Calculation method and terminal of node slip coefficient of GFRP composite pipe insulation spanning frame

Abstract

The present invention relates to the field of power engineering technology, specifically to a method and terminal for calculating the slip coefficient of a node of an insulated spanning frame made of GFRP composite pipes. The present invention comprises the following steps: obtaining the number of turnovers of a fastener, the initial torque, and the nominal diameter of the bolts in the fastener, and obtaining the slip pressure and preload at the fastener node after pre-processing; replacing the actual non-closed fastener with a full-circle virtual kit with a closed positive pressure distribution characteristic circumferentially distributed around the vertical axis of the GFRP splicing rod node, integrating the friction force at each point on the inner surface of the virtual kit, and replacing the uneven circumferential friction coefficient of the inner side of the fastener with the slip coefficient at the fastener node. The present invention is simple and convenient in calculation, and can quickly and accurately obtain the slip coefficient value, thereby solving the current situation in which there is a lack of applicable formulas in the design and verification of GFRP material spanning frames, and ultimately generating important theoretical significance and practical value for promoting the safe and cost-effective application of GFRP materials in actual engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power engineering, and in particular to a method and a terminal for calculating a node slip coefficient of a GFRP composite pipe insulation spanning frame. Background Art

[0002] In new construction and renovation projects of high-voltage transmission lines, they often intersect and intersect with important projects such as high-speed railways, highways, and bridges. To ensure the normal operation of these infrastructure projects, crossing frames are generally installed to provide crossover protection and support for the transmission lines.

[0003] A stable support structure formed by assembling and combining multiple splicing rods is one of the common structures of a spanning frame, and its structural form is described in the text of a spanning frame for power transmission spanning construction with the Chinese patent publication number CN112531556A. Since radial openings on the splicing rods will reduce the strength and rigidity of the splicing rods, the splicing nodes of the spanning frame are mostly assembled in the form of fasteners. The fasteners are mostly an annular clamping structure with a middle break, and bolts are provided at the break. The annular clamping structure can be a one-piece molding or a two-section structure hinged to each other. When in use, after the splicing rod to be assembled is placed in the fastener, a locking force is applied by the bolts to gradually close the break, thereby making the fastener and the splicing rod to be assembled tightly, thereby completing the assembly of the splicing rod. The structure of the fastener is described in the Chinese Patent Publication No. CN107355070B entitled "Scaffolding Fastener" and the Chinese Patent Publication No. CN208884974U entitled "Fastencil."

[0004] Due to the live working nature of transmission line installation, the high-voltage electric shielding performance of metal structure spanning frames is poor, and improper operation can easily cause electric shock accidents, posing a greater threat to the safety of construction workers. Therefore, GFRP glass fiber reinforced plastic materials with high strength and insulation are gradually being used in the spanning frame direction. Since the assembly nodes of the splicing rods are vertically arranged splicing rods and horizontal splicing rods that are locked by fasteners, the design load at the assembly node is closely related to the slip coefficient between the fasteners and the splicing rods. However, the calculation of the slip coefficient in the existing technology is mostly the slip coefficient of contact between steel and steel, and the calculation of the slip coefficient in the existing technology is mostly for the form of direct contact between bolts and splicing rods, which undoubtedly puts a severe test on the accuracy of the design data of the insulating frame. Therefore, it is urgent to solve this problem. Summary of the Invention

[0005] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a method and terminal for calculating the slip coefficient of the nodes of GFRP composite pipe insulated spanning frames. The calculation is simple and convenient, and the slip coefficient value can be obtained quickly and accurately, thereby solving the current problem of lack of applicable formulas in the design and verification of GFRP material spanning frames. Ultimately, it has important theoretical significance and practical value for promoting the safe and cost-effective application of GFRP materials in actual engineering.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The method for calculating the slip coefficient of the node of the GFRP composite pipe insulation spanning frame includes the following steps:

[0008] S1. Obtain the number of fastener rotations, initial torque, and nominal diameter of the bolts in the fastener, and obtain the slip pressure and preload at the fastener node after preprocessing;

[0009] S2. A virtual circular assembly with a closed positive pressure distribution characteristic circumferentially distributed around the vertical axis of the GFRP splicing rod node is used to replace the actual non-closed fastener. The friction force at each point on the inner surface of the virtual assembly is integrated, and the slip coefficient at the fastener node is used to replace the uneven friction coefficient on the inner side of the fastener. A slip coefficient calculation model is obtained that relates the slip coefficient at the fastener node to the preload and maximum static friction force.

[0010] S3. Substituting the maximum static friction force with the slip pressure obtained in step S1, and inputting the obtained preload force into the slip coefficient calculation model, thereby obtaining the slip coefficient at the fastener node.

[0011] As a further solution of the present invention, the process of pre-processing the sliding pressure at the fastener node in step S1 is specifically as follows:

[0012] Obtaining a first conversion coefficient through the number of turnovers;

[0013] Obtaining a second conversion coefficient through the initial torque;

[0014] Inputting the obtained first conversion coefficient and second conversion coefficient into a slip pressure calculation model to obtain the slip pressure at the fastener node;

[0015] The first conversion coefficient is specifically:

[0016] ;

[0017] Where: is the first conversion coefficient, dimensionless;

[0018] is the number of turnovers of the fastener, dimensionless;

[0019] The second conversion coefficient is specifically:

[0020] ;

[0021] Where: is the second conversion coefficient, dimensionless;

[0022] T is the initial torque of the fastener, in units of .

[0023] As a further solution of the present invention: the sliding pressure calculation model is specifically: ;

[0024] Where, is the slip pressure at the fastener node, in units of .

[0025] As a further solution of the present invention: the slip coefficient calculation model in step S2 is specifically: ;

[0026] Where: is the slip coefficient at the fastener node, dimensionless;

[0027] is the preload force at the fastener node, in units of ;

[0028] is the maximum static friction force at the fastener node, in units of .

[0029] As a further solution of the present invention: the preload force is specifically: ;

[0030] Where: is the initial torque of the fastener, in units of ;

[0031] is the torque coefficient, dimensionless;

[0032] is the nominal diameter of the bolt, in units of .

[0033] As a further solution of the present invention, the initial torque is obtained in the following manner: after tightening the bolt with a torque wrench, the torque wrench directly outputs the value of the initial torque.

[0034] As a further solution of the present invention: the turnover number is specifically the number of times the fastener is used, which is obtained by searching the usage records of the fastener.

[0035] A terminal includes a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to implement the method for calculating the node slip coefficient of a GFRP composite pipe insulation spanning frame when executing the computer program.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This application replaces the non-circular open fastener with a fully closed virtual kit and integrates the friction force at each point on the virtual kit's inner surface. Simultaneously, the slip coefficient at the fastener's nodes replaces the uneven circumferential friction coefficient on the fastener's inner side. A slip coefficient calculation model is constructed that relates the slip coefficient at the fastener's nodes to the preload and maximum static friction, thereby deriving the slip coefficient between the fastener and the GFRP rod. This application fully considers the specific working conditions of GFRP rods and the complex slip behavior between the vertically distributed rods and fasteners. The calculation is simple and convenient, enabling rapid and accurate determination of the slip coefficient value. This addresses the current lack of applicable formulas for the design and verification of GFRP spanning frames, ultimately contributing significant theoretical and practical value to promoting the safe and cost-effective application of GFRP materials in practical engineering projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flowchart of the workflow of the present invention.

[0039] Figure 2 Schematic diagram of the connection between the fastener and the GFRP splicing rod in the present invention.

[0040] Figure 3 Schematic diagram of the actual positive pressure distribution of the fastener on the GFRP spliced ​​rod in the present invention.

[0041] Figure 4 Schematic diagram of the simulated positive pressure distribution of the fastener on the GFRP spliced ​​rod in the present invention.

[0042] In the figure: 10, fastener; 11, bolt; 20, GFRP splicing rod. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] For ease of understanding, the specific structure and working mode of the present invention are further described below with reference to the accompanying drawings:

[0045] The present invention specifically refers to Figures 1 to 4 As shown, it mainly includes the following steps:

[0046] S1. Obtain the number of turnovers, initial torque, and nominal diameter of the bolt 11 in the fastener 10, and obtain the slip pressure and preload force at the node of the fastener 10 after preprocessing.

[0047] S2. A virtual circular kit with a closed positive pressure distribution characteristic circumferentially distributed around the vertical axis of the GFRP splicing rod 20 nodes is used to replace the actual non-closed fastener 10. The friction force at each point on the inner surface of the virtual kit is integrated, and the slip coefficient at the node of the fastener 10 is used to replace the uneven friction coefficient on the inner side of the fastener 10. A slip coefficient calculation model is obtained that associates the slip coefficient at the node of the fastener 10 with the preload force and the maximum static friction force.

[0048] S3. Substituting the maximum static friction force with the slip pressure obtained in step S1, and inputting the obtained preload force into the slip coefficient calculation model, thereby obtaining the slip coefficient at the node of the fastener 10.

[0049] The specific process of pre-processing the sliding pressure at the node of the fastener 10 in step S1 is as follows:

[0050] Obtaining a first conversion coefficient through the number of turnovers;

[0051] Obtaining a second conversion coefficient through the initial torque;

[0052] The first conversion coefficient and the second conversion coefficient obtained are input into the sliding pressure calculation model to obtain the sliding pressure at the node of the fastener 10.

[0053] The first conversion coefficient is specifically:

[0054] ;

[0055] The second conversion coefficient is specifically:

[0056] ;

[0057] The specific slip pressure calculation model is: ;

[0058] Where, is the number of turnovers of the fastener 10, dimensionless;

[0059] T is the initial torque of fastener 10, in units of ;

[0060] is the first conversion coefficient, dimensionless;

[0061] is the second conversion coefficient, dimensionless;

[0062] is the slip pressure at the node of fastener 10, in kN.

[0063] Specifically, the above sliding pressure calculation model is obtained by linear fitting.

[0064] On the basis of the above, in step S1, the pre-tightening force is obtained by applying an initial torque to the bolt 11 through a torque wrench. T , thereby generating a pre-tightening force on the fastener 10 .

[0065] The specific preload force is: ;

[0066] Where, is the preload force at the 10th node of the fastener, in units of ;

[0067] is the initial torque of fastener 10, in units of ;

[0068] is the torque coefficient, which is 0.11-0.15;

[0069] is the nominal diameter of bolt 11, in units of .

[0070] The preload The fastener 10 is transferred to the contact surface of the vertical GFRP splicing rod 20, such as Figure 3 As shown, each point on the inner surface of the fastener 10 forms a vertical inward positive pressure At this time, the fastener 10 is subjected to a force to produce an inward closing movement trend, but the rigid constraint of the vertical GFRP splicing rod 20 hinders this trend, resulting in the formation of an interaction force balance system between the fastener 10 and the GFRP splicing rod 20, that is, the preload force The reaction force of the vertical GFRP splicing rod 20 is equal in magnitude and opposite in direction. Further induce tangential friction , its direction is always opposite to the relative sliding trend of the vertical GFRP splicing rod 20, and follows the classical friction law , where is the friction coefficient.

[0071] As the top of the vertical GFRP splicing rod 20 is subjected to external pressure Increase friction Synchronously reinforced to resist sliding until external pressure Reaching the critical value, that is, the slip pressure F f reaches a critical value, at which point the friction When the maximum value is reached, the fastener 10 is in a critical state of being about to slide.

[0072] The positive pressure at each point is distributed along the direction of the reaction force and perpendicular to the direction of the reaction force , from the stress characteristics of fastener 10, we can see that , so we only need to consider the direction of the reaction force .

[0073] It is generally believed that the positive pressure at each point on the inner surface of the fastener 10 is evenly distributed. However, due to the different distances between each point inside the fastener 10 and the torque application point, and the surface roughness affecting the local pressure transmission, the deviation calculated based on the uniform distribution is large. Considering the direction of the reaction force of the GFRP splicing rod 20 and the positive pressure distribution at each point on the inner surface of the fastener 10, the final non-closed positive pressure distribution characteristic of the fastener 10 is formed with a small opening in the full circle angle. This application adopts the following method: Figure 4 The distribution characteristics shown replace the actual non-closed fastener 10 with a full-circle virtual kit with a closed positive pressure distribution characteristic circumferentially distributed around the vertical axis of the GFRP splicing rod 20 node.

[0074] Based on the above ideas, the slip coefficient at the 10th node of the fastener is calculated. Theoretical derivation:

[0075] Due to the reaction force of GFRP splicing rod 20 and the preload Equal, that is ;

[0076] Also because , therefore, .

[0077] According to the positive pressure distribution characteristics of the inner surface of the virtual kit, we can know that:

[0078] ,

[0079] ;

[0080] This application is based on ;

[0081] According to the classical friction law, the friction force at each point on the inner surface of the virtual kit is integrated:

[0082] ;

[0083] Due to positive pressure exist and The distribution is symmetrical. Further processing of the above formula can be considered:

[0084] ;

[0085] After processing, the slip coefficient calculation model in step S2 can be obtained as follows: ;

[0086] is the maximum static friction force at the virtual assembly node, that is, the maximum static friction force at the fastener 10 node, in kN;

[0087] is the slip coefficient at the node 10 of the fastener, dimensionless;

[0088] is the preload force at the 10th node of the fastener, in units of .

[0089] because Numerically, it is the slip pressure The sum of the weight of the GFRP splicing rod 20, but the GFRP splicing rod 20 is a lightweight material with a small weight, which can be approximately considered Therefore, in step S3, the maximum static friction force is replaced by the sliding pressure obtained in step S1.

[0090] According to the current initial tightening torque specification for the fastener 10 of the scaffold or span frame tightened by the bolt 11, the initial torque of the fastener 10 should not be less than 40 , and should not be greater than 65 However, since the pipe material of the scaffolding or spanning frame specified in the specification is a steel structure, and the stiffness of the GFRP composite pipe in this application cannot reach the pipe stiffness of the steel pipe scaffolding in the standard, if the initial torque is too large, it will cause the GFRP composite pipe to rupture. Therefore, in the practice of the following embodiments, the value of the initial torque is 20 and 50 In practice, the initial torque is obtained by tightening the bolt 11 with a torque wrench to the initial torque value set in the embodiment, and then directly outputting the initial torque value from the torque wrench. In addition, since the fastener 10 will have friction loss after use, its number of uses is closely related to the slip coefficient. Therefore, the number of uses of the fastener 10 needs to be recorded after each use; this application defines the number of uses of the fastener 10 as the number of turnovers, and the number of uses of the fastener 10 is obtained by searching the usage records of the fastener 10.

[0091] Example 1

[0092] Use a torque wrench to connect the two GFRP splicing rods 20 through the fastener 10. The number of turnovers of the fastener 10 is 4 times and the initial torque is 20 .

[0093] Example 2

[0094] Based on Example 1, the difference is that the number of turnovers is 8.

[0095] Example 3

[0096] Based on Example 1, the difference is that the number of turnovers is 12.

[0097] Example 4

[0098] Based on Example 1, the difference is that the number of turnovers is 16.

[0099] Example 5

[0100] Based on Example 1, the difference is that the number of turnovers is 20.

[0101] Example 6

[0102] Based on Example 1, the difference is that the number of turnovers is 24.

[0103] Example 7

[0104] Based on Example 1, the difference is that the number of turnovers is 8 and the initial torque is 30 .

[0105] Example 8

[0106] Based on Example 1, the difference is that the number of turnovers is 8 and the initial torque is 40 .

[0107] Example 9

[0108] Based on Example 1, the difference is that the number of turnovers is 8 and the initial torque is 50 .

[0109] In practice, under the implementation conditions of the above-mentioned embodiments 1 to 9, the number of turnovers and the initial torque of the buckle 10 in each embodiment are input into the slip pressure calculation model, and the slip pressure at the node of the fastener 10 is obtained according to the slip pressure calculation model of the present application. The calculated value of .

[0110] Furthermore, under the implementation conditions of Examples 1 to 9, actual sliding pressure tests were performed on the actual structures of the two GFRP spliced ​​rods 20 connected by the fasteners 10 in each example, thereby obtaining test values ​​of the sliding pressure.

[0111] The calculated values ​​of the sliding pressure at the nodes of the fastener 10 obtained by the sliding pressure calculation model are compared with the experimental values ​​of the sliding pressure obtained by the actual test, forming a comparison table of the calculated values ​​of the sliding pressure and the experimental values ​​of the sliding pressure as shown in Table 1 below:

[0112] Table 1 Sliding pressure comparison table

[0113] ;

[0114] In addition, under the implementation conditions of the above-mentioned embodiments 1 to 9, the preload force values ​​in each embodiment are calculated. In the preload force calculation, the nominal diameter of the bolt 11 is taken as 16 mm according to the actual value, and the torque coefficient is taken as 0.14. The calculated preload force value and the above-mentioned slip pressure calculation model are used to obtain the slip pressure at the node of the fastener 10. The calculated values ​​are input into the slip coefficient calculation model of this application, and the slip coefficient at the node of fastener 10 is obtained according to the slip coefficient calculation model of this application. The calculated value of .

[0115] Under the implementation conditions of Examples 1 to 9, actual slip coefficient tests were conducted on the actual structures of the two GFRP spliced ​​rods 20 in each example connected by the fasteners 10, thereby obtaining test values ​​of the slip coefficients.

[0116] The calculated value of the slip coefficient at the node of the fastener 10 obtained by the slip coefficient calculation model is compared with the experimental value of the slip coefficient obtained through actual testing, forming a comparison table of the calculated value of the slip coefficient and the experimental value of the slip coefficient as shown in Table 2 below:

[0117] Table 2 Slip coefficient comparison table

[0118] ;

[0119] As can be seen from Tables 1 and 2 above, by fully considering the specific operating conditions of GFRP spliced ​​rods 20 and the complex slip behavior between them and fasteners 10, the slip pressure and slip coefficient obtained using the present invention's solution exhibit relatively small relative errors compared to experimental values, i.e., small deviations from actual operating conditions. This demonstrates the high accuracy of the slip coefficient at the fastener 10 node obtained using the present invention's method. Specifically, by fully considering the specific operating conditions of GFRP spliced ​​rods and the complex slip behavior between the vertically distributed spliced ​​rods and fasteners, the present invention's calculations are simple and convenient, enabling rapid and accurate determination of slip coefficient values. This addresses the current lack of applicable formulas for the design and verification of GFRP spanning structures, ultimately contributing significant theoretical and practical value to promoting the safe and cost-effective application of GFRP materials in practical engineering projects.

[0120] In addition, an embodiment of the present application further provides a terminal comprising a memory and a processor, wherein the memory is used to store a computer program, and when the processor is used to execute the computer program, a method for calculating the slip coefficient of a node of an insulated spanning frame made of GFRP composite pipe is implemented.

[0121] Since this computer program adopts all the technical solutions of all the aforementioned embodiments when executed by the processor, it has at least all the beneficial effects brought about by all the technical solutions of all the aforementioned embodiments, which will not be described one by one here.

[0122] Of course, it will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, but also encompasses the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and it is intended that all variations that fall within the meaning and range of equivalents of the claims be encompassed within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0123] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0124] The technology, shape, and structure not described in detail in the present invention are all well-known technologies.

Claims

1. A method for calculating the node slip coefficient of a GFRP composite pipe insulation spanning frame is characterized in that: The following steps are involved: S1, obtaining the number of revolutions and the initial torque of the fastener (10), and calculating the slip pressure at the node of the fastener (10) based on the number of revolutions and the initial torque; obtaining the initial torque of the fastener (10) and the nominal diameter of the bolt (11) in the fastener (10), and calculating the preload based on the initial torque and the nominal diameter; S2. A virtual circular kit with a closed positive pressure distribution characteristic circumferentially distributed around the vertical axis of the GFRP splicing rod (20) node is used to replace the actual non-closed fastener (10). The friction force at each point on the inner surface of the virtual kit is integrated, and the slip coefficient at the fastener (10) node is used to replace the uneven friction coefficient of the inner side of the fastener (10). A slip coefficient calculation model is obtained that associates the slip coefficient at the fastener (10) node with the preload and the maximum static friction force. The slip coefficient calculation model is specifically as follows: Where, is the slip coefficient at the node of fastener (10), dimensionless; is the preload force at the node of fastener (10), in units of ; is the maximum static friction force at the node of fastener (10), in units of ; S3, replacing the maximum static friction force with the slip pressure obtained in step S1, and inputting the obtained preload force into the slip coefficient calculation model, thereby obtaining the slip coefficient at the node of the fastener (10).

2. The method for calculating the node slip coefficient of the GFRP composite pipe insulation spanning frame according to claim 1, characterized in that: The specific process of calculating the sliding pressure at the node of the fastener (10) in step S1 is as follows: Obtaining a first conversion coefficient through the number of turnovers; Obtaining a second conversion coefficient through the initial torque; Inputting the obtained first conversion coefficient and the second conversion coefficient into a slip pressure calculation model to obtain the slip pressure at the node of the fastener (10); Wherein, the first conversion coefficient is specifically: Where: is the first conversion coefficient, dimensionless; is the number of turnovers of the fastener (10), dimensionless; The second conversion coefficient is specifically: Where: is the second conversion coefficient, dimensionless; T is the initial torque of the fastener (10), in units of .

3. The method for calculating the node slip coefficient of the GFRP composite pipe insulation spanning frame according to claim 2, characterized in that: The slip pressure calculation model is specifically as follows: Where, is the slip pressure at the node of fastener (10), in units of .

4. The method for calculating the node slip coefficient of the GFRP composite pipe insulation spanning frame according to claim 1, characterized in that: The preload force is specifically: Where: is the initial torque of the fastener (10), in units of ; is the torque coefficient, dimensionless; is the nominal diameter of the bolt (11), in units of .

5. The method for calculating the node slip coefficient of the GFRP composite pipe insulation spanning frame according to claim 1, characterized in that: The initial torque is obtained in the following manner: after tightening the bolt (11) with a torque wrench, the torque wrench directly outputs the value of the initial torque.

6. The method for calculating the node slip coefficient of the GFRP composite pipe insulation spanning frame according to claim 1, characterized in that: The turnover number is specifically the number of times the fastener (10) is used, and is obtained by searching the usage record of the fastener (10).

7. A terminal, characterized in that: The method comprises a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to implement the method for calculating the node slip coefficient of the GFRP composite pipe insulation spanning frame according to any one of claims 1 to 6 when executing the computer program.

Images