CN115962199A - A kind of composite material pipe connection structure and preparation method thereof - Google Patents

Abstract

The invention discloses a composite material tube connection structure, which comprises a metal inner cannula inserted into the composite material tube, with an adhesive layer between the two, and a connecting screw provided on the composite material tube The hole passed through, the rod body of the connecting screw is covered with an I-shaped fiber braided tube, and the upper and lower end surfaces are respectively clamped on the outer wall and inner wall of the composite material tube, the upper end surface of the fiber braided tube and the connecting screw The intermediate ring is surrounded by a bionic reinforcing ring; the preparation method of the structure is as follows: each part in the composite pipe connection structure is prepared sequentially, and then assembled and connected, solidified, cleaned and polished and processed. The invention arranges the fiber braided pipe and the bionic reinforcement ring to reinforce the opening of the composite material pipe, and realizes the comprehensive overall reinforcement effect on the inner wall and the outer wall of the composite material pipe; the invention prepares the bionic reinforcement ring based on stress distribution simulation calculation , achieving excellent and precise reinforcement effect, simple process, high production efficiency and low overall production cost.

Description

Composite pipe connection structure and preparation method thereof

technical field

The invention belongs to the technical field of pipe connection structures, and in particular relates to a composite material pipe connection structure and a preparation method thereof.

Background technique

Based on different material properties, when connecting composite material pipes with dissimilar materials such as metal pipes, one or a combination of bonding, rivet or bolt connection, and thread connection is often used. The bonded connection is achieved by coating the adhesive between the composite material pipe and the metal pipe, without opening holes in the composite material pipe, effectively ensuring its original strength and other properties. The performance difference is quite large, the connection effect is limited, and the adhesive layer has the risk of peeling failure during the repeated deformation process of the composite material pipe, which cannot fundamentally solve the bonding defect; The opening of the tube and the metal tube leads to the discontinuity of the fiber in the composite tube, seriously damages the strength of the composite tube, and easily leads to cracking of the composite tube, and the connection of rivets or bolts often leads to excessive extrusion at the edge of the hole. Setting results in extrusion failure at the opening. In the prior art, metal pipes are usually reinforced to reinforce the composite material pipes, and most of the outer walls of the composite material pipes are reinforced, but the inner wall of the composite material pipes cannot be reinforced, and the opening defects inside the pipes cannot be solved. . Other reinforcement methods such as pre-embedded metal methods are complicated to implement and the overall cost is high; the hole edge stitching process needs to be carried out before the composite material pipe is cured, which is only applicable to flat-plate products and cannot be applied to round pipes, so its use is limited. In addition, threaded connection and the combination of thread and adhesive are commonly used in the connection of metal pipes, but the thread production of composite material pipes is relatively difficult, and the traditional mechanical processing method will cause great damage to the fibers of the pipe wall, resulting in The overall connection strength is low. Making threads through special molds can enhance the thread strength of composite materials, but the forming process is more complicated and the overall production cost is higher.

Contents of the invention

The technical problem to be solved by the present invention is to provide a composite material pipe connection structure for the above-mentioned deficiencies in the prior art. The composite pipe connection structure achieves a stable connection between the composite pipe and the metal by inserting the composite pipe and the metal inner tube, setting an adhesive layer in the insertion area, and connecting the connecting screw. The opening of the material tube is covered with continuous fibers, combined with the bionic reinforcing ring, the comprehensive overall reinforcement of the inner and outer walls of the composite material tube is realized, and the strength drop caused by the opening of the surface of the composite material tube is compensated.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a composite material pipe connection structure, which is characterized in that it includes a metal inner cannula, and the metal inner cannula is inserted into the composite material pipe, and the insertion part There is an adhesive layer between the outer wall of the metal inner cannula and the inner wall of the composite material tube, and the tube wall of the composite material tube in the insertion part is provided with a hole for the connecting screw to pass through, and the lower end of the connecting screw penetrates into the In the tube wall of the metal inner tube, the upper ring of the rod body of the connecting screw is covered with an I-shaped fiber braided tube, and the upper end surface of the fiber braided tube is clamped on the outer wall of the composite material tube, and the lower end surface is clamped on the composite material tube. On the inner wall of the material pipe, a bionic reinforcing ring is encircled between the upper end surface of the fiber braided pipe and the nut of the connecting screw.

The above-mentioned composite pipe connection structure is characterized in that the bottom of the nut of the connecting screw is completely attached to the ring body of the bionic reinforcement ring, and the top of the nut is lower than the top of the bionic reinforcement ring.

In addition, the present invention also discloses a method for preparing the above-mentioned composite pipe connection structure, which is characterized in that the method includes the following steps:

Step 1. Using metal pipes or metal plates as raw materials, metal pipe blanks are obtained by mechanical processing, and carbon fibers, glass fibers, aramid fibers, high-strength polyethylene fibers or basalt fibers are used as raw materials, and are wound, twisted, coiled or drawn. Composite material tube blanks are obtained by tube extrusion process;

Step 2, opening a positioning hole in the socket area of the metal tube blank obtained in step 1 and the composite material tube blank, and then adopting 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 tube is inserted, and at the same time, the positioning hole in the composite material tube blank is machined and reamed to obtain the composite material tube;

Step 3, using the metal bar as the raw material, the connecting screw is prepared by machining;

Step 4. Use the finite element analysis software or the simulation analysis software that comes with the 3D drawing to simulate the stress distribution at the edge of the joint of the positioning hole in the composite pipe 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 are used as raw materials, and the bionic reinforcing ring is prepared by molding or winding;

Step 5, using carbon fibers, glass fibers, aramid fibers, high-strength polyethylene fibers or basalt fibers as raw materials, and preparing fiber braided tubes by weaving and winding processes;

Step 6. Set 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 in order to obtain a reinforced connection assembly;

Step 7. Apply adhesive glue on the outer wall of the sleeve area of the metal inner cannula and the inner wall of the sleeve area of the composite material tube in step 2, and then sleeve the metal inner cannula into the composite material tube, and make the two The positioning holes coincide to obtain the connecting pipe assembly;

Step 8. Apply adhesive to the outer surface of the fiber braided tube in the reinforced connection assembly obtained in step 6, and fold the top surface outward to form the upper end surface, and then insert the composite material tube and the metal inner tube into the connecting tube assembly In the coincident positioning hole, the bottom surface of the fiber braided tube is folded outward to form the lower end surface by using the gap extrusion between the composite material tube and the metal inner tube, and the lower end surface is clamped on the composite material tube and the metal inner tube Between, 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, and at the same time, the end of the connecting screw in the reinforcing connection component is passed through the inner hole wall of the positioning hole in the metal inner insertion tube The thread is tightened and fixed, and then the adhesive is cured, so that an adhesive layer is formed between the outer wall of the socket area of the metal inner cannula and the inner wall of the socket area of the composite material tube. After cleaning, grinding and processing, a composite material tube connection is obtained. structure.

The above-mentioned method is characterized in that the process of preparing the bionic reinforcing ring described in step 4 is: first, according to the simulation calculation results of the stress distribution, select the raw material and design the area and thickness of the reinforcing area of the bionic reinforcing ring, and divide the designed The bionic reinforcement ring is used to reinforce the composite material pipe, and the stress distribution at the edge of the joint of the positioning hole in the reinforced composite material pipe is simulated and calculated again, and the above design process and reinforcement process are repeated, and the simulation calculation process is repeated. The stress distribution until the connection of the positioning hole in the composite pipe is below the force failure range.

The above-mentioned method is characterized in that the bionic reinforcing ring in step 4 is composed of a hoop-direction fiber layup composed of continuous fibers, or a hoop-direction fiber layup with a volume content of 60%, and distributed in the hoop-direction fiber layup The horizontal fiber layup with a volume content of 20% and the vertical fiber layup with a volume content of 20% are composed.

The above-mentioned method is characterized in that the fiber braided tube in step 5 is processed from tubular fabric, or wound from a flat fabric, and the flat fabric is braided from raw material fibers in a cross direction or an oblique direction.

Compared with the prior art, the present invention has the following advantages:

1. The composite material tube connection structure of the present invention realizes the stable connection between the composite material tube and the metal by inserting the composite material tube and the metal inner cannula, setting an adhesive glue layer in the insertion area, and adopting connecting screws to connect the composite material tube and the metal, and setting the fiber The braided tube and the bionic reinforcing ring reinforce the opening of the composite material tube to form a continuous fiber coating on the opening, which realizes a comprehensive overall reinforcement effect on the inner and outer walls of the composite material tube and greatly enhances the reinforcement The effect is to make up for the decrease in strength caused by the opening of the composite tube surface.

2. The composite pipe connection structure of the present invention is completely attached to the ring body of the bionic reinforcement ring by setting the bottom of the nut of the connecting screw, and the top of the nut is lower than the top of the bionic reinforcement ring, which improves the bionic reinforcement. The structural stability of the ring enhances the reinforcing effect of the fiber braided tube and the bionic reinforcing ring, reduces the excessive extrusion of the hole edge, and realizes the protection effect of the bionic reinforcing ring on the connecting screws.

3. The composite material pipe of the present invention has simple connection structure, low cost, easy assembly and wide application range.

4. The present invention determines the area and thickness of the reinforcement area of the bionic reinforcement ring according to the simulation calculation results of the stress distribution at the edge of the joint of the positioning hole in the composite material tube after the metal intubation tube and the composite material tube are inserted, and prepares The bionic reinforcement ring is used to prepare the adapted fiber braided tube, which improves the accuracy of the size and structure of the bionic reinforcement ring and the fiber braided tube, achieves excellent and precise reinforcement effect, effectively avoids the extrusion damage of the tube structure, and effectively The weight of the overall structure is greatly reduced, especially in the connection between the metal pipe and the composite material pipe with a small insertion depth (due to the limited overall structural space, which cannot meet the larger insertion depth), its connection advantages are more prominent, and at the same time avoid Material waste.

5. The present invention improves the strength of the bionic reinforcing ring by using continuous fibers to form the hoop fiber layer of the bionic reinforcing ring, and is suitable for higher stress loads.

6. The present invention adopts two weaving methods of flat fabric winding or tubular fabric processing to form a fiber braided tube with complete structure, so as to carry out continuous fiber coating and reinforcement on the opening of the composite material tube, which significantly improves the local load resistance capacity, wherein , the fiber braided tube made of tubular fabric does not need to cut the fiber when it is turned over, and the fiber continuity is better. , the cost is lower than tubular fabric.

7. The preparation method of the present invention can directly assemble, solidify, polish and clean the metal pipe and the composite material pipe after simple processing, and does not need to be assembled before the composite material pipe is not cured. It is easy to implement and is suitable for composite materials of various shapes. Material pipe products have expanded the scope of use, and the process is simple, the production efficiency is high, and the overall production cost is low.

The technical solutions of the present invention will be described in further detail below with reference to the drawings and embodiments.

Description of drawings

Fig. 1 is a schematic diagram of the biomimetic-based composite pipe connection structure of the present invention.

Fig. 2 is a structural schematic diagram of a bionic reinforcing ring in the bionic-based composite pipe connection structure of the present invention.

Fig. 3 is a structural schematic diagram of the fiber braided pipe in the bionics-based composite pipe connection structure of the present invention.

Fig. 4 is a schematic structural diagram of the reinforcing connection assembly in the present invention.

Fig. 5 is a structural schematic diagram of the connecting pipe assembly in the present invention.

Explanation of reference signs

1—metal intubation tube; 2—composite material tube; 3—connecting screw;

4—bionic reinforcement ring; 5—fiber braided tube; 6—adhesive glue layer.

Detailed ways

The composite pipe connection structure of the present invention is described in detail through Example 1.

Example 1

As shown in Figures 1 to 3, the composite material pipe connection structure of this embodiment includes a metal inner insert 1, the metal inner insert 1 is inserted into the composite material pipe 2, and the metal inner insert 1 at the insertion position An adhesive layer 6 is provided between the outer wall of the composite material tube 2 and the inner wall of the composite material tube 2, and a hole for the connecting screw 3 to pass is opened on the tube wall of the composite material tube 2 in the plug-in part, and the lower end of the connecting screw 3 penetrates into the In the tube wall of the metal inner cannula 1, an I-shaped fiber braided tube 5 is sheathed 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 tube 2, and the lower The end face is clamped on the inner wall of the composite material tube 2 , and a bionic reinforcing ring 4 is encircled between the upper end face of the fiber braided tube 5 and the nut of the connecting screw 3 .

The composite material tube connection structure of this embodiment includes a metal inner insert tube 1 and a composite material tube 2 connected by plugging, and an adhesive is set 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. The glue layer 6 improves the connecting force between the metal inner cannula 1 and the composite material tube 2 by bonding. At the same time, in this embodiment, holes are opened on the tube wall of the composite material tube 2 in the plug-in position, and holes are also opened on the tube wall of the metal inner cannula 1 at the corresponding position, so that the connecting screw 3 passes through the tubes of the two in turn. wall, so that the metal inner tube 1 and the composite material tube 2 are connected and fixed, and the I-shaped fiber braided tube 5 is looped on the rod body of the connecting screw 3, and the upper end surface of the fiber braided tube 5 is clamped on the composite material tube. On the outer wall of the composite material tube 2, the lower end face is clamped on the inner wall of the composite material tube 2 to realize the stable socketing of the fiber braided tube 5, and the fiber braided tube 5 is used to be looped on the rod body of the connecting screw 3 to block the filling screw 3 and the composite material. The gap between the holes in the material tube 2, and cover the upper and lower surfaces of the hole, that is, the outer wall and inner wall of the composite material tube 2, to form a continuous fiber coating on the opening, play a reinforcing role, and make up for the opening caused by the composite material. The strength reduction defect caused by the discontinuity of the material pipe 2, and at the same time, the outer wall and the inner wall of the composite material pipe 2 at the opening are reinforced, which improves the overall strength of the composite material pipe 2, and avoids the opening defects of the inner wall of the composite material pipe and Use extended defects.

In actual operation, adhesive glue is usually coated on the outer surface of the fiber braided pipe 5, so that the fiber braided pipe 5 and the hole wall, outer wall, and inner wall of the composite material pipe 2 are bonded by adhesive glue to improve the fiber braided pipe. Assembly stability and firmness of tube 5.

In the composite material tube connection structure of this embodiment, the bionic reinforcement ring 4 is encircled between the upper end surface of the fiber braided tube 5 and the nut of the connecting screw 3, and the fiber braided tube 5 cooperates with the outer wall of the composite material tube 2 opening. Reinforcement further enhances the reinforcement effect. At the same time, the fastening force of the connecting screw 3 acts directly on the fiber braided tube 5, and acts on the bionic reinforcing ring 4 through the fiber braided tube 5, realizing the conduction and dispersion of the fastening force , reducing the excessive extrusion of the connecting screw 3 on the edge of the opening, avoiding the tensile damage of the tube structure at the opening due to excessive stress, and ensuring the fixed connection between the composite material tube 2 and the metal inner tube 1 stability. In addition, in this embodiment, the fiber braided tube 5 effectively isolates the connecting screw 3 from the hole wall of the composite material tube 2, avoiding the wear and tear of the connecting screw 3 usually made of metal material on the hole wall of the composite material tube 2, and further reducing the composite material. The strength reduction phenomenon at the opening of the material tube 2.

Further, the bottom of the nut of the connecting screw 3 fits completely 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 . In this embodiment, the bottom of the nut of the connecting screw 3 is completely attached to the ring body of the bionic reinforcing ring 4. On the one hand, the bionic reinforcing ring 4 is stably fixed between the connecting screw 3 and the fiber braided tube 5. Give full play to the synergistic reinforcing effect, avoid the movement or falling off of the bionic reinforcing ring 4, on the other hand, make the fiber braided tube 5, the bionic reinforcing ring 4 and the connecting screw 3 form an integral structure, and further strengthen the fiber braided tube 5 pair of composite material tubes 2. The continuous fiber coating reinforcement at the opening, the reinforcement of the bionic reinforcement ring 4, and the reduction of excessive extrusion at the edge of the hole. At the same time, the top of the nut is lower than the top of the bionic reinforcement ring 4, so that the connection The nut portion of the screw 3 beyond the outer wall of the composite material tube 2 is completely placed in the bionic reinforcement ring 4, which realizes the protection effect on the connecting screw 3, ensures the fixed connection effect of the connecting screw 3, and improves the surface of the composite material tube 2. consistency and aesthetics.

The preparation method of the composite pipe connection structure of the present invention is described in detail through Example 2.

Example 2

The preparation process of the composite pipe connection structure of this embodiment is as follows:

Step 1. Using metal pipes or metal plates as raw materials, metal pipe blanks are obtained by mechanical processing, and carbon fibers, glass fibers, aramid fibers, high-strength polyethylene fibers or basalt fibers are used as raw materials, and are wound, twisted, coiled or drawn. Composite material tube blanks are obtained by tube extrusion process;

Step 2, opening a positioning hole in the socket area of the metal tube blank obtained in step 1 and the composite material tube blank, and then adopting 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 tube 1 is machined and reamed at the positioning hole in the composite material tube blank to obtain the composite material tube 2;

Step 3, using the metal bar as the raw material, the connecting screw 3 is prepared by machining;

Step 4: Use ANSYS finite element analysis software to simulate the stress distribution at the edge of the joint of the positioning hole in the composite material pipe 2 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 is used as a raw material, and the bionic reinforcing ring 4 is prepared by molding or winding process; the bionic reinforcing ring 4 is composed of hoop-direction fiber laminates composed of continuous fibers;

The process of preparing the bionic reinforcing ring 4 is as follows: use ANSYS finite element analysis software to first calculate that the metal intubation tube 1 is plugged into the composite material tube 2 and the connection screw 3 is pierced, and the adhesive layer 6 is set. The maximum load that can be borne by being destroyed (calculated by continuously reducing the load until it is not damaged), and the maximum load that can be borne by the metal insert tube 1 and the composite material tube 2 without being damaged, are obtained. The difference is the load difference F _C , and then through the formula A ₁ (initial area of the bottom surface of the bionic reinforcement ring 4) = F _C /R ₁ (bonding strength of the adhesive layer 6), to obtain the bionic reinforcement ring 4 The initial area of the bottom surface, and at the same time determine the main thickening position (maximum stress area) of the bionic reinforcement ring 4 according to the stress distribution characteristics in the calculation process of the load difference _FC , through the formula A ₂ (cross-section of the stress concentration area of the bionic reinforcement ring 4 Area) = F _C /R ₂ (compressive strength in the direction of the stress concentration zone of the reinforcement ring), to obtain the cross-sectional area of the stress concentration zone of the bionic reinforcement ring 4, and then use the curve optimization to complete the bionic reinforcement on the basis of A ₁ and A ₂ For the initial design of the strong ring 4, the initially designed bionic reinforcing ring 4 is used to reinforce the composite material pipe 2, and the stress distribution at the edge of the joint of the positioning hole in the reinforced composite material pipe 2 is simulated again, Repeat the above design process and reinforcement process, and simulate the calculation process again until the stress distribution at the joint of the positioning hole in the composite material tube 2 is below the force damage range, determine the structural size of the bionic reinforcement ring 4, and prepare the bionic reinforcement ring 4. strong ring 4;

Step 5, using carbon fibers, glass fibers, aramid fibers, high-strength polyethylene fibers or basalt fibers as raw materials, and adopting weaving and winding processes to prepare fiber braided tubes 5; the fiber braided tubes 5 are processed from tubular fabrics;

Step 6. Set the bionic reinforcing ring 4 in step 4 and the fiber braided tube 5 in step 5 on the outer surface of the connecting screw 3 obtained in step 3 in order to obtain a reinforcing connection assembly, as shown in FIG. 4 ;

Step 7. Apply adhesive glue on the outer wall of the socket area of the metal inner cannula 1 and the inner wall of the sleeve area of the composite material tube 2 in step 2, and then socket the metal inner cannula 1 into the composite material tube 2, And make the positioning holes of the two overlap to obtain the connecting pipe assembly, as shown in Figure 5;

Step 8: Apply adhesive glue on the outer surface of the fiber braided tube 5 in the reinforced connection assembly obtained in step 6, and turn the top surface outward to form the upper end surface, and then insert the composite material tube 2 into the metal inner surface of the connecting tube assembly. The positioning hole where the intubation tube 1 overlaps, and the bottom surface of the fiber braided tube 5 is turned outward to form the lower end surface by using the gap extrusion between the composite material tube 2 and the metal inner intubation tube 1, and the lower end surface is clamped on the composite material Between the tube 2 and the metal inner tube 1, 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, and at the same time, the end of the connecting screw 3 in the reinforcing connection assembly is passed through The inner hole wall of the positioning hole in the metal inner cannula 1 is screwed and fixed, and then the adhesive is cured, so that the outer wall of the socketed area of the metal inner cannula 1 and the inner wall of the sleeved area of the composite material tube 2 are bonded. The glue layer 6 is cleaned, polished and processed to obtain a composite pipe connection structure.

In Step 4 of this embodiment, the simulation analysis software included with the three-dimensional drawing can also be used to simulate and calculate the stress distribution at the edge of the joint of the positioning hole in the composite material pipe 2; the bionic reinforcing ring 4 described in Step 4 can also be calculated by volume content 60 % hoop fiber lay-up, and the horizontal fiber lay-up of volume content 20% and the vertical fiber lay-up of volume content 20% that are distributed in the hoop-direction fiber lay-up are formed; The plane fabric is wound, and the plane fabric is obtained by weaving raw material fibers in a cross direction or an oblique direction.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent changes made to the above embodiments according to the technical essence of the invention still belong to the protection scope of the technical solution of the invention.

Claims (6)

1. The composite material pipe connecting structure is characterized by comprising a metal inner inserting pipe (1), wherein the metal inner inserting pipe (1) is inserted into a composite material pipe (2), a bonding adhesive layer (6) is arranged between the outer wall of the metal inner inserting pipe (1) at the inserting position and the inner wall of the composite material pipe (2), a hole for a connecting screw (3) to penetrate through is formed in the pipe wall of the composite material pipe (2) at the inserting position, the lower end of the connecting screw (3) penetrates into the pipe wall of the metal inner inserting pipe (1), an I-shaped fiber woven pipe (5) is annularly sleeved on a rod body of the connecting screw (3), the upper end face of the fiber woven pipe (5) is connected to the outer wall of the composite material pipe (2) in a clamped mode, the lower end face of the fiber woven pipe is connected to the inner wall of the composite material pipe (2) in a clamped mode, and a reinforcing ring (4) is annularly sleeved between the upper end face of the fiber woven pipe (5) and a bionic nut of the connecting screw (3).

2. The composite material pipe connection structure according to claim 1, wherein the bottom of the nut of the connection 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).

3. A method of preparing a composite material pipe joint structure according to claim 1 or 2, comprising the steps of:

step one, a metal pipe or a metal plate is used as a raw material, a metal pipe blank is obtained through machining, carbon fiber, glass fiber, aramid fiber, high-strength polyethylene fiber or basalt fiber is used as a raw material, and a composite material pipe blank is obtained through winding, pipe twisting, pipe coiling or pipe pultrusion processes;

step two, forming positioning holes in the sleeving areas of the metal pipe blank and the composite material pipe blank obtained in the step one, then manufacturing internal threads on the inner hole walls of the positioning holes in the metal pipe blank by adopting stamping, welding and machining processes to obtain a metal inner inserting pipe (1), and simultaneously performing hole expanding on the positioning holes in the composite material pipe blank to obtain a composite material pipe (2);

step three, taking a metal bar as a raw material, and machining to obtain a connecting screw (3);

step four, carrying out simulation calculation on the stress distribution of the edge of the connecting position of the positioning hole in the composite material pipe (2) in the step two by using finite element analysis software or simulation analysis software carried by a three-dimensional drawing, and preparing a bionic reinforcing ring (4) by using carbon fibers, glass fibers, aramid fibers, high-strength polyethylene fibers or basalt fibers as raw materials and adopting a die pressing or winding process according to the simulation calculation result of the stress distribution;

step five, preparing a fiber braided tube (5) by taking carbon fibers, glass fibers, aramid fibers, high-strength polyethylene fibers or basalt fibers as raw materials and adopting the processes of braiding and winding;

step six, sleeving a bionic reinforcing ring (4) in the step four and a fiber braided tube (5) in the step five on the outer surface of the connecting screw (3) obtained in the step three in sequence to obtain a reinforcing connecting assembly;

step seven, coating adhesive glue on the outer wall of the sleeving area of the metal inner insert tube (1) and the inner wall of the sleeving area of the composite material tube (2) in the step two, sleeving the metal inner insert tube (1) into the composite material tube (2), and enabling positioning holes of the metal inner insert tube and the composite material tube to be overlapped to obtain a connecting tube assembly;

and step eight, coating adhesive glue on the outer surface of the fiber woven tube (5) in the reinforcing connecting assembly obtained in the step six, turning the top surface outwards and folding the top surface to form an upper end surface, then inserting the fiber woven tube into a positioning hole formed by the composite material tube (2) in the connecting tube assembly and the metal inner insert tube (1) in a superposition manner, extruding the composite material tube (2) and the metal inner insert tube (1) by utilizing a gap between the composite material tube (2) and the metal inner insert tube to enable the bottom surface of the fiber woven tube (5) to be turned outwards to form a lower end surface, clamping the lower end surface between the composite material tube (2) and the metal inner insert tube (1), clamping the upper end surface on the outer surface of the composite material tube (2) to obtain the fiber woven tube (5) with an I-shaped structure, fixing the tail end of a connecting screw (3) in the reinforcing connecting assembly through the inner hole wall threads of the positioning hole in the metal inner insert tube (1), then curing the adhesive glue, enabling an adhesive glue layer (6) to be formed between the outer wall of the sleeving region of the metal inner insert tube (1) and the inner wall of the sleeving region of the composite material tube (2), cleaning, polishing and processing to obtain the connecting structure of the composite tube.

4. The method according to claim 3, wherein the process for preparing the biomimetic reinforced ring (4) in step four is as follows: firstly, according to the simulation calculation result of stress distribution, selecting raw materials and designing the area and the thickness of a reinforcing area of a bionic reinforcing ring (4), using the designed bionic reinforcing ring (4) for reinforcing the composite material pipe (2), performing simulation calculation again on the stress distribution of the edge of a connecting position of a positioning hole in the reinforced composite material pipe (2), repeating the design process, the reinforcing process and the simulation calculation process again until the stress distribution of the connecting position of the positioning hole in the composite material pipe (2) is below a stress failure range, determining the structural size of the bionic reinforcing ring (4), and preparing to obtain the bionic reinforcing ring (4).

5. The method according to claim 3, wherein the bionic reinforcement ring (4) in the fourth step consists of a circumferential fiber layer consisting of continuous fibers, or consists of a circumferential fiber layer with a volume content of 60%, and a horizontal fiber layer with a volume content of 20% and a vertical fiber layer with a volume content of 20% distributed in the circumferential fiber layer.

6. A method according to claim 3, characterized in that in step five the fibre woven tube (5) is processed from a tubular fabric or is wound from a flat fabric, and the flat fabric is woven from raw fibres in a criss-cross or oblique direction.

Images