A method and device for predicting electrical contact behavior of rough surface based on boundary element method

Abstract

The embodiment of the present application provides a method for predicting the electrical contact behavior of a rough surface based on the boundary element method. According to the surface morphology or surface parameters, a rough surface is numerically generated to obtain a first target parameter; the electrical contact load condition, material parameters and contact parameters are determined to obtain a second target parameter; an iterative optimization method is determined, and according to the first target parameter and the second target parameter, the electrical contact behavior is numerically predicted based on the boundary element method of Fourier transform to obtain an electrical contact result. Among them, the basic solution of the multi-field coupled electrical contact result in the frequency domain is derived by the Fourier transform method, and the displacement solution that meets the contact conditions can be obtained by the iterative optimization method. After determining the final contact pressure, the contact area is determined based on the analysis of the contact pressure distribution, and the contact resistance, temperature distribution, etc. are determined at the same time. This application not only greatly improves the prediction efficiency of the electrical contact result of the rough surface, but also can ensure the same calculation accuracy as the finite element.

Description

Technical Field

[0001] The present application relates to the field of electrical contact technology, and in particular to a method for predicting electrical contact behavior of a rough surface based on a boundary element method. Background Art

[0002] Electrical contact is a common phenomenon in electronics, communications, control, and power systems. Electrical contact is required between components of modern industrial systems, between entire machines, and even between systems to achieve electrical connection. Commonly used electrical contact components in industry include electrical connectors, relays, switches, potentiometers, rheostats, brushes, conductive slip rings, etc. The electrical contact problem is a typical electric-thermal-mechanical multi-field coupling problem, and the roughness of the contact interface needs to be considered. Real contact occurs on the rough peaks of the contact surface. The rough peaks are mechanically deformed, and contact resistance is formed when current flows through these contact spots. Due to the Joule heating of the contact resistance, the temperature of the contact interface rises, further affecting the contact behavior of the rough surface.

[0003] Existing research mainly focuses on the field of mechanical contact mechanics, as well as the calculation and prediction of contact resistance. It is difficult to consider multi-field coupling and rough surface modeling in theoretical methods. The simulation method based on the finite element method can naturally consider the impact of multi-field coupling, and thus becomes a more commonly used method. However, since the finite element simulation method requires a large number of grids to discretize the rough surface, the modeling is complex and the calculation efficiency is low. Therefore, it is necessary to develop efficient numerical methods to analyze the electrical contact problem on rough surfaces and determine the electrical contact results such as the contact force, contact area, contact resistance, current, and temperature rise distribution on the surface of the electrical contact behavior. Summary of the invention

[0004] The purpose of the embodiment of the present application is to provide a rough surface electrical contact behavior prediction method based on the boundary element method to improve the efficiency of analyzing rough surface electrical contact problems. The specific technical solution is as follows:

[0005] In a first aspect of the implementation of the present application, a method for predicting electrical contact behavior of a rough surface based on a boundary element method is first provided, comprising:

[0006] According to the real rough surface morphology or surface parameters, a rough surface is numerically generated to obtain a first target parameter; the surface morphology and surface parameters include: at least one of a morphology function, a power spectrum density function and a height distribution law; the rough surface is characterized as a group of discrete nodes;

[0007] Determine electrical contact load conditions, material parameters and contact parameters to obtain second target parameters, wherein the contact parameters include: contact conductance and contact thermal conductance;

[0008] An iterative optimization method is determined, and according to the first target parameter and the second target parameter, the electrical contact behavior is numerically predicted based on the boundary element method of Fourier transform to obtain an electrical contact result.

[0009] Optionally, the iterative optimization method includes: a conjugate gradient method and a steepest descent method; the iterative optimization method is determined, according to the first target parameter and the second target parameter, based on a boundary element method of Fourier transform, to perform numerical prediction on the electrical contact behavior, including:

[0010] Determine an iterative optimization method and initialize iterative parameters, wherein the iterative parameters include: a maximum iterative parameter, a tolerance, and a contact pressure, wherein the initial values ​​of the contact pressure must all be non-negative values;

[0011] The electrical contact behavior is numerically predicted using the first target parameter and the second target parameter, as well as the basic solution of the displacement and temperature distribution in the frequency domain, combined with the objectives and constraints of the optimization iteration, wherein the displacement and temperature distribution appear multiple times during the iteration process, and the result at the end of the iteration process is the electrical contact result, and the results at other times are the intermediate values ​​generated by the Fourier transform.

[0012] Optionally, the objectives of the optimization iteration include:

[0013]

[0014] The constraints are:

[0015]

[0016]

[0017]

[0018] Among them, g kl represents the normal gap between each node on the contact surface and the rough surface, p kl represents the contact pressure, and the subscripts k and l represent the node numbers of the discrete rough surface in the x and y directions, respectively satisfying 1≤k≤N x ,1≤l≤N y ,; represents the set of nodes involved in the contact, l x With l y are the lengths of the discrete grid in two directions, N x ×N y Characterize the number of discrete nodes on the rough surface.

[0019] Optionally, numerically generating a rough surface according to the surface morphology or surface parameters includes:

[0020] The rough surface is numerically generated using the topography function; the topography function includes:

[0021]

[0022] Where D is the fractal dimension, G is the fractal scale factor, L represents the length of the surface, n min and n max are the minimum and maximum wave numbers on the surface, respectively, M represents the maximum number of ridges on the surface, γ is the wavelength ratio, and h(x, y) characterizes the rough surface.

[0023] Optionally, the load conditions include contact force and total voltage, and the material parameters include elastic modulus, Poisson's ratio, thermal expansion coefficient, heat transfer coefficient and resistivity.

[0024] Optionally, the contact conductance is a function related to contact pressure or contact gap.

[0025] In a second aspect of the implementation of the present application, a rough surface electrical contact behavior prediction device based on a boundary element method is also provided, comprising:

[0026] A numerical generation module, used to numerically generate a rough surface according to a surface morphology or a surface parameter to obtain a first target parameter; the surface morphology and the surface parameter include: at least one of a morphology function, a power spectrum density function and a height distribution law; the rough surface is characterized as a group of discrete nodes;

[0027] A parameter input module is used to determine the electrical contact load condition, material parameters and contact parameters to obtain a second target parameter, wherein the contact parameters include: contact conductance and contact thermal conductance;

[0028] The method determination module is used to determine the iterative optimization method, and according to the first target parameter and the second target parameter, the boundary element method based on Fourier transform is used to numerically predict the electrical contact behavior to obtain the electrical contact result.

[0029] Optionally, the iterative optimization method includes: a conjugate gradient method and a steepest descent method; the method determination module is specifically used to determine the iterative optimization method, and numerically predict the electrical contact behavior based on the boundary element method of Fourier transform according to the first target parameter and the second target parameter, including:

[0030] Determine an iterative optimization method and initialize iterative parameters, wherein the iterative parameters include: a maximum iterative parameter, a tolerance, and a contact pressure, wherein the initial values ​​of the contact pressure must all be non-negative values;

[0031] The electrical contact behavior is numerically predicted using the first target parameter and the second target parameter, as well as the basic solution of the displacement and temperature distribution in the frequency domain, combined with the objectives and constraints of the optimization iteration, wherein the displacement and temperature distribution appear multiple times during the iteration process, and the result at the end of the iteration process is the electrical contact result, and the results at other times are the intermediate values ​​generated by the Fourier transform.

[0032] Optionally, the objectives of the optimization iteration include:

[0033]

[0034] The constraints are:

[0035]

[0036]

[0037]

[0038] Among them, g kl represents the normal gap between each node on the contact surface and the rough surface, p kl represents the contact pressure, and the subscripts k and l represent the node numbers of the discrete rough surface in the x and y directions, respectively satisfying 1≤k≤N x ,1≤l≤N y ,; represents the set of nodes involved in the contact, l x With l y are the lengths of the discrete grid in two directions respectively.

[0039] In another aspect of the implementation of the present application, an embodiment of the present application provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus;

[0040] Memory, used to store computer programs;

[0041] The processor is used to implement the steps of a method for predicting electrical contact behavior of rough surface based on boundary element method when executing the program stored in the memory.

[0042] The embodiment of the present application provides a method for predicting the electrical contact behavior of a rough surface based on the boundary element method. According to the surface morphology or surface parameters, the rough surface is numerically generated to obtain the first target parameter; the electrical contact load condition, material parameter and contact parameter are determined to obtain the second target parameter; the iterative optimization method is determined, and according to the first target parameter and the second target parameter, the electrical contact behavior is numerically predicted based on the boundary element method of Fourier transform to obtain the electrical contact result. Among them, the basic solution of the multi-field coupled electrical contact result in the frequency domain is derived by the Fourier transform method, and the displacement solution that meets the contact condition can be obtained by the iterative optimization method, and the contact pressure distribution can be determined at the same time; the contact conductance can be set to be related to the contact pressure or to the contact gap, so as to determine the current density distribution on the contact surface; the potential distribution is determined according to the current density iteration, and the contact resistance and current are further calculated; after determining the final contact pressure, the contact area is determined according to the analysis of the contact pressure distribution. The present application not only greatly improves the prediction efficiency of the electrical contact result of the rough surface, but also can ensure the same calculation accuracy as the finite element. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0044] Figure 1 This is a flow chart of a method for predicting electrical contact behavior on a rough surface based on the boundary element method in an embodiment of the present application.

[0045] Figure 2 It is a schematic diagram of the multi-field coupled rough surface electrical contact problem applicable to the present application;

[0046] Figure 3 It is a schematic diagram of cyclic arrangement and zero padding used in the frequency domain in this application;

[0047] Figure 4 is an iterative solution flow chart of an embodiment of the present application;

[0048] Figure 5 is a schematic diagram of the contact area calculation method of the present application;

[0049] Figure 6 It is the finite element verification model diagram of this application;

[0050] Figure 7 is a rough surface profile diagram used in the embodiments of the present application;

[0051] Figure 8 is a comparison chart of the calculation results of this application and the finite element results;

[0052] Fig. 9It is a comparison chart between the temperature distribution calculation results of this application and the finite element results;

[0053] Fig.10 It is a comparison chart of the calculation time of this application and the calculation time of the finite element model. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] In order to solve the problems in the prior art, the present application provides a rough surface electrical contact behavior prediction method based on the boundary element method to improve the efficiency of analyzing rough surface electrical contact problems.

[0056] It should be noted that the rough surface electrical contact behavior prediction method based on the boundary element method provided in the embodiment of the present application can be applied to electronic devices. In practical applications, the electronic device can be: smart phones, tablet computers, laptop computers and other devices, which is reasonable.

[0057] The following first introduces a method for predicting electrical contact behavior of a rough surface based on the boundary element method provided in an embodiment of the present application.

[0058] like Figure 1 As shown, a method for predicting electrical contact behavior of a rough surface based on a boundary element method provided in an embodiment of the present application may include the following steps:

[0059] S101, numerically generate a rough surface according to a real rough surface morphology or surface parameters to obtain a first target parameter; the surface morphology and surface parameters include: at least one of a morphology function, a power spectrum density function and a height distribution law; the rough surface is characterized as a set of discrete nodes.

[0060] It is understandable that in order to facilitate the numerical prediction of the electrical contact behavior, the rough surface can be numerically processed, for example, the rough surface can be characterized as a set of discrete nodes.

[0061] For example, Figure 2 As shown, it is assumed that a rigid body with a rough surface compresses a deformable elastic base Β under the action of contact force. The base height is h0 and the nominal area is L x ×L y The total voltage ΔV is applied to each contact roughness peak. When a current flows (current density is J), a surface heat flux Q will be generated due to the effect of Joule heat. s , the heat flow is evenly divided between the upper and lower surfaces. Therefore, the electrical contact process is a multi-field coupling problem of electricity, heat, and force, and the main heat generation location is on the contact surface.

[0062] Exemplarily, in one implementation, numerically generating a rough surface according to a surface morphology or a surface parameter may include: numerically generating a rough surface using a morphology function; the morphology function may include:

[0063]

[0064] Where D is the fractal dimension, G is the fractal scale factor, L represents the length of the surface, n min and n max are the minimum and maximum wave numbers on the surface, respectively, M represents the maximum number of ridges on the surface, γ is the wavelength ratio, and h(x, y) characterizes the rough surface. The topography function can be a two-dimensional Weierstrass-Mandelbrot function.

[0065] Then, through this topography function, the rough surface can be characterized as a set of discrete nodes (number N x ×N y ), and determine the height h0 of the base and the nominal area L of the contact surface x ×L y .

[0066] In addition, the power spectrum density function and height distribution law in the present application may be related functions or parameters that can realize numerical rough surface in the prior art, and will not be described in detail here.

[0067] S102, determining electrical contact load conditions, material parameters and contact parameters to obtain second target parameters, wherein the contact parameters include: contact electrical conductance and contact thermal conductance;

[0068] It can be understood that in order to obtain electrical contact results, it is necessary to first determine relevant conditions or parameters, such as electrical contact load conditions, material parameters, and contact parameters, etc., wherein the electrical contact load conditions may include: contact force and total voltage (or current), etc., and the material parameters may include elastic modulus, Poisson's ratio, heat transfer coefficient, thermal expansion coefficient, and resistivity, etc.; the contact parameters may include contact conductance and contact thermal conductance, etc., wherein, in this embodiment, the contact conductance can be set as a function related to the contact pressure or contact gap.

[0069] In addition, in order to obtain electrical contact results under different materials and contact conditions (for example, contact force, contact area, contact resistance, current, distribution of temperature rise on the surface, etc.), the settings of material parameters and contact parameters may be different, which is reasonable.

[0070] S103, determining an iterative optimization method, and numerically predicting the electrical contact behavior based on the first target parameter and the second target parameter and the boundary element method of Fourier transform to obtain an electrical contact result.

[0071] It is understandable that there may be a variety of iterative optimization methods, such as the conjugate gradient method and the steepest descent method.

[0072] Exemplarily, in one implementation, determining the iterative optimization method, and numerically predicting the electrical contact behavior based on the boundary element method of Fourier transform according to the first target parameter and the second target parameter may include:

[0073] Determine an iterative optimization method and initialize iterative parameters, the iterative parameters including: maximum iterative parameter, tolerance and contact pressure, wherein the initial values ​​of the contact pressure must all be non-negative values;

[0074] The electrical contact behavior is numerically predicted using the first target parameter and the second target parameter, as well as the basic solution of the displacement and temperature distribution in the frequency domain, combined with the objectives and constraints of the optimization iteration, wherein the displacement and temperature distribution appear multiple times during the iteration process, and the result at the end of the iteration process is the electrical contact result, and the results at other times are the intermediate values ​​generated by the Fourier transform.

[0075] Among them, the basic solution of displacement and temperature distribution in the frequency domain is derived from the stress equilibrium equation, geometric equation and thermoelastic constitutive equation in elastic mechanics, as well as the heat conduction equation in the frequency domain. The above equations can obtain the equations of the basic solution of displacement and temperature distribution in the frequency domain.

[0076] For example, the basic solution of displacement and temperature distribution in the frequency domain can be expressed as:

[0077]

[0078]

[0079] in represents the displacement field in the frequency domain, and the subscript 3 represents the z direction of the three-dimensional rectangular coordinate system. represents the temperature in the frequency domain, and the brackets (q,z) represent the coordinates of the discrete nodes in the frequency domain. When z is 0, it represents the contact surface. represents the displacement component of each discrete point on the contact surface in the z direction. The displacement components of all discrete points constitute the displacement field of the contact in this direction (this definition also applies below). The symbols v and μ represent the Poisson's ratio and shear modulus of the material respectively. e represents the base of the natural logarithm (a constant with a value of 2.71828...), and h0 is the height of the base of the electrical contact problem under study. and They represent the contact pressure distribution and heat flux density on the contact surface in the frequency domain, respectively, and α and κ represent the thermal expansion coefficient and thermal conductivity coefficient of the material, respectively. According to the meaning of the iterative optimization process, these results will make the intermediate quantities such as tolerances approach the conditions for the end of the iteration during the optimization iteration process.

[0080] It is understandable that after determining the iterative optimization method, parameter initialization settings can be made for the selected iterative optimization method and the electrical contact results to be obtained, wherein the iterative parameters may include: maximum iteration parameter, tolerance, contact pressure, etc. Exemplarily, after determining the optimization iterative method, the ratio of the contact force to the nominal contact area can be used as the initial value of the contact pressure distribution, and the maximum number of iterations, iteration tolerance, and other necessary parameters can be determined.

[0081] In addition, in the iterative optimization process, due to the need for calculation, intermediate quantities will be generated. In order to eliminate the calculation errors caused by the finite size and asymmetric conditions of the intermediate quantities, for example, Figure 3 As shown in the figure, the intermediate quantities will be filled with zeros. For example, the calculated intermediate quantity heat flux distribution and contact pressure distribution will be filled with zeros, and the frequency domain solutions of displacement and temperature will be cyclically arranged to make them symmetrical about the zero-frequency characteristic quantity to meet the symmetry characteristics required by Fourier transform. The contact pressure distribution can be used to calculate the contact area, and other electrical contact results can be obtained in the iterative solution process.

[0082] It should be noted that in order to obtain electrical contact results, after determining the iterative optimization method, the optimization iteration objectives and constraints will be set.

[0083] Exemplarily, in one implementation, the objectives of the optimization iteration include:

[0084]

[0085] The constraints are:

[0086]

[0087]

[0088]

[0089] Among them, gkl represents the normal gap between each node on the contact surface and the rough surface, p kl represents the contact pressure, and the subscripts k and l represent the node numbers of the discrete rough surface in the x and y directions, respectively satisfying 1≤k≤N x ,1≤l≤N y ,; represents the set of nodes involved in the contact, l x With l y are the lengths of the discrete grid in two directions, N x ×N y Characterize the number of discrete nodes on the rough surface.

[0090] Exemplarily, the conditions for terminating the optimization iterative algorithm may be determined according to the algorithm, for example, when the iterative error between two results reaches the required tolerance range, or when the difference between the integral of the contact pressure on the contact surface and the contact force reaches the tolerance requirement, or when the number of iterations reaches the maximum number of iterations, or when multiple consecutive iterations fail to reduce the error.

[0091] In this application, a rough surface is numerically generated according to the real rough surface morphology or surface parameters to obtain the first target parameter; the electrical contact load condition, material parameters and contact parameters are determined to obtain the second target parameter; an iterative optimization method is determined, and according to the first target parameter and the second target parameter, the boundary element method based on Fourier transform is used to numerically predict the electrical contact behavior to obtain the electrical contact result. Among them, the basic solution of the multi-field coupled electrical contact result in the frequency domain is derived by the Fourier transform method, and the displacement solution that meets the contact condition can be obtained by the iterative optimization method, and the contact pressure distribution can be determined at the same time; the contact conductance can be set to be related to the contact pressure or to the contact gap, so as to determine the current density distribution on the contact surface; the potential distribution is determined according to the current density iteration, and the contact resistance and current are further calculated; after determining the final contact pressure, the contact area is determined according to the analysis of the contact pressure distribution. This application not only greatly improves the prediction efficiency of the electrical contact result of the rough surface, but also can ensure the same calculation accuracy as the finite element.

[0092] In order to further illustrate the solution of the present application, the following is combined with a specific example, selecting the iterative optimization method as the conjugate gradient method, and introducing a method for predicting electrical contact behavior on a rough surface based on the boundary element method of the present application.

[0093] like Figure 4 As shown, a method for predicting electrical contact behavior of a rough surface based on a boundary element method may include the following steps:

[0094] Step A, input the rough surface profile h(x,y), load conditions P and ΔV, and material parameters;

[0095] Step B, initializing the contact pressure p0(x,y)≥0 on each node;

[0096] Step C, determine the iteration parameters: maximum number of iterations k max and tolerance ε err , and set the number of iterations k = 1;

[0097] Step D, calculate the potential V based on the frequency domain solution of the electric field and the contact pressure distribution k (x,y,0), current density ECD k and heat flux Q s,k ;

[0098] The calculation method of the electric potential is briefly described as follows: the electric potential drop between the contact surfaces is calculated by the product of the current density and the contact conductance, and the electric potential distribution on the contact surface is calculated by the current density distribution combined with the frequency domain solution of the electric potential. The sum of the electric potential drop on the contact surface and the surface electric potential distribution is a given voltage. With this restriction, the electric potential distribution can be determined within a finite number of iterations. The distribution of the current density is the same as the contact pressure distribution, that is, the current density at the node where the contact pressure is zero is also zero. Therefore, the current density can be updated after each contact pressure distribution update, and then the electric potential distribution, current, and contact resistance can be calculated.

[0099] For example, the frequency domain solution of the potential distribution and the current density on the contact surface can be expressed as

[0100]

[0101]

[0102]

[0103] in, is the frequency domain solution of the electric potential, which is derived from the distribution equation of the electric potential (satisfying the Laplace equation) in the frequency domain by considering the finite boundary. (q x ,q y ,z) is the coordinate of the discrete point in the frequency domain, ρ is the resistivity of the material, represents the Fourier transform of the current density, A0 represents the nominal contact area of ​​the contact surface, and the remaining symbols and parameters have been defined above.

[0104] Step E, calculate the displacement field u according to the frequency domain solution of the displacement field and temperature field 3,k (x,y,0) and temperature field T k (x,y,0);

[0105] Step F, calculating the optimization direction and iteration step size of the conjugate gradient method;

[0106] Step G, update the contact pressure distribution p k (x, y);

[0107] Step H, determining whether the iterative optimization end condition is met, if so, proceeding to step I, if not, setting k=k+1 and returning to step D;

[0108] The end condition includes: when the difference between the integral of the contact pressure on the contact surface and the contact force reaches the tolerance requirement, that is, ||p k -p k-1 ||<ε err , or when the number of iterations reaches the maximum number of iterations, that is, k>k max ;

[0109] Step I, calculating the actual contact area according to the contact pressure distribution p(x, y);

[0110] For example, Figure 5 As shown in the figure, the method for calculating the contact area of ​​the present application is as follows: first, the contact spot area is segmented and identified according to the eight-connectedness rule or the four-connectedness rule. Taking the eight-connectedness rule as an example, its meaning is to divide the nodes adjacent to a node in the horizontal, vertical and diagonal directions and the current node into the same area, and each connected area is a contact spot. At a certain contact spot, the discrete contact area is the node area with a positive contact pressure, and the boundary area is the node grid contained in the perimeter of the spot. The present invention uses Figure 5 The sum of the discrete contact area and the corrected contact area is the contact area.

[0111] Step J, output contact force P, contact area A r , contact pressure distribution p(x, y), displacement field u3(x, y, 0), potential distribution V(x, y, 0), potential drop ΔV on the contact surface f , current I, contact resistance R c And the surface temperature increment distribution T(x,y,0).

[0112] Next, the finite element method is used to compare and verify the present invention. A 10mm×10mm×2mm cuboid is established as an elastic substrate, and a rigid plate with a rough surface, such as Figure 6 As shown. Abaqus software is used to set the material parameters in Table 1, and the electric-thermal-mechanical full coupling module is used for calculation. The contact mode uses face-to-face contact, and the rough surface is set as the main contact surface. After the calculation is completed, the corresponding electrical contact results are extracted and compared with the results determined by the present invention.

[0113] Table 1 Material parameters

[0114]

[0115] In this embodiment, a fractal surface is generated using a topography function (two-dimensional Weierstrass-Mandelbrot function), M is 10, and γ is 1.5. Figure 7 The parameters used for the middle surface are: D = 2.3, G = 7.49 × 10 -6 μm、n min =5, n max =11, L=10mm and N p =320, where N p is the number of scattered points in all directions on the surface. In this embodiment, N x =N y =N p .

[0116] This application uses the conjugate gradient method to optimize and iterate to determine the electrical contact results, including the contact area-contact force curve, the contact resistance-contact force curve, the current-contact force curve and the surface maximum temperature-contact force curve, such as Figure 8 The results are in good agreement with the finite element results. By comparison, the error between the electrical contact results determined by this application and the finite element results is within 1%, which proves the effectiveness of the rough surface electrical contact behavior prediction method based on the boundary element method in this application. In addition, the temperature distribution results when the contact force is 5.35kN in the calculation results are extracted and compared with the finite element results. The comparison results are shown in Fig. 9 As shown, it can be seen that the temperature distribution results are equally accurate.

[0117] In order to prove that the calculation efficiency of the present invention is higher than that of the finite element method, a single rough peak electrical contact problem and a sinusoidal wave surface electrical contact problem are selected to compare the calculation time. The calculation time is summarized as follows: Fig.10 The number of computer cores used by the two methods is 64 cores for the present invention and 128 cores for the finite element method. It can be seen that the present invention greatly shortens the calculation time compared with the finite element method.

[0118] With respect to the above method embodiment, the present application embodiment provides a numerical prediction device for electrical contact behavior based on the boundary element method, which may include:

[0119] A numerical generation module, used to numerically generate a rough surface according to a surface morphology or a surface parameter to obtain a first target parameter; the surface morphology and the surface parameter include: at least one of a morphology function, a power spectrum density function and a height distribution law; the rough surface is characterized as a group of discrete nodes;

[0120] A parameter input module is used to determine the electrical contact load condition, material parameters and contact parameters to obtain a second target parameter, wherein the contact parameters include: contact conductance and contact thermal conductance;

[0121] The method determination module is used to determine the iterative optimization method, and according to the first target parameter and the second target parameter, the boundary element method based on Fourier transform is used to numerically predict the electrical contact behavior to obtain the electrical contact result.

[0122] In this embodiment, according to the surface morphology or surface parameters, a rough surface is numerically generated to obtain the first target parameter; the electrical contact load condition, material parameters and contact parameters are determined to obtain the second target parameter; an iterative optimization method is determined, and according to the first target parameter and the second target parameter, the electrical contact behavior is numerically predicted based on the boundary element method of Fourier transform to obtain the electrical contact result. Among them, the basic solution of the multi-field coupled electrical contact result in the frequency domain is derived by the Fourier transform method, and the displacement solution that meets the contact condition can be obtained by the iterative optimization method, and the contact pressure distribution can be determined at the same time; the contact conductivity can be set to be related to the contact pressure or to the contact gap, so as to determine the current density distribution on the contact surface; the potential distribution is determined according to the current density iteration, and the contact resistance and current are further calculated; after determining the final contact pressure, the contact area is determined according to the analysis of the contact pressure distribution. This application not only greatly improves the prediction efficiency of the electrical contact result of the rough surface, but also can ensure the same calculation accuracy as the finite element.

[0123] Optionally, the iterative optimization method includes: a conjugate gradient method and a steepest descent method; the method determination module is specifically used to determine the iterative optimization method, and according to the first target parameter and the second target parameter, a boundary element method based on Fourier transform is used to numerically predict the electrical contact behavior, including:

[0124] Determine an iterative optimization method and initialize iterative parameters, wherein the iterative parameters include: a maximum iterative parameter, a tolerance, and a contact pressure, wherein the initial values ​​of the contact pressure must all be non-negative values;

[0125] The electrical contact behavior is numerically predicted using the first target parameter and the second target parameter, as well as the basic solution of the displacement and temperature distribution in the frequency domain, combined with the objectives and constraints of the optimization iteration, wherein the displacement and temperature distribution appear multiple times during the iteration process, and the result at the end of the iteration process is the electrical contact result, and the results at other times are the intermediate values ​​generated by the Fourier transform.

[0126] Optionally, the goals of the optimization iteration include:

[0127]

[0128] The constraints are:

[0129]

[0130]

[0131]

[0132] Among them, g kl represents the normal gap between each node on the contact surface and the rough surface, p kl represents the contact pressure, and the subscripts k and l represent the node numbers of the discrete rough surface in the x and y directions, respectively satisfying 1≤k≤N x ,1≤l≤N y ,; represents the set of nodes involved in the contact, l x With l y are the lengths of the discrete grid in two directions respectively.

[0133] Optionally, the numerical generation module specifically adopts the topography function to numerically generate a rough surface; the topography function includes:

[0134]

[0135] Where D is the fractal dimension, G is the fractal scale factor, L represents the length of the surface, n min and n max are the minimum and maximum wave numbers on the surface, respectively, M represents the maximum number of ridges on the surface, γ is the wavelength ratio, and h(x, y) characterizes the rough surface.

[0136] Optionally, the load conditions include contact force and total voltage, and the material parameters include elastic modulus, Poisson's ratio, thermal expansion coefficient, heat transfer coefficient and resistivity.

[0137] Optionally, the contact conductance is a function related to contact pressure or contact gap.

[0138] The embodiment of the present application also provides an electronic device, including a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus.

[0139] Memory, used to store computer programs;

[0140] The processor is used to implement a rough surface electrical contact behavior prediction method based on the boundary element method provided in an embodiment of the present application when executing the program stored in the memory xx3.

[0141] The communication bus mentioned in the above terminal can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus.

[0142] The communication interface is used for communication between the above terminal and other devices.

[0143] The memory may include a random access memory (RAM) or a non-volatile memory, such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0144] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0145] In another embodiment provided in the present application, a computer-readable storage medium is also provided, in which a computer program is stored. When the computer program is executed by a processor, the numerical prediction method of electrical contact behavior based on the boundary element method described in any of the above embodiments is implemented.

[0146] In another embodiment provided in the present application, a computer program product comprising instructions is also provided, which, when executed on a computer, enables the computer to execute the numerical prediction method for electrical contact behavior based on the boundary element method as described in any of the above embodiments.

[0147] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive Solid State Disk (SSD)), etc.

[0148] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0149] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0150] The above description is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A method for predicting electrical contact behavior of rough surfaces based on boundary element method, characterized in that: include: According to the real rough surface morphology or surface parameters, a rough surface is numerically generated to obtain a first target parameter; The surface morphology and surface parameters include: at least one of a morphology function, a power spectrum density function and a height distribution law; the rough surface is characterized as a group of discrete nodes; Determine electrical contact load conditions, material parameters and contact parameters to obtain second target parameters, wherein the contact parameters include: contact conductance and contact thermal conductance; Determine an iterative optimization method, perform numerical prediction on the electrical contact behavior based on the first target parameter and the second target parameter and the boundary element method of Fourier transform to obtain an electrical contact result; The iterative optimization method includes: a conjugate gradient method and a steepest descent method; the iterative optimization method is determined, according to the first target parameter and the second target parameter, based on the boundary element method of Fourier transform, to perform numerical prediction on the electrical contact behavior, including: Determine an iterative optimization method and initialize iterative parameters, wherein the iterative parameters include: a maximum iterative parameter, a tolerance, and a contact pressure, wherein the initial values ​​of the contact pressure must all be non-negative values; The first target parameter and the second target parameter, as well as the basic solution of the displacement and temperature distribution in the frequency domain, are used to numerically predict the electrical contact behavior in combination with the target and constraint conditions of the optimization iteration; wherein the displacement and temperature distribution appear multiple times during the iteration process, and the result at the end of the iteration process is the electrical contact result, and the results at other times are the intermediate values ​​generated by Fourier transform; Among them, the basic solutions of displacement and temperature distribution in the frequency domain are derived from the stress equilibrium equation, geometric equation and thermoelastic constitutive equation in elastic mechanics, as well as the heat conduction equation in the frequency domain; The basic solution of displacement and temperature distribution in the frequency domain is expressed as: in represents the displacement field in the frequency domain, and the subscript 3 represents the z direction of the three-dimensional rectangular coordinate system. represents the temperature in the frequency domain, and the brackets (q,z) represent the coordinates of the discrete nodes in the frequency domain. When z is 0, it represents the contact surface. represents the displacement component of each discrete point on the contact surface in the z direction. The displacement components of all discrete points constitute the displacement field of the contact in this direction. The symbols v and μ represent the Poisson's ratio and shear modulus of the material respectively. e represents the base of the natural logarithm. h0 is the height of the base of the electrical contact problem under study. and They represent the contact pressure distribution and heat flux density on the contact surface in the frequency domain, respectively. α and κ are the thermal expansion coefficient and thermal conductivity coefficient of the material, respectively.

2. The method according to claim 1, characterized in that The goals of the optimization iterations include: The constraints are: Among them, g kl represents the normal gap between each node on the contact surface and the rough surface, p kl represents the contact pressure, and the subscripts k and l represent the node numbers of the discrete rough surface in the x and y directions, respectively satisfying 1≤k≤N x ,1≤l≤N y ,; represents the set of nodes involved in the contact, l x With l y are the lengths of the discrete grid in two directions, N x ×N y Characterize the number of discrete nodes on the rough surface.

3. The method according to claim 1 or 2, characterized in that: The method of numerically generating a rough surface according to the real rough surface morphology or surface parameters comprises: The rough surface is numerically generated using the topography function; the topography function includes: Where D is the fractal dimension, G is the fractal scale factor, L represents the length of the surface, n min and n max are the minimum and maximum wave numbers on the surface, respectively, M represents the maximum number of ridges on the surface, γ is the wavelength ratio, and h(x, y) characterizes the rough surface.

4. The method according to claim 1 or 2, characterized in that: The load conditions include contact force and total voltage, and the material parameters include elastic modulus, Poisson's ratio, thermal expansion coefficient, heat transfer coefficient and resistivity.

5. The method according to claim 1, characterized in that The contact conductance is a function related to the contact pressure or the contact gap.

6. A numerical prediction device for electrical contact behavior based on boundary element method, characterized in that: The method for implementing the prediction method in claim 1 comprises: A numerical generation module, used to numerically generate a rough surface according to a surface morphology or a surface parameter to obtain a first target parameter; the surface morphology and the surface parameter include: at least one of a morphology function, a power spectrum density function and a height distribution law; the rough surface is characterized as a group of discrete nodes; A parameter input module is used to determine the electrical contact load condition, material parameters and contact parameters to obtain a second target parameter, wherein the contact parameters include: contact conductance and contact thermal conductance; The method determination module is used to determine the iterative optimization method, and according to the first target parameter and the second target parameter, the boundary element method based on Fourier transform is used to numerically predict the electrical contact behavior to obtain the electrical contact result.

7. The device according to claim 6, characterized in that The iterative optimization method includes: a conjugate gradient method and a steepest descent method; the method determination module is specifically used to determine the iterative optimization method, and numerically predict the electrical contact behavior based on the boundary element method of Fourier transform according to the first target parameter and the second target parameter, including: Determine an iterative optimization method and initialize iterative parameters, wherein the iterative parameters include: a maximum iterative parameter, a tolerance, and a contact pressure, wherein the initial values ​​of the contact pressure must all be non-negative values; The electrical contact behavior is numerically predicted using the first target parameter and the second target parameter, as well as a basic solution of displacement and temperature distribution in the frequency domain, combined with the objectives and constraints of the optimization iteration.

8. The device according to claim 7, characterized in that The goals of the optimization iterations include: The constraints are: Among them, g kl represents the normal gap between each node on the contact surface and the rough surface, p kl represents the contact pressure, and the subscripts k and l represent the node numbers of the discrete rough surface in the x and y directions, respectively satisfying 1≤k≤N x ,1≤l≤N y ,; represents the set of nodes involved in the contact, l x With l y are the lengths of the discrete grid in two directions respectively.

9. An electronic device, characterized in that: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; Memory, used to store computer programs; A processor, for implementing the method steps described in any one of claims 1 to 5 when executing a program stored in a memory.

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