CN111695272B - Rivet type contact surface roughness characterization method based on rotation fusion - Google Patents
Rivet type contact surface roughness characterization method based on rotation fusion Download PDFInfo
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Abstract
The invention discloses a rivet type contact surface roughness characterization method based on rotary fusion, which comprises the following steps: acquiring the surface height information of the rivet-shaped contact and converting the surface height information into a monochromatic matrix; the contact edge recognition obtains irregular intermittent black contact edges; fitting the radius value to obtain the most suitable fitting circle; determining the maximum inscribed rectangle of the fitting circle; selecting a proper rotation angle, and calculating the initial rectangular roughness effective area ratio and the surface roughness effective area ratio of the rivet-shaped contact obtained after rotation; calculating roughness of the monochromatic matrix in different directions; and fusing the roughness in different directions to obtain the roughness of the fitting original surface, obtaining rectangular roughness parameters corresponding to different angles through rotation of the maximum inscribed rectangle, and fusing the rivet type roughness parameters to obtain the surface roughness characterization parameters of the rivet type contact. The method of the invention covers the whole rivet-shaped contact surface, and solves the problem that the traditional rectangular area roughness calculation is easy to cause part of useful information to be lost.
Description
Technical Field
The invention relates to an electrical element contact surface roughness characterization technology, in particular to a rivet type contact surface roughness characterization method based on rotation fusion.
Background
The surface morphology of the relay contact directly affects the contact state and the service life of the relay, and has anisotropic and multi-scale characteristics, namely, the roughness changes along with the change of the scale and the direction. The currently used roughness parameter calculation method is suitable for rectangular surfaces under a single scale, and under different resolutions, fractal dimension is calculated to quantify the roughness parameters of the steel surface. The whole plane of the contact is in a non-rectangular state, and the shape parameter of the whole contact is measured by only taking the rectangular roughness parameter. The current roughness calculation is suitable for rectangular areas, and the surface morphology analysis of the rivet-type contact of the relay is only carried out in the research mode, so that the problem that part of useful information is lost and the whole part is hard to characterize is easily caused.
Disclosure of Invention
Aiming at the defects that the surface roughness characterization method of the relay contact in the prior art is easy to cause partial useful information to be lost and the like, the invention aims to provide the rivet type contact surface roughness characterization method based on rotary fusion, which is more scientific and comprehensive in characterization of the overall appearance of the contact.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention discloses a rivet type contact surface roughness characterization method based on rotary fusion, which comprises the following steps:
s1) acquiring the height information of the surface of the rivet-shaped contact, converting the height information data into a monochromatic matrix, and enhancing the contrast;
s2) identifying the contact edge, taking a monochromatic matrix as input, and adopting a Roberts edge detection operator to obtain an irregular intermittent black contact edge;
s3) fitting the numerical value of the fitting radius, namely fitting the irregular intermittent black edge into an approximate circle, searching a fitting circle with the highest fitting degree by utilizing the estimation range of the radius, selecting different thresholds, and detecting the fitting degree of more circles to obtain the most suitable fitting circle;
s4) determining the maximum inscribed rectangle of the fitting circle;
s5) selecting a proper rotation angle, taking a certain point (x, y) on the circular arc of a fitting circle as a center with the center (x 0, y 0) of the fitting circle surface, rotating the angle delta theta to obtain a point (x 1, y 1), further obtaining a rotation equation corresponding to the point (x, y) and the point (x 0, y 0), calculating the initial rectangular roughness effective area ratio and the rivet-shaped contact surface roughness effective area ratio obtained after rotation, and selecting a proper rotation angle theta;
s6) calculating roughness of the monochromatic matrix in different directions;
s7) fusing the roughness in different directions to obtain the roughness of the fitting original surface, obtaining rectangular roughness parameters corresponding to different angles through rotation of the largest inscribed rectangle, and fusing the rivet type roughness parameters to obtain the surface roughness characterization parameters of the rivet type contact.
In the step S4), the maximum inscribed rectangle of the fitting circle is determined and calculated by adopting a rotation coverage shape parameter, which is specifically as follows:
the coordinates of the circle center (x 0, y 0) of the fitting circle are ensured to be unchanged, the x axis and the y axis under the rectangular coordinate system are placed in a plane, a certain point (x, y) on the circular arc of the fitting circle is selected as a reference point variable, the point is connected with the circle center (x 0, y 0) of the image, four points are obtained by rotating 0 degrees, 90 degrees, 180 degrees and 270 degrees, and the four points are connected to obtain a square, namely the largest inscribed rectangle of the circle.
In the step S5), the initial rectangular roughness effective area ratio and the rivet-shaped contact surface roughness effective area ratio obtained after rotation are calculated, and a proper rotation angle θ is selected, and the method is realized by the following formula:
wherein ：Pq For the effective area duty ratio, R is the radius of the fitting circle, x is the abscissa of the boundary point of the fitting circle, y is the ordinate of the boundary point of the fitting circle,
θ is the selected rotation angle.
In the step S6), the roughness of the whole image in different directions is calculated, including the following steps:
moving the center point of the fitting circle to a (0, 0) point, and finding four coordinate points corresponding to positive and negative 1/2 length of a X, Y axis under a rectangular coordinate system, wherein a range matrix is the maximum inscription matrix of the fitting circle;
reversely rotating the largest inscribed rectangle around the (0, 0) point according to the rotation angle until the whole contact surface is covered, and repeatedly searching the largest inscribed matrix data;
processing the image in minimum unit, selecting the size of the active window as 2 k ×2 k The new matrix value is the average intensity value of the pixels in the active window, and the expression is as follows:
wherein x is the abscissa of the boundary point of the fitting circle, y is the ordinate of the boundary point of the fitting circle, k is more than or equal to 1, and g (i, j) is the gray value of the pixel (i, j);
for each pixel, the average intensity difference between windows of non-overlapping portions in both horizontal and vertical directions with the pixel as a center point is calculated as follows:
wherein ,Ek，h (x, y) is the difference in horizontal direction of the window mean value of each pixel in the image, E k，v (x, y) is the difference in vertical direction of the window mean for each pixel in the image;
comparing the window mean difference values in the horizontal direction and the vertical direction, and taking the larger value as the window mean difference value of the current pixel:
E k (x,y)＝max(E k,h (x,y),E k,v (x,y))
setting the optimal size S best (x,y)＝2 k Such that:
E k ＝E max ＝max(E 1 ,E 2 ,...E L )
wherein E is a window mean difference value, L is the number of windows, and k=1 to L.
In the step S7), rivet type roughness parameter fusion is carried out, and the steps are as follows:
selecting a rectangular roughness parameter mean value corresponding to a moving window with a rotation angle of 180 degrees as basic data, wherein the formula is as follows:
wherein t is the initial rotation angle, F crs (i) F is a rectangular roughness parameter value corresponding to a moving window with a rotation angle of 180 DEG E (i) The average value of the rectangular roughness parameters corresponding to the moving window with the rotation angle of 180 degrees is obtained.
Each moving window roughness data was fitted to a rivet-type roughness parameter value by the following formula:
wherein ,
to fit the post-circular roughness parameter value, F E (i) At a rotation angle of 180 DEGAnd H (i) is the H weight of different angles.
The weight H solving step is as follows:
s701) dividing the sequence of rectangular roughness parameters into different segments to form a data sequence P of length M i Calculating the data sequence P one by one i To generate a new data sequence R i Length n=m-1, the goal is to reduce short-term autocorrelation of the sequence;
R i ＝log(P i+1 /P i )i＝1,2,...,M-1.
s702) the new data sequence Ri with the length A is divided into n adjacent subintervals I a A=1, 2,..n, the mean value for each subset was calculated and noted as e a ：
S703) for each subset a, calculating a relative subset mean e a Accumulated dispersion X of (2) a ：
S704) calculating a maximum gap R for each of the dispersion sequences a Standard deviation S a ：
S705) calculating R/S value:
n is n adjacent subintervals selected in step S702);
s706) increasing the length of a, repeating steps S701) to S705) until a= (M-1)/2; linear regression fitting was performed with log (n) as the independent variable and log (R/S) as the dependent variable:
log(R/S)＝log(c)+H·log(n)+ε
the intercept of the regression equation is a constant in the above relationship, and ε is a constant value.
The estimated value of the slope is the calculated H weight.
The invention has the following beneficial effects and advantages:
1. according to the invention, through the analysis and research of the rivet-type relay contact, the mode of covering the whole rivet-type contact surface by utilizing the maximum inscribed rectangular rotation of the rivet-type research area is provided, the roughness in different directions is calculated, the roughness is fitted into the roughness of a circular surface, the problem that part of useful information is easy to be lost in the traditional calculation of the roughness of the rectangular area is avoided, and the overall appearance of the contact can be more scientifically and comprehensively represented.
2. The invention utilizes the rivet type surface roughness characterization method to calculate the roughness, further researches the surface morphology of the contact, and can more comprehensively analyze the contact performance of the contact group, further discusses the performance degradation mechanism of the relay.
Drawings
FIG. 1 is a flow chart of a method for characterizing rotational fusion surface roughness of a rivet-type contact, according to an embodiment of the present invention;
FIG. 2 is a three-dimensional topography of a contact in the present invention;
FIG. 3 is a grey scale view of a contact in the present invention;
FIG. 4 is a graph of contact edge line extraction and approximate circle fitting in accordance with the present invention;
FIG. 5 is a flow chart of the calculation of the weight H in the present invention;
FIG. 6 is a graph of calculated roughness in each direction in the present invention;
FIG. 7 is a graph showing the calculated values of the weights H in each direction according to the present invention.
Detailed Description
The invention is further elucidated below in connection with the drawings of the specification.
As shown in fig. 1, the rivet-type contact surface roughness characterization method based on rotary fusion comprises the following steps:
s1) acquiring the height information of the surface of the rivet-shaped contact, converting the height information data into a monochromatic matrix, and enhancing the contrast;
s2) identifying the contact edge, taking a monochromatic matrix as input, and adopting a Roberts edge detection operator to obtain an irregular intermittent black contact edge;
s3) fitting the numerical value of the fitting radius, namely fitting the irregular intermittent black edge into an approximate circle, searching a fitting circle with the highest fitting degree by utilizing the estimation range of the radius, selecting different thresholds, and detecting the fitting degree of more circles to obtain the most suitable fitting circle;
s4) determining the maximum inscribed rectangle of the fitting circle;
s5) selecting a proper rotation angle, taking a certain point (x, y) on the circular arc of a fitting circle as a center with the center (x 0, y 0) of the fitting circle surface, rotating the angle delta theta to obtain a point (x 1, y 1), further obtaining a rotation equation corresponding to the point (x, y) and the point (x 0, y 0), calculating the initial rectangular roughness effective area ratio and the rivet-shaped contact surface roughness effective area ratio obtained after rotation, and selecting a proper rotation angle theta;
s6) calculating roughness of the monochromatic matrix in different directions;
s7) fusing the roughness in different directions to obtain the roughness of the fitting original surface, obtaining rectangular roughness parameters corresponding to different angles through rotation of the largest inscribed rectangle, and fusing the rivet type roughness parameters to obtain the surface roughness characterization parameters of the rivet type contact.
According to the method, the boundary area of the rivet-type contact is automatically identified, the circle center radius value of the rivet-type contact is obtained through fitting, the circular area is accurately obtained, the largest inscribed rectangle is determined, the surface roughness of the contact in different directions is calculated in a mode that the largest inscribed rectangle rotates to cover the whole circular surface, the surface roughness parameter value of the rivet-type contact is calculated in different directions in a fusion mode, and a feasibility method is provided for the local characterization of the contact morphology. The shape of the relay contact is taken as an important influencing factor for evaluating the contact performance, and the service life of the relay contact is directly influenced. The rivet type surface roughness characterization method is used for calculating the roughness, the surface morphology of the contact is studied in depth (the three-dimensional morphology and the gray level diagram of the contact are respectively shown in fig. 2 and 3), the contact performance of the contact group can be analyzed more comprehensively, and further the performance degradation mechanism of the relay is studied in depth.
In step S2), the contact edge identification is to take a monochromatic matrix as input, adopt Roberts edge detection operators to derive each point of the monochromatic matrix, find the position of the gradient maximum value, mark and derive to obtain the irregular intermittent black contact edge, see black edge line in fig. 4.
In step S3), the radius values are fitted. The contact circular area is fitted first, and the radius search range needs to be determined. An interactive tool is used to estimate the diameter range of the edge, finding the appropriate approximate estimate of the radius range is 450, 550. Fitting the irregular intermittent black edges into approximate circles, searching for a fitting circle with highest fitting degree by using the radius estimation range, selecting different thresholds, and detecting fitting degrees of more circles to obtain the most suitable fitting circle. The center and radius values of the final fit circles are shown in Table 1 below.
Table 1 circle center and radius values of fitting circle
In step S4), the maximum inscribed rectangle of the fitting circle is determined and calculated by using the rotation coverage shape parameters, specifically:
the coordinates of the circle center (x 0, y 0) of the fitting circle are ensured to be unchanged, the x axis and the y axis under the rectangular coordinate system are placed in a plane, a certain point (x, y) on the circular arc of the fitting circle is selected as a reference point variable, the point is connected with the circle center (x 0, y 0) of the image, four points are obtained by rotating 0 degrees, 90 degrees, 180 degrees and 270 degrees, and the four points are connected to obtain a square, namely the largest inscribed rectangle of the circle.
In step S5), calculating the initial rectangular roughness effective area ratio and the rivet-shaped contact surface roughness effective area ratio obtained after rotation, selecting a proper rotation angle theta, and realizing the method by the following formula:
wherein ：Pq For the effective area duty ratio, R is the radius of the fitting circle, x is the abscissa of the boundary point of the fitting circle, y is the ordinate of the boundary point of the fitting circle,
θ is the selected rotation angle.
The rotation angle theta is selected to be 1 degrees, the effective area for calculating the surface roughness of the rivet-shaped contact is improved from 63.66% to 96.03%, and the greatest detailed information can be obtained as much as possible.
In step S6), the roughness of the whole image in different directions is calculated, comprising the steps of:
moving the center point of the fitting circle to a (0, 0) point, and finding four coordinate points corresponding to positive and negative 1/2 length of a X, Y axis under a rectangular coordinate system, wherein a range matrix is the maximum inscription matrix of the fitting circle;
reversely rotating the largest inscribed rectangle around the (0, 0) point according to the rotation angle until the whole contact surface is covered, and repeatedly searching the largest inscribed matrix data;
processing the image in minimum unit, selecting the size of the active window as 2 k ×2 k The new matrix value is the average intensity value of the pixels in the active window, and the expression is as follows:
wherein x is the abscissa of the boundary point of the fitting circle, y is the ordinate of the boundary point of the fitting circle, k is more than or equal to 1, and g (i, j) is the gray value of the pixel (i, j);
for each pixel, the average intensity difference between windows of non-overlapping portions in both horizontal and vertical directions with the pixel as a center point is calculated as follows:
wherein ,Ek，h (x, y) is the difference in horizontal direction of the window mean value of each pixel in the image, E k，v (x, y) is the difference in vertical direction of the window mean for each pixel in the image;
comparing the window mean difference values in the horizontal direction and the vertical direction, and taking the larger value as the window mean difference value of the current pixel:
E k (x,y)＝max(E k,h (x,y),E k,v (x,y))
setting the optimal size S best (x,y)＝2 k Such that:
E k ＝E max ＝max(E 1 ,E 2 ,...E L )
wherein E is a window mean difference value, L is the number of windows, and k=1 to L.
And setting the optimal scale to enable the E value to reach the maximum k value, and further obtaining the roughness value of the whole image.
The rotation angle is 1 degree and 360 degrees, the roughness values of 360 different angles are obtained, part of data are shown in table 2, and the roughness values are shown in fig. 6.
Table 2 roughness calculations for different angles
| Angle of | Roughness of | Angle of | Roughness of | Angle of | Roughness of | Angle of | Roughness of | Angle of | Roughness of |
| 1 | 30.1620 | 73 | 30.1038 | 145 | 30.1396 | 217 | 30.0227 | 289 | 30.0943 |
| 7 | 30.1567 | 81 | 30.1351 | 153 | 30.1280 | 225 | 30.1303 | 297 | 29.9927 |
| 17 | 30.1123 | 89 | 30.1607 | 161 | 30.1280 | 233 | 30.1579 | 305 | 30.0726 |
| 25 | 29.9657 | 97 | 30.1635 | 169 | 30.1580 | 241 | 30.1358 | 313 | 30.1099 |
| 33 | 30.0828 | 105 | 30.1465 | 177 | 30.1470 | 249 | 30.1367 | 321 | 30.1794 |
| 41 | 30.0451 | 113 | 30.0049 | 185 | 30.1815 | 257 | 30.1817 | 329 | 30.1486 |
| 49 | 30.1647 | 121 | 30.0378 | 193 | 30.1767 | 265 | 30.1585 | 337 | 30.1377 |
| 57 | 30.1408 | 129 | 30.0229 | 201 | 30.0662 | 273 | 30.1865 | 345 | 30.1359 |
| 65 | 30.1299 | 137 | 30.1484 | 209 | 29.9983 | 281 | 30.1841 | 353 | 30.1543 |
In the step S7), rivet type roughness parameter fusion is carried out, and the steps are as follows:
selecting a rectangular roughness parameter mean value corresponding to a moving window with a rotation angle of 180 degrees as basic data, wherein the formula is as follows:
wherein t is the initial rotation angle, F crs (i) F is a rectangular roughness parameter value corresponding to a moving window with a rotation angle of 180 DEG E (i) The average value of the rectangular roughness parameters corresponding to the moving window with the rotation angle of 180 degrees is obtained.
Each moving window roughness data was fitted to a rivet-type roughness parameter value by the following formula:
wherein ,
to fit the post-circular roughness parameter value, F E (i) And H (i) is H weight values of different angles, wherein the H is the average value of rectangular roughness parameters corresponding to a moving window with a rotation angle of 180 degrees.
The step of solving the weight H is shown in fig. 5, and specifically includes the following steps:
s701) dividing the sequence of rectangular roughness parameters into different segments to form a data sequence P of length M i Calculating the data sequence P one by one i To generate a new data sequence R i Length n=m-1, the goal is to reduce short-term autocorrelation of the sequence;
R i ＝log(P i+1 /P i )i＝1,2,...,M-1.
s702) the new data sequence Ri with the length A is divided into n adjacent subintervals I a A=1, 2,..n, the mean value for each subset was calculated and noted as e a ：
S703) for each subset a, calculating a relative subset mean e a Accumulated dispersion X of (2) a ：
S704) calculating a maximum gap R for each of the dispersion sequences a Standard deviation S a ：
S705) calculating R/S value:
n is n adjacent subintervals selected in step S702);
s706) increasing the length of a, repeating steps S701) to S705) until a= (M-1)/2; linear regression fitting was performed with log (n) as the independent variable and log (R/S) as the dependent variable:
log(R/S)＝log(c)+H·log(n)+ε
the intercept of the regression equation is a constant in the above relationship, and ε is a constant value.
The estimated value of the slope is the calculated H weight.
Data from different angles to 180 degrees of rotation angle are used as moving windows, 1 degree is set as angle difference, the R/S method is cycled, the weight H is calculated, part of the data is shown in Table 3, and the weight H of each direction is shown in FIG. 7.
Table 3 shows H values for different angles
And fusing the roughness of the round surface. Obtaining rectangular roughness parameters corresponding to different angles through rotation of the largest inscribed rectangle, fusing rivet type roughness parameters, selecting a rectangular roughness parameter mean value corresponding to a moving window with a rotation angle of 180 degrees as basic data, and adopting the formula:
fitting the product of the roughness data of each moving window and the ratio of the obtained weight H to a rivet-type roughness parameter value, wherein the formula is as follows:
the above procedure was used to fuse 30.1287, 28.9377, 29.1494, 28.3618, 27.7384 and 27.6924 for 6 different rivet contact roughness parameters.
The rotation fitting roughness obtained through fusion breaks the limit of the rectangular square matrix on the calculation of the current roughness, and a feasibility method is provided for the whole of the local characterization of the contact morphology. The shape of the relay contact is taken as an important influencing factor for evaluating the contact performance, and the service life of the relay contact is directly influenced. The method has the advantages that the circular roughness research method is utilized for extracting different texture features, the surface morphology of the contacts is further researched, the contact performance of the contact set can be more comprehensively analyzed, and further the performance degradation mechanism of the relay is further discussed.
Claims (2)
1. The rivet type contact surface roughness characterization method based on the rotary fusion is characterized by comprising the following steps of:
s1) acquiring the height information of the surface of the rivet-shaped contact, converting the height information data into a monochromatic matrix, and enhancing the contrast;
s2) identifying the contact edge, taking a monochromatic matrix as input, and adopting a Roberts edge detection operator to obtain an irregular intermittent black contact edge;
s3) fitting the numerical value of the fitting radius, namely fitting the irregular intermittent black edge into an approximate circle, searching a fitting circle with the highest fitting degree by utilizing the estimation range of the radius, selecting different thresholds, and detecting the fitting degree of more circles to obtain the most suitable fitting circle;
s4) determining the maximum inscribed rectangle of the fitting circle;
s5) selecting a proper rotation angle, taking a certain point (x, y) on the circular arc of a fitting circle as a center with the center (x 0, y 0) of the fitting circle surface, rotating the angle delta theta to obtain a point (x 1, y 1), further obtaining a rotation equation corresponding to the point (x, y) and the point (x 0, y 0), calculating the initial rectangular roughness effective area ratio and the rivet-shaped contact surface roughness effective area ratio obtained after rotation, and selecting a proper rotation angle theta;
s6) calculating roughness of the monochromatic matrix in different directions;
s7) fusing the roughness in different directions to obtain the roughness of the fitting original surface, obtaining rectangular roughness parameters corresponding to different angles through rotation of the largest inscribed rectangle, and fusing rivet type roughness parameters to obtain the surface roughness characterization parameters of the rivet type contact;
in the step S4), the maximum inscribed rectangle of the fitting circle is determined and calculated by adopting a rotation coverage shape parameter, which is specifically as follows:
ensuring that the coordinates of the circle center (x 0, y 0) of the fitting circle are unchanged, putting the x axis and the y axis in a rectangular coordinate system into a plane, selecting a certain point (x, y) on the circular arc of the fitting circle as a reference point variable, connecting the point with the circle center (x 0, y 0) of the image, rotating 0 degrees, 90 degrees, 180 degrees and 270 degrees to obtain four points, and connecting the four points to obtain a square, namely a maximum inscribed rectangle of the circle surface;
in the step S5), the initial rectangular roughness effective area ratio and the rivet-shaped contact surface roughness effective area ratio obtained after rotation are calculated, and a proper rotation angle θ is selected, and the method is realized by the following formula:
wherein ：Pq For the effective area duty ratio, R is the radius of the fitting circle, x is the abscissa of the boundary point of the fitting circle, y is the ordinate of the boundary point of the fitting circle,
θ is the selected rotation angle;
in the step S6), the roughness of the whole image in different directions is calculated, including the following steps:
moving the center point of the fitting circle to a (0, 0) point, and finding four coordinate points corresponding to positive and negative 1/2 length of a X, Y axis under a rectangular coordinate system, wherein a range matrix is the maximum inscription matrix of the fitting circle;
reversely rotating the largest inscribed rectangle around the (0, 0) point according to the rotation angle until the whole contact surface is covered, and repeatedly searching the largest inscribed matrix data;
processing the image in minimum unit, selecting the size of the active window as 2 k ×2 k The new matrix value is the average intensity value of the pixels in the active window, and the expression is as follows:
wherein x is the abscissa of the boundary point of the fitting circle, y is the ordinate of the boundary point of the fitting circle, k is more than or equal to 1, and g (i, j) is the gray value of the pixel (i, j);
for each pixel, the average intensity difference between windows of non-overlapping portions in both horizontal and vertical directions with the pixel as a center point is calculated as follows:
wherein ,Ek，h (x, y) is the difference in horizontal direction of the window mean value of each pixel in the image, E k，v (x, y) is the difference in vertical direction of the window mean for each pixel in the image;
comparing the window mean difference values in the horizontal direction and the vertical direction, and taking the larger value as the window mean difference value of the current pixel:
E k (x,y)＝max(E k,h (x,y),E k,v (x,y))
setting the optimal size S best (x,y)＝2 k Such that:
E k ＝E max ＝max(E 1 ,E 2 ,...E L )
wherein E is a window mean value difference value, L is the number of windows, and k=1 to L;
in the step S7), rivet type roughness parameter fusion is carried out, and the steps are as follows:
selecting a rectangular roughness parameter mean value corresponding to a moving window with a rotation angle of 180 degrees as basic data, wherein the formula is as follows:
wherein t is the initial rotation angle, F crs (i) F is a rectangular roughness parameter value corresponding to a moving window with a rotation angle of 180 DEG E (i) The average value of rectangular roughness parameters corresponding to a moving window with a rotation angle of 180 degrees;
each moving window roughness data was fitted to a rivet-type roughness parameter value by the following formula:
wherein ,
to fit the post-circular roughness parameter value, F E (i) And H (i) is H weight values of different angles, wherein the H is the average value of rectangular roughness parameters corresponding to a moving window with a rotation angle of 180 degrees.
2. The method for characterizing the surface roughness of the rivet-type contact based on the rotation fusion according to claim 1, wherein the step of solving the weight H is as follows:
s701) dividing the sequence of rectangular roughness parameters into different segments to form a data sequence P of length M i Calculating the data sequence P one by one i To generate a new data sequence R i Length n=m-1, the goal is to reduce short-term autocorrelation of the sequence;
R i ＝log(P i+1 /P i )i＝1,2,...,M-1.
s702) the new data sequence Ri with the length A is divided into n adjacent subintervals I a A=1, 2,..n, the mean value for each subset was calculated and noted as e a ：
S703) for each subset a, calculating a relative subset mean e a Accumulated dispersion X of (2) a ：
S704) calculating a maximum gap R for each of the dispersion sequences a Standard deviation S a ：
S705) calculating R/S value:
n is n adjacent subintervals selected in step S702);
s706) increasing the length of a, repeating steps S701) to S705) until a= (M-1)/2; linear regression fitting was performed with log (n) as the independent variable and log (R/S) as the dependent variable:
log(R/S)＝log(c)+H·log(n)+ε
the intercept of the regression equation is a constant in the above relation, and ε is a constant value;
the estimated value of the slope is the calculated H weight.
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