Conductive slip ring rough surface modeling method based on finite element

Abstract

The invention discloses a conductive slip ring rough surface modeling method based on a finite element, and the method comprises the steps: S1, obtaining the surface topography data of a conductive slip ring rough surface, converting the surface topography data into a two-dimensional matrix, carrying out the interpolation processing, and determining a circular ring region of a slip ring; s2, extracting data points in the circular ring area, converting the data points into data points in a Cartesian coordinate system, and further determining node representation of circular ring modeling; s3, node representation of the circular ring modeling is converted into a Node data format and an Element data format respectively; and S4, forming a modeling file by using the data in the Node data format and the Element data format, and importing the modeling file into modeling software to generate a rough surface model of the conductive slip ring.

Description

Technical Field

[0001] The invention belongs to the field of computer-aided design (CAD) and engineering simulation, and in particular relates to a finite element-based modeling method for a rough surface of a conductive slip ring. Background Art

[0002] In engineering practice, rough surface modeling is crucial for simulating real engineering problems and accurately predicting material behavior and performance. However, existing rough surface modeling methods have certain limitations, such as cumbersome modeling steps, low efficiency, low model accuracy, and limited modeling shapes. An existing method for modeling real rough surfaces is to use programming languages ​​to build solid models in finite element software, but this method is inefficient for models with more rough surface details and cannot independently define circular ring shape models.

[0003] For the circular surface of the conductive slip ring, the traditional modeling method can only establish a square rough surface solid model, and then generate a circular ring through the cutting function, which is extremely inefficient. The import of a large amount of data will make it very easy for the solid model to fail to be successfully established. In view of the situation that the surface of the space conductive slip ring is rough due to wear during operation, it is impossible to effectively and conveniently model the surface roughness of the circular ring in the finite element calculation. Therefore, it is necessary to propose a modeling method for the rough surface of the conductive slip ring. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the finite element-based rough surface modeling method of a conductive slip ring provided by the present invention solves the problem that the traditional modeling method for the annular surface of a conductive slip ring has extremely low modeling efficiency and the import of a large amount of data will result in the problem that the solid model is very likely to fail to be successfully established.

[0005] In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: a method for modeling the rough surface of a conductive slip ring based on finite elements, comprising the following steps:

[0006] S1, obtaining the surface morphology data of the rough surface of the conductive slip ring, converting it into a two-dimensional matrix and performing interpolation processing to determine the circular ring area of ​​the slip ring;

[0007] S2, extracting data points in the annular region and converting them into data points in a Cartesian coordinate system, thereby determining node representations for annular modeling;

[0008] S3, converting the node representation of the ring modeling into Node data format and Element data format respectively;

[0009] S4. The data in the Node data format and the Element data format are formed into a modeling file and imported into the modeling software to generate a rough surface model of the conductive slip ring.

[0010] Furthermore, the step S1 is specifically as follows:

[0011] S11, obtaining the surface morphology data of the rough surface of the conductive slip ring, and converting it into a two-dimensional matrix of m0×n0; each data in the two-dimensional matrix corresponds to a value in the z direction;

[0012] S12, according to the two-dimensional matrix m0×n0, set the length L of the surface morphology in the x direction x =(n0-1)*Δx and y length L y =(m0-1)*Δy; where Δx and Δy are the distances between data in the x-direction and the y-direction respectively;

[0013] S13, performing spline interpolation processing on the two-dimensional matrix of m0×n0 to generate a two-dimensional matrix of m1×n1; wherein m1>m0, n1>n0;

[0014] S14. Based on the m1×n1 two-dimensional matrix, according to L x and L y , determine the annular area of ​​the slip ring.

[0015] Furthermore, in step S14, the inner diameter r of the annular region inter and outer diameter r outer Satisfy: min(L x , L y )>r outer >r inter .

[0016] Furthermore, the step S2 is specifically as follows:

[0017] S21, extracting data points within the annular region and constructing a polar coordinate system;

[0018] The data points in the polar coordinate system are represented as:

[0019]

[0020]

[0021] In the formula, theta represents the angle, R represents the radius, and x and y represent the horizontal and vertical coordinates in the Cartesian coordinate system;

[0022] S22, re-interpolate the data points in the polar coordinate system to generate a two-dimensional matrix of size m2×n2 consisting of angle theta and radius R;

[0023] S23, according to the m2×n2 two-dimensional matrix, convert the polar coordinate system into a Cartesian coordinate system, and then generate an m3×n3 two-dimensional matrix;

[0024] S24, according to the two-dimensional matrix of m3×n3, determine the node representation (x i，j ,y i,j );

[0025] x i，j =R*cos(theta);

[0026] y i，j =R*sin(theta);

[0027] In the formula, x i，j is the x-coordinate of the node, i=1,...,m3,j=1,...,n3,m3 is the number of nodes on the outer diameter of the annular region, and n3 is the number of radial node layers in the annular region.

[0028] Furthermore, in step S23, in the generated two-dimensional matrix of m3×n3, the slip ring radius satisfies:

[0029]

[0030] In the formula, r inter and r outer Represent the inner and outer diameters of the annular area respectively.

[0031] Furthermore, in step S24, when the thickness of the slip ring is considered, the node representation of the ring modeling also includes:

[0032] z i，j,k =z i，j,1 -(k-1)×h / (hNum-1);

[0033] In the formula, z i，j,k is the z-axis coordinate of the node, i=1,...,m3, j=1,...,n3, k=1,...,hNum, h is the reference thickness of the slip ring, and hNum is the number of node layers in the thickness direction.

[0034] Furthermore, in step S3, the Node data format is expressed as:

[0035] (NodeN=1,...,i×j), (x i，j ), (y i，j ), (z i，j,k );

[0036] In the formula, i=1,...,m3, j=1,...,n3.

[0037] Further, in step S3, the Element data format includes a quadrilateral unit format for a shell model and a hexahedral unit format for a three-dimensional solid model;

[0038] The shell model is expressed as:

[0039]

[0040] The three-dimensional solid model is represented as:

[0041]

[0042]

[0043]

[0044]

[0045] The beneficial effects of the present invention are:

[0046] (1) The present invention can customize the rough grid shell model of the ring with different inner and outer diameters, and the rough three-dimensional grid model of the ring with different inner and outer diameters and different shapes.

[0047] (2) The present invention establishes a coarse grid model, which, compared with a coarse solid model, can still ensure a very high modeling efficiency in the case of a large amount of data.

[0048] (3) The rough surface morphology data in the present invention can be obtained by an optical profilometer or other instrument, or the surface morphology can be generated separately according to the roughness or other requirements. The rough surface data has high controllability and a high degree of freedom. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A flow chart of the finite element based conductive slip ring rough surface modeling method provided by the present invention.

[0050] Figure 2 Schematic diagram of the slip ring extraction process provided by the present invention.

[0051] Figure 3 This is a schematic diagram of the shell model provided by the present invention.

[0052] Figure 4 This is a schematic diagram of a three-dimensional solid model provided by the present invention.

[0053] Figure 5 A schematic diagram of the modeling process in the Abaqus finite element software provided by the present invention. DETAILED DESCRIPTION

[0054] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0055] The embodiment of the present invention provides a method for modeling a rough surface of a conductive slip ring based on finite elements, such as Figure 1 As shown, the following steps are included:

[0056] S1, obtaining the surface morphology data of the rough surface of the conductive slip ring, converting it into a two-dimensional matrix and performing interpolation processing to determine the circular ring area of ​​the slip ring;

[0057] S2, extracting data points in the annular region and converting them into data points in a Cartesian coordinate system, thereby determining node representations for annular modeling;

[0058] S3, converting the node representation of the ring modeling into Node data format and Element data format respectively;

[0059] S4. The data in the Node data format and the Element data format are formed into a modeling file and imported into the modeling software to generate a rough surface model of the conductive slip ring.

[0060] Exemplarily, in this embodiment, taking Abaqus finite element software as an example, the python tool is used to write the code of the above method to realize the modeling function.

[0061] For example, Figure 2 As shown, the extraction process of the ring area and its modeling node representation in the above method is demonstrated.

[0062] In this embodiment, step S1 is specifically as follows:

[0063] S11, obtaining the surface morphology data of the rough surface of the conductive slip ring, and converting it into a two-dimensional matrix of m0×n0; each data in the two-dimensional matrix corresponds to a value in the z direction;

[0064] Optionally, the surface topography data is automatically generated using a python tool or the surface topography data of the rough surface is obtained using an optical profilometer;

[0065] Optionally, the values ​​of m0 and n0 are at least greater than 100, because too little data does not have much meaning for the rough surface morphology;

[0066] S12, according to the two-dimensional matrix m0×n0, set the length L of the surface morphology in the x direction x=(n0-1)*Δx and y length L y =(m0-1)*Δy; where Δx and Δy are the distances between data in the x-direction and the y-direction respectively;

[0067] S13, performing spline interpolation processing on the two-dimensional matrix of m0×n0 to generate a two-dimensional matrix of m1×n1; wherein m1>m0, n1>n0;

[0068] In this embodiment, the data volume is increased by performing spline interpolation processing on the two-dimensional matrix to prepare for the subsequent extraction of slip ring mapping data;

[0069] S14. Based on the m1×n1 two-dimensional matrix, according to L x and L y , determine the annular area.

[0070] In step S14 of this embodiment, after data interpolation processing, a large amount of data is available in the ring to generate a fine rough surface mesh model. Based on this, the inner diameter r of the annular area is inter and outer diameter r outer Satisfy: min(L x , L y )>r outer >r inter .

[0071] Step S2 of the embodiment of the present invention is specifically as follows:

[0072] S21, extracting data points within the annular region and constructing a polar coordinate system;

[0073] The data points in the polar coordinate system are represented as:

[0074]

[0075]

[0076] In the formula, theta represents the angle, R represents the radius, and x and y represent the horizontal and vertical coordinates in the Cartesian coordinate system;

[0077] S22, re-interpolate the data points in the polar coordinate system to generate a two-dimensional matrix of size m2×n2 consisting of angle theta and radius R;

[0078] In this embodiment, since the data of the slip ring and the rectangle are not completely equivalent and compatible, NaN will appear in the play. Therefore, in order to process this missing data, this type of data will only appear at the edge of the ring and the number is relatively small, so the nearest equal idea is adopted to assign the value;

[0079] Optionally, the interpolation in this embodiment adopts spline interpolation. In the polar coordinate system, the angle is evenly divided into m2 angles from -π to π, R is between the inner diameter and the outer diameter, including the inner and outer diameters, and the ring is evenly divided into n2 circles according to the radius; the angle and radius here are polar coordinates. After conversion to the polar coordinate system, a radius and angle can determine the position of a point;

[0080] S23, according to the m2×n2 two-dimensional matrix, convert the polar coordinate system into a Cartesian coordinate system, and then generate an m3×n3 two-dimensional matrix;

[0081] S24, according to the two-dimensional matrix of m3×n3, determine the node representation (x i,j ,y i,j );

[0082] x i,j =R*cos(theta);

[0083] y i,j =R*sin(theta);

[0084] In the formula, x i,j is the x-coordinate of the node, i=1,...,m3,j=1,...,n3,m3 is the number of nodes on the outer diameter of the annular region, and n3 is the number of radial node layers in the annular region.

[0085] In step S23 of this embodiment, in the generated two-dimensional matrix of m3×n3, the slip ring radius satisfies:

[0086]

[0087] In the formula, r inter and r outer Represent the inner and outer diameters of the annular area respectively.

[0088] In this embodiment, the shape of the m3×n3 matrix is ​​rectangular, and the purpose is to obtain a circular ring shape. However, this matrix is ​​converted from polar coordinates to Cartesian coordinates. It should have been circular, but after conversion to Cartesian coordinates, it becomes an m3×n3 matrix. Therefore, it is only necessary to connect the matrix end to end to form a circular ring.

[0089] For example, in Figure 2 It shows how to convert the polar coordinate system to the Cartesian coordinate system to generate a matrix, connect the matrix end to end to form a ring, and map each point of the matrix onto the ring.

[0090] In step S24 of this embodiment, when the thickness of the slip ring is considered, the node representation of the ring modeling further includes:

[0091] zi,j,k =z i,j,1 -(k-1)×h / (hNum-1);

[0092] In the formula, z i,j,k is the z-axis coordinate of the node, i=1,...,m3, j=1,...,n3, k=1,...,hNum, h is the reference thickness of the slip ring, and hNum is the number of node layers in the thickness direction.

[0093] For example, since the value of k only affects the z direction, x i，j,k =x i,j ,y i,j,k =y i,j .

[0094] In step S3 of this embodiment, for the inp file, the Node data format is: Node number, x, y, z;

[0095] The mathematical form of the Node data format is:

[0096] (NodeN=1,...,i×j), (x i，j ), (y i，j ), (z i,j,k );

[0097] In the formula, i=1,...,m3, j=1,...,n3.

[0098] In step S3 of this embodiment, the Element data format includes a quadrilateral unit format for a shell model and a hexahedral unit format for a three-dimensional solid model;

[0099] Specifically, the shell model is expressed as:

[0100]

[0101] Among them, the four nodes corresponding to each N4 are connected in sequence to form a minimum quadrilateral unit.

[0102] The three-dimensional solid model is represented as:

[0103]

[0104]

[0105]

[0106]

[0107] Among them, the eight nodes corresponding to each N8 are connected in sequence to form a minimum hexahedral unit.

[0108] Exemplarily, the modeling file in step S4 of this embodiment is an inp file of Node data and Element data, and the modeling software is Abaqus software.

[0109] Specifically, after writing the Node data and Element data into the inp file, manually import it into the software (Abaqus finite element software), or use the following statement to import it:

[0110] mdb.ModelFromInputFile(name=Model_name, inputFileName=inp_path);

[0111] A rough surface model of the ring with customizable ring size and rough surface data can be generated for simulation analysis and performance optimization of conductive slip rings, as well as simulation analysis of the rough surface of the ring involving other application approaches.

[0112] like Figure 5 As shown in the figure, the process of implementing the rough surface modeling of the conductive slip ring in Abaqus based on the above method is given. Figure 5 It can be seen that when obtaining the surface contour of a face, the normal height data of a rectangular face is usually obtained, and it is impossible to set it separately for the shape, which leads to difficulties in finite element calculation.

[0113] First of all, the shape of the ring plays an important role in specific simulation conditions. Taking the optical profilometer as an example, the surface morphology obtained is in the form of a two-dimensional matrix. The idea of ​​the present invention is to select a ring in the matrix and peel it out to prepare for the subsequent node coordinate allocation. Therefore, the original data (two-dimensional matrix) is encrypted by spline interpolation and then the data in the ring is extracted. The significance of interpolation here is that the data of the inner and outer diameter edges of the ring can be richer, which can fully reduce the distortion of the ring morphology.

[0114] Secondly, directly building a rough solid model is inefficient, time-consuming, and even distorted in some areas. As the basis of finite element calculation, the rough mesh model only needs to reasonably control the position of each node to ensure that the rough mesh model can be calculated normally. This method of only controlling the position of each node is very fast with the code implementation.

[0115] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0116] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A rough surface modeling method of conductive slip ring based on finite element, It is characterized in that The following steps are involved: S1, obtaining the surface morphology data of the rough surface of the conductive slip ring, converting it into a two-dimensional matrix and performing interpolation processing to determine the circular ring area of ​​the slip ring; S2, extracting data points in the annular region and converting them into data points in a Cartesian coordinate system, thereby determining node representations for annular modeling; S3, converting the node representation of the ring modeling into Node data format and Element data format respectively; S4. The data in the Node data format and the Element data format are formed into a modeling file and imported into the modeling software to generate a rough surface model of the conductive slip ring.

2. According to the finite element based conductive slip ring rough surface modeling method of claim 1, It is characterized in that The step S1 is specifically as follows: S11, obtain the surface morphology data of the rough surface of the conductive slip ring and convert it into m 0 ×n 0 A two-dimensional matrix; each data in the two-dimensional matrix corresponds to a value in the z direction; S12, according to m 0 ×n 0 The two-dimensional matrix sets the surface morphology in the x-direction length L x =(n 0 -1)*ΔThe length L in x and y directions y =(m 0 -1)*Δy; where Δx and Δy are the distances between data in the x-direction and y-direction respectively; S13, for m 0 ×n 0 The two-dimensional matrix is ​​processed by spline interpolation to generate m 1 ×n 1 A two-dimensional matrix; where m 1 >m 0 , n 1 >n 0 ; S14, in m 1 ×n 1 Based on the two-dimensional matrix, according to L x and L y , determine the annular area of ​​the slip ring.

3. According to the finite element-based rough surface modeling method of a conductive slip ring according to claim 2, It is characterized in that In step S14, the inner diameter r of the annular region inter and outer diameter r outer Satisfy: min(L x , L y )>r outer >r inter .

4. According to the finite element-based rough surface modeling method of a conductive slip ring according to claim 1, It is characterized in that The step S2 is specifically as follows: S21, extracting data points within the annular region and constructing a polar coordinate system; The data points in the polar coordinate system are represented as: In the formula, theta represents the angle, R represents the radius, and x and y represent the horizontal and vertical coordinates in the Cartesian coordinate system; S22. Re-interpolate the data points in the polar coordinate system to generate a value of size m consisting of angle theta and radius R 2 ×n 2 A two-dimensional matrix of S23, according to m 2 ×n 2 The two-dimensional matrix converts the polar coordinate system into the Cartesian coordinate system, and then generates m 3 ×n 3 A two-dimensional matrix of S24, according to m 3 ×n 3 The two-dimensional matrix determines the node representation of the ring modeling (x i，j ,y i，j ); x i，j =R*cos(theta); the i，j =R*sin(theta); In the formula, x i，j is the x-coordinate of the node, i=1,...,m 3 ,j=1,...,n 3 , m 3 is the number of nodes on the outer diameter of the annular region, n 3 is the number of radial node layers in the annular region.

5. According to the finite element-based rough surface modeling method of a conductive slip ring according to claim 4, It is characterized in that In the step S23, the generated m 3 ×n 3 In the two-dimensional matrix, the slip ring radius satisfies: In the formula, r inter and r outer Represent the inner and outer diameters of the annular area respectively.

6. The method for modeling the rough surface of a conductive slip ring based on finite element according to claim 4, It is characterized in that In step S24, when the thickness of the slip ring is considered, the node representation of the ring modeling also includes: z i，j,k (z.) i，j,1 -(k-1)×h / (hNum-1) In the formula, z i，j,k is the z-axis coordinate of the node, i=1,...,m 3 ,j=1,...,n 3 , k=1,...,hNum, h is the reference thickness of the slip ring, and hNum is the number of node layers in the thickness direction.

7. The method for modeling the rough surface of a conductive slip ring based on finite element according to claim 6, It is characterized in that In step S3, the Node data format is expressed as: (NodeN=1,...,i×j),(x i,j ),(y i，j ),(z i,j,k ); Where i = 1, ..., m 3 ,j=1,...,n 3 .

8. The method for modeling the rough surface of a conductive slip ring based on finite element according to claim 7, It is characterized in that In the step S3, the Element data format includes a quadrilateral unit format for a shell model and a hexahedral unit format for a three-dimensional solid model; The shell model is expressed as: The three-dimensional solid model is represented as:

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