Efficient method for analyzing welding temperature field

Abstract

The application discloses a kind of welding temperature field high-efficiency analytical method, it is characterized in that, comprising the following steps: S1: establishing weld local geometric three-dimensional model;S2: loading volume / area distribution heat flow melting welding heat source model;S3: obtaining the first evolution result of temperature field distribution;S4: with the function definition model node temperature of analytical heat source temperature field to solve temperature field, obtain the second evolution result of temperature field distribution;S5: to the temperature gradient of analytical temperature field is corrected;S6: with the boundary condition of function definition model node temperature of analytical heat source temperature field to solve temperature field, obtain the third evolution result of temperature field distribution;S7: increase grid size, and repeat the step S6, obtain the fourth evolution result of temperature field distribution;S8: using the function definition model of analytical heat source temperature field to carry out high-efficiency solving of welding temperature field;The scheme can be carried out high-efficiency solving to welding temperature field, significantly improve the calculation efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of welding temperature field analysis, and in particular to a high-efficiency analysis method for welding temperature field. Background Art

[0002] At present, there are mainly the following methods for solving the finite element temperature field of fusion welding:

[0003] 1. Transient Heat Transfer Solution for a Moving Distributed Heat Source: Spatially distributed volume / area heat sources are often used in arc welding to solve welding temperature field results. These include double ellipsoidal volume heat sources, Gaussian volume distribution heat sources, and Gaussian area distribution heat sources. Applying a spatially distributed heat source, combined with the model geometry, initial temperature conditions, and convection-radiation heat transfer boundary conditions set in the calculation software, typically yields ideal temperature field calculation results that are highly consistent with actual temperature field test results.

[0004] However, when solving the welding temperature field using a spatially distributed heat source, sufficient mesh density is required in the weld area to ensure mesh convergence. Typically, a mesh size of less than 2 mm and a mesh count of more than 12 within the weld pool are required to meet the heat flux integral calculation requirements of the nonlinear spatially distributed heat source during transient heat transfer. While this method offers high accuracy for solving the welding temperature field, it is also expensive. This is particularly true for the temperature field of large welded structures, where the small mesh size and high nonlinear solution cost of transient heat transfer pose significant challenges. Excessively large meshes increase the computational cost and time required for the solution.

[0005] 2. Analytical temperature field solution method: usually used for ideal models of welding structures with simple geometric shapes (such as semi-infinite bodies, infinite thin plates, etc.), such as Figure 1 As shown in the figure, the formula for solving the analytical temperature field of a semi-infinite instantaneous point heat source moving along a straight line is as follows:

[0006]

[0007] in, q is, λ is the thermal conductivity of the material, a is the thermal diffusivity of the material, v is the walking speed of the heat source, r is the distance between the current observation point and the center of the heat source, x It is the horizontal distance between the current observation point and the center of the heat source.

[0008] By ignoring material and structural nonlinearities and assigning boundary values ​​to model nodes through analytical temperature field analysis, the computational speed is significantly improved, eliminating the need to solve the large set of transient heat transfer differential equations. Furthermore, by eliminating the need to increase the weld mesh density to integrate the distributed heat flux, the model mesh size can be further reduced, significantly lowering computational costs. This method has significant application value in temperature field calculations for large welded structures.

[0009] However, due to the simplification of the thermophysical properties of the material in the analytical calculation (the thermophysical properties that change nonlinearly with temperature are simplified to constants that do not change with temperature), and the neglect of the model geometric size (the model is considered infinite), and the neglect of the convection and radiation exchange between the model and the surrounding fluid media such as air, there is a large deviation between the temperature field solved analytically and the actual temperature field distribution, and the solution results using spatially distributed volume / area heat sources. Summary of the Invention

[0010] In response to the above-mentioned shortcomings of the prior art, the present invention provides an efficient analysis method for the welding temperature field. Based on the moving point analysis of the heat source temperature field, the analysis temperature is corrected to obtain a high-precision temperature field solution to solve the technical problems mentioned in the above background technology.

[0011] To achieve the above object, the technical solution adopted by the present invention is:

[0012] A method for efficiently analyzing a welding temperature field is provided, which is characterized by comprising the following steps:

[0013] S1: Establish a local geometric three-dimensional model of the weld and input the material's thermal physical properties that vary with temperature;

[0014] S2: Melting welding heat source model with volume / area distribution heat flux;

[0015] S3: Calculate and solve the transient heat transfer temperature and obtain the first evolution result of the temperature field distribution;

[0016] S4: On the same local geometric 3D model, only the temperature boundary conditions are loaded, and the model node temperatures are defined by the function of the analytical heat source temperature field to solve the temperature field and obtain the second evolution result of the temperature field distribution;

[0017] S5: The temperature distribution results of the first evolution result and the second evolution result of the temperature field are derived respectively, and the temperature distributions in the x-direction, y-direction, and z-direction are output respectively with the heat source of the quasi-steady-state temperature field as the center, and the temperature gradients in the x-direction, y-direction, and z-direction of the analytical temperature field are corrected respectively, where the x-direction is the welding movement direction, the y-direction is the width direction of the heat source, and the z-direction is the depth direction of the heat source;

[0018] S6: On the same local geometric three-dimensional model, the boundary conditions of the model node temperatures are defined by the function of modifying the analytical heat source temperature field to solve the temperature field and obtain the third evolution result of the temperature field distribution;

[0019] S7: Increase the grid size and repeat step S6 to obtain the fourth evolution result of the temperature field distribution, and make the temperature gradient of the modified analytical heat source temperature field and the volume / area distribution heat source calculation results consistent;

[0020] S8: Apply the function definition model of the modified analytical heat source temperature field to efficiently solve the welding temperature field.

[0021] Furthermore, the thermophysical performance parameters in step S1 include density, thermal conductivity and specific heat capacity.

[0022] Furthermore, step S2 includes setting the initial temperature of the melting welding heat source model, the ambient temperature, and the convection and radiation boundary conditions with the surrounding environment.

[0023] Furthermore, the calculation formula for analyzing the heat source temperature field in step S4 is:

[0024]

[0025] in, q is the welding line energy, λ is the thermal conductivity of the material, a is the thermal diffusivity of the material, v is the walking speed of the heat source, r is the distance between the current observation point and the center of the heat source, x It is the horizontal distance between the current observation point and the center of the heat source.

[0026] Furthermore, in step S5, the temperature gradients in the x-direction, y-direction, and z-direction of the analytical temperature field are corrected using correction factors in three directions, and the calculation formula for correcting the analytical heat source temperature field is:

[0027] ;

[0028] ;

[0029] ;

[0030] ;

[0031] in, CV 1. CV 2. CV 3 are the correction factors in the x, y and z directions respectively; C 1. C2. C 3 is the shape coefficient in the x-direction,A 1. A 2. A 3 is the shape coefficient in the y direction, B 1. B 2. B 3 is the shape coefficient in the z direction; through these three groups of shape coefficients, the temperature gradient distribution in the three temperature transfer directions is adjusted respectively.

[0032] Furthermore, in step S7, the method for correcting the temperature gradient of the analytical heat source temperature field and maintaining consistency with the volume / area distribution heat source calculation results is that the error between the third evolution result and the fourth evolution result is less than the solution accuracy of the analytical temperature field.

[0033] Furthermore, the value range of the increased grid size in step S7 is 8 mm to 15 mm.

[0034] The beneficial effects of the present invention are:

[0035] Based on the moving point analytical heat source temperature field, this scheme corrects the analytical temperature to obtain the corrected analytical heat source temperature field, and applies the function definition model of the corrected analytical heat source temperature field to efficiently solve the welding temperature field. On the basis of ensuring the accuracy of the temperature solution, the calculation efficiency is significantly improved, and the dependence of the welding temperature field calculation on the grid density is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the analytical heat source temperature field model for uniform motion.

[0037] Figure 2 Schematic diagram of the structure of aluminum alloy profile welding.

[0038] Figure 3 Schematic diagram of the first evolution result of the temperature field of the double ellipsoid heat source.

[0039] Figure 4 Schematic diagram of the second evolution result of the analytical heat source temperature field.

[0040] Figure 5 Schematic diagram of the temperature field gradient distribution in the width direction of the heat source.

[0041] Figure 6 Schematic diagram of the temperature field gradient distribution in the depth direction of the heat source.

[0042] Figure 7 Schematic diagram of the third evolution result of the modified analytical heat source temperature field.

[0043] Figure 8 Schematic diagram of the fourth evolution result after increasing the grid size. DETAILED DESCRIPTION

[0044] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0045] like Figure 2 As shown in the figure, this scheme takes the aluminum alloy profile welding model as an example. It has a large number of free surfaces for convective and radiative heat exchange with the surrounding environment. When the moving point heat source analytical temperature field model is used to solve it, there is a large error compared with the volume / area distribution heat source calculation results. The application of the efficient analytical method for the welding temperature field proposed in this scheme can significantly reduce the calculation cost and time.

[0046] The specific application steps of this solution are as follows:

[0047] S1: A 3D model of a thin-walled aluminum alloy profile was constructed using shell-solid coupling modeling. The weld area was treated as a solid with a 2mm mesh size, while the principle weld area was treated as a shell with a 4mm mesh size. The number of solid meshes was 80,000, and the number of shell meshes was 55,000. The mesh types were: shell (temperature field: DS4; stress field: S4R) and solid (temperature field: DC3D8; stress field: C3D8R).

[0048] S2: Applied welding heat source: arc welding, double ellipsoid heat source.

[0049] The front ellipsoid and back ellipsoid heat source models are:

[0050] ;

[0051] ;

[0052] in Q = μUI (μ is the effective coefficient, welding voltage U =25V, welding current I =220A), f f 、 f r is the energy distribution coefficient of the front and rear ellipsoids ( f f : f r =3:7), a 、 b f 、 b r 、 cis the shape parameter of the double ellipsoid heat source ( a = c =5mm, b f =0.6a, b r =1.4 a );

[0053] The welding speed is 20 mm / s. The welding order is from left to right. The initial temperature of the model is 20 degrees Celsius, and convection and radiation heat transfer occurs between the free surface and the surrounding environment.

[0054] S3: Perform transient heat transfer temperature calculation and solve to obtain the first evolution result of temperature field distribution, such as Figure 3 shown.

[0055] S4: On the same local geometric 3D model, only the temperature boundary conditions are loaded, and the temperature field is solved by defining the node temperatures of the model using the analytical heat source temperature field function to obtain the second evolution result of the temperature field distribution. Specifically, the calculation formula of the analytical heat source temperature field is:

[0056]

[0057] in q = μUI / v , solve to obtain the second evolution result of temperature field distribution, such as Figure 4 As shown;

[0058] S5: The temperature distribution results of the first evolution result and the second evolution result of the temperature field are derived respectively, and the temperature distributions in the x-direction, y-direction, and z-direction are output respectively with the heat source of the quasi-steady-state temperature field as the center. The temperature gradients in the x-direction, y-direction, and z-direction of the analytical temperature field are then corrected using correction factors in the three directions, where the x-direction is the welding movement direction, the y-direction is the width direction of the heat source, and the z-direction is the depth direction of the heat source;

[0059] The calculation formula for the corrected analytical heat source temperature field is:

[0060]

[0061] The correction factor for the welding movement direction is:

[0062]

[0063] The correction factors in the heat source width direction and heat source depth direction are:

[0064] ;

[0065]

[0066] in, CV1. CV 2. CV 3 are the correction factors in the x, y and z directions respectively; C 1. C2. C 3 is the shape coefficient in the x-direction, A 1. A 2. A 3 is the shape coefficient in the y direction, B 1. B 2. B 3 is the shape factor in the z direction.

[0067] After comparing the first evolution result with the second evolution result, the temperature gradient distribution in the three temperature transfer directions is adjusted by the shape coefficients of these three groups. The correction results are as follows: Figure 5 and Figure 6 The correction coefficient is shown in the following table:

[0068]

[0069] S6: Apply the modified analytical heat source to solve the temperature field and obtain the third evolution result of the temperature field distribution, such as Figure 7 shown.

[0070] S7: Increase the grid size (8mm grid in the weld area) and repeat step S6 to obtain the fourth evolution result of the temperature field distribution, such as Figure 8 As shown; and the temperature gradient of the corrected analytical heat source temperature field is consistent with the volume / area distribution heat source calculation results, so that the reduction of the grid density has little effect on the solution accuracy of the analytical temperature field.

[0071] S8: Apply the function definition model of the modified analytical heat source temperature field to efficiently solve the welding temperature field. The calculation efficiency comparison is shown in the following table:

[0072]

[0073] In summary, this solution significantly improves computational efficiency by applying a modified analytical method for the heat source temperature field. While ensuring the accuracy of the temperature solution, the computational efficiency is increased by approximately 16.4 times. At the same time, the dependence of the welding temperature field calculation on mesh density is reduced.

Claims

1. An efficient analysis method for welding temperature field, characterized in that: The following steps are involved: S1: Establish a local geometric three-dimensional model of the weld and input the material's thermal physical properties that vary with temperature; S2: Melting welding heat source model with volume / area distribution heat flux; S3: Calculate and solve the transient heat transfer temperature and obtain the first evolution result of the temperature field distribution; S4: On the same local geometric 3D model, only the temperature boundary conditions are loaded, and the model node temperatures are defined by the function of the analytical heat source temperature field to solve the temperature field and obtain the second evolution result of the temperature field distribution; S5: The temperature distribution results of the first evolution result and the second evolution result of the temperature field are derived respectively, and the temperature distributions in the x-direction, y-direction, and z-direction are output respectively with the quasi-steady-state temperature field heat source as the center, and the temperature gradients in the x-direction, y-direction, and z-direction of the analytical temperature field are corrected respectively, wherein the x-direction is the welding movement direction, the y-direction is the heat source width direction, and the z-direction is the heat source depth direction; specifically, the temperature gradients in the x-direction, y-direction, and z-direction of the analytical temperature field are corrected respectively using correction factors in the three directions. The calculation formula for correcting the analytical heat source temperature field is: ； ； ； ； in, q is the welding line energy, λ is the thermal conductivity of the material, a is the thermal diffusivity of the material, v is the walking speed of the heat source, r is the distance between the current observation point and the center of the heat source, x is the horizontal distance between the current observation point and the center of the heat source; CV 1. CV 2. CV 3 are the correction factors in the x, y and z directions respectively; C 1. C2. C 3 is the shape coefficient in the x-direction, A 1. A 2. A 3 is the shape coefficient in the y direction, B 1. B 2. B 3 is the shape coefficient in the z direction; through these three groups of shape coefficients, the temperature gradient distribution in the three temperature transfer directions is adjusted respectively; S6: On the same local geometric three-dimensional model, the boundary conditions of the model node temperatures are defined by the function of modifying the analytical heat source temperature field to solve the temperature field and obtain the third evolution result of the temperature field distribution; S7: Increase the grid size and repeat step S6 to obtain the fourth evolution result of the temperature field distribution, and make the temperature gradient of the modified analytical heat source temperature field and the volume / area distribution heat source calculation results consistent; S8: Apply the function definition model of the modified analytical heat source temperature field to efficiently solve the welding temperature field.

2. The efficient analysis method of welding temperature field according to claim 1, characterized in that: The thermophysical performance parameters in step S1 include density, thermal conductivity and specific heat capacity.

3. The efficient analysis method of welding temperature field according to claim 1, characterized in that: Step S2 includes setting the initial temperature of the melting welding heat source model, the ambient temperature, and the convection and radiation boundary conditions with the surrounding environment.

4. The efficient analysis method of welding temperature field according to claim 1, characterized in that: The calculation formula for analyzing the heat source temperature field in step S4 is: in, q is the welding line energy, λ is the thermal conductivity of the material, a is the thermal diffusivity of the material, v is the walking speed of the heat source, r is the distance between the current observation point and the center of the heat source, x It is the horizontal distance between the current observation point and the center of the heat source.

5. The efficient analysis method of welding temperature field according to claim 1, characterized in that: The method for correcting the temperature gradient of the analytical heat source temperature field and the volume / area distribution heat source calculation results to be consistent in step S7 is: the error between the third evolution result and the fourth evolution result is less than the solution accuracy of the analytical temperature field.

6. The efficient analysis method of welding temperature field according to claim 1, characterized in that: The value range of the increased grid size in step S7 is 8 mm to 15 mm.

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