A post-corrosion modeling method for metal surfaces with arbitrary initial morphology

Abstract

The present invention discloses a post-corrosion modeling method for a metal surface of arbitrary initial morphology, including: (a) determining the development law of the corrosion morphology based on the average corrosion depth and surface roughness characteristics of steel standard samples after different corrosion times; (b) determining its corrosion characteristics based on the corrosion time of the metal surface, including the average corrosion depth and surface roughness parameters; (c) generating random corrosion amounts at each point of the path through the Monte Carlo method based on the roughness parameters; (d) determining the initial surface profile of the cross section based on the geometric measurement results; (e) determining the normal direction of each point of the initial surface profile, superimposing the corresponding corrosion amounts of each point along the normal direction, and determining the post-corrosion surface profile. The present invention can be used to generate the post-corrosion surface profile of any initial morphology surface, and can be used for both the profile coordinate data obtained based on scanning and the straight line segment established by constructing the endpoint coordinates.

Description

Technical Field

[0001] The invention relates to a method for modeling a metal surface with arbitrary initial morphology after corrosion, and in particular to a method for geometric modeling of a corrosion surface taking into account the initial morphology of the metal surface and the roughness of the surface after corrosion. Background Art

[0002] Steel structures are widely used in various engineering structures such as long-span steel bridges, offshore platforms, and offshore wind power plants due to their advantages such as light weight and high strength. During their service life, these structures will be degraded by environmental corrosion, which will endanger the safety of the structure. Therefore, it is necessary to study the mechanical properties of steel structures after corrosion. However, corrosion tests have problems such as high economic cost, long time consumption, and limited specimen size. Therefore, it is necessary to carry out numerical analysis of the mechanical properties of corroded steel structures. The accurate establishment of the geometric model of the metal surface after corrosion is the basis for the finite element refinement analysis of corroded steel structures. At present, most of the modeling methods for the surface of steel structures after corrosion do not consider the roughness characteristics of the surface after corrosion, and cannot accurately reflect the morphological characteristics of the metal surface after corrosion, which will lead to the simulation results being unable to accurately reflect the influence of local corrosion characteristics on the stress distribution of structural parts. At the same time, most of the existing post-corrosion modeling methods can only be applied to regular geometric models and are difficult to apply to irregular surfaces, which makes it difficult to establish the post-corrosion morphology of metal structures such as welded structures, complex components, and additive manufacturing. The post-corrosion modeling method based on inverse modeling is difficult to separate from the corrosion test, and has problems such as poor accuracy and low efficiency. Therefore, in order to accurately establish the geometric model of the metal structure surface after corrosion, it is necessary to establish a corrosion surface geometric modeling method that takes into account the initial morphology of the metal surface and the surface roughness after corrosion. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for geometric modeling of a corrosion surface that takes into account the initial morphology of the metal surface and the roughness of the surface after corrosion. The method can be applied to the post-corrosion modeling of any initial surface, and can accurately reflect the roughness characteristics of the surface morphology after corrosion, thereby realizing the rapid modeling of the surface after corrosion of metal structural parts. The present invention can be used for the initial surface post-corrosion geometric modeling of irregular surfaces based on scanning coordinate information, and can also be used for the initial surface post-corrosion geometric modeling of regular surfaces based on feature point coordinate information.

[0004] The present invention provides a method for modeling a metal surface after corrosion with any initial morphology, comprising:

[0005] (a) Based on the average corrosion depth d of a standard steel sample (i.e. a small steel sample with a flat surface) after exposure to a corrosive environment for a period of time t u And surface roughness parameter S a ,S q ,S z, determine the development of surface corrosion characteristics with corrosion time, including d u -t,S a -d u ,S q -d u ,S z -d u ; wherein the S a ,S q ,S z They are the arithmetic mean height, root mean square height and maximum depth respectively;

[0006] (b) Determine the surface corrosion characteristics, including the average corrosion depth d', based on the exposure time t' of the metal surface in the corrosive environment u and surface roughness parameter S' a ,S' q ,S' z ;

[0007] (c) Based on the geometric measurement results, determine the initial surface profile and the surface profile length l, and determine the points P on the surface profile i Length of the path from the endpoint l i With point P i Coordinate (x i ,y i ) corresponding relationship;

[0008] (d) Based on the surface roughness parameter S' a ,S' q ,S' z , through the Monte Carlo method, the path length l from the end point on the surface contour length l is generated i Each point P i Random corrosion amount d i ;

[0009] (e) Calculate the initial surface contour at each point P i The corresponding normal direction n i , establish each point P i Geometric information matrix G i =(x i ,y i ,l i ,n i );

[0010] (f) For each point P along the surface contour path i Along its normal direction n i The movement corresponds to the random corrosion amount d i , determine P i Move point P' i Coordinate (x' i ,y' i ), point P'i That is the post-corrosion point P i Corresponding position.

[0011] According to a specific implementation method, in step (a), a small steel sheet sample with a flat surface is used to calibrate the development law of corrosion characteristics, and its geometric dimensions and mass need to be measured before being exposed to a corrosive environment.

[0012] According to a specific implementation method, in step (a), S a ,S q ,S z are the arithmetic mean height, root mean square height and maximum depth respectively. For the metal surface obtained by the corrosion exposure test, it can be calculated based on the following formula S z =|max(Z(x,y))-min(Z(x,y))|;

[0013] According to a specific implementation method, in step (a), when it is impossible to carry out corrosion exposure test, the corrosion characteristic development law can be determined by existing metal environmental corrosion data. Among them, for structural steel, the corrosion rate can be determined according to "Atmospheric Corrosion of Metals and Alloys Part 1: Classification, Determination and Evaluation" (GB / T 19292.1-2018); the corrosion morphology characteristics can be calculated according to the following formula:

[0014] S a =0.0077×w+0.0031

[0015] S q =0.0096×w+0.0015

[0016] S z =0.0592×w+0.0544

[0017] Among them, w is the corrosion rate, w = (m0-m1) / m0, m0 is the initial mass, m1 is the mass after corrosion;

[0018] According to a specific implementation method, in step (a), according to different corrosion exposure time t corrosion characteristics d u ,S a ,S q ,S z , establish S a ,S q ,S z The average corrosion depth d u The corresponding relationship between

[0019] According to a specific implementation method, in step (b), the exposure time t is the exposure time of the established surface in the corrosive environment, which is the service life of the evaluated structural component;

[0020] According to a specific implementation method, in step (b), according to the d established in step (a), u -t relationship, determine the average corrosion depth d after corrosion u According to the S established in step (a) a -d u ,S q -d u ,S z -d u Relationship, determine the surface roughness parameter S after corrosion a ,S q ,S z ;

[0021] According to a specific implementation method, in the step (c), the initial surface profile is geometrically measured, and for surfaces with complex surface morphology, the coordinate information of each point on the surface profile can be obtained by laser scanning or other methods;

[0022] According to a specific implementation method, in step (c), the initial surface profile is geometrically measured. For a regular geometric surface, only the endpoint coordinates can be input, and interpolation is performed between the endpoints to obtain N data points P i The initial coordinate information of

[0023] According to a specific implementation method, in the step (c), the initial cross section is simplified into multiple broken lines by inputting the initial contour through the endpoint coordinates. The number of data points N in each broken line can be determined by the surface contour length l. The number of data points N will affect the modeling accuracy of the surface contour after corrosion Δ=l / N. For modeling of the rough surface after corrosion, in order to ensure the authenticity of the morphology, it is recommended that Δ is not greater than 0.02 mm;

[0024] According to a specific implementation method, in step (c), each point P on the surface profile i Length of the path from the endpoint l i is the distance from the end point of the section along the initial surface contour to point P i Circumference of the surface contour within the range;

[0025] According to a specific implementation method, in step (d), a one-dimensional rough surface is generated by a Monte Carlo method, and a one-dimensional rough surface sample with a surface contour length of l and N data points is generated. The longitudinal coordinates of each point on the rough surface are each point P i Random corrosion amount d i ,i=1~N;

[0026] According to a specific implementation method, in step (d), the corrosion amount d of each point on the surface profile length l is determined by step

[025] . i,The number of corrosion points on the surface contour length l is N, i = 1 ~ N;

[0027] According to a specific implementation method, in step (e), each point P on the surface contour length l is determined i Normal n i , and each point P i The geometric information is stored in the geometric information matrix G i =(x i ,y i ,l i ,n i ), i=1~N;

[0028] According to a specific implementation method, in step (f), it is considered that the corrosion develops in the direction perpendicular to the metal surface toward the inside of the metal matrix, that is, at each point P along the surface contour path i Along its normal direction n i Movement corresponding to corrosion amount d i , determine P i After moving P' i Point coordinates (x' i ,y' i ), point P' i That is the post-corrosion point P i Corresponding position.

[0029] The beneficial effects of the present invention include: the method can take into account any initial morphology of metal surfaces during the corrosion development process, and realize geometric modeling of surfaces with complex initial morphology after corrosion; the method can take into account surface roughness during corrosion modeling, and reflect the evolution of corrosion morphology during the corrosion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A flow chart of a post-corrosion modeling method for metal surfaces with arbitrary initial morphology;

[0031] Figure 2 This is a schematic diagram of corrosion of a standard small steel sheet;

[0032] Figure 3 It is a schematic diagram of the average corrosion depth development;

[0033] Figure 4 It is a schematic diagram of the corrosion morphology development;

[0034] Figure 5 is a schematic diagram of the initial outline;

[0035] Figure 6 is the path length l i Schematic diagram;

[0036] Figure 7 is the random corrosion amount di Schematic diagram;

[0037] Figure 8 is the normal n of each point on the surface contour i Schematic diagram;

[0038] Fig. 9 P i and P' i Schematic diagram;

[0039] Fig.10 This is a schematic diagram of the cross-sectional profile after corrosion. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the accompanying drawings.

[0041] The present invention discloses a method for modeling a metal surface with any initial morphology after corrosion. The specific process is as follows: Figure 1 The first step is to calculate the average corrosion depth d after exposure time t in a corrosive environment based on a standard steel sample, i.e. a small steel sample with a flat surface. u And surface roughness parameter S a ,S q ,S z , determine the development of corrosion characteristics over time, including d u -t,S a -d u ,S q -d u ,S z -d u ; The second step is to determine the corrosion characteristics of the metal surface based on the exposure time t' in the corrosive environment, including the average corrosion depth d' u and surface roughness parameter S' a ,S' q ,S' z ; The third step is to determine the initial surface profile and the surface profile length l based on the geometric measurement results, and determine the points P on the surface profile i Length of the path from the endpoint l i Its coordinates (x i ,y i ) corresponding relationship; the fourth step, based on the roughness parameter S' a ,S' q ,S' z , through the Monte Carlo method, the path length l from the end point on the surface contour length l is generated i Each point P i Random corrosion amount d i ; Step 5: Calculate each point P on the initial surface contour i The corresponding normal direction n i , establish each point Pi Geometric information matrix G i =(x i ,y i ,l i ,n i ); Step 6: align each point P along the surface contour path i Along its normal direction n i Movement corresponding to corrosion amount d i , determine P i After moving P' i Point coordinates (x' i ,y' i ), point P' i That is the post-corrosion point P i Corresponding position.

[0042] Corrosion test of small steel sheet with flat surface Figure 2 shown.

[0043] The average corrosion depth of structural steel develops over time. Figure 3 shown.

[0044] Corrosion characteristics d according to different corrosion exposure time t u ,S a ,S q ,S z , establish S a ,S q ,S z The average corrosion depth d u The corresponding relationship, such as Figure 4 As shown;

[0045] According to the established d u -t relationship, determine the average corrosion depth d after corrosion u ; According to the S established in step (a) a -d u ,S q -d u ,S z -d u Relationship, determine the surface roughness parameter S after corrosion a ,S q ,S z ;

[0046] Perform geometric measurements on the initial surface profile and establish the initial profile, such as Figure 5 For surfaces with complex morphology, the coordinate information of each point on its surface contour can be obtained by laser scanning or other methods; for regular geometric surfaces, only the endpoint coordinates can be input, and interpolation between the endpoints can be performed to obtain N data points P i The initial coordinate information of

[0047] The initial section is simplified into multiple broken lines by inputting the initial contour through the endpoint coordinates. The number of data points N in each broken line can be determined by the surface contour length l. The number of data points N will affect the modeling accuracy of the surface contour after corrosion Δ=l / N. For modeling of rough surfaces after corrosion, it is recommended that Δ should not be greater than 0.02mm to ensure the authenticity of the morphology.

[0048] Each point P on the surface contour i Length of the path from the endpoint l i is the distance from the end point of the section along the initial surface contour to point P i The perimeter of the surface contour within the range, such as Figure 6 As shown;

[0049] Generate a one-dimensional rough surface by using the Monte Carlo method, generate a one-dimensional rough surface sample with a surface contour length of l and N data points, and the longitudinal coordinates of each point on the rough surface are P i Random corrosion amount d i ,i=1~N, such as Figure 7 As shown;

[0050] Determine the points P on the surface contour length l i Normal n i ,like Figure 8 As shown, each point P i The geometric information is stored in the geometric information matrix G i =(x i ,y i ,l i ,n i ), i=1~N;

[0051] Consider that corrosion develops vertically to the metal surface toward the inside of the metal matrix, that is, along the surface contour path, the i Along its normal direction n i Movement corresponding to corrosion amount d i , determine P i After moving P' i Point coordinates (x' i ,y' i ), point P' i That is the post-corrosion point P i Corresponding position, such as Fig. 9 As shown;

[0052] Determine the cross-sectional profile after corrosion, such as Fig.10 As shown;

[0053] The method can take into account any metal surface with initial morphology during the corrosion development process, and realize geometric modeling of the surface with complex initial morphology after corrosion;

[0054] The method can take into account the surface roughness in the corrosion modeling process and reflect the evolution of the corrosion morphology during the corrosion process.

Claims

1. A method for modeling a metal surface after corrosion with arbitrary initial morphology, characterized in that: The post-corrosion surface established by the method can accurately reflect the roughness characteristics of the metal surface in the actual corrosion environment and can be applied to any initial morphology surface; the method comprises: (a) Average corrosion depth d based on the steel standard specimen after exposure to the corrosive environment for time t u And surface roughness parameter S a ,S q ,S z , determine the development of corrosion characteristics over time, including d u -t,S a -d u ,S q -d u ,S z -d u ; wherein the S a ,S q ,S z They are the arithmetic mean height, root mean square height and maximum depth respectively; wherein the standard steel sample is a small steel sheet sample with a flat surface; (b) Determine the surface corrosion characteristics, including the average corrosion depth d', based on the exposure time t' of the metal surface in the corrosive environment u and surface roughness parameter S' a ,S' q ,S' z ; (c) Based on the geometric measurement results, determine the initial surface profile and the surface profile length l, and determine the points P on the surface profile i Length of the path from the endpoint l i With point P i Coordinate (x i ,y i ); where each point P on the surface contour i Length of the path from the endpoint l i is the distance from the end point of the section along the initial surface contour to point P i Circumference of the surface contour within the range; (d) Based on the surface roughness parameter S' a ,S' q ,S' z , through the Monte Carlo method, the path length l from the end point on the surface contour length l is generated i Each point P i Random corrosion amount d i ; (e) Calculate the initial surface contour at each point P i The corresponding normal direction n i , establish each point P i Geometric information matrix G i =(x i ,y i ,l i ,n i ); (f) For each point P along the surface contour path i Along its normal direction n i The movement corresponds to the random corrosion amount d i , determine P i Move point P' i Coordinate (x' i ,y' i ), point P' i That is the post-corrosion point P i Corresponding position.

2. The method according to claim 1, characterized in that In step (a), the small steel sheet sample with a flat surface is used to calibrate the development law of corrosion characteristics, and its geometric dimensions and mass need to be measured before being exposed to the corrosive environment; Alternatively, when it is not possible to conduct a corrosion exposure test in step (a), the development law of corrosion characteristics can be determined through existing metal environmental corrosion data; Alternatively, the surface roughness parameter S in step (a) a ,S q ,S z Calculated based on the following formula:

3. The method according to claim 1, characterized in that The exposure time t' in step (b) is the exposure time of the established surface in the corrosive environment, according to the d established in step (a). u -t relationship, determine the average corrosion depth d' after corrosion u According to the S established in step (a) a -d u ,S q -d u ,S z -d u Relationship, determine the surface roughness parameter S' after corrosion a ,S' q ,S' z .

4. The method according to claim 1, characterized in that In step (c), the initial surface profile is geometrically measured. For surfaces with complex surface morphology, the coordinate information of each point on the surface profile can be obtained by laser scanning method; Alternatively, in step (c), the initial surface profile is geometrically measured. For a regular geometric surface, only the endpoint coordinates can be input, and interpolation is performed between the endpoints to obtain N data points P. i The initial coordinate information.

5. The method according to claim 1, characterized in that In the step (d), a one-dimensional rough surface is generated by the Monte Carlo method, and a one-dimensional rough surface sample with a surface contour length of l and N data points is generated. The longitudinal coordinates of each point on the rough surface are the longitudinal coordinates of each point P. i Random corrosion amount d i , where i=1~N.

6. The method according to claim 5, characterized in that In the step (d), the random corrosion amount d at each point on the surface profile length l is determined i , the number of corrosion points on the surface contour length l is N, where i = 1~N.

7. The method according to claim 1, characterized in that In the step (e), determine the surface contour length l of each point P i Normal n i , and each point P i The geometric information is stored in the geometric information matrix G i =(x i ,y i ,l i ,n i ), i=1~N.

8. The method according to claim 1, characterized in that In the step (f), it is considered that the corrosion develops in the direction perpendicular to the metal surface toward the inside of the metal matrix, that is, the surface contour path is perpendicular to the surface contour path of each point P. i Along its normal direction n i The movement corresponds to the random corrosion amount d i , determine P i Move point P' i Coordinate (x' i ,y' i ), point P' i That is the post-corrosion point P i Corresponding position.

9. The method according to any one of claims 1 to 8, characterized in that: The method can take into account any metal surface with initial morphology during the corrosion development process, and realize geometric modeling of a surface with complex initial morphology after corrosion.

10. The method according to any one of claims 1 to 8, characterized in that: The method can take into account the surface roughness in the corrosion modeling process and reflect the evolution of the corrosion morphology during the corrosion process.

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