] Embodiment 1

[0037] As Figures 1 to 3As shown in the figure, the composite material pipe connection structure of this embodiment includes a metal inner socket 1, which is inserted into the composite material pipe 2. A bonding adhesive layer 6 is provided between the outer wall of the metal inner socket 1 at the insertion part and the inner wall of the composite material pipe 2. A hole for the connecting screw 3 to pass through is provided in the pipe wall of the composite material pipe 2 at the insertion part, and the lower end of the connecting screw 3 penetrates into the pipe wall of the metal inner socket 1. An I-shaped fiber braided tube 5 is sleeved on the rod body of the connecting screw 3, and the upper end surface of the fiber braided tube 5 is clamped on the outer wall of the composite material pipe 2, and the lower end surface is clamped on the inner wall of the composite material pipe 2. A bionic reinforcement ring 4 is sleeved between the upper end surface of the fiber braided tube 5 and the nut of the connecting screw 3.

[0038] The composite material pipe connection structure of this embodiment includes a metal inner socket 1 and a composite material pipe 2 connected by an insertion method, and a bonding adhesive layer 6 is provided between the outer wall of the metal inner socket 1 and the inner wall of the composite material pipe 2 at the insertion part, thereby improving the connection force between the metal inner socket 1 and the composite material pipe 2 by bonding. At the same time, in this embodiment, a hole is opened in the pipe wall of the composite material pipe 2 at the insertion part, and a hole is also opened in the corresponding pipe wall of the metal inner socket 1 for the connecting screw 3 to pass through the pipe walls of both successively, so as to connect and fix the metal inner socket 1 and the composite material pipe 2. By sleeving an I-shaped fiber braided tube 5 on the rod body of the connecting screw 3, and the upper end surface of the fiber braided tube 5 is clamped on the outer wall of the composite material pipe 2, and the lower end surface is clamped on the inner wall of the composite material pipe 2, the stable socket connection of the fiber braided tube 5 is realized. The fiber braided tube 5 is sleeved on the rod body of the connecting screw 3 to block and fill the gap between the screw 3 and the hole in the composite material pipe 2, and cover the upper and lower surfaces of the hole, that is, the outer wall and the inner wall of the composite material pipe 2, to form continuous fiber cladding at the opening, playing a reinforcement role, making up for the strength reduction defect caused by the discontinuity of the composite material pipe 2 due to the opening. At the same time, both the outer wall and the inner wall of the composite material pipe 2 at the opening are reinforced, improving the overall strength of the composite material pipe 2 and avoiding the opening defect and use expansion defect of the inner wall of the composite material pipe.

[0039] In actual operation, usually an adhesive is coated on the outer surface of the fiber braided tube 5, so that the fiber braided tube 5 is bonded to the hole wall, outer wall and inner wall of the composite material pipe 2 through the adhesive to improve the assembly stability and firmness of the fiber braided tube 5.

[0040] In the composite material pipe connection structure of this embodiment, a bionic reinforcement ring 4 is sleeved between the upper end face of the fiber braided pipe 5 and the nut of the connecting screw 3, which cooperates with the fiber braided pipe 5 to reinforce the outer wall of the opening of the composite material pipe 2, further enhancing the reinforcement effect. At the same time, the fastening force of the connecting screw 3 directly acts on the fiber braided pipe 5 and acts on the bionic reinforcement ring 4 through the fiber braided pipe 5, realizing the conduction and dispersion of the fastening force, reducing the over extrusion phenomenon of the connecting screw 3 on the hole edge of the opening, avoiding the tensile failure of the pipe structure at the opening due to excessive force, and ensuring the fixed connection stability between the composite material pipe 2 and the metal inner insertion pipe 1. In addition, in this embodiment, the fiber braided pipe 5 effectively isolates the connecting screw 3 from the hole wall of the composite material pipe 2, avoiding the wear and tear of the hole wall of the composite material pipe 2 by the connecting screw 3 usually made of metal materials, and further reducing the phenomenon of strength reduction at the opening of the composite material pipe 2.

[0041] Furthermore, the bottom of the nut of the connecting screw 3 is completely attached to the ring body of the bionic reinforcement ring 4, and the top of the nut is lower than the top of the bionic reinforcement ring 4. In this embodiment, by setting the bottom of the nut of the connecting screw 3 to be completely attached to the ring body of the bionic reinforcement ring 4, on the one hand, the bionic reinforcement ring 4 is stably fixed between the connecting screw 3 and the fiber braided pipe 5, giving full play to the synergistic reinforcement effect and avoiding the movement or falling off of the bionic reinforcement ring 4. On the other hand, the fiber braided pipe 5, the bionic reinforcement ring 4 and the connecting screw 3 form an integral structure, further enhancing the continuous fiber wrapping reinforcement effect of the fiber braided pipe 5 on the opening of the composite material pipe 2, the reinforcement effect of the bionic reinforcement ring 4 and the reduction of over extrusion at the hole edge. At the same time, combined with the setting that the top of the nut is lower than the top of the bionic reinforcement ring 4, the nut part of the connecting screw 3 exceeding the outer wall of the composite material pipe 2 is completely placed in the bionic reinforcement ring 4, realizing the protection of the connecting screw 3, ensuring the fixed connection effect of the connecting screw 3, and improving the consistency and aesthetics of the surface of the composite material pipe 2.

[0042] The preparation method of the composite material pipe connection structure of the present invention is described in detail through Embodiment 2.

[0043] Embodiment 2

[0044] The preparation process of the composite material pipe connection structure of this embodiment is as follows:

[0045] Step 1: Using metal pipes or metal plates as raw materials, metal pipe blanks are obtained through machining. Using carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber or basalt fiber as raw materials, composite material pipe blanks are obtained by using winding, tube twisting, tube rolling or pultrusion processes.

[0046] Step 2: Drill positioning holes in the socket area of the metal tube blank and the composite material tube blank obtained in Step 1. Then, use stamping, welding, and machining processes to make internal threads on the inner hole wall of the positioning hole in the metal tube blank to obtain the metal inner insertion tube 1. At the same time, perform machining and reaming on the positioning holes in the composite material tube blank to obtain the composite material tube 2;

[0047] Step 3: Use a metal bar as the raw material and prepare the connecting screw 3 through machining;

[0048] Step 4: Use ANSYS finite element analysis software to perform simulation calculations on the stress distribution at the edge of the connection of the positioning holes in the composite material tube 2 in Step 2. According to the simulation calculation results of the stress distribution, use carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber, or basalt fiber as the raw material, and use the molding or winding process to prepare the bionic reinforcement ring 4; the bionic reinforcement ring 4 is composed of circumferential fiber plies composed of continuous fibers;

[0049] The process of preparing the bionic reinforcement ring 4 is as follows: Use ANSYS finite element analysis software to first calculate the maximum load that the metal inner insertion tube 1 can withstand without being damaged when inserted into the composite material tube 2 and passing through the connecting screw 3 and setting the adhesive layer 6 (by continuously reducing the load for simulation calculations until it is not damaged), and the maximum load that the metal inner insertion tube 1 and the composite material tube 2 can withstand without being damaged in the non-opening state, and obtain the difference between the two, that is, the load difference F C , and then through the formula A1 (the initial bottom area of the bionic reinforcement ring 4) = F C / R1 (the bonding strength of the adhesive layer 6), obtain the initial bottom area of the bionic reinforcement ring 4. At the same time, determine the main thickening position (the area with the maximum stress) of the bionic reinforcement ring 4 according to the stress distribution characteristics during the calculation process of the load difference F C . Through the formula A2 (the cross-sectional area of the stress concentration area of the bionic reinforcement ring 4) = F C / R2 (the compressive strength in the direction of the stress concentration area of the reinforcement ring), obtain the cross-sectional area of the stress concentration area of the bionic reinforcement ring 4. Then, based on A1 and A2, use curve optimization to complete the initial design of the bionic reinforcement ring 4. Use the initially designed bionic reinforcement ring 4 to reinforce the composite material tube 2, and perform simulation calculations on the stress distribution at the edge of the connection of the positioning holes in the reinforced composite material tube 2 again. Repeat the above design process, reinforcement process, and re-simulation calculation process until the stress distribution at the connection of the positioning holes in the composite material tube 2 is below the force failure range, determine the structural dimensions of the bionic reinforcement ring 4, and prepare the bionic reinforcement ring 4;

[0050] Step 5: Use carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber, or basalt fiber as the raw material, and use the braiding and winding processes to prepare the fiber braided tube 5; the fiber braided tube 5 is obtained by processing tubular fabric;

[0051] Step 6: The bionic reinforcement ring 4 in step 4 and the fiber braided tube 5 in step 5 are sequentially sleeved on the outer surface of the connecting screw 3 obtained in step 3 to obtain a reinforced connection assembly, such as Figure 4 As shown;

[0052] Step 7: In step 2, apply adhesive on the outer wall of the sleeve area of ​​the metal inner tube 1 and the inner wall of the sleeve area of ​​the composite tube 2, and then sleeve the metal inner tube 1 into the composite tube 2, and make the positioning holes of the two overlap to obtain a connecting tube assembly, such as Figure 5 As shown;

[0053] Step 8. Apply adhesive to the outer surface of the fiber braided tube 5 in the reinforced connection assembly obtained in step 6, and fold the top surface outward to form an upper end surface, and then insert it into the positioning hole where the composite material tube 2 and the metal inner tube 1 overlap in the connecting tube assembly, and use the gap between the composite material tube 2 and the metal inner tube 1 to squeeze the bottom surface of the fiber braided tube 5 outward to form a lower end surface, and the lower end surface is clamped between the composite material tube 2 and the metal inner tube 1, and the upper end surface is clamped on the outer surface of the composite material tube 2 to obtain an I-shaped fiber braided tube 5. At the same time, the end of the connecting screw 3 in the reinforced connection assembly is tightened and fixed through the inner hole wall thread of the positioning hole in the metal inner tube 1, and then the adhesive is cured to form an adhesive layer 6 between the outer wall of the sleeve area of ​​the metal inner tube 1 and the inner wall of the sleeve area of ​​the composite material tube 2. After cleaning, polishing and processing, a composite material tube connection structure is obtained.

[0054] In step 4 of this embodiment, the simulation analysis software provided by the three-dimensional drawing can also be used to simulate and calculate the stress distribution at the edge of the positioning hole connection in the composite material tube 2; the bionic reinforcement ring 4 described in step 4 can also be composed of a circumferential fiber ply with a volume content of 60%, and a horizontal fiber ply with a volume content of 20% and a vertical fiber ply with a volume content of 20% distributed in the circumferential fiber ply; the fiber braided tube 5 described in step 5 can also be formed by winding a plane fabric, and the plane fabric is woven from raw materials in a cross direction or an inclined direction.

[0055] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A connecting structure for a composite material pipe, characterized in that The invention comprises a metal inner insert tube (1), the metal inner insert tube (1) being inserted into a composite material tube (2), and an adhesive layer (6) being arranged between the outer wall of the metal inner insert tube (1) and the inner wall of the composite material tube (2) at the insertion position, a hole for a connecting screw (3) to pass through being opened on the tube wall of the composite material tube (2) at the insertion position, and the lower end of the connecting screw (3) is inserted into the tube wall of the metal inner insert tube (1), an I-shaped fiber braided tube (5) is sleeved on the rod body of the connecting screw (3), and the upper end face of the fiber braided tube (5) is clamped on the outer wall of the composite material tube (2), and the lower end face is clamped on the inner wall of the composite material tube (2), and a bionic reinforcing ring (4) is sleeved between the upper end face of the fiber braided tube (5) and the nut of the connecting screw (3).

2. The connection structure of a composite material pipe according to claim 1, characterized in that, The bottom of the nut of the connecting screw (3) is completely fitted on the ring body of the bionic reinforcement ring (4), and the top of the nut is lower than the top of the bionic reinforcement ring (4).

3. A method for preparing a composite material pipe connection structure as described in claim 1 or 2, characterized in that, The method comprises the following steps: Step 1: Using metal pipes or metal sheets as raw materials, a metal pipe blank is obtained by mechanical processing; using carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber or basalt fiber as raw materials, a composite material pipe blank is obtained by winding, rolling, rolling or pultruding processes; Step 2: opening a positioning hole in the sleeve joint area of ​​the metal tube blank obtained in step 1 and the composite tube blank, and then making an internal thread on the inner hole wall of the positioning hole in the metal tube blank by using stamping, welding and machining processes to obtain a metal inner insert tube (1), and at the same time, expanding the positioning hole in the composite tube blank by machining to obtain a composite tube (2); Step 3: Using metal bars as raw materials, machining to obtain connecting screws (3); Step 4: using finite element analysis software or simulation analysis software provided by three-dimensional drawing to simulate and calculate the stress distribution at the edge of the positioning hole connection in the composite material tube (2) in step 2, and based on the simulation calculation result of the stress distribution, using carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber or basalt fiber as raw materials, a bionic reinforcement ring (4) is prepared by molding or winding process; Step 5: Using carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber or basalt fiber as raw materials, a fiber braided tube (5) is prepared by a weaving and winding process; Step 6: The bionic reinforcement ring (4) in step 4 and the fiber braided tube (5) in step 5 are sequentially sleeved on the outer surface of the connection screw (3) obtained in step 3 to obtain a reinforcement connection assembly; Step 7: In step 2, adhesive is applied to the outer wall of the sleeve area of ​​the metal inner insert tube (1) and the inner wall of the sleeve area of ​​the composite material tube (2), and then the metal inner insert tube (1) is sleeved into the composite material tube (2) so that the positioning holes of the two coincide with each other, thereby obtaining a connecting tube assembly; Step Eight: Apply adhesive on the outer surface of the fiber braided tube (5) in the reinforcement connection assembly obtained in Step Six, and turn the top surface outwards to form an upper end surface. Then insert it into the positioning hole where the composite material tube (2) and the metal inner inserting tube (1) in the connection tube assembly overlap. Use the gap between the composite material tube (2) and the metal inner inserting tube (1) to extrude so that the bottom surface of the fiber braided tube (5) turns outwards to form a lower end surface, and the lower end surface is clamped between the composite material tube (2) and the metal inner inserting tube (1), and the upper end surface is clamped on the outer surface of the composite material tube (2) to obtain a fiber braided tube (5) with an I-shaped structure. At the same time, screw the end of the connection screw (3) in the reinforcement connection assembly tightly through the inner hole wall of the positioning hole in the metal inner inserting tube (1), and then cure the adhesive so that an adhesive layer (6) is formed between the outer wall of the socket area of the metal inner inserting tube (1) and the inner wall of the socket area of the composite material tube (2). After cleaning, grinding and processing, a composite material tube connection structure is obtained.

4. The method according to claim 3, wherein The process of preparing the bionic reinforcement ring (4) in Step Four is as follows: First, according to the simulation calculation results of stress distribution, select raw materials and design the reinforcement area area and thickness of the bionic reinforcement ring (4). Use the designed bionic reinforcement ring (4) to reinforce the composite material tube (2), and perform simulation calculation on the stress distribution at the edge of the positioning hole connection in the reinforced composite material tube (2) again. Repeat the above design process, reinforcement process, and simulation calculation process again until the stress distribution at the positioning hole connection in the composite material tube (2) is below the stress failure range. Determine the structural dimensions of the bionic reinforcement ring (4) and prepare the bionic reinforcement ring (4).

5. The method according to claim 3, characterized in that, The bionic reinforcement ring (4) described in Step Four is composed of circumferential fiber plies composed of continuous fibers, or is composed of circumferential fiber plies with a volume content of 60%, and horizontal fiber plies with a volume content of 20% and vertical fiber plies with a volume content of 20% distributed in the circumferential fiber plies.

6. The method according to claim 3, wherein The fiber braided tube (5) described in Step Five is obtained by processing tubular fabric or is wound from flat fabric, and the flat fabric is woven from raw material fibers in a cross-cross direction or an inclined direction.

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