A method for constructing a temperature field simulation model of an aluminum-steel arc brazing workpiece

Abstract

The application discloses a kind of construction methods of aluminum steel electric arc fusion brazing workpiece temperature field simulation model, it is related to welding processing technical field, the present application not only model aluminum metal and steel base plate as solid, but also model arc plasma in welding as fluid, simultaneously model arc as arc calculation domain, also set arc calculation domain as moving grid, moving grid can be moved along the workpiece work body modeled and carry out heat transfer;Then in simulation software, energy and momentum source term that fluid and solid are added to characterize fluid flow and fluid heat transfer process, and solid heat transfer process, that is, it is only necessary to obtain welding parameters, i.e.welding current, welding speed and protective gas flow in welding process, in the heat transfer process of simulation simulation, heat transfer can be simulated directly by the equivalent moving grid of arc calculation domain to calculate arc temperature, workpiece temperature and welding thermal cycle curve of any point, can greatly reduce experimental cost.

Description

Technical Field

[0001] This invention relates to the field of welding processing, and in particular to a method, apparatus, equipment and medium for constructing a temperature field simulation model of aluminum-steel electric arc brazing workpieces. Background Technology

[0002] Aluminum-steel arc fusion brazing is a welding method that combines the characteristics of fusion welding and brazing. Based on the difference in melting points between aluminum alloys and steel, this method precisely controls the welding heat input to ensure that only aluminum is in a molten state while the steel remains undisturbed. This allows the molten aluminum and the solid-phase steel / iron to bond together through a metallurgical reaction, forming both a fusion weld and a brazed joint, thus achieving a high-quality, high-strength metallurgical connection between aluminum and steel. Aluminum-steel arc fusion brazing is highly sensitive to welding parameters (such as welding current, welding speed, butt joint gap, arc position, and welding torch angle). Even small changes in these parameters can lead to significant variations in weld formation and joint performance. However, by using numerical models to simulate the temperature field changes of the workpiece throughout the welding process, the melting state of the aluminum-steel workpiece can be predicted, thereby predicting the joint performance.

[0003] Most current simulation models of temperature field in aluminum-steel arc welding workpieces model the workpiece itself and apply the arc heat input to the workpiece surface using analytical formulas, such as Gaussian heat sources or double ellipsoidal heat sources. However, some parameters in these analytical formulas are related to current and voltage, and these parameters need to be roughly determined through welding experiments in advance. Therefore, the accuracy is low when simulating the temperature field of aluminum-steel arc welding workpieces with different parameters, making it difficult to perform high-precision simulations. Summary of the Invention

[0004] This invention provides a method for constructing a simulation model of the temperature field of an aluminum-steel electric arc brazing workpiece. This method can solve the problem in the prior art where the accuracy of simulating the temperature field of an aluminum-steel electric arc brazing workpiece with different parameters is low, making it difficult to perform high-precision simulation.

[0005] This invention provides a method for constructing a temperature field simulation model of an aluminum-steel arc-welded workpiece, comprising the following steps: Based on the geometric dimensions of the lap joint of aluminum and steel, a three-dimensional geometric model suitable for aluminum-steel arc welding workpieces is constructed. Importing the three-dimensional geometric model into simulation software, a temperature field simulation model of the aluminum-steel electric arc brazing workpiece is constructed; the specific steps for constructing the temperature field simulation model of the aluminum-steel electric arc brazing workpiece include: In the simulation software, the arc plasma in aluminum-steel arc fusion brazing is treated as a fluid, the aluminum metal and steel substrate in aluminum-steel arc fusion brazing are treated as solids, and the arc in aluminum-steel arc fusion brazing is treated as a region containing high-temperature plasma to form an arc calculation domain, and the arc calculation domain is treated as a moving mesh; wherein, the moving mesh can move along the aluminum-steel welding direction, and heat can be transferred between the arc calculation domain and the workpiece domain formed by the solid during the movement; In the simulation software, the heat transfer and flow state of the fluid and the heat transfer state of the solid are determined. Fluid energy and momentum source terms characterizing the fluid flow and the heat transfer process through the moving mesh are added to the fluid, and solid energy and momentum source terms characterizing the heat transfer process through the moving mesh are added to the solid. Boundary conditions and fluid property parameters are set for the fluid and solid. Based on the fluid energy and momentum source terms, solid energy and momentum source terms, and welding parameters in the welding process, the temperature field and heat in the arc calculation domain and the workpiece domain during heat transfer, as well as the temperature field during the welding process, are obtained.

[0006] Preferably, the construction of a three-dimensional geometric model suitable for aluminum-steel arc welding includes: The physical properties of aluminum and steel at different temperatures were obtained, including thermal conductivity, specific heat capacity, density, coefficient of thermal expansion, yield strength, and elastic modulus. Simultaneously, the geometric dimensions of the aluminum-steel lap joint are obtained, and a three-dimensional geometric model is constructed using three-dimensional modeling software. The three-dimensional geometric model reflects the geometric characteristics of the aluminum and steel thickness, lap length, gap, or pre-set welding material shape.

[0007] Preferably, during the simulation in the simulation software, the fluid and solid also follow conservation control equations, which include: The mass conservation equation is expressed as: ; The energy conservation equation is expressed as: ; The momentum conservation equation is expressed as: ; in: t Indicates time, T Indicates temperature; ρ , H , λ , μ These represent density, enthalpy, thermal conductivity, and viscosity, respectively. Represents the velocity vector. p Indicates pressure, Represents the stress tensor; S Represents the energy source term. This represents the momentum source term.

[0008] Preferably, the addition of fluid energy and momentum source terms characterizing fluid flow and the fluid heat transfer process through the moving grid to the fluid, and the addition of solid energy and momentum source terms characterizing the solid heat transfer process through the moving grid to the solid, includes: Energy source term of electric arc plasma S Including the Joule heat source term, the electron migration heat transfer term, and the radiation loss term, it is represented as: ; The energy source term at the interface between the welding wire and the electric arc plasma is represented as: ; The energy source term between the arc plasma and the aluminum-steel interface is represented as: ; in: Indicates current density, Indicates electrical conductivity. K B Represents the Boltzmann constant. e Represents electron charge, S R Indicates radiation loss. j a and j c These represent the current densities in the anode sheath and cathode sheath, respectively. V a and V c These represent the voltage drops at the anode and cathode sheaths, respectively. φ a and φ c These represent the operating functions of the anode and cathode, respectively. ε a and ε c These represent the emissivity of the anode and cathode materials, respectively. α This represents the Stefan-Boltzmann constant; The momentum source term of the electric arc plasma is expressed as: ; in: Represents the gravity of the electric arc plasma; The electromagnetic force representing the electric arc plasma; The electromagnetic force of an electric arc plasma is represented as: ; in: This represents the self-induced magnetic flux density generated by the welding current. This represents the external magnetic flux density induced by an electromagnet. This represents the current density.

[0009] Preferably, the setting of the moving grid includes: In the simulation software, the electric arc is set as a region containing high-temperature plasma, and the region containing high-temperature plasma forms the electric arc calculation domain. The electric arc calculation domain is set as a moving mesh, and the moving mesh moves along the aluminum-steel welding direction at the welding speed. When moving within the electric arc computational domain, Ansys Mesh is used to generate the moving mesh. In regions far from the electric arc, where the temperature gradient and fluid flow velocity are small, a large mesh is used. In regions close to the electric arc, where the high temperature and high energy density result in a large temperature gradient and fluid flow velocity, a small mesh is selected. At the same time, use the quality index command in Ansys Mesh to check the aspect ratio, Jacobian ratio, and mesh cell quality of the mesh cells.

[0010] Preferably, the setting of the boundary conditions between the fluid and the solid, and the fluid property parameters, includes: The boundary conditions include initial conditions, temperature field boundaries, momentum boundaries, and electric field boundaries; The initial conditions are: at the initial moment when the electric arc starts to burn, t=0s, the room temperature T0=300K, and the initial velocity of the grid V=0.01 m / s; The temperature field boundaries are as follows: the welding wire tip temperature is set to 2600K; the workpiece temperature is set to room temperature 300K; and the total reflow temperature at the pressure outlet is set to 700K. The momentum boundary is defined as follows: the inlet of the shielding gas, i.e., the lower end face of the actual MIG welding torch nozzle, has a radial flow velocity of 0 and a longitudinal flow velocity of: ; in: Q To protect the airflow, R To protect the outer radius of the air inlet, r To protect the inner radius of the air inlet; The electric field boundary is defined as follows: the electric field boundary of the anode is set according to the actual welding parameters, and the z-direction current density is set at the end face of the welding wire; the heat absorbed by the molten droplet per unit heat input is expressed as: ; The effective current used to heat the electric arc is expressed as: ; The effective current density at the end of the welding wire is expressed as: ; in: C p This indicates the specific heat capacity of the welding wire. ρ This indicates the density of the welding wire. r 1 indicates the radius of the welding wire. V f Indicates the wire feeding speed, Δ T Indicates temperature difference. U Indicates arc voltage. I Indicates welding current. S This indicates the surface area of ​​the welding wire end face; The cathode voltage is set to 0, the remaining boundaries are insulated, and the magnetic vector... A The gradient is 0 at each boundary; Fluid properties include viscosity, density, heat flux, radiation coefficient, thermal conductivity, and electrical conductivity.

[0011] This invention also provides a device for constructing a temperature field simulation model of an aluminum-steel arc-welded workpiece, comprising: The 3D geometry model building module is used to build a 3D geometry model suitable for aluminum-steel arc welding workpieces based on the geometric dimensions of the lap joint of aluminum and steel. The simulation model construction module imports the three-dimensional geometric model into the simulation software to construct a simulation model of the temperature field of the aluminum-steel electric arc brazing workpiece; the specific steps for constructing the simulation model of the temperature field of the aluminum-steel electric arc brazing workpiece include: In the simulation software, the arc plasma in aluminum-steel arc fusion brazing is treated as a fluid, the aluminum metal and steel substrate in aluminum-steel arc fusion brazing are treated as solids, and the arc in aluminum-steel arc fusion brazing is treated as a region containing high-temperature plasma to form an arc calculation domain, and the arc calculation domain is treated as a moving mesh; wherein, the moving mesh can move along the aluminum-steel welding direction, and heat can be transferred between the arc calculation domain and the workpiece domain formed by the solid during the movement; In the simulation software, the heat transfer and flow state of the fluid and the heat transfer state of the solid are determined. Fluid energy and momentum source terms characterizing the fluid flow and the heat transfer process through the moving mesh are added to the fluid, and solid energy and momentum source terms characterizing the heat transfer process through the moving mesh are added to the solid. Boundary conditions and fluid property parameters are set for the fluid and solid. Based on the fluid energy and momentum source terms, solid energy and momentum source terms, and welding parameters in the welding process, the temperature field and heat in the arc calculation domain and the workpiece domain during heat transfer, as well as the temperature field during the welding process, are obtained.

[0012] This invention also provides an electronic device, including a memory and a processor; The memory is used to store computer programs; When the processor executes the computer program stored in the memory, it implements the steps of the method for constructing a temperature field simulation model of an aluminum-steel electric arc welding workpiece as described above.

[0013] This invention also provides a computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the steps of a method for constructing a temperature field simulation model of an aluminum-steel arc welding workpiece as described above.

[0014] This invention provides a method for constructing a temperature field simulation model of an aluminum-steel electric arc brazing workpiece. Compared with the prior art, its advantages are as follows: In constructing the simulation model, this invention not only models aluminum metal and steel substrate as solids, but also models the arc plasma during welding as a fluid. Simultaneously, it models the arc as an arc computational domain and sets the arc computational domain as a moving mesh. This moving mesh can move along the modeled workpiece and transfer heat. Then, in the simulation software, energy and momentum source terms representing fluid flow and heat transfer processes, as well as solid heat transfer processes, are added to the fluid and solid. This means that by obtaining the welding parameters—welding current, welding speed, and shielding gas flow rate—heat transfer can be directly simulated through the equivalent moving mesh of the arc computational domain during the simulated heat transfer process. This allows for the calculation of arc temperature, workpiece temperature, and welding thermal cycle curves at any point, significantly reducing experimental costs. Attached Figure Description

[0015] Figure 1 A schematic diagram of the overall process for constructing a simulation model of the temperature field of an aluminum-steel electric arc brazing workpiece, provided in an embodiment of the present invention; Figure 2 A schematic diagram of a three-dimensional model of a magnetically controlled aluminum / steel arc-welded lap joint, which is provided in an embodiment of the present invention for constructing a simulation model of the temperature field of an aluminum-steel arc-welded workpiece. Figure 3 A cross-sectional schematic diagram of a magnetically controlled aluminum / steel arc-welded lap joint model for constructing a temperature field simulation model of an aluminum-steel arc-welded workpiece provided in an embodiment of the present invention. Figure 4 A schematic diagram of the arc calculation domain for a method of constructing a temperature field simulation model for an aluminum-steel arc-welded workpiece according to an embodiment of the present invention; Figure 5 A schematic diagram of the three-dimensional mesh model of the magnetically controlled aluminum / steel arc-welded lap joint after dividing the workpiece temperature field simulation model provided in this embodiment of the invention. Figure 6A schematic diagram of the viscosity of pure argon gas at different temperatures, illustrating a method for constructing a temperature field simulation model of an aluminum-steel electric arc welding workpiece according to an embodiment of the present invention. Figure 7 A schematic diagram of the density of pure argon gas at different temperatures, illustrating a method for constructing a temperature field simulation model of an aluminum-steel electric arc brazing workpiece according to an embodiment of the present invention. Figure 8 A schematic diagram of the hot melting of pure argon gas at different temperatures, illustrating a method for constructing a temperature field simulation model of an aluminum-steel electric arc welding workpiece provided in an embodiment of the present invention. Figure 9 A schematic diagram of the radiation coefficient of pure argon gas at different temperatures, illustrating a method for constructing a temperature field simulation model of an aluminum-steel electric arc welding workpiece according to an embodiment of the present invention. Figure 10 A schematic diagram of the thermal conductivity of pure argon gas at different temperatures, illustrating a method for constructing a temperature field simulation model of an aluminum-steel electric arc welding workpiece according to an embodiment of the present invention. Figure 11 A schematic diagram of the conductivity of pure argon gas at different temperatures, illustrating a method for constructing a simulation model of the temperature field of an aluminum-steel electric arc welding workpiece according to an embodiment of the present invention. Figure 12 A schematic diagram of the simulated arc morphology of a method for constructing a simulation model of the temperature field of an aluminum-steel electric arc welding workpiece provided in an embodiment of the present invention; Figure 13 A schematic diagram of the simulated arc plasma velocity in a method for constructing a simulation model of the temperature field of an aluminum-steel arc-welded workpiece, provided in an embodiment of the present invention. Figure 14 A schematic diagram illustrating the evolution of the temperature field during aluminum / steel lap joint brazing, provided in an embodiment of the present invention, illustrates a method for constructing a simulation model of the temperature field of an aluminum / steel workpiece in arc fusion brazing. Figure 15 The simulated joint temperature cloud map is provided by a method for constructing a temperature field simulation model of an aluminum-steel electric arc welding workpiece according to an embodiment of the present invention. Detailed Implementation

[0016] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0017] See Figure 1This invention provides a method for constructing a temperature field simulation model for aluminum / steel arc brazing workpieces. Specifically, it is a coupled numerical model of the aluminum / steel arc brazing arc and workpiece, which not only models the workpiece but also the arc plasma. Given welding process parameters, the model constructed by this invention can calculate the temperature field and heat of the entire arc and transfer the heat to the workpiece through a fluid-structure interaction model, thereby calculating the temperature field of the entire workpiece during the welding process. Therefore, by using this method, only process parameters such as welding current, welding speed, and shielding gas flow rate are needed to calculate the arc temperature, workpiece temperature, and welding thermal cycle curve at any point, greatly reducing experimental costs.

[0018] Specifically: I. Simplify the conditions.

[0019] In the aluminum / steel MIG arc welding process, the base materials have different melting points, and there are many factors affecting heat input control. Furthermore, the welding arc is a complex plasma with highly complex flow and heat transfer processes, making it difficult to solve for thermodynamic parameters and numerical calculations that cannot account for all factors. Therefore, given the complexity of the aluminum / steel arc welding process, the following assumptions and simplifications are made to simplify the model, improve computational efficiency, and reduce computational costs: ① The initial temperature of the weldment is the same as the ambient temperature, both set at 300K.

[0020] ②The flow in the entire fluid computational domain is laminar.

[0021] ③ The parameters of plasma thermodynamics and transport properties are variable factors with temperature as the main factor.

[0022] ④ The arc plasma is an optically thin body that does not absorb radiation, and the effects of gravity and viscous dissipation are ignored.

[0023] ⑤ Without considering heat conduction between the test bench and the fixture, as well as the influence of the fixture on the weldment, the evolution of welding stress in the free state is simulated.

[0024] ⑥ The effects of the intermetallic compound layer, the overlap gap between the aluminum plate and the steel plate, and the aluminum alloy side plate on the temperature field and stress-strain distribution are not considered.

[0025] ⑦ The material is a homogeneous, continuous medium, isotropic, and its physical properties change with temperature.

[0026] II. Governing equations and source terms.

[0027] In the model designed in this invention, the electric arc plasma is treated as a fluid, while aluminum and steel substrates are treated as solids. For the fluid, heat transfer and fluid flow are considered, while for the solid, only heat transfer is considered. The same conservation equations are solved throughout the computational domain, but various energy and momentum source terms are added for different stages. The conservation equations used are as follows:

[0028] The mass conservation equation is: .

[0029] The energy conservation equation is: .

[0030] The momentum conservation equation is: .

[0031] in: t Indicates time, T Indicates temperature; ρ , H , λ , μ These represent density, enthalpy, thermal conductivity, and viscosity, respectively. Represents the velocity vector. p Indicates pressure, Represents the stress tensor; S Represents the energy source term. This represents the momentum source term.

[0032] The energy source terms of arc plasma include Joule heating, electron migration heat transfer, and radiation loss; therefore, the formula for calculating S is: .

[0033] At the welding wire-plasma interface and the plasma-workpiece interface, there are anode / cathode sheath layers that deviate from thermodynamic equilibrium. Therefore, this invention adopts the "LTE-diffusion approximation" method proposed by Lowke et al., which simplifies the complex sheath thermal effects and applies it to the energy source term at the welding wire-plasma interface. S Represented as: .

[0034] In the plasma-workpiece interface, the energy source term S Represented as: .

[0035] in: Indicates current density, Indicates electrical conductivity. K B Represents the Boltzmann constant. e Represents electron charge, S R Indicates radiation loss. j a and j c These represent the current densities in the anode sheath and cathode sheath, respectively. Va and V c These represent the decreasing voltages of the anode sheath and cathode sheath, respectively. φ a and φ c These represent the operating functions of the anode and cathode, respectively. ε a and ε c These represent the emissivity of the anode and cathode materials, respectively. α This represents the Stefan-Boltzmann constant.

[0036] The source term for the additional momentum in the fluid region is expressed as: .

[0037] In an electric arc plasma, only gravity is considered. and electromagnetic force Electromagnetic force Calculated using current density and magnetic flux density, it can be expressed as: .

[0038] in: This represents the self-induced magnetic flux density generated by the welding current. This represents the external magnetic flux density induced by an electromagnet.

[0039] The equation for the continuity of current is: .

[0040] in: It represents electric potential.

[0041] According to Ohm's law, the current density can be calculated as follows: .

[0042] in: σ It represents the electrical conductivity of a fluid.

[0043] In a three-dimensional non-axisymmetric model, the magnetic vector potential method can be used to solve for the magnetic flux density of a known current density distribution. The magnetic vector potential equation is expressed as:

[0044] .

[0045] The magnetic induction intensity is: .

[0046] in: Represents electric potential; μ 0 Indicates the permeability of free space; It represents the magnetic vector potential.

[0047] III. Model Establishment.

[0048] This invention establishes a three-dimensional model suitable for aluminum / steel lap arc brazing, such as... Figure 2 and Figure 3 As shown; the joint workpiece is constructed by overlapping a 200mm×50mm×1mm aluminum alloy plate and a 200mm×50mm×2mm galvanized steel plate; the arc calculation area is a 20mm×20mm×19mm cube, as shown. Figure 4 As shown; the arc calculation domain is set as a moving grid, that is, the arc domain moves along the welding direction, and the moving speed is the welding speed.

[0049] In numerical simulations, the number of grid cells directly impacts computational efficiency. Too many grid cells may cause errors or even crashes during computation, while too few may compromise accuracy. Therefore, it is crucial to consider the impact of grid cell number on computational accuracy while ensuring efficient computation to meet accuracy requirements. The number of elements in the model of this invention is shown in Table 1, ensuring both computational accuracy and high efficiency.

[0050] Table 1 Number of Model Nodes and Elements The mesh density plays a crucial role in the computational efficiency and accuracy of the model. By appropriately controlling the mesh density, both computational efficiency and accuracy can be improved. A denser mesh is used in the main stress-bearing areas of the model to ensure more accurate calculation results in these critical regions. In non-critical areas, a relatively sparse mesh is used to reduce the computational burden and improve efficiency. This invention imports the established 3D model into Ansys Workbench and uses Ansys Mesh for mesh generation. When simulating the temperature field, due to the extremely high and drastic temperature changes in the arc region, a fine mesh is used to obtain more accurate temperature gradient data. Simultaneously, a local mesh refinement method is employed to balance computational efficiency. Larger mesh sizes are selected in areas far from the arc to reduce computational load and increase calculation speed, while smaller mesh sizes are used in areas close to the arc. For the simulation of the stress-strain field, since the stress is located in the plate, the mesh size, although slightly larger than that in the arc region, is still considered fine. Based on the above analysis, the resulting mesh model is as follows: Figure 5 As shown, there are a total of 415,177 nodes and 209,001 cells.

[0051] After mesh generation, it is crucial to evaluate the rationality of the mesh geometry. Mesh quality has a significant impact on computational accuracy, so it must be ensured that it meets certain standards. When evaluating mesh quality, the main focus is on indicators such as element aspect ratio, Jacobian ratio, and element quality. Multiple indicators in the mesh can be checked using the quality index command in Ansys Mesh.

[0052] IV. Boundary conditions and fluid properties.

[0053] 1. Boundary conditions.

[0054] ① Initial conditions: At the initial moment when the electric arc begins to burn, t=0s, the room temperature T0=300K, and the initial velocity of the grid V=0.01 m / s.

[0055] ② Temperature field boundary: The welding wire tip temperature is set to 2600K; the workpiece temperature is set to room temperature 300K; and the total pressure outlet reflow temperature is set to 700K.

[0056] ③Momentum boundary: The shielding gas inlet is the lower end face of the actual MIG welding torch nozzle, where the radial flow velocity is 0 and the longitudinal flow velocity is: .

[0057] in: Q To protect the airflow, R To protect the outer radius of the air inlet, r To protect the inner radius of the air inlet.

[0058] The protective gas outlet is a one-way pressure outlet, and the relative pressure is set to 0.

[0059] ④ Electric field boundary: The electric field boundary of the anode is set according to the actual welding parameters, and the z-direction current density is set at the end face of the welding wire; the heat absorbed by the molten droplet per unit heat input is expressed as: .

[0060] The effective current used to heat the electric arc is expressed as: .

[0061] The effective current density at the end of the welding wire is expressed as: .

[0062] in: C p This indicates the specific heat capacity of the welding wire. ρ This indicates the density of the welding wire. r1 indicates the radius of the welding wire. V f Indicates the wire feeding speed, Δ T Indicates temperature difference. U Indicates arc voltage. I Indicates welding current. S This indicates the surface area of ​​the welding wire end face.

[0063] Cathode voltage set to 0; all other boundaries insulated; magnetic vector. A The gradient at each boundary is 0; the boundary conditions of the electric arc model are shown in Table 2.

[0064] Table 2 Boundary conditions for the electric arc model 2. Fluid physical properties.

[0065] It is assumed that the physical properties of argon plasma are only temperature-dependent; the values ​​of the thermophysical properties, transport coefficient, and radiation coefficient of pure argon at different temperatures are all from literature sources, and the specific values ​​are as follows: Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 and Figure 11 As shown.

[0066] The simulated arc morphology diagram is as follows Figure 12 As shown; the simulated arc plasma velocity is as follows Figure 13 As shown; the evolution of the temperature field during the brazing of aluminum / steel lap joints is as follows: Figure 14 As shown; the simulated joint temperature contour map is as follows. Figure 15 As shown.

[0067] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for constructing a simulation model of the temperature field of an aluminum-steel electric arc brazing workpiece, characterized in that, Includes the following steps: Based on the geometric dimensions of the lap joint of aluminum and steel, a three-dimensional geometric model suitable for aluminum-steel arc welding workpieces is constructed. Importing the three-dimensional geometric model into simulation software, a temperature field simulation model of the aluminum-steel electric arc brazing workpiece is constructed; the specific steps for constructing the temperature field simulation model of the aluminum-steel electric arc brazing workpiece include: In the simulation software, the arc plasma in aluminum-steel arc fusion brazing is treated as a fluid, the aluminum metal and steel substrate in aluminum-steel arc fusion brazing are treated as solids, and the arc in aluminum-steel arc fusion brazing is treated as a region containing high-temperature plasma to form an arc calculation domain, and the arc calculation domain is treated as a moving mesh; wherein, the moving mesh can move along the aluminum-steel welding direction, and heat can be transferred between the arc calculation domain and the workpiece domain formed by the solid during the movement; In the simulation software, the heat transfer and flow state of the fluid and the heat transfer state of the solid are determined. Fluid energy and momentum source terms characterizing the fluid flow and the heat transfer process through the moving mesh are added to the fluid, and solid energy and momentum source terms characterizing the heat transfer process through the moving mesh are added to the solid. Boundary conditions and fluid property parameters are set for the fluid and solid. Based on the fluid energy and momentum source terms, solid energy and momentum source terms, and welding parameters in the welding process, the temperature field and heat in the arc calculation domain and the workpiece domain during heat transfer, as well as the temperature field during the welding process, are obtained. The construction of a three-dimensional geometric model suitable for aluminum-steel arc welding includes: The physical properties of aluminum and steel at different temperatures were obtained, including thermal conductivity, specific heat capacity, density, coefficient of thermal expansion, yield strength, and elastic modulus. Simultaneously, the geometric dimensions of the aluminum-steel lap joint are obtained, and a three-dimensional geometric model is constructed using three-dimensional modeling software. The three-dimensional geometric model reflects the geometric characteristics of the aluminum and steel thickness, lap length, gap, or pre-set welding material shape. When the simulation is performed in the simulation software, the fluid and solid also follow the conservation control equations, which include: The mass conservation equation is expressed as: ； The energy conservation equation is expressed as: ； The momentum conservation equation is expressed as: ； in: t Indicates time, T Indicates temperature; ρ , H , λ These represent density, enthalpy, and thermal conductivity, respectively. Represents the velocity vector. p Indicates pressure, Represents the stress tensor; S Represents the energy source term. Represents the momentum source term; The addition of fluid energy and momentum source terms characterizing fluid flow and heat transfer through a moving grid to the fluid, and the addition of solid energy and momentum source terms characterizing heat transfer through a moving grid to the solid, include: Energy source term of electric arc plasma S Including the Joule heat source term, the electron migration heat transfer term, and the radiation loss term, it is represented as: ； The energy source term at the interface between the welding wire and the electric arc plasma is represented as: ； The energy source term between the arc plasma and the aluminum-steel interface is represented as: ； in: Indicates current density, Indicates electrical conductivity. K B Represents the Boltzmann constant. e Represents electron charge, S R Indicates radiation loss. j a and j c These represent the current densities in the anode sheath and cathode sheath, respectively. V a and V c These represent the voltage drops at the anode and cathode sheaths, respectively. φ a and φ c These represent the operating functions of the anode and cathode, respectively. ε a and ε c These represent the emissivity of the anode and cathode materials, respectively. α This represents the Stefan-Boltzmann constant; The momentum source term of the electric arc plasma is expressed as: ； in: Represents the gravity of the electric arc plasma; The electromagnetic force representing the electric arc plasma; The electromagnetic force of an electric arc plasma is represented as: ； in: This represents the self-induced magnetic flux density generated by the welding current. This represents the external magnetic flux density induced by an electromagnet. Indicates current density; The settings for the moving grid include: In the simulation software, the electric arc is set as a region containing high-temperature plasma, and the region containing high-temperature plasma forms the electric arc calculation domain. The electric arc calculation domain is set as a moving mesh, and the moving mesh moves along the aluminum-steel welding direction at the welding speed. When moving within the electric arc computational domain, Ansys Mesh is used to generate the moving mesh. In regions far from the electric arc, where the temperature gradient and fluid flow velocity are small, a large mesh is used. In regions close to the electric arc, where the high temperature and high energy density result in a large temperature gradient and fluid flow velocity, a small mesh is selected. At the same time, the quality index command in Ansys Mesh is used to check the aspect ratio, Jacobian ratio, and mesh cell quality of the mesh cells; The setting of boundary conditions and fluid property parameters for fluid and solid includes: The boundary conditions include initial conditions, temperature field boundaries, momentum boundaries, and electric field boundaries; The initial conditions are: at the initial moment when the electric arc starts to burn, t=0s, the room temperature T0=300K, and the initial velocity of the grid V=0.01 m / s; The temperature field boundaries are as follows: the welding wire tip temperature is set to 2600K; the workpiece temperature is set to room temperature 300K; and the total reflow temperature at the pressure outlet is set to 700K. The momentum boundary is defined as follows: the inlet of the shielding gas, i.e., the lower end face of the actual MIG welding torch nozzle, has a radial flow velocity of 0 and a longitudinal flow velocity of: ； in: Q To protect the airflow, R To protect the outer radius of the air inlet, r To protect the inner radius of the air inlet; The electric field boundary is defined as follows: the electric field boundary of the anode is set according to the actual welding parameters, and the z-direction current density is set at the end face of the welding wire; the heat absorbed by the molten droplet per unit heat input is expressed as: ； The effective current used to heat the electric arc is expressed as: ； The effective current density at the end of the welding wire is expressed as: ； in: C p This indicates the specific heat capacity of the welding wire. ρ This indicates the density of the welding wire. r 1 indicates the radius of the welding wire. V f Indicates the wire feeding speed, Δ T Indicates temperature difference. U Indicates arc voltage. I Indicates welding current. S This indicates the surface area of ​​the welding wire end face; The cathode voltage is set to 0, the remaining boundaries are insulated, and the magnetic vector... A The gradient is 0 at each boundary; Fluid properties include viscosity, density, heat flux, radiation coefficient, thermal conductivity, and electrical conductivity.

2. A device for constructing a temperature field simulation model of an aluminum-steel electric arc brazing workpiece, used to implement the steps of the method for constructing a temperature field simulation model of an aluminum-steel electric arc brazing workpiece as described in claim 1, characterized in that, include: The 3D geometry model building module is used to build a 3D geometry model suitable for aluminum-steel arc welding workpieces based on the geometric dimensions of the lap joint of aluminum and steel. The simulation model construction module imports the three-dimensional geometric model into the simulation software to construct a simulation model of the temperature field of the aluminum-steel electric arc brazing workpiece. The specific steps for constructing the simulation model of the temperature field of the aluminum-steel electric arc brazing workpiece include: In the simulation software, the arc plasma in aluminum-steel arc fusion brazing is treated as a fluid, the aluminum metal and steel substrate in aluminum-steel arc fusion brazing are treated as solids, and the arc in aluminum-steel arc fusion brazing is treated as a region containing high-temperature plasma to form an arc calculation domain, and the arc calculation domain is treated as a moving mesh; wherein, the moving mesh can move along the aluminum-steel welding direction, and heat can be transferred between the arc calculation domain and the workpiece domain formed by the solid during the movement; In the simulation software, the heat transfer and flow state of the fluid and the heat transfer state of the solid are determined. Fluid energy and momentum source terms characterizing the fluid flow and the heat transfer process through the moving mesh are added to the fluid, and solid energy and momentum source terms characterizing the heat transfer process through the moving mesh are added to the solid. Boundary conditions and fluid property parameters are set for the fluid and solid. Based on the fluid energy and momentum source terms, solid energy and momentum source terms, and welding parameters in the welding process, the temperature field and heat in the arc calculation domain and the workpiece domain during heat transfer, as well as the temperature field during the welding process, are obtained.

3. An electronic device, characterized in that, include: Memory and processor; The memory is used to store computer programs; When the processor executes the computer program stored in the memory, it implements the steps of the method for constructing a temperature field simulation model of an aluminum-steel electric arc welding workpiece as described in claim 1.

4. A computer-readable storage medium, characterized in that, Used to store computer programs, which, when executed by a processor, implement the steps of the method for constructing a temperature field simulation model of an aluminum-steel arc welding workpiece as described in claim 1.

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