Method and system for simulating galvanic corrosion of dissimilar metal lap joint structure of airplane

Abstract

The invention relates to the technical field of corrosion simulation, and particularly provides a galvanic corrosion simulation method and system for a dissimilar metal lap joint structure of an airplane, and the method comprises the steps: constructing a Heaviside function for representing boundary discontinuity based on a defined domain and boundary; converting the Heaviside function into a basic function which introduces a first-order fuzzy approximation interface, and constructing an interface description model based on the basic function; constructing a level set mechanism model based on the interface description model and a level set basic function; and setting the particle concentration in the electrolyte domain to be the same, and solving the horizontal mechanism model to obtain the dynamic change of the corrosion interface. According to the method, the Heaviside function and the level set mechanism are combined, the Nernst-Planck equation is combined, the level set mechanism model is constructed, corrosion dynamic interface evolution simulation is achieved, and the goodness of fit with the real galvanic corrosion process of the airplane dissimilar metal lap joint structure is higher.

Description

Technical Field

[0001] The invention belongs to the technical field of corrosion simulation, and in particular relates to a method and system for simulating galvanic corrosion of aircraft dissimilar metal overlap structures. Background Art

[0002] Aircrafts are in a complex service environment and are often affected by humid atmosphere, marine atmosphere, industrial atmosphere and other environmental factors. Corrosion under environmental influences is an important form of aircraft structural damage. Since the aircraft body structure contains a large number of overlapping forms of dissimilar materials, galvanic corrosion caused by the contact of dissimilar materials has become one of the most common forms of corrosion in aircraft structures.

[0003] At present, the most widely used method in galvanic corrosion structural deformation is based on the Arbitrary Lagrangian-Eulerian Formulation (ALE). This method not only absorbs the advantages of the two finite element simulations, the Lagrangian algorithm and the Eulerian algorithm, but also overcomes some shortcomings of the two traditional methods. Specifically, ALE discretizes the finite element model and writes the control equation as a function of the grid coordinates. These grid coordinates have a one-to-one mapping relationship with the current computational domain space coordinates. If the grid displacement is too large or the grid quality is too low during the calculation process, the computational domain will be re-divided, and all the variables to be solved will be mapped from the old grid to the new grid. In this way, the control equation is redefined on the freely changing grid. The ALE method allows the grid coordinates to be separated from the material coordinates, so it can describe the physical problems of large deformations with higher accuracy. However, when the structure has large topological deformations, this method will have serious numerical singularity problems, resulting in non-convergence of the results.

[0004] Due to the high computational cost, singularity in the mesh, and non-convergence in the calculation, the existing galvanic corrosion model cannot calculate the structural deformation, and therefore cannot accurately simulate the galvanic corrosion of the aircraft's dissimilar metal lap joint structure. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method and system for simulating galvanic corrosion of aircraft dissimilar metal overlap structures to solve the above-mentioned technical problems.

[0006] In a first aspect, the present invention provides a method for simulating galvanic corrosion of an aircraft dissimilar metal overlap structure, comprising: Based on the defined domain and boundary, the Heaviside function is constructed to characterize the boundary discontinuity. Converting the Heaviside function into a basis function for introducing a first-order fuzzy approximate interface, and constructing an interface description model based on the basis function; Based on the interface description model and the level set basic function, a level set mechanism model is constructed; The particle concentration in the electrolyte domain is assumed to be the same, and the horizontal mechanism model is solved to obtain the dynamic changes of the corrosion interface.

[0007] In an optional embodiment, based on the defined domain and boundary, a Heaviside function for characterizing boundary discontinuity is constructed, including: Assume that the domain Ω is divided into two subdomains Ω1 and Ω2, and Ω2=Ω\Ω1. Assume that Г is the boundary between subdomains Ω1 and Ω2. The bound Г is implicitly defined as the regularized characteristic function, Phase change is achieved through the interface Г; Introduce the Heaviside function: .

[0008] In an optional implementation, the Heaviside function is converted into a basis function that introduces a first-order fuzzy approximate interface, and an interface description model is constructed based on the basis function, including: Introduce the Heaviside function of the first-order fuzzy approximation interface: ; in Represents the thickness of the interface Г, which usually depends on the mesh size.

[0009] In an optional implementation, a level set mechanism model is constructed based on the interface description model and the level set basic function, including: Based on the non-fixed contour and thickness of the interface, the smoothness of the discontinuous interface is maintained and a compression term is added after each time step: , represents the compression flux; By setting , so that the compression flux acts on region and along the interface normal direction, where is the set time value; To avoid breakpoints in the interface, Introducing the viscosity term into ,in stands for Laplace operator; Will With the level set basic function By combining them, we get the level set control function ,in , γ is the thickness change threshold, Represents the interface thickness parameter; Integrate over a domain: ; Solving for the conductivity in the domain , the formula is: ,in is the electrolyte conductivity of the electrolyte, The conductivity of the electrode's electrolyte; Constructing the Heaviside function H The derivative in the normal direction, that is, the Dirac function: , where is the normal vector on the level set boundary; Will Substituting into the Dirac function we get: ,in, ; The surface integral on the interface Г is defined as: ; By the Dirac function Domain Except for the border Г Delete all areas outside and track the interface Г; right The function is regularized to approximate, ensuring , obtained by regularization The function is: ; After regularization The function is: ; Introducing the electrolyte current source term Q l The boundary reaction integral is converted into a domain integral for solution, and the electrolyte current source term Q l The expression function is: , i loc is the local current density on the electrode surface.

[0010] In an optional embodiment, the particle concentration in the electrolyte domain is set to be the same, and the horizontal mechanism model is solved to obtain the dynamic change of the corrosion interface, including: Assume that the electrolyte solution is a static dilute solution, that is, the particle concentration in the electrolyte domain is the same everywhere, there is no concentration gradient, and ignore the convection and diffusion terms of the Nernst-Planck equation. The Nernst-Planck equation includes: ,in is the diffusion term, is the convection term, is the electromigration term, is the net flux; Charged particles in the electrolyte solution only form current through electromigration. The current density vector in the electrolyte solution is i l The representation is: ; In dilute solutions, the conductivity of an electrolyte can be expressed as the sum of the contributions of each ion, i.e.: ; The current density vector i l The representation is converted to: ; Based on the preset net charge in the electrolyte domain being 0, the current conservation equation ,right The solution is: ; By solving the electrolyte potential φ l The Laplace equation is used to obtain the potential distribution law in the corrosion electric field, and then substituted into the formula , and obtain the current density distribution; The current density value is calculated according to Faraday's law and the current density value equation is: ; The metal corrosion rate is obtained from the current density equation: ; Where: It reflects the change of corrosion depth over time, that is, the corrosion rate v ; i loc is the local current density; n is the chemical equivalence coefficient; M is the relative molecular mass; is the density; Local current density at the interface i loc for: ; Where: Overpotential , is the electrode potential, which is taken as 0; is the electrolyte potential; Corrosion rate v It is the driving force that controls the change of the level set function. In the two-dimensional solution domain, the level set function The velocity vector is x and y Direction Component and Can be characterized as: ; ; The amount and Substitute the level set control equation for solution and obtain the dynamic changes of the corrosion interface.

[0011] In a second aspect, the present invention provides a galvanic corrosion simulation system for aircraft dissimilar metal overlap structures, comprising: Function building module, used to build Heaviside functions for characterizing boundary discontinuities based on defined domains and boundaries; A function transformation module, used for converting the Heaviside function into a basis function for introducing a first-order fuzzy approximate interface, and constructing an interface description model based on the basis function; A model building module, used for building a level set mechanism model based on the interface description model and the level set basic function; The model solving module is used to set the particle concentration in the electrolyte domain to be the same, solve the horizontal mechanism model, and obtain the dynamic changes of the corrosion interface.

[0012] In an optional embodiment, the function building module includes: Assume that the domain Ω is divided into two subdomains Ω1 and Ω2, and Ω2=Ω\Ω1. Assume that Г is the boundary between subdomains Ω1 and Ω2. The bound Г is implicitly defined as the regularized characteristic function, Phase change is achieved through the interface Г; Introduce the Heaviside function: .

[0013] In an optional implementation, the function transformation module includes: Introduce the Heaviside function of the first-order fuzzy approximation interface: ; in Represents the thickness of the interface Г, which usually depends on the mesh size.

[0014] In an optional embodiment, the model building module includes: Based on the non-fixed contour and thickness of the interface, the smoothness of the discontinuous interface is maintained and a compression term is added after each time step: , represents the compression flux; By setting , so that the compression flux acts on region and along the interface normal direction, where is the set time value; To avoid breakpoints in the interface, Introducing the viscosity term into ,in stands for Laplace operator; Will With the level set basic function By combining them, we can get the level set control function ,in , γ is the thickness change threshold, Represents the interface thickness parameter; Integrate over a domain: ; Solving for the conductivity in the domain , the formula is: ,in is the electrolyte conductivity of the electrolyte, The conductivity of the electrode's electrolyte; Constructing the Heaviside function H The derivative in the normal direction, that is, the Dirac function: , where is the normal vector on the level set boundary; Will Substituting into the Dirac function we get: ,in, ; The surface integral on the interface Г is defined as: ; By the Dirac function Domain Except for the border Г Delete all areas outside and track the interface Г; right The function is regularized to approximate, ensuring , obtained by regularization The function is: ; After regularization The function is: ; Introducing the electrolyte current source term Q l The boundary reaction integral is converted into a domain integral for solution, and the electrolyte current source term Q l The expression function is: , i loc is the local current density on the electrode surface.

[0015] In an optional embodiment, the model solving module includes: Assume that the electrolyte solution is a static dilute solution, that is, the particle concentration in the electrolyte domain is the same everywhere, there is no concentration gradient, and ignore the convection and diffusion terms of the Nernst-Planck equation. The Nernst-Planck equation includes: ,in is the diffusion term, is the convection term, is the electromigration term, is the net flux; Charged particles in the electrolyte solution only form current through electromigration. The current density vector in the electrolyte solution is i l The representation is: ; In dilute solutions, the conductivity of an electrolyte can be expressed as the sum of the contributions of each ion, i.e.: ; The current density vector i l The representation is converted to: ; Based on the preset net charge in the electrolyte domain being 0, the current conservation equation ,right The solution is: ; By solving the electrolyte potential φ l The Laplace equation is used to obtain the potential distribution law in the corrosion electric field, and then substituted into the formula , and obtain the current density distribution; The current density value is calculated according to Faraday's law and the current density value equation is: ; The metal corrosion rate is obtained from the current density equation: ; Where: It reflects the change of corrosion depth over time, that is, the corrosion rate v ; i loc is the local current density; n is the chemical equivalence coefficient; M is the relative molecular mass; is the density; Local current density at the interface i loc for: ; Where: Overpotential , is the electrode potential, which is taken as 0; is the electrolyte potential; Corrosion rate v It is the driving force that controls the change of the level set function. In the two-dimensional solution domain, the level set function The velocity vector is x and y Direction Component and Can be characterized as: ; ; The amount and Substitute the level set control equation for solution and obtain the dynamic changes of the corrosion interface.

[0016] The beneficial effect of the present invention is that the method and system for simulating galvanic corrosion of aircraft dissimilar metal lap structures provided by the present invention combine the Heaviside function and the level set mechanism, and combine with the Nernst-Planck equation to construct a level set mechanism model, realize the simulation of the dynamic interface evolution of corrosion, and have a higher degree of consistency with the actual galvanic corrosion process of the aircraft dissimilar metal lap structures.

[0017] In addition, the invention has a reliable design principle, a simple structure and a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 is a schematic flow chart of a method according to an embodiment of the present invention.

[0020] Figure 2 It is a schematic diagram of a model of a method according to an embodiment of the present invention.

[0021] Figure 3 is a schematic block diagram of a system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0024] The method for simulating galvanic corrosion of an aircraft dissimilar metal overlap structure provided by an embodiment of the present invention is executed by a computer device, and accordingly, the system for simulating galvanic corrosion of an aircraft dissimilar metal overlap structure runs in the computer device.

[0025] Figure 1 is a schematic flow chart of a method according to an embodiment of the present invention. Figure 1 The execution subject can be a galvanic corrosion simulation system for aircraft dissimilar metal overlap structures. According to different requirements, the order of the steps in the flow chart can be changed, and some can be omitted.

[0026] like Figure 1 As shown, the method includes: Step 110, constructing a Heaviside function for characterizing boundary discontinuity based on the defined domain and boundary; Step 120, converting the Heaviside function into a basis function for introducing a first-order fuzzy approximate interface, and constructing an interface description model based on the basis function; Step 130, constructing a level set mechanism model based on the interface description model and the level set basic function; Step 140, setting the particle concentration in the electrolyte domain to be the same, solving the horizontal mechanism model, and obtaining the dynamic changes of the corrosion interface.

[0027] To facilitate understanding of the present invention, the following is a further description of the method for simulating galvanic corrosion of dissimilar metal lap joints of aircraft provided by the present invention based on the principle of the method for simulating galvanic corrosion of dissimilar metal lap joints of aircraft provided by the present invention and the process of simulating galvanic corrosion of dissimilar metal lap joints of aircraft provided by the present invention in combination with the embodiment.

[0028] For details, please refer to Figure 2 , the simulation method of galvanic corrosion of aircraft dissimilar metal lap joint structure includes: S1. Based on the defined domain and boundary, a Heaviside function is constructed to characterize boundary discontinuities.

[0029] The level set method is a conservative level set model for tracking moving interfaces under the premise of a given velocity vector. It has been widely used in tracking phase interfaces in two-phase flow. Assume that the domain Ω is divided into two subdomains Ω1 and Ω2, and Ω2=Ω\Ω1. Assume that Г is the boundary between subdomains Ω1 and Ω2. The bound Г is implicitly defined as the regularized characteristic function, Phase change is achieved through the interface Г; Introduce the Heaviside function: .

[0030] S2. Convert the Heaviside function into a basic function that introduces a first-order fuzzy approximate interface, and construct an interface description model based on the basic function.

[0031] Usually choose The contour line of is taken as the interface Г. Since this method is conservative, is completely conserved. If the Heaviside function with a clear interface is used, the evolution of the closed curve (surface) can be accurately tracked. However, on a discrete grid, it is difficult for the position of the interface to change suddenly from 0 to 1. In order to enhance the numerical robustness, a first-order fuzzy approximate interface Heaviside function is introduced: ; in Represents the thickness of the interface Г, which usually depends on the mesh size.

[0032] S3. Constructing a level set mechanism model based on the interface description model and the level set basic function.

[0033] Since the contour and thickness of the interface are difficult to remain constant during the calculation process, based on the non-fixed contour and thickness of the interface and maintaining the smoothness of the discontinuous interface, a compression term is added after each time step, which can be regarded as an intermediate step in solving the conservation law: , represents the compression flux; By setting , so that the compression flux acts on region and along the interface normal direction, where It is the set time value, not the actual time t .

[0034] It can be seen that is a hyperbolic differential equation. Assuming time The increase of the interface makes it difficult to ensure the stability of the interface. Introducing the viscosity term into ,in stands for Laplace operator.

[0035] Will With the level set basic function By combining them, we get the level set control function ; in , γ is the thickness change threshold, reinitialize the parameters γ It can ensure that the gradient in the level set function gradually concentrates on the free surface, that is, the phase interface, over time. It does not set the surface thickness, but it can ensure that the change of the level set function is within the thickness range. If the parameter value is set too low, the change of the level set function may be trapped in the same domain, and then the two-phase interface is generated out of thin air. Too high a value often results in too small a time step and too long a calculation time. The interface thickness parameter is more intuitive to understand, and its only function is to control the thickness of the region where the level set function changes. Too thick will blur the shape of the free surface. Although this makes the problem easier to solve, it loses the shape accuracy of the free surface. A value smaller than the mesh cell size is good for generating clear surfaces, but this also requires the mesh to have a corresponding resolution. It does not make sense to set a value smaller than the mesh cell size, because this will make the interface irregular and the surface tension cannot be resolved, which may cause velocity distortion. The setting is generally 1 / 4 of the largest unit near the surface.

[0036] The integral over the domain is defined using the Heaviside function: ; To solve the conductivity in the domain For example, the formula is: ,in is the electrolyte conductivity of the electrolyte, Electrolyte conductivity of the electrode; electrolyte conductivity in the electrolyte domain describes the actual chemical problem, and the definition of electrolyte conductivity in the electrode domain is only to help numerical convergence and has no practical significance.

[0037] Since the electrode reactions all occur on the electrode surface, that is, the interface between the electrolyte and the electrode, by definition, the Heaviside function H The derivative in the normal direction is the Dirac function: , where is the normal vector on the level set boundary, Substituting into the Dirac function we get: , in, .

[0038] The surface integral on the interface Г is defined as: ; Dirac function You can delete the domain Except for the border Г All areas outside the interface are tracked.

[0039] right The function is regularized to approximate, ensuring , obtained by regularization The function is: ; After regularization The function is: ; The local current density on the electrode surface i loc For example, when defining the electrode surface reaction, unlike the ALE method, simply defining the cathode and anode reactions on the boundary cannot meet the requirements. The electrolyte current source term is introduced. Q l The boundary reaction integral is converted into a domain integral for solution, and the electrolyte current source term Q l The expression function is: , i loc is the local current density on the electrode surface.

[0040] S4. The particle concentration in the electrolyte domain is set to be the same, and the horizontal mechanism model is solved to obtain the dynamic changes of the corrosion interface.

[0041] Establish assumptions up front, including: (1) Assume that the oxygen reduction reaction only occurs on the surface of TA15 titanium alloy, and the active dissolution of metal only occurs on the surface of 2A12 aluminum alloy; (2) Assume that the electrolyte is an infinitely dilute solution, that is, all physical parameters are independent of the substance concentration; (3) An acidic electrolyte solution with a pH of 4 is used, assuming that the corrosion products do not undergo dense deposition and have no effect on the corrosion reaction.

[0042] Assume that the electrolyte solution is a static dilute solution, that is, the particle concentration in the electrolyte domain is the same everywhere, there is no concentration gradient, and ignore the convection and diffusion terms of the Nernst-Planck equation. The Nernst-Planck equation includes: ,in is the diffusion term, is the convection term, is the electromigration term, is the net flux; Charged particles in the electrolyte solution only form current through electromigration. The current density vector in the electrolyte solution is i l The representation is: ; In dilute solutions, the conductivity of an electrolyte can be expressed as the sum of the contributions of each ion, i.e.: ; The current density vector i l The representation is converted to: ; This equation has the same form as Ohm's law, based on the assumption that the net charge in the electrolyte domain is zero, and the current conservation equation ,right The solution is: ; By solving the electrolyte potential φ l The Laplace equation is used to obtain the potential distribution law in the corrosion electric field, and then substituted into the formula , and obtain the current density distribution.

[0043] The current density value is calculated according to Faraday's law and the current density value equation is: ; The metal corrosion rate is obtained from the current density equation: ; Where: It reflects the change of corrosion depth over time, that is, the corrosion rate v ; i loc is the local current density; n is the chemical equivalence coefficient; M is the relative molecular mass; is the density.

[0044] Local current density at the interface i loc for: ; Where: Overpotential , is the electrode potential, which is taken as 0; is the electrolyte potential.

[0045] Corrosion ratev It is the driving force that controls the change of the level set function. In the two-dimensional solution domain, the level set function The velocity vector is x and y Direction Component and Can be characterized as: ; ; The amount and Substitute the level set control equation in step S3 and solve it to obtain the dynamic changes of the corrosion interface.

[0046] In some embodiments, the aircraft dissimilar metal overlap structure galvanic corrosion simulation system may include multiple functional modules composed of computer program segments. The computer program of each program segment in the aircraft dissimilar metal overlap structure galvanic corrosion simulation system may be stored in the memory of a computer device and executed by at least one processor to execute (see Figure 1 Description) Functionality for galvanic corrosion simulation of aircraft dissimilar metal joint structures.

[0047] In this embodiment, the aircraft dissimilar metal overlap structure galvanic corrosion simulation system can be divided into multiple functional modules according to the functions it performs, such as Figure 3 As shown. The functional modules of the system 300 may include: a function construction module 310, a function transformation module 320, a model construction model 330 and a model solving model 340. The module referred to in the present invention refers to a series of computer program segments that can be executed by at least one processor and can complete fixed functions, which are stored in a memory. In this embodiment, the functions of each module will be described in detail in subsequent embodiments.

[0048] Function building module, used to build Heaviside functions for characterizing boundary discontinuities based on defined domains and boundaries; A function transformation module, used for converting the Heaviside function into a basis function for introducing a first-order fuzzy approximate interface, and constructing an interface description model based on the basis function; A model building module, used for building a level set mechanism model based on the interface description model and the level set basic function; The model solving module is used to set the particle concentration in the electrolyte domain to be the same, solve the horizontal mechanism model, and obtain the dynamic changes of the corrosion interface.

[0049] Optionally, as an embodiment of the present invention, the function building module includes: Assume that the domain Ω is divided into two subdomains Ω1 and Ω2, and Ω2=Ω\Ω1. Assume that Г is the boundary between subdomains Ω1 and Ω2. The bound Г is implicitly defined as the regularized characteristic function, Phase change is achieved through the interface Г; Introduce the Heaviside function: .

[0050] Optionally, as an embodiment of the present invention, the function transformation module includes: Introduce the Heaviside function of the first-order fuzzy approximation interface: ; in Represents the thickness of the interface Г, which usually depends on the mesh size.

[0051] Optionally, as an embodiment of the present invention, the model building module includes: Based on the non-fixed contour and thickness of the interface, the smoothness of the discontinuous interface is maintained and a compression term is added after each time step: , represents the compression flux; By setting , so that the compression flux acts on region and along the interface normal direction, where is the set time value; To avoid breakpoints in the interface, Introducing the viscosity term into ,in stands for Laplace operator; Will With the level set basic function By combining them, we get the level set control function ,in , γ is the thickness change threshold, Represents the interface thickness parameter; Integrate over a domain: ; Solving for the conductivity in the domain , the formula is: ,in is the electrolyte conductivity of the electrolyte, The conductivity of the electrode's electrolyte; Constructing the Heaviside function H The derivative in the normal direction, that is, the Dirac function: , where is the normal vector on the level set boundary; Will Substituting into the Dirac function we get: ,in, ; The surface integral on the interface Г is defined as: ; By the Dirac function Domain Except for the border Г Delete all areas outside and track the interface Г; right The function is regularized to approximate, ensuring , obtained by regularization The function is: ; After regularization The function is: ; Introducing the electrolyte current source term Q l The boundary reaction integral is converted into a domain integral for solution, and the electrolyte current source term Q l The expression function is: , i loc is the local current density on the electrode surface.

[0052] Optionally, as an embodiment of the present invention, the model solving module includes: Assume that the electrolyte solution is a static dilute solution, that is, the particle concentration in the electrolyte domain is the same everywhere, there is no concentration gradient, and ignore the convection and diffusion terms of the Nernst-Planck equation. The Nernst-Planck equation includes: ,in is the diffusion term, is the convection term, is the electromigration term, is the net flux; Charged particles in the electrolyte solution only form current through electromigration. The current density vector in the electrolyte solution is i l The representation is: ; In dilute solutions, the conductivity of an electrolyte can be expressed as the sum of the contributions of each ion, i.e.: ; The current density vector i l The representation is converted to: ; Based on the preset net charge in the electrolyte domain being 0, the current conservation equation ,right The solution is: ; By solving the electrolyte potential φ l The Laplace equation is used to obtain the potential distribution law in the corrosion electric field, and then substituted into the formula , and obtain the current density distribution; The current density value is calculated according to Faraday's law and the current density value equation is: ; The metal corrosion rate is obtained from the current density equation: ; Where: It reflects the change of corrosion depth over time, that is, the corrosion rate v ; i loc is the local current density; n is the chemical equivalence coefficient; M is the relative molecular mass; is the density; Local current density at the interface i loc for: ; Where: Overpotential , is the electrode potential, which is taken as 0; is the electrolyte potential; Corrosion rate v It is the driving force that controls the change of the level set function. In the two-dimensional solution domain, the level set function The velocity vector is x and y Direction Component and Can be characterized as: ; ; The amount and Substitute the level set control equation for solution and obtain the dynamic changes of the corrosion interface.

[0053] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A method for simulating galvanic corrosion of aircraft dissimilar metal overlap structures, characterized in that: include: Based on the defined domain and boundary, the Heaviside function is constructed to characterize the boundary discontinuity. Converting the Heaviside function into a basis function for introducing a first-order fuzzy approximate interface, and constructing an interface description model based on the basis function; Based on the interface description model and the level set basic function, a level set mechanism model is constructed; The particle concentration in the electrolyte domain is assumed to be the same, and the horizontal mechanism model is solved to obtain the dynamic changes of the corrosion interface.

2. The method according to claim 1, characterized in that Based on the defined domain and boundary, the Heaviside function used to characterize boundary discontinuities is constructed, including: Assume that the domain Ω is divided into two subdomains Ω1 and Ω2, and Ω2=Ω\Ω1. Assume that Г is the boundary between subdomains Ω1 and Ω2. The bound Г is implicitly defined as the regularized characteristic function, Phase change is achieved through the interface Г; Introduce the Heaviside function: .

3. The method according to claim 2, characterized in that The Heaviside function is converted into a basis function for introducing a first-order fuzzy approximate interface, and an interface description model is constructed based on the basis function, including: Introduce the Heaviside function of the first-order fuzzy approximation interface: ; in Represents the thickness of the interface Г, which usually depends on the mesh size.

4. The method according to claim 3, characterized in that: Based on the interface description model and the level set basic function, a level set mechanism model is constructed, including: Based on the non-fixedness of the interface profile and thickness, the smoothness of the discontinuous interface is maintained and a compression term is added after each time step: , represents the compression flux; By setting , so that the compression flux acts on region and along the interface normal direction, where is the set time value; To avoid breakpoints in the interface, Introducing the viscosity term into ,in stands for Laplace operator; Will With the level set basic function By combining them, we get the level set control function ,in , γ is the thickness change threshold, Represents the interface thickness parameter; Integrate over a domain: ; Solving for the conductivity in the domain , the formula is: ,in is the electrolyte conductivity of the electrolyte, The conductivity of the electrode's electrolyte; Constructing the Heaviside function H The derivative in the normal direction, that is, the Dirac function: , where is the normal vector on the level set boundary; Will Substituting into the Dirac function we get: ,in, ; The surface integral on the interface Г is defined as: ; By the Dirac function Domain Except for the border Г Delete all areas outside and track the interface Г; right The function is regularized to approximate, ensuring , obtained by regularization The function is: ; After regularization The function is: ; Introducing the electrolyte current source term Q l The boundary reaction integral is converted into a domain integral for solution, and the electrolyte current source term Q l The expression function is: , i loc is the local current density on the electrode surface.

5. The method according to claim 4, characterized in that The particle concentration in the electrolyte domain is assumed to be the same, and the horizontal mechanism model is solved to obtain the dynamic changes of the corrosion interface, including: Assume that the electrolyte solution is a static dilute solution, that is, the particle concentration in the electrolyte domain is the same everywhere, there is no concentration gradient, and ignore the convection and diffusion terms of the Nernst-Planck equation. The Nernst-Planck equation includes: ,in is the diffusion term, is the convection term, is the electromigration term, is the net flux; Charged particles in the electrolyte solution only form current through electromigration. The current density vector in the electrolyte solution is i l The representation is: ； In dilute solutions, the conductivity of an electrolyte can be expressed as the sum of the contributions of each ion, i.e.: ； The current density vector i l The representation is converted to: ； Based on the preset net charge in the electrolyte domain being 0, the current conservation equation ,right The solution is: ； By solving the electrolyte potential φ l The Laplace equation is used to obtain the potential distribution law in the corrosion electric field, and then substituted into the formula , and obtain the current density distribution; The current density value is calculated according to Faraday's law and the current density value equation is: ； The metal corrosion rate is obtained from the current density equation: ； Where: It reflects the change of corrosion depth over time, that is, the corrosion rate v ; i loc is the local current density; n is the chemical equivalence coefficient; M is the relative molecular mass; is the density; Local current density at the interface i loc for: ； Where: Overpotential , is the electrode potential, which is taken as 0; is the electrolyte potential; Corrosion rate v It is the driving force that controls the change of the level set function. In the two-dimensional solution domain, the level set function The velocity vector is x and y Direction Component and Can be characterized as: ； ； The amount and Substitute the level set control equation for solution and obtain the dynamic changes of the corrosion interface.

6. A galvanic corrosion simulation system for aircraft dissimilar metal lap joint structures, characterized in that: include: Function building module, used to build Heaviside functions for characterizing boundary discontinuities based on defined domains and boundaries; A function transformation module, used for converting the Heaviside function into a basis function for introducing a first-order fuzzy approximate interface, and constructing an interface description model based on the basis function; A model building module, used for building a level set mechanism model based on the interface description model and the level set basic function; The model solving module is used to set the particle concentration in the electrolyte domain to be the same, solve the horizontal mechanism model, and obtain the dynamic changes of the corrosion interface.

7. The system according to claim 6, characterized in that The function building block includes: Assume that the domain Ω is divided into two subdomains Ω1 and Ω2, and Ω2=Ω\Ω1. Assume that Г is the boundary between subdomains Ω1 and Ω2. The bound Г is implicitly defined as the regularized characteristic function, Phase change is achieved through the interface Г; Introduce the Heaviside function: .

8. The system according to claim 7, characterized in that The function transformation module comprises: Introduce the Heaviside function of the first-order fuzzy approximation interface: ; in Represents the thickness of the interface Г, which usually depends on the mesh size.

9. The system according to claim 8, characterized in that The model building module includes: Based on the non-fixedness of the interface profile and thickness, the smoothness of the discontinuous interface is maintained and a compression term is added after each time step: , represents the compression flux; By setting , so that the compression flux acts on region and along the interface normal direction, where is the set time value; To avoid breakpoints in the interface, Introducing the viscosity term into ,in stands for Laplace operator; Will With the level set basic function By combining them, we get the level set control function ,in , γ is the thickness change threshold, Represents the interface thickness parameter; Integrate over a domain: ; Solving for the conductivity in the domain , the formula is: ,in is the electrolyte conductivity of the electrolyte, The conductivity of the electrode's electrolyte; Constructing the Heaviside function H The derivative in the normal direction, that is, the Dirac function: , where is the normal vector on the level set boundary; Will Substituting into the Dirac function we get: ,in, ; The surface integral on the interface Г is defined as: ; By the Dirac function Domain Except for the border Г Delete all areas outside and track the interface Г; right The function is regularized to approximate, ensuring , obtained by regularization The function is: ; After regularization The function is: ; Introducing the electrolyte current source term Q l The boundary reaction integral is converted into a domain integral for solution, and the electrolyte current source term Q l The expression function is: , i loc is the local current density on the electrode surface.

10. The system according to claim 9, characterized in that The model solving module includes: Assume that the electrolyte solution is a static dilute solution, that is, the particle concentration in the electrolyte domain is the same everywhere, there is no concentration gradient, and ignore the convection and diffusion terms of the Nernst-Planck equation. The Nernst-Planck equation includes: ,in is the diffusion term, is the convection term, is the electromigration term, is the net flux; Charged particles in the electrolyte solution only form current through electromigration. The current density vector in the electrolyte solution is i l The representation is: ； In dilute solutions, the conductivity of an electrolyte can be expressed as the sum of the contributions of each ion, i.e.: ； The current density vector i l The representation is converted to: ； Based on the preset net charge in the electrolyte domain being 0, the current conservation equation ,right The solution is: ； By solving the electrolyte potential φ l The Laplace equation is used to obtain the potential distribution law in the corrosion electric field, and then substituted into the formula , and obtain the current density distribution; The current density value is calculated according to Faraday's law and the current density value equation is: ； The metal corrosion rate is obtained from the current density equation: ； Where: It reflects the change of corrosion depth over time, that is, the corrosion rate v ; i loc is the local current density; n is the chemical equivalence coefficient; M is the relative molecular mass; is the density; Local current density at the interface i loc for: ； Where: Overpotential , is the electrode potential, which is taken as 0; is the electrolyte potential; Corrosion rate v It is the driving force that controls the change of the level set function. In the two-dimensional solution domain, the level set function The velocity vector is x and y Direction Component and Can be characterized as: ； ； The amount and Substitute the level set control equation for solution and obtain the dynamic changes of the corrosion interface.

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