A Simulation Modeling Method for the Double-Curved Rough Surface of a Preformed Line Splices

Abstract

The present invention relates to a simulation modeling method for the double-curved rough surface of a preformed wire clamp, including the following steps: S1. Determine the structural parameters of the preformed wire clamp; S2. Construct a two-dimensional geometric model of the wire clamp according to the determined structural parameters; S3. Use the W-M fractal function to simulate the rough surface effect of the preformed wire clamp; S4. Convert the W-M fractal function into a rough surface profile with a hyperbolic linear shape; S5. Use MATLAB to generate the fractal contour curve and export the fractal contour points; S6. Write the fractal contour points into a script program through Python programming, and establish a simulation model of the double-curved rough surface of the preformed wire clamp in finite element software; considering the contact surface of the preformed wire clamp as a double-curved rough surface contact form, which is consistent with the actual contact situation between the preformed wire and the wire, effectively simulating the formation of a non-smooth surface of the wire clamp due to manufacturing, transportation, etc. Therefore, it is very necessary to study the fretting wear of the rough surface.

Description

Technical Field

[0001] The invention belongs to the technical field of electric power, and relates to a simulation modeling method for a hyperbolic rough surface of a preformed clamp. Background Art

[0002] At present, the energy and power industry is in a period of rapid transformation and development. In response to China's electricity demand, the State Grid Corporation of China has clearly put forward the strategic goal of "three types and two networks, world-class". A smart grid development layout has been formed, with the UHV grid as the main backbone grid, the intelligent distribution grid as the branch, and the coordinated development of power grids at all levels. The safe and stable operation of UHV transmission lines is a limited means to ensure the realization of the strategic goal. As an important part of overhead transmission lines, once a preformed clamp is damaged, it will cause the conductor and ground wire to fall and the circuit to trip, posing a serious threat to the stable operation of the power system.

[0003] Due to the characteristics of long transmission distance and complex service environment of overhead transmission lines, they will be affected by external climate factors, geographical factors, etc., resulting in continuous vibration of overhead transmission lines during service. The most dangerous effect is aeolian vibration, which has a long continuous action time, accounting for about 30% - 50% of the total annual time. The preformed clamp is in this cyclic vibration state for a long time, which is extremely likely to cause wear and damage to the clamp, and the damage has a certain degree of concealment. It generally occurs at the contact part between the conductor and the preformed clamp and cannot be directly detected from the outside. Usually, only when wire breakage occurs, it will attract the attention of line patrol personnel, bringing certain difficulties to the line patrol work; and due to factors such as manufacturing and transportation, the contact interface between the preformed wire and the conductor is not a smooth plane, which greatly increases the risk of damage to the preformed wire. Therefore, it is very necessary to carry out research and analysis on the hyperbolic rough surface of the preformed clamp.

[0004] At present, the research on fretting wear of preformed clamps is a research method combining theory and experiment. This method cannot reflect the stress changes in the whole process of fretting wear, cannot obtain the relationship between stress and wear depth in any process, ignores the influence of the structural curve interface and roughness on fretting wear, and it is difficult to systematically evaluate the action law of fretting factors on the degree of fretting wear. Therefore, it is necessary to find a simulation calculation method for fretting wear that can evaluate the true morphology of the preformed wire, so as to provide a reference for reducing the risk of fretting wear of the preformed clamp and ensuring the safety and stability of the preformed clamp under various working conditions. Summary of the Invention

[0005] In view of this, in order to solve the problems in the prior art that the fretting factors have an impact on the degree of wear when the preformed clamp undergoes fretting wear, the conventional modeling cannot reflect the structural curve interface of the clamp, and the true rough morphology of the contact interface of the clamp is ignored, the invention provides a simulation modeling method for the hyperbolic rough surface of the preformed clamp.

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

[0007] A simulation modeling method for the double-curved rough surface of a preformed clamp, comprising the following steps:

[0008] S1. Determine the structural parameters of the preformed strands and the conductor in the preformed clamp;

[0009] S2. Construct a two-dimensional double-curved contact model of the clamp according to the determined structural parameters;

[0010] S3. Use the W-M fractal function to simulate the rough surface effect of the preformed clamp;

[0011] Assign values to the parameters in the W-M fractal function. The specific W-M fractal function is:

[0012]

[0013] Z is the curve height; x is the coordinate position; G is the characteristic length scale coefficient; D is the fractal dimension; γ is the spatial frequency of the profile; n is the spatial frequency coefficient, and n1 is the coefficient corresponding to the lowest cut-off frequency.

[0014] S4. Convert the W-M fractal function into a hyperbolic linear rough surface profile, use MATLAB to generate the fractal profile curve, and export the fractal profile points;

[0015] Convert the W-M fractal function into a hyperbolic linear surface, convert the linear rough surface into a rough surface with surface characteristics through the straightening curve formula, use MATLAB to generate the fractal profile curve, and export the fractal profile points; specifically, the straightening curve formula is:

[0016] Δy = y i ′ - y i (2)

[0017] y i ′ = y i +Δy = y i +(R 2 -x i 2 ) 1 / 2 (3)

[0018] Where y i ′ is a point on the curve, y i is a point on the straight line, Δy is the vertical distance between the curve point and the straight line point, R is the radius of the clamp, x is the horizontal axis coordinate of the point, and the straightening curve formula is imported into matlab to generate the fractal profile points.

[0019] S5. Write the profiling contour points into a script program through Python programming, and establish a simulation model of the hyperbolic rough surface of the preformed clamp in the ABAQUS finite element software.

[0020] Furthermore, the structural parameters in step S1 include the radius r1 of the preformed wire, the radius r2 of the conductor, the angle θ between the preformed wire and the conductor, and the material properties, where the material properties refer to the density, elastic modulus, and Poisson's ratio of the material.

[0021] Furthermore, in the hyperbolic two-dimensional contact model in step S2, the contact form between the preformed wire and the conductor is the point contact form of double circular cross-sections; since the preformed wire and the conductor are in the same direction of twisting, the spiral angles between the wires are not much different and can be approximately regarded as parallel. At this time, θ = 0, and the contact form is regarded as the line-line contact form in the contact area.

[0022] Furthermore, in step S3, when the surface profile is normally distributed, γ takes 1.5, and n1 is related to the intercepted length L.

[0023] Furthermore, in step S5, the fractal contour points are established through Python language programming and then imported into ABAQUS for visual analysis.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The simulation modeling method of the hyperbolic rough surface of the preformed clamp disclosed by the present invention adopts the strategy of a two-dimensional simplified model. Compared with the three-dimensional model, it greatly saves the calculation cost and improves the solution efficiency of the model.

[0026] 2. The simulation modeling method of the hyperbolic rough surface of the preformed clamp disclosed by the present invention adopts the double circular cross-section contact form, which is closer to the real contact state compared with the surface-plane contact form, and effectively simulates the non-smooth surface of the clamp caused by manufacturing, transportation, etc. Therefore, it is very necessary to study the fretting wear of the rough surface.

[0027] 3. The simulation modeling method of the hyperbolic rough surface of the preformed clamp disclosed by the present invention. The W-M fractal function has characteristics such as continuity, non-differentiability everywhere, and self-affinity, so it is often used to characterize the microscopic profile of the machined surface; the W-M fractal function is used to simulate the contact interface between the preformed wire and the conductor. When D is fixed, a unique rough surface profile can be obtained, which can restore the real morphology, and the calculation results are more reliable and can provide a reference for the prevention and control of preformed clamp diseases.

[0028] Other advantages, objectives, and features of the present invention will be set forth to some extent in the following description, and to some extent, will be obvious to those skilled in the art based on an examination of the following, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following description. Brief Description of the Drawings

[0029] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0030] Figure 1 is a schematic diagram of wear contact in a simulation modeling method for a hyperbolic rough surface of a preformed clamp in the present invention;

[0031] Figure 2 is a schematic diagram of a two-dimensional contact simplified model in a simulation modeling method for a hyperbolic rough surface of a preformed clamp in the present invention;

[0032] Figure 3 is a schematic diagram of a linear rough surface profile in a simulation modeling method for a hyperbolic rough surface of a preformed clamp in the present invention;

[0033] Figure 4 is a schematic diagram of straightening a curve in a simulation modeling method for a hyperbolic rough surface of a preformed clamp in an embodiment of the present invention; Figure 4 (a) is a schematic diagram of straightening a curve when the characteristic length scale coefficient G is fixed; Figure 4 (b) is a schematic diagram of straightening a curve when the fractal dimension D is fixed;

[0034] Figure 5 is a schematic diagram of a rough surface of a curved surface profile in a simulation modeling method for a hyperbolic rough surface of a preformed clamp in an embodiment of the present invention;

[0035] Figure 6 is a schematic diagram of a finite element contact profile of a rough surface profile in a simulation modeling method for a hyperbolic rough surface of a preformed clamp in an embodiment of the present invention;

[0036] Figure 7 is a schematic diagram of the ratio of contact stress between a smooth surface and a rough surface in a simulation modeling method for a hyperbolic rough surface of a preformed clamp in an embodiment of the present invention. Detailed Embodiments

[0037] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. All details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments only schematically illustrate the basic concept of the present invention. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0038] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams rather than physical diagrams, and should not be construed as limiting the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which do not represent the dimensions of actual products; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0039] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0040] A simulation modeling method for the double-curved rough surface of a preformed wire clamp includes the following steps:

[0041] S1. Determine the structural parameters of the preformed wires and the conductor in the preformed wire clamp. The structural parameters include the radius r1 of the preformed wire, the radius r2 of the conductor, the included angle θ between the preformed wire and the conductor, and the material properties;

[0042] S2. Refer to Figure 1 、 Figure 2 , and construct a double-curved two-dimensional contact model of the wire clamp according to the determined structural parameters;

[0043] In the double-curved two-dimensional contact model, the contact form between the preformed wire and the conductor is a double-circular cross-section point contact form; since the preformed wire and the conductor are in the same-direction twisting manner and the spiral angles between the wires are not much different, they can be approximately regarded as parallel. At this time, θ = 0, and at the contact area, it can be regarded as a line-line contact form. At the same time, in order to save the calculation cost, considering that the wear point enters and then leaves the contact interface, only the fretting wear situation of one contact point between the preformed wire and the conductor is studied.

[0044] S3. Use the W-M (WeierStrass-Mandellbrot) fractal function to simulate the rough surface effect of the preformed clamp;

[0045] Assign values to the parameters in the W-M fractal function. The specific W-M fractal function is:

[0046]

[0047] Z is the curve height; x is the coordinate position; G is the characteristic length scale coefficient; D is the fractal dimension; γ is the spatial frequency of the profile, taking 1.5 when the surface profile is normally distributed; n is the spatial frequency coefficient, and n1 is the coefficient corresponding to the lowest cut-off frequency, related to the intercepted length L.

[0048] S4. Refer to Figure 3 , convert the W-M fractal function into a hyperbolic linear rough surface profile, use MATLAB to generate the fractal contour curve, and export the fractal contour points;

[0049] Convert the W-M fractal function into a hyperbolic linear surface, convert the linear rough surface into a rough surface with surface characteristics through the straightening curve formula, use MATLAB to generate the fractal contour curve, and export the fractal contour points; specifically, the straightening curve formula is:

[0050] Δy = y i ′ - y i (2)

[0051] y i ′ = y i +Δy = y i +(R 2 -x i 2 ) 1 / 2 (3)

[0052] where y i ′ is a point on the curve, y i is a point on the straight line, Δy is the vertical distance between the curve point and the straight line point, R is the radius of the clamp, x is the horizontal axis coordinate of the point. Import the straightening curve formula into matlab to generate the fractal contour points.

[0053] S5. Write the fractal contour points into the script program through Python programming, and establish a simulation model of the hyperbolic rough surface of the preformed clamp in the ABAQUS finite element software. The fractal contour points are established through Python language programming and then imported into ABAQUS for visual analysis.

[0054] Taking the micro-motion wear contact analysis of the preformed clamp as an example, this implementation illustrates a simulation modeling method for the hyperbolic rough surface of the preformed clamp. The specific implementation steps are as follows:

[0055] (1) In MATLAB, select x = 0.3 mm as the sampling length, and 0.0025 mm as the interval for each micro-protrusion, with a total of 120 fractal contour points. The fractal parameters are shown in Table 1, and the rough surface is as Figure 4 shown.

[0056] Table 1 Fractal function parameters

[0057]

[0058] (2) Convert the linear rough surface into a curved surface linear rough surface according to the straightening curve formula, as Figure 5 shown.

[0059] (3) Write a program in Python language and import it into ABAQUS to establish a hyperbolic rough surface contact model, and assign the structural parameters shown in Table 2. The finite element model of the hyperbolic rough contact surface is as Figure 6 shown.

[0060] (4) By applying vertical loads to the two-dimensional smooth contact model and the two-dimensional hyperbolic rough surface contact model, as Figure 7 shown, the results show that for the smooth surface, the stress distribution is uniform and symmetric on the left and right; there are multiple stress concentration positions on the rough surface, which is significantly different from the finite element results of the smooth surface. The main factors affecting fretting wear (contact stress, contact slip) are directly related to the contact state, indicating that the rough surface has an impact on fretting wear.

[0061] Table 2 Geometric dimensions and material parameters of the preformed clamp

[0062]

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A simulation modeling method for the double-curved rough surface of a preformed clamp, characterized in that It includes the following steps: S1. Determine the structural parameters of the preformed strands and the conductor in the preformed clamp; S2. Construct a hyperbolic two-dimensional contact model of the clamp according to the determined structural parameters; S3. Use the W-M fractal function to simulate the rough surface effect of the preformed clamp; Assign values to the parameters in the W-M fractal function. Specifically, the W-M fractal function is: Z is the curve height; x is the coordinate position; G is the characteristic length scale coefficient; D is the fractal dimension; γ is the spatial frequency of the profile; n is the spatial frequency coefficient, and n1 is the coefficient corresponding to the lowest cut-off frequency; S4. Convert the W-M fractal function into a hyperbolic linear rough surface profile, use MATLAB to generate the profiled contour curve, and export the profiled contour points; Convert the W-M fractal function into a hyperbolic linear surface, convert the linear rough surface into a rough surface with surface characteristics through the straightening curve formula, use MATLAB to generate the profiled contour curve, and export the profiled contour points. Specifically, the straightening curve formula is: Δy = y i ′ - y i (2) y i ′ = y i +Δy = y i +(R 2 -x i 2 ) 1 / 2 (3) where y i ′ is a point on the curve, y i is a point on the straight line, Δy is the vertical distance between the curve point and the straight line point, R is the radius of the wire clamp, x is the horizontal coordinate of the point. The straightening-to-curve formula is imported into Matlab to generate fractal contour points. S5. Write the profiled contour points into the script program, and establish a simulation model of the hyperbolic rough surface of the preformed clamp in the ABAQUS finite element software. The structural parameters in step S1 include the radius r1 of the preformed strand, the radius r2 of the conductor, the included angle θ between the preformed strand and the conductor, and the material properties. The material properties refer to the density, elastic modulus, and Poisson's ratio of the material. In the hyperbolic two-dimensional contact model in step S2, the contact form between the preformed strand and the conductor is a double-circular cross-section point contact form; since the preformed strand and the conductor are in the same-direction twisting method and the spiral angles between the strands are not much different, they are approximately regarded as parallel states. At this time, θ = 0, and the contact form is regarded as a line-line contact form in the contact area.

2. The simulation modeling method of the double-curved rough surface of the preformed clamp according to claim 1, wherein, In step S3, when the surface profile is normally distributed, γ is taken as 1.5, and n1 is related to the intercepted length L.

3. The simulation modeling method of the double-curved rough surface of the preformed wire clamp according to claim 1, wherein In step S5, the profiled contour points are established through Python language programming and then imported into ABAQUS for visual analysis.

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