Aviation metal braided conductor point cloud data entity modeling method based on cellular corrosion

Abstract

The invention belongs to the technical field of metal corrosion numerical simulation analysis, and particularly relates to an aviation metal braided conductor point cloud data entity modeling method based on cellular corrosion, which comprises the following steps: S1, establishing a three-dimensional cellular space for simulating an aviation metal braided conductor corrosion environment; s2, conducting wire corrosion process simulation modeling according to the three-dimensional cellular space, and determining wire cellular transformation and diffusion rules and corresponding corrosion and diffusion probabilities; s3, constructing a lead cell three-dimensional space point cloud equation, and generating lead grid units; and S4, splicing the wire tetrahedral mesh units to generate a smooth curved surface, and completing aviation metal braided wire point cloud data materialized modeling. According to the method, the three-dimensional discrete points, generated in the cellular automaton, of the aviation metal braided conductor can be converted into entities in finite element simulation software, the complex surface appearance of the aviation metal braided conductor is reserved, the conversion process from simulation to an entity model is optimized, and the method is good in applicability.

Description

Technical Field

[0001] The invention belongs to the technical field of numerical simulation analysis of metal corrosion, and in particular relates to a point cloud data entity modeling method for aviation metal braided wires based on cellular corrosion. Background Art

[0002] Traditional corrosion research mainly relies on experimental methods to simulate complex corrosion environments. It is difficult to accurately control all variables during the experiment, resulting in poor repeatability and controllability of the results. At the same time, the experiment can only provide local or surface information, and it is difficult to fully and continuously reveal the dynamic evolution of corrosion of materials during long-term service. In recent years, numerical simulation has been widely used in related fields such as metal corrosion due to its high efficiency and observable process. Compared with other numerical simulation methods such as finite element method and boundary element method, the cellular automaton algorithm introduces randomness and is suitable for simulating the development law of irregular pitting corrosion at a smaller scale. However, the calculation results of the cellular automaton are three-dimensional discrete points that cannot be imported into the finite element software for subsequent simulation analysis. At present, the related research on importing cellular automata into finite element software is mostly single pit corrosion or multi-pit corrosion after simplified processing, which is difficult to reflect the true morphology of the pit.

[0003] However, the cellular automaton method also has some limitations, especially when applied to practical engineering problems. The calculation results of cellular automata are often discrete three-dimensional point clouds, which cannot be directly compatible and linked with finite element analysis software such as ANSYS and ABAQUS. This is because finite element software requires the input model to be a continuous, solidified geometric body, while the cellular automaton generates point cloud data composed of a large number of discrete points. However, since point cloud data is a data structure composed of a large number of discrete three-dimensional coordinate points and the corrosion morphology generated by cellular automata has strong randomness and complexity, it is an urgent problem to convert it into a high-precision solid model that can be subsequently calculated by finite elements in a simple and fast manner. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a point cloud data entity modeling method for aviation metal braided wires based on cellular corrosion, which can quickly convert the three-dimensional discrete points of aviation metal braided wires generated in a cellular automaton into aviation metal braided wire entities calculated in finite element simulation software, and can retain the complex surface morphology of aviation metal braided wires, optimize the conversion process from simulation to entity model, and can be generalized and applied to a variety of metal materials.

[0005] To achieve the above object, the present invention discloses a point cloud data entity modeling method for aviation metal braided wire based on cellular corrosion, which comprises:

[0006] S1: Establish a three-dimensional cellular space simulating the corrosion environment of aviation metal braided wires; transform the reaction transformation elements involved in the corrosion process during the pitting corrosion of aviation metal braided wires into each cell in the three-dimensional cellular space of aviation metal braided wires;

[0007] S2: Performing simulation modeling of the corrosion process of aviation metal braided wires according to the three-dimensional cellular space in step S1, and determining the cellular transformation and diffusion rules of the aviation metal braided wires and the corresponding corrosion and diffusion probabilities;

[0008] S21: Determine the cellular transformation rules and corrosion probability of the aviation metal braided wire; based on the corrosion model of small anode and large cathode, during the reaction process, the surface of the anti-corrosion coating randomly generates a damage point with probability P1, and a hemispherical pit is generated with the damage point as the center of the circle. The inside of the pit is a hydrogen ion cell H. The first probability P1 of the pit generated on the surface of the aviation metal braided wire is:

[0009]

[0010] Wherein, P1 is the first probability of corrosion pits on the surface of aviation metal braided wire; k is the corrosion parameter of aviation metal braided wire; N is the number of corrosion steps of aviation metal braided wire;

[0011] S22: When the aviation metal braided wire contacts the hydrogen ion solution, an anodic reaction occurs. The corresponding transformation rule and corrosion probability are:

[0012]

[0013] P2=mN H +nN W ;

[0014] Where R is the corroded metal cell; C is the ion cell generated by corrosion; P2 is the second probability of pits on the surface of aviation metal braided wire; m is the weight coefficient of hydrogen ion cell H; n is the weight coefficient of corrosive solution cell W; N H is the number of hydrogen ion cells H; N W is the number of corrosive solution cells W;

[0015] S23: When the aviation metal braided wire contacts the metal ion solution, a passivation reaction occurs, and the corresponding transformation rule is:

[0016]

[0017] Where C is the ion cell generated by corrosion; W n is a random corrosive solution unit cell; P3 is the third probability of generating pits on the surface of aviation metal braided wire; p is a passivation product unit cell; H n is a random S hydrogen ion cell; C nis the ion cell generated by random corrosion; P4 is the fourth probability of generating pits on the surface of aviation metal braided wire; P n is the random passivation product cell;

[0018] S24: Determine the diffusion rule of the corrosion process of the aviation metal braided wire as follows: the ion cell C and the hydrogen ion cell H generated by the corrosion randomly move to one of the nearby solution cells during the diffusion process. If the ion cell C and the hydrogen ion cell H generated by the corrosion move to the cell position with the same state, no position exchange occurs. If they move to the cell position with different states, they exchange positions. If there are solid cells around the passivation product cell P, they do not move. Otherwise, they exchange positions with one of the randomly encountered solution cells.

[0019] S25: setting the number of corrosion steps N for the aviation metal braided wire, repeating steps S21-S24 for N cycles and ending, and obtaining the corroded metal cell R as the corrosion simulation result of the corrosion process simulation of the aviation metal braided wire;

[0020] S3: construct the three-dimensional space point cloud equation of the aviation metal braided wire cell to generate the aviation metal braided wire grid unit;

[0021] S31: Output the corrosion simulation results of the metal cell R corroded in step S2 as three-dimensional discrete points, and obtain the coordinate judgment equation of the aviation metal braided wire cell in three-dimensional space:

[0022]

[0023] Among them, MetalSurface(i,j,k) is the coordinate of the aviation metal braided wire cell in three-dimensional space; is in contact with the passivation product cell P, the corroded metal cell R and the anti-corrosion coating cell D; i is the horizontal coordinate of the aviation metal braided wire cell in space; j is the vertical coordinate of the aviation metal braided wire cell in space; k is the vertical coordinate of the aviation metal braided wire cell in space; if is a function to judge whether the condition is met; otherwiye is a function to judge whether the condition is not met;

[0024] S32: Determine whether the three-dimensional discrete point output in step S2 is an aviation metal braided wire cell according to the coordinate judgment equation in step S31, and extract the coordinate (x i ,y i ,z i ), construct the three-dimensional point cloud equation PoCl of aviation metal braided wire;

[0025] S33: for the three-dimensional space point cloud equation PoCl of the aviation metal braided wire in step S32, an octree optimization algorithm is used to distinguish the corrosion range of the three-dimensional point cloud of the aviation metal braided wire, and generate a triangular mesh unit of the aviation metal braided wire;

[0026] S34: segmenting the aviation metal braided wire triangular mesh unit generated in step S33, and converting the aviation metal braided wire triangular mesh unit into the aviation metal braided wire tetrahedral mesh unit using a curvature minimization smoothing algorithm;

[0027] S4: The tetrahedral mesh units of the aviation metal braided wire in step S3 are spliced ​​to generate a smooth surface, completing the solid modeling of the aviation metal braided wire point cloud data.

[0028] Preferably, the reaction conversion elements in step S1 refer to the metals, solutions and corrosion products involved in the corrosion reaction, specifically including: aviation metal braided wire cells M, corroded metal cells R, anti-corrosion coating cells D, passivation product cells P, corrosive solution cells W, hydrogen ion cells H and ion cells C generated by corrosion.

[0029] Preferably, the anode reaction in step S22 is specifically as follows: the corroded metal cell R is converted into an ion cell C generated by corrosion, wherein the second probability P2 of generating a pit on the surface of the aviation metal braided wire is equal to the number N of hydrogen ion cells H adjacent to the corroded metal cell R. H and the number of corrosive solution cells W N W There is a positive correlation between the weight coefficient m of the hydrogen ion cell H and the weight coefficient n of the corrosive solution cell w; compared with the corrosive solution cell W, the hydrogen ion cell H can directly dissolve with the metal matrix. Therefore, the weight coefficient m of the hydrogen ion cell H is greater than the weight coefficient n of the corrosive solution cell W.

[0030] Preferably, the passivation reaction in step S23 is specifically as follows: the ion cell C generated by corrosion randomly selects a contact cell. If the selected contact cell is a corrosive solution cell W, the corrosion product is converted into a passivation product cell P, and the corrosive solution cell W is converted into a hydrogen ion cell H, whose probability value is the third probability P3 of generating pits on the surface of the aviation metal braided wire, which is related to the concentration, temperature, and reactivity factors of the solution and needs to be determined through experimental fitting; when two ion cells C generated by corrosion meet, that is, when the contact cell selected by the ion cell C generated by corrosion is the ion cell C generated by corrosion, the fourth probability P4 of generating pits on the surface of the aviation metal braided wire where the passivation reaction occurs will increase, which is related to the passivation product, hydrogen ion concentration and ion cell generated by corrosion, and needs to be determined through experimental fitting, and the ion cell C generated by corrosion is converted into the passivation product cell P; the fourth probability P4 of generating pits on the surface of the aviation metal braided wire is greater than the third probability P3 of generating pits on the surface of the aviation metal braided wire.

[0031] Preferably, the hydrogen ion cell H generated by the passivation reaction in step S23 will cause the hydrolysis reaction to be reversible, that is, the contact cell selected by the passivation product cell P is the hydrogen ion cell H, and the passivation product cell P and the hydrogen ion cell H are converted into the ion cell C generated by corrosion, and the probability thereof is the fifth probability P5 of generating pits on the surface of the aviation metal braided wire, and the corresponding conversion rule is:

[0032]

[0033] Wherein, P5 is the fifth probability of generating pits on the surface of the aviation metal braided wire.

[0034] Preferably, the solution cell and the solid cell in step S24 are specifically:

[0035] The solution cells include: ion cells C generated by corrosion, hydrogen ion cells H and corrosive solution cells W;

[0036] The solid cells include: corroded metal cells R, anti-corrosion coating cells D and aviation metal braided wire cells M.

[0037] Preferably, in step S24, the diffusion rule of the corrosion process of the aviation metal braided wire is determined, specifically: the ion cell C and the hydrogen ion cell H generated by the corrosion generate N in each corrosion reaction step. diff Second diffusion, the passivation product cell P undergoes N diff_I diffusion, and the probability of exchange between cells is the same; since the ion cells C and hydrogen ion cells H generated by corrosion exist in the solution in the form of ions, and the passivation product cells P are suspended in the electrolyte solution in the form of colloid, it can be concluded that N diff >N diff_I.

[0038] Preferably, in step S32, the three-dimensional point cloud equation POCl of the aviation metal braided wire is constructed as follows:

[0039] PoCl={(x1,y1,z1),(x2,y2,z2),…,(x n ,y n ,z n )};

[0040] Among them, PoCl is the three-dimensional point cloud equation of the aviation metal braided wire; x1 is the horizontal coordinate of the first point in the three-dimensional space; y1 is the vertical coordinate of the first point in the three-dimensional space; z1 is the vertical coordinate of the first point in the three-dimensional space; x2 is the horizontal coordinate of the second point in the three-dimensional space; y2 is the vertical coordinate of the second point in the three-dimensional space; z2 is the vertical coordinate of the second point in the three-dimensional space; x n is the horizontal coordinate of the nth point in three-dimensional space; y n is the vertical coordinate of the nth point in three-dimensional space; z n is the vertical coordinate of the nth point in three-dimensional space.

[0041] Preferably, in step S33, an octree optimization algorithm is used to distinguish the corrosion range of the three-dimensional point cloud of the aviation metal braided wire and generate a triangular mesh unit of the aviation metal braided wire, specifically:

[0042] For each point in the point cloud of the three-dimensional space of the aviation metal braided wire, the normal vector is calculated using the points in the neighborhood; the target point in the point cloud is The points in the neighborhood are {(Pa1,Pa2,……,Pa n}, then the triangular mesh of the target point is obtained according to the normal vector of the target point in the point cloud:

[0043]

[0044] Among them, n i is the triangular mesh of the i-th target point in the point cloud; Pa i is the normal vector of the i-th target point in the point cloud; Pa j is the normal vector of the jth target point in the point cloud; i is the first number of the target point in the point cloud; j is the second number of the target point in the point cloud; m is the total number of target points in the point cloud;

[0045] To speed up the calculation of the normal vector, set the octree radius r to distinguish the relative range of the inner and outer parts of the point cloud, and obtain the triangular mesh n of the i-th target point in the point cloud. i for:

[0046]

[0047] Preferably, in step S34, the aviation metal braided wire triangular mesh unit generated in step S33 is segmented, and the aviation metal braided wire triangular mesh unit is converted into the aviation metal braided wire tetrahedral mesh unit using a smooth algorithm that minimizes curvature, specifically:

[0048] Each triangle patch △(v1, v2, v3) of the triangular mesh unit is divided into 4 secondary triangular patches; the midpoint of each edge corresponding to each triangular patch is connected to the center point of the original triangle to generate 4 secondary triangular patches, and the secondary vertex v4 is the centroid of the initial triangular patch; each triangular patch will be continuously refined until the triangular mesh unit contains enough tetrahedral mesh units, and the secondary vertex v4 of the tetrahedral mesh is obtained as:

[0049]

[0050] Among them, v4 is the secondary vertex of the tetrahedron mesh; v1 is the first vertex of the triangle patch; v2 is the second vertex of the triangle patch; v3 is the third vertex of the triangle patch;

[0051] Use a smoothing algorithm based on curvature minimization to smooth the tetrahedral mesh. Based on the above meshing, give each tetrahedral mesh an initial position v i , its updated position v′ i is the weighted average of the positions of its adjacent vertices, which can be obtained by:

[0052]

[0053] Among them, v′ i is the updated position of the tetrahedral mesh; v j is the initial position of the tetrahedral mesh; N(i) is the initial position v of the tetrahedral mesh i The set of adjacent vertices of a vertex is determined by the number of adjacent vertices of the vertex.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) The present invention realizes accurate point cloud generation and surface extraction through a cellular corrosion simulation algorithm, which truly reflects the surface morphology of aviation metal braided wires after corrosion. Compared with other numerical simulation methods, this method introduces randomness and is suitable for simulating the development law of irregular pitting corrosion at a smaller scale.

[0056] (2) The present invention converts the three-dimensional point cloud of aviation metal braided wire into a mesh and performs post-processing through Cloud Compare, thereby optimizing the conversion process from simulation to solid model, simplifying the cumbersome steps in traditional modeling methods, and improving conversion efficiency.

[0057] (3) The present invention can be adjusted for different metals and different corrosion conditions, and is applicable to a variety of metal materials, providing accurate model data for subsequent finite element analysis, thereby facilitating engineering design, optimization and safety assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a flow chart of the point cloud data entity modeling method of aviation metal braided wire based on cellular corrosion of the present invention;

[0059] Figure 2 A schematic diagram of the space of the aviation metal braided wire cell of the CA model of the corrosion process in an embodiment of the present invention;

[0060] Figure 3 A schematic diagram of the morphology of corrosion pits of an aviation metal braided wire simulated in an embodiment of the present invention;

[0061] Figure 4 A point cloud schematic diagram of an aviation metal braided wire in an embodiment of the present invention;

[0062] Figure 5 A schematic diagram of a mesh of an aviation metal braided wire in an embodiment of the present invention;

[0063] Figure 6 It is a schematic diagram of the curved surface of the aviation metal braided wire in an embodiment of the present invention;

[0064] Figure 7 This is a physical picture of the copper braided wire after immersion corrosion in an embodiment of the present invention;

[0065] Figure 8 It is a schematic diagram of the aviation metal braided wire entity in an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0067] The embodiment of the present invention uses an aviation metal braided wire model of a certain aviation product as a specific research and analysis object, and provides an aviation metal braided wire point cloud data entity modeling method based on cellular corrosion, such as Figure 1As shown, a three-dimensional cellular space is established to simulate the corrosion environment of aviation metal braided wires; the corrosion process of aviation metal braided wires is simulated and modeled according to the three-dimensional cellular space, and the transformation and diffusion rules of aviation metal braided wires and the corresponding corrosion and diffusion probabilities are determined; the three-dimensional space point cloud equation of aviation metal braided wire cells is constructed to generate aviation metal braided wire grid units; the tetrahedral grid units of aviation metal braided wires are spliced ​​to generate smooth surfaces, and the point cloud data of aviation metal braided wires is solidified and modeled; it includes:

[0068] Step S1: Establish a three-dimensional cellular space that simulates the corrosion environment of aviation metal braided wires and express it with three-dimensional coordinates, such as Figure 2 It is a schematic diagram of the space of the aviation metal braided wire cell of the CA model of the corrosion process in an embodiment of the present invention, Figure 2 1 is the aviation metal braided wire; the reaction transformation elements participating in the corrosion process of the aviation metal braided wire during pitting are transformed into each cell in the three-dimensional cellular space of the aviation metal braided wire; the reaction transformation elements refer to the metals, solutions and generated corrosion products participating in the corrosion reaction, specifically including: aviation metal braided wire cell M, corroded metal cell R, anti-corrosion coating cell D, passivation product cell P, corrosive solution cell W, hydrogen ion cell H and ion cell C generated by corrosion.

[0069] Step S2: Based on the three-dimensional cellular space in step S1, simulation modeling of the corrosion process of the aviation metal braided wire is performed to determine the cellular transformation and diffusion rules of the aviation metal braided wire and the corresponding corrosion and diffusion probabilities.

[0070] Step S21: Determine the cellular transformation rules and corrosion probability of the aviation metal braided wire; based on the corrosion model of small anode and large cathode, the inside of the corrosion pit is an anode reaction, no cathode reaction occurs, and during the reaction, the surface of the anti-corrosion coating randomly generates a damage point with probability P1, and a hemispherical corrosion pit is generated with the damage point as the center of the circle. The inside of the corrosion pit is a hydrogen ion cell H. The first probability P1 of the corrosion pit on the surface of the aviation metal braided wire is:

[0071]

[0072] Wherein, P1 is the first probability of corrosion pits on the surface of the aviation metal braided wire; k is the corrosion parameter of the aviation metal braided wire; and N is the number of corrosion steps of the aviation metal braided wire.

[0073] Step S22: When the aviation metal braided wire contacts the hydrogen ion solution, an anodic reaction can occur, specifically: the corroded metal cell R is converted into an ion cell C generated by corrosion, wherein the second probability P2 of generating a pit on the surface of the aviation metal braided wire is equal to the number N of hydrogen ion cells H adjacent to the corroded metal cell R. Hand the number of corrosive solution cells W N W There is a positive correlation between the weight coefficient m of the hydrogen ion cell H and the weight coefficient n of the corrosive solution cell W; compared with the corrosive solution cell W, the hydrogen ion cell H can directly dissolve with the metal matrix. Therefore, the weight coefficient m of the hydrogen ion cell H is greater than the weight coefficient n of the corrosive solution cell W. The corresponding transformation rule and corrosion probability are obtained as follows:

[0074]

[0075] P2=mN H +nN W ;

[0076] Where R is the corroded metal cell; C is the ion cell generated by corrosion; P2 is the second probability of pits on the surface of aviation metal braided wire; m is the weight coefficient of hydrogen ion cell H; n is the weight coefficient of corrosive solution cell W; N H is the number of hydrogen ion cells H; N W is the number of corrosive solution cells W.

[0077] Step S23: When the aviation metal braided wire contacts the metal ion solution, a passivation reaction can occur, specifically: the ion cell C generated by corrosion randomly selects a contact cell. If the selected contact cell is a corrosive solution cell W, the corrosion generated is converted into a passivation product cell P, and the corrosive solution cell W is converted into a hydrogen ion cell H. Its probability value is the third probability P3 of the generation of pits on the surface of the aviation metal braided wire, which is related to the concentration, temperature, and reactivity factors of the solution, and needs to be determined through experimental fitting; when two ion cells C generated by corrosion meet, that is, when the contact cell selected by the ion cell C generated by corrosion is the ion cell C generated by corrosion, the fourth probability P4 of the generation of pits on the surface of the aviation metal braided wire where the passivation reaction occurs will increase, which is related to the passivation product, hydrogen ion concentration, and ion cells generated by corrosion, and needs to be determined through experimental fitting. The ion cells C generated by corrosion are all converted into passivation product cells P; the fourth probability P4 of the generation of pits on the surface of the aviation metal braided wire is greater than the third probability P3 of the generation of pits on the surface of the aviation metal braided wire. The corresponding conversion rules are:

[0078]

[0079] Where C is the ion cell generated by corrosion; W n is a random corrosive solution cell; P3 is the third probability of generating pits on the surface of aviation metal braided wire; P is a passivation product cell; H n is a random S hydrogen ion cell; C nis the ion cell generated by random corrosion; P4 is the fourth probability of generating pits on the surface of aviation metal braided wire; P n is a random passivation product cell.

[0080] The hydrogen ion cell H generated by the passivation reaction will lead to the reversibility of the hydrolysis reaction, that is, the contact cell selected by the passivation product cell P is the hydrogen ion cell H. The passivation product cell P and the hydrogen ion cell H are converted into the ion cell C generated by corrosion. The probability is the fifth probability P5 of the generation of pits on the surface of the aviation metal braided wire. The corresponding conversion rule is:

[0081]

[0082] Wherein, P5 is the fifth probability of generating pits on the surface of the aviation metal braided wire.

[0083] Step S24: Determine the diffusion rule of the corrosion process of the aviation metal braided wire; the ion cells C and hydrogen ion cells H generated by the corrosion have N in each corrosion reaction step. diff Second diffusion, the passivation product cell P undergoes N diff_I diffusion, and the probability of exchange between cells is the same; since the ion cells C and hydrogen ion cells H generated by corrosion exist in the solution in the form of ions, and the passivation product cells P are suspended in the electrolyte solution in the form of colloid, it can be concluded that N diff >N diff_I ; The diffusion rule of the corrosion process of aviation metal braided wire is: the ion cell C and hydrogen ion cell H generated by corrosion randomly move to one of the nearby solution cells during the diffusion process. If the ion cell C and hydrogen ion cell H generated by corrosion move to the cell position with the same state, there is no position exchange. If they move to the cell position with different states, they exchange positions. If there are solid cells around the passivation product cell P, they will not move, otherwise they will exchange positions with one of the randomly encountered solution cells. Solution cells include: ion cells C, hydrogen ion cells H and corrosive solution cells W generated by corrosion. Solid cells include: corroded metal cells R, anti-corrosion coating cells D and aviation metal braided wire cells M.

[0084] Step S25: Set the number of corrosion steps N for the aviation metal braided wire, repeat steps S21-S24 for N cycles, and then end. The corroded metal cell R is the corrosion simulation result of the aviation metal braided wire corrosion process simulation, which represents the simulated corrosion pit morphology, such as Figure 3 The figure shows a schematic diagram of the etch pit morphology of the aviation metal braided wire simulated in the embodiment of the present invention, which accurately and in detail depicts the etch pit morphology and position of the embodiment in the spatial coordinate system.

[0085] Step S3: construct the three-dimensional space point cloud equation of the aviation metal braided wire cell to generate the aviation metal braided wire grid unit.

[0086] Step S31: Output the corrosion simulation results of the metal cell R corroded in step S2 as three-dimensional discrete points, and obtain the coordinate judgment equation of the aviation metal braided wire cell in three-dimensional space:

[0087]

[0088] Among them, MetalSurface(i,j,k) is the coordinate of the aviation metal braided wire cell in three-dimensional space; It is in contact with the passivation product cell P, the corroded metal cell R and the anti-corrosion coating cell D; i is the horizontal coordinate of the aviation metal braided wire cell in space; j is the vertical coordinate of the aviation metal braided wire cell in space; k is the vertical coordinate of the aviation metal braided wire cell in space; if is a function to judge whether the condition is met; otherwiye is a function to judge whether the condition is not met.

[0089] Step S32: Determine whether the three-dimensional discrete point output in step S2 is an aviation metal braided wire cell according to the coordinate judgment equation in step S31, and extract the coordinates (x i ,y i ,z i ),like Figure 4 The figure shows a point cloud schematic diagram of an aviation metal braided wire in an embodiment of the present invention; the three-dimensional point cloud equation PoCl for constructing the aviation metal braided wire is:

[0090] PoCl={(x1,y1,z1),(x2,y2,z2),…,(x n ,y n ,z n )};

[0091] Among them, PoCl is the three-dimensional point cloud equation of the aviation metal braided wire; x1 is the horizontal coordinate of the first point in the three-dimensional space; y1 is the vertical coordinate of the first point in the three-dimensional space; z1 is the vertical coordinate of the first point in the three-dimensional space; x2 is the horizontal coordinate of the second point in the three-dimensional space; y2 is the vertical coordinate of the second point in the three-dimensional space; z2 is the vertical coordinate of the second point in the three-dimensional space; x n is the horizontal coordinate of point b in three-dimensional space; y n is the vertical coordinate of the nth point in three-dimensional space; z n is the vertical coordinate of the nth point in three-dimensional space.

[0092] Step S33: For the three-dimensional space point cloud equation PoCl of the aviation metal braided wire in step S32, an octree optimization algorithm is used to distinguish the corrosion range of the three-dimensional point cloud of the aviation metal braided wire, and generate a triangular mesh unit of the aviation metal braided wire, specifically:

[0093] For each point in the point cloud of the three-dimensional space of the aviation metal braided wire, the normal vector is calculated using the points in the neighborhood; the target point in the point cloud is The points in the neighborhood are {(Pa1,Pa2,……,Pa n}, then the triangular mesh of the target point is obtained according to the normal vector of the target point in the point cloud:

[0094]

[0095] Among them, n i is the triangular mesh of the i-th target point in the point cloud; Pa i is the normal vector of the i-th target point in the point cloud; Pa j is the normal vector of the jth target point in the point cloud; i is the first number of the target point in the point cloud; j is the second number of the target point in the point cloud; m is the total number of target points in the point cloud.

[0096] To speed up the calculation of the normal vector, set the octree radius r to distinguish the relative range of the inner and outer parts of the point cloud, such as Figure 5 The figure shows a schematic diagram of the mesh of the aviation metal braided wire in the embodiment of the present invention; the triangular mesh n of the i-th target point in the point cloud is obtained. i for:

[0097]

[0098] Step S34: segment the aviation metal braided wire triangular mesh unit generated in step S33, and use a smoothing algorithm that minimizes curvature to transform the aviation metal braided wire triangular mesh unit into an aviation metal braided wire tetrahedral mesh unit, specifically:

[0099] Each triangle patch △(v1, v2, v3) of the triangular mesh unit is divided into 4 secondary triangular patches; the midpoint of each edge corresponding to each triangular patch is connected to the center point of the original triangle to generate 4 secondary triangular patches, and the secondary vertex v4 is the centroid of the initial triangular patch; each triangular patch will be continuously refined until the triangular mesh unit contains enough tetrahedral mesh units, and the secondary vertex v4 of the tetrahedral mesh is obtained as:

[0100]

[0101] Among them, v4 is the secondary vertex of the tetrahedral mesh; v1 is the first vertex of the triangle patch; v2 is the second vertex of the triangle patch; and v3 is the third vertex of the triangle patch.

[0102] like Figure 6 The schematic diagram of the surface of the aviation metal braided wire in the embodiment of the present invention is as follows; the triangular mesh with complex topological relationship is transformed into a tetrahedral mesh, and then a smooth polysurface spliced ​​by the G1 continuous phase is generated. The tetrahedral mesh is smoothed using a smoothing algorithm based on curvature minimization. Based on the above mesh division, the initial position of each tetrahedral mesh is given as v i , its updated position v′ i is the weighted average of the positions of its adjacent vertices, which can be obtained by:

[0103]

[0104] Among them, v′ i is the updated position of the tetrahedral mesh; v j is the initial position of the tetrahedral mesh; N(i) is the initial position v of the tetrahedral mesh i The set of adjacent vertices of a vertex is determined by the number of adjacent vertices of the vertex.

[0105] Step S4: splicing the tetrahedral grid units of the aviation metal braided wire in step S3 to generate a smooth surface, and completing the solid modeling of the aviation metal braided wire point cloud data;

[0106] The copper braided wire after immersion corrosion in the embodiment of the present invention is as follows Figure 7 As shown in the figure, the copper braided wire was immersed in 3.5% NaCl solution for 16 days, and corrosion products were visible on the surface. After the corrosion product removal treatment, the corrosion weight loss was measured to be 0.0431g, and the relative corrosion weight loss was 1.47%. The resistance before and after corrosion was measured by the four-wire method to be 596.3μΩ and 621μΩ respectively, and the relative growth rate of resistance was 4.14%. The corrosion morphology after 160 steps of corrosion simulation using the cellular automaton algorithm of the present invention is shown in the figure. Figure 3 The main parameters of the model are shown in Table 1.

[0107] Table 1 Model parameters

[0108] parameter Numeric k 20 m 0.1 n 0.005 <![CDATA[P3]]> 0.2 <![CDATA[P4]]> 0.5 <![CDATA[P5]]> 0.1 <![CDATA[N diff ]]> 50 <![CDATA[N diff_I ]]> 10

[0109] In this example, every 10 corrosion steps corresponds to approximately 1 day of immersion corrosion. The corresponding corrosion weight loss rate calculated from the number of cells is 1.52%. Using the solid modeling method of the present invention, the corresponding three-dimensional solid morphology is obtained as follows Figure 8 As shown, Figure 8The schematic diagram of the aviation metal braided wire entity in the embodiment of the present invention is the aviation metal braided wire entity model in the finite element software. The resistance before and after corrosion is calculated to be 588.2μΩ and 611.4μΩ respectively in the COMSOL software, and the relative growth rate of resistance is 3.95%. Compared with the experimental results, it is found that the error of the corrosion weight loss rate and the relative growth rate of resistance is small, which proves the feasibility of the method in the present invention.

[0110] The beneficial effects of the present invention are as follows: the present invention provides a point cloud data entity modeling method for aviation metal braided conductors based on cellular corrosion. The corrosion simulation in the embodiment of the present invention can be used to guide accelerated corrosion tests. By setting specific environmental parameters, the simulation software can simulate the corrosion of equipment or components under accelerated corrosion conditions. It helps to identify potential corrosion risk points in the design stage, thereby optimizing the anti-corrosion design. The solid model of the corrosion simulation results can be widely used in finite element analysis (FEA), including: architecture, machinery, aviation and other fields. The entity is imported for finite element analysis to simulate structural analysis such as stress, deformation and heat conduction of different materials and structures. In fluid mechanics, the fluid mechanics properties of equipment or structures are evaluated by simulating fluid flow. In the fields of electronic products, engines, etc., finite element analysis is used to perform heat conduction analysis, evaluate temperature distribution and thermal expansion effects, etc.

[0111] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A point cloud data entity modeling method for aviation metal braided wire based on cellular corrosion, characterized in that: It includes: S1: Establish a three-dimensional cellular space simulating the corrosion environment of aviation metal braided wires; transform the reaction transformation elements involved in the corrosion process during the pitting corrosion of aviation metal braided wires into each cell in the three-dimensional cellular space of aviation metal braided wires; S2: Performing simulation modeling of the corrosion process of aviation metal braided wires according to the three-dimensional cellular space in step S1, and determining the cellular transformation and diffusion rules of the aviation metal braided wires and the corresponding corrosion and diffusion probabilities; S21: Determine the cellular transformation rules and corrosion probability of the aviation metal braided wire; based on the corrosion model of small anode and large cathode, during the reaction process, the surface of the anti-corrosion coating randomly generates a damage point with probability P1, and a hemispherical pit is generated with the damage point as the center of the circle. The inside of the pit is a hydrogen ion cell H. The first probability P1 of the pit generated on the surface of the aviation metal braided wire is: Wherein, P1 is the first probability of corrosion pits on the surface of aviation metal braided wire; k is the corrosion parameter of aviation metal braided wire; N is the number of corrosion steps of aviation metal braided wire; S22: When the aviation metal braided wire contacts the hydrogen ion solution, an anodic reaction occurs. The corresponding transformation rule and corrosion probability are: P2=mN H +nN W Where R is the corroded metal cell; C is the ion cell generated by corrosion; P2 is the second probability of pits on the surface of aviation metal braided wire; m is the weight coefficient of hydrogen ion cell H; n is the weight coefficient of corrosive solution cell W; N H is the number of hydrogen ion cells H; N W is the number of corrosive solution cells W; S23: When the aviation metal braided wire contacts the metal ion solution, a passivation reaction occurs, and the corresponding transformation rule is: Where C is the ion cell generated by corrosion; W n is a random corrosive solution cell; P3 is the third probability of generating pits on the surface of aviation metal braided wire; P is a passivation product cell; H n is a random S hydrogen ion cell; C n is the ion cell generated by random corrosion; P4 is the fourth probability of generating pits on the surface of aviation metal braided wire; P n is the random passivation product cell; S24: Determine the diffusion rule of the corrosion process of the aviation metal braided wire as follows: the ion cell C and the hydrogen ion cell H generated by the corrosion randomly move to one of the nearby solution cells during the diffusion process. If the ion cell C and the hydrogen ion cell H generated by the corrosion move to the cell position with the same state, no position exchange occurs. If they move to the cell position with different states, they exchange positions. If there are solid cells around the passivation product cell P, they do not move. Otherwise, they exchange positions with one of the randomly encountered solution cells. S25: setting the number of corrosion steps N for the aviation metal braided wire, repeating steps S21-S24 for N cycles and ending, and obtaining the corroded metal cell R as the corrosion simulation result of the corrosion process simulation of the aviation metal braided wire; S3: construct the three-dimensional space point cloud equation of the aviation metal braided wire cell to generate the aviation metal braided wire grid unit; S31: Output the corrosion simulation results of the metal cell R corroded in step S2 as three-dimensional discrete points, and obtain the coordinate judgment equation of the aviation metal braided wire cell in three-dimensional space: Among them, MetalSur face (i, j, k) is the coordinate of the aviation metal braided wire cell in three-dimensional space; is in contact with the passivation product cell P, the corroded metal cell R and the anti-corrosion coating cell D; i is the horizontal coordinate of the aviation metal braided wire cell in space; j is the vertical coordinate of the aviation metal braided wire cell in space; k is the vertical coordinate of the aviation metal braided wire cell in space; if is a function to judge whether the condition is met; otherwiye is a function to judge whether the condition is not met; S32: Determine whether the three-dimensional discrete point output in step S2 is an aviation metal braided wire cell according to the coordinate judgment equation in step S31, and extract the coordinate (x i ,y i ,z i ), construct the three-dimensional point cloud equation PoCl of aviation metal braided wire; S33: for the three-dimensional space point cloud equation PoCl of the aviation metal braided wire in step S32, an octree optimization algorithm is used to distinguish the corrosion range of the three-dimensional point cloud of the aviation metal braided wire, and generate a triangular mesh unit of the aviation metal braided wire; S34: segmenting the aviation metal braided wire triangular mesh unit generated in step S33, and converting the aviation metal braided wire triangular mesh unit into the aviation metal braided wire tetrahedral mesh unit using a curvature minimization smoothing algorithm; S4: The tetrahedral mesh units of the aviation metal braided wire in step S3 are spliced ​​to generate a smooth surface, completing the solid modeling of the aviation metal braided wire point cloud data.

2. The point cloud data entity modeling method for aviation metal braided wire based on cellular corrosion according to claim 1 is characterized by: The reaction conversion elements in step S1 refer to the metals, solutions and corrosion products involved in the corrosion reaction, specifically including: aviation metal braided wire cells M, corroded metal cells R, anti-corrosion coating cells D, passivation product cells P, corrosive solution cells W, hydrogen ion cells H and ion cells C generated by corrosion.

3. The point cloud data entity modeling method for aviation metal braided wire based on cellular corrosion according to claim 1 is characterized by: The specific anode reaction in step S22 is: the corroded metal cell R is converted into the ion cell C generated by corrosion, wherein the second probability P2 of the corrosion pit on the surface of the aviation metal braided wire is the number N of hydrogen ion cells H adjacent to the corroded metal cell R H and the number of corrosive solution cells w N W There is a positive correlation between the weight coefficient m of the hydrogen ion cell H and the weight coefficient n of the corrosive solution cell W; compared with the corrosive solution cell W, the hydrogen ion cell H can directly dissolve with the metal matrix. Therefore, the weight coefficient m of the hydrogen ion cell H is greater than the weight coefficient n of the corrosive solution cell W.

4. The point cloud data entity modeling method for aviation metal braided wire based on cellular corrosion according to claim 1 is characterized by: The passivation reaction in step S23 is specifically as follows: the ion cell C generated by corrosion randomly selects a contact cell. If the selected contact cell is a corrosive solution cell W, the ion cell generated by corrosion is converted into a passivation product cell P, and the corrosive solution cell W is converted into a hydrogen ion cell H. Its probability value is the third probability P3 of generating pits on the surface of the aviation metal braided wire, which is related to the concentration, temperature, and reactivity factors of the solution and needs to be determined through experimental fitting. When two ion cells C generated by corrosion meet, that is, when the contact cell selected by the ion cell C generated by corrosion is the ion cell C generated by corrosion, the fourth probability P4 of generating pits on the surface of the aviation metal braided wire where the passivation reaction occurs will increase, which is related to the passivation product, hydrogen ion concentration, and ion cell generated by corrosion, and needs to be determined through experimental fitting. The ion cell C generated by corrosion is converted into the passivation product cell P. The fourth probability P4 of generating pits on the surface of the aviation metal braided wire is greater than the third probability P3 of generating pits on the surface of the aviation metal braided wire.

5. The method for point cloud data entity modeling of aviation metal braided wire based on cellular corrosion according to claim 1 is characterized by: The hydrogen ion cell H generated by the passivation reaction in step S23 will cause the hydrolysis reaction to be reversible, that is, the contact cell selected by the passivation product cell P is the hydrogen ion cell H, and the passivation product cell P and the hydrogen ion cell H are converted into the ion cell C generated by corrosion, and the probability thereof is the fifth probability P5 of generating pits on the surface of the aviation metal braided wire, and the corresponding conversion rule is: Wherein, P5 is the fifth probability of generating pits on the surface of the aviation metal braided wire.

6. The method for point cloud data entity modeling of aviation metal braided wire based on cellular corrosion according to claim 1 is characterized by: The solution cell and the solid cell in step S24 are specifically: The solution cells include: ion cells C generated by corrosion, hydrogen ion cells H and corrosive solution cells W; The solid cells include: corroded metal cells R, anti-corrosion coating cells D and aviation metal braided wire cells M.

7. The method for point cloud data entity modeling of aviation metal braided wire based on cellular corrosion according to claim 1, characterized in that: In step S24, the diffusion rule of the corrosion process of the aviation metal braided wire is determined, specifically: the ion cell C and the hydrogen ion cell H generated by the corrosion generate N in each corrosion reaction step. diff Second diffusion, the passivation product cell P undergoes N diff_I diffusion, and the probability of exchange between cells is the same; since the ion cells C and hydrogen ion cells H generated by corrosion exist in the solution in the form of ions, and the passivation product cells P are suspended in the electrolyte solution in the form of colloid, it can be concluded that N diff >N diff_I .

8. The method for point cloud data entity modeling of aviation metal braided wire based on cellular corrosion according to claim 1, characterized in that: In step S32, the three-dimensional point cloud equation PoCl of the aviation metal braided wire is constructed as follows: PoCl={(x1,y1,z1),(x2,y2,z2),…,(x n ,y n ,z n )} Among them, PoCl is the three-dimensional point cloud equation of the aviation metal braided wire; x1 is the horizontal coordinate of the first point in the three-dimensional space; y1 is the vertical coordinate of the first point in the three-dimensional space; z1 is the vertical coordinate of the first point in the three-dimensional space; x2 is the horizontal coordinate of the second point in the three-dimensional space; y2 is the vertical coordinate of the second point in the three-dimensional space; z2 is the vertical coordinate of the second point in the three-dimensional space; x n is the horizontal coordinate of the nth point in three-dimensional space; y n is the vertical coordinate of the nth point in three-dimensional space; z n is the vertical coordinate of the nth point in three-dimensional space.

9. The method for point cloud data entity modeling of aviation metal braided wire based on cellular corrosion according to claim 1, characterized in that: In step S33, an octree optimization algorithm is used to distinguish the corrosion range of the three-dimensional point cloud of the aviation metal braided wire and generate a triangular mesh unit of the aviation metal braided wire, specifically: For each point in the point cloud of the three-dimensional space of the aviation metal braided wire, the normal vector is calculated using the points in the neighborhood; the target point in the point cloud is The points in the neighborhood are {(Pa1,Pa2,……,Pa n }, then the triangular mesh of the target point is obtained according to the normal vector of the target point in the point cloud: Among them, n i is the triangular mesh of the i-th target point in the point cloud; Pa i is the normal vector of the i-th target point in the point cloud; Pa j is the normal vector of the jth target point in the point cloud; i is the first number of the target point in the point cloud; j is the second number of the target point in the point cloud; m is the total number of target points in the point cloud; To speed up the calculation of the normal vector, set the octree radius r to distinguish the relative range of the inner and outer parts of the point cloud, and obtain the triangular mesh n of the i-th target point in the point cloud. i for:

10. The method for point cloud data entity modeling of aviation metal braided wire based on cellular corrosion according to claim 1, characterized in that: In step S34, the triangular mesh unit of the aviation metal braided wire generated in step S33 is segmented, and the triangular mesh unit of the aviation metal braided wire is converted into a tetrahedral mesh unit of the aviation metal braided wire using a smooth algorithm that minimizes curvature, specifically: Each triangle patch △(v1, v2, v3) of the triangular mesh unit is divided into 4 secondary triangular patches; the midpoint of each edge corresponding to each triangular patch is connected to the center point of the original triangle to generate 4 secondary triangular patches, and the secondary vertex v4 is the centroid of the initial triangular patch; each triangular patch will be continuously refined until the triangular mesh unit contains enough tetrahedral mesh units, and the secondary vertex v4 of the tetrahedral mesh is obtained as: Among them, v4 is the secondary vertex of the tetrahedron mesh; v1 is the first vertex of the triangle patch; v2 is the second vertex of the triangle patch; v3 is the third vertex of the triangle patch; Use a smoothing algorithm based on curvature minimization to smooth the tetrahedral mesh. Based on the above meshing, give each tetrahedral mesh an initial position v i , its updated position v′ i is the weighted average of the positions of its adjacent vertices, which can be obtained by: Among them, v′ i is the updated position of the tetrahedral mesh; v j is the initial position of the tetrahedral mesh; N(i) is the initial position v of the tetrahedral mesh i The set of adjacent vertices of a vertex is determined by the number of adjacent vertices of the vertex.

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