Weld simulation modeling method

Abstract

The application discloses a welding seam simulation modeling method, comprising the following steps: obtaining a base material test piece and a lap type welding test piece; establishing a welding seam grid according to the welding seam size on the lap type welding test piece; performing a tensile test on the base material test piece to obtain a real stress-strain curve of the base material; substituting data groups on the stress-strain curve into a base material hardening model to calculate all to-be-determined coefficients and determine a hardening curve of the base material; establishing a welding finite element model according to the hardening curve and the welding seam grid; performing a tensile test and a bending test on the lap type welding test piece to obtain a displacement-force curve; inputting the welding finite element model and the displacement-force curve into an optimization platform to output a welding seam hardening curve and a welding seam fracture curve; and assigning the welding seam hardening curve and the welding seam fracture curve to the welding seam grid to establish a welding seam simulation finite element model. The above method can realize accurate simulation and crack generation tendency prediction, improve the digital level of vehicle manufacturing, ensure the structural safety from the design end and reduce the research and development cost.

Description

Technical Field

[0001] This invention belongs to the field of weld simulation technology, and in particular relates to a weld simulation modeling method. Background Technology

[0002] In the field of vehicle manufacturing, welding technology is a core process for connecting key components such as the body, frame, and chassis. Fixing two identical or different base materials together through welding is fundamental to achieving structural integrity, lightweighting, and safety in vehicles. However, the welding process is a transient physical process involving high-temperature heat sources, material melting and solidification, and complex thermo-mechanical coupling; its process quality directly determines the performance of the welded joint.

[0003] In actual production and quality control, a particularly prominent problem is that microscopic or macroscopic irregular cracks often appear in the welded joint area (i.e., the weld and its heat-affected zone) during subsequent testing or use. These cracks, due to their small size and irregular shape, are difficult to detect completely in conventional inspections, but they pose a serious threat to the long-term reliability and safety of the vehicle structure. Cracks are highly prone to propagation under cyclic or impact loads, potentially leading to sudden structural failure and safety accidents.

[0004] To predict and avoid welding defects, traditional solutions mainly rely on a trial-and-error approach, which involves repeatedly adjusting welding parameters (such as current, voltage, and speed) and conducting numerous physical experiments and destructive tests. This method is not only time-consuming and costly, but also heavily dependent on engineers' experience, making it difficult to deeply understand the mechanistic mechanisms of crack initiation and propagation. Therefore, developing a numerical simulation method that can accurately simulate and predict crack initiation tendencies is crucial and urgent for improving the digitalization level of vehicle manufacturing, ensuring structural safety from the design stage, and reducing R&D costs and timelines. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a weld simulation modeling method.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] The weld simulation modeling method includes the following steps:

[0008] S1, Obtain base material specimens and lap-type welded specimens;

[0009] S2, Establish a weld mesh based on the weld size on the lap-type welded specimen;

[0010] S3, Perform a tensile test on the base material specimen to obtain the true stress-strain curve of the base material;

[0011] S4, Substitute the data sets from the actual stress-strain curve obtained in step S3 into the initial base material hardening model to calculate all the undetermined coefficients in the base material hardening model, and then calibrate the base material hardening model of the current base material to determine the hardening curve of the current base material; the expression of the initial base material hardening model is: ;

[0012] in σ true The actual stress of the parent material can be obtained from the stress-strain curve in step S2; The true strain can be obtained from the stress-strain curve in step S2; These are weighting coefficients; For the undetermined coefficients in the Swift criteria, These are the undetermined coefficients of the Hockett-Sherby criterion;

[0013] S5. Based on the hardening curve obtained in step S4 and the weld mesh established in step S2, establish a welding finite element model of the lap-type welding specimen.

[0014] S6, Perform tensile and bending tests on the lap-type welded specimen to obtain the displacement-force curve of the lap-type welded specimen;

[0015] S7. Input the welding finite element model established in step S5 and the displacement-force curve obtained in step S6 into the optimization platform for calculation, and output the weld hardening curve and weld fracture curve.

[0016] S8. Assign the weld hardening curve and the weld fracture curve described in step S7 to the weld mesh established in step S2 to form a weld simulation finite element model.

[0017] Preferably, the weld mesh includes units A and B arranged side by side along the direction of the base material; the upper nodes of units A and B are connected to the first base material; and the lower nodes of units A and B are connected to the second base material.

[0018] Preferably, step S2 specifically includes:

[0019] S21, extend the upper surface of the base material in the lap-type welded specimen to form an extension line; observe the intersection of the extension line and the outer surface of the weld through a magnifying glass, and determine the intersection point as point a;

[0020] S22. Observe the root position of the weld connecting the two base materials with a magnifying glass. Draw a perpendicular line from the root of the weld towards the base material. The intersection of this perpendicular line and the coincident line of the two base materials is determined as point b.

[0021] S23, observe the landing point of the weld on the upper surface of the second base material using a magnifying glass; this landing point is point c.

[0022] S24, determine the length of unit A based on the distance between point a and point b; determine the length of unit B based on the distance between point a and point c;

[0023] S25, determine the height of unit A and unit B based on the distance between the transverse axes of the two parent materials, and determine the width of unit A and unit B based on the smaller width of the two parent materials.

[0024] Preferably, step S4 further includes: substituting the data set composed of the actual stress-strain data obtained in step S3 into the expression of the base material hardening model in sequence, and combining the least squares method to fit all the undetermined coefficients, including α, in the base material hardening model.

[0025] Preferably, the welding finite element model in step S5 includes the base material and the weld mesh; the unit A is located entirely between the base material one and the base material two, and is connected to the base material one and the base material two by a tie; the unit B protrudes from the end of the base material one and is connected to the base material two by a tie; the tie connection point between the unit A and the unit B is located at the end of the base material one near the base material two.

[0026] Preferably, the tensile test in step S6 specifically includes:

[0027] S61, a speckled coating is sprayed onto the surface of the lap-type welded specimen, and the two ends of the lap-type welded specimen are clamped by a testing machine;

[0028] S62, Start the testing machine so that one end of the lap-type welded specimen moves away from its other end at a uniform speed until the weld on the lap-type welded specimen breaks and then stops.

[0029] S63, the displacement and force data are collected by the testing machine, and the displacement-force curve of the lap-type welded specimen under tensile test is generated.

[0030] Preferably, the bending test in step S6 specifically includes:

[0031] S61', Spraying speckle coating onto the surface of the lap-type welded specimen, and fixing both ends of the lap-type welded specimen by a testing machine;

[0032] S62', Start the testing machine so that the pressure head on the testing machine moves at a constant speed toward the surface of the lap-type welded specimen and applies force to the lap-type welded specimen until the weld on the lap-type welded specimen breaks and stops.

[0033] S63': Displacement and force data are collected using a testing machine, and displacement-force curves of the lap-type welded specimen under bending test are generated.

[0034] Preferably, the optimization platform determines the weld hardening curve according to the following formula: ;

[0035] in, σ true-f This represents the actual stress in the base material; To respond to real situations; These are weighting coefficients; For the undetermined coefficients in the Swift criteria, These are the undetermined coefficients of the Hockett-Sherby criterion.

[0036] Preferably, the optimization platform determines the weld fracture curve according to the following formula: ;

[0037] in, These are the undetermined coefficients in the Swift-HS hardening criterion; Undetermined coefficients for the improved Hosford-Coulomb fracture model; For fracture equivalent strain; For stress triaxiality; Here are the nominal Rhodes angle parameters; .

[0038] Preferably, the values ​​of all undetermined coefficients in the weld hardening model and the fracture model are in the range of -1000 to 1000.

[0039] The advantages of the technical solution of this invention are mainly reflected in:

[0040] Tensile tests were conducted on the base material specimens to obtain their stress-strain curves. These curves were then input into a hardening model to obtain the hardening curves. A welding finite element model was established based on these hardening curves and the weld mesh created by observing the lap-type welded specimens. Tensile and bending tests were conducted on the lap-type welded specimens to obtain displacement-force curves. The optimization platform obtained the weld hardening curve and weld fracture curve based on the displacement-force curves and the welding finite element model. These two curves were then assigned to the weld mesh to achieve accurate simulation and predict crack initiation tendency, effectively improving the digitalization level of vehicle manufacturing, ensuring structural safety from the design stage, and reducing R&D costs.

[0041] The range of values ​​for all undetermined coefficients is relatively wide and they are not concentrated in a certain local area, thus ensuring that a more accurate meta-model of the maximum force is obtained, laying the foundation for the accuracy of subsequent simulation model establishment. Attached Figure Description

[0042] Figure 1 Flowchart of a preferred embodiment of the present invention;

[0043] Figure 2 : Establish weld mesh based on lap-type welded specimens, where Figure 2 Part (a) is a structural diagram of the lap-type welded specimen of a preferred embodiment of the present invention; Figure 2 Part (b) is a structural diagram of the weld mesh establishment according to a preferred embodiment of the present invention;

[0044] Figure 3 : A three-dimensional view of the welding finite element model of a preferred embodiment of the present invention;

[0045] Figure 4 The preferred embodiment of the present invention shows the morphology of the weld mesh under tensile test conditions, wherein... Figure 4 Part (a) in the diagram shows the structure after the weld fractures; Figure 4 Part (b) in the figure shows the displacement-force curve of the weld during the test;

[0046] Figure 5 The preferred embodiment of the present invention shows the morphology of the weld mesh under bending test conditions, wherein... Figure 5 Part (a) shows the structure after the weld fracture; Figure 5 Part (b) in the figure shows the displacement-force curve of the weld during the test;

[0047] Figure 6 : A flowchart of the weld hardening curve of a preferred embodiment of the present invention. Detailed Implementation

[0048] The objectives, advantages, and features of this invention will be illustrated and explained through the following non-limiting description of preferred embodiments. These embodiments are merely typical examples of applying the technical solutions of this invention, and all technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by this invention.

[0049] In the description of the solution, it should be noted that the terms "center," "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience and simplification of description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Also, in the description of the solution, with the operator as a reference, the direction closer to the operator is the proximal end, and the direction farther from the operator is the distal end.

[0050] like Figure 1 As shown, this invention discloses a weld simulation modeling method, comprising the following steps:

[0051] S1, Obtain the base material specimen and as shown in the figure. Figure 2 The lap-type welded specimen shown in part (a) is described above. The base material specimen can be made of known materials such as aluminum, steel, or alloys, and is not limited thereto. The lap-type welded specimen consists of two base materials placed vertically offset, i.e., a lap-type welded specimen with two base materials, one vertically offset and the other vertically offset, welded together to form a single specimen. In this case, the two base materials can be made of the same or different materials.

[0052] S2, establish a system based on the weld dimensions on the lap-type welded specimen as follows: Figure 2 The weld mesh shown in section (b) of the diagram.

[0053] Specifically, the weld mesh includes units A and B arranged side-by-side along the direction of the base material. The upper nodes of units A and B are connected to the first base material; the lower nodes of units A and B are connected to the second base material. This achieves a rigid connection between the components by seamlessly connecting units A, B, and the two base materials.

[0054] like Figure 2 As shown in section (b), the specific steps for establishing the weld mesh include:

[0055] S21, extend the upper surface of the base material in the lap-type welded specimen to form an extension line; observe the intersection of the extension line and the outer surface of the weld through a magnifying glass, and determine the intersection point as point a;

[0056] S22. Observe the root position of the weld connecting the two base materials with a magnifying glass. Draw a perpendicular line from the root of the weld towards the base material. The intersection of this perpendicular line and the coincident line of the two base materials is determined as point b.

[0057] S23, observe the landing point of the weld on the upper surface of the second base material using a magnifying glass; this landing point is point c.

[0058] S24, determine the length of unit A based on the distance between point a and point b; determine the length of unit B based on the distance between point a and point c;

[0059] S25, determine the heights of unit A and unit B based on the distance between the transverse axes of the two base materials, and determine the widths of unit A and unit B based on the smaller width of the two base materials. This concludes the process. Figure 3 The weld mesh shown has been created, and it has not been assigned any parameters; it exists only as a weld mesh model.

[0060] S3. Perform a tensile test on the base material specimen to obtain the true stress-strain curve of the base material. Specifically, obtain the engineering stress-strain curve of the base material by performing a tensile test on the base material specimen. Then, substitute the stress data from the stress-strain curve of the engineering base material into the formula sequentially. The true stress value of the base material is obtained from this formula. σ true The actual stress of the base material. σ eng For the engineering stress of the parent material, The strain is the engineering strain of the parent material. Simultaneously, the strain data from the stress-strain curve of the parent material are sequentially substituted into the formula. The true strain value of the parent material is obtained from this formula. ε true For the actual strain of the parent material, The stress-strain value is the engineering strain value of the base material. The true stress-strain curve is obtained using the true stress value and the true strain value.

[0061] The tensile test specifically includes the following steps:

[0062] S31, a speckled coating is sprayed onto the surface of the lap-type welded specimen, and the two ends of the base material are clamped by a testing machine;

[0063] S32, Start the testing machine so that one end of the lap-type welded specimen moves away from the other end at a uniform speed until the weld on the lap-type welded specimen breaks and stops; The test speed in this invention is preferably 1 mm / min, but this speed can be adjusted according to the test requirements and is not limited here;

[0064] S33, stress and strain data of the base material are collected by the testing machine, and stress-strain curves of the base material specimen under tensile test are generated.

[0065] S4. Substitute the data set from the actual stress-strain curve obtained in step S3 into the initial base material hardening model to calculate all the undetermined coefficients in the base material hardening model, and then calibrate the current base material hardening model to determine the hardening curve of the base material. That is, select a set of stress-strain sample data from the actual stress-strain curve in step S3 to form a data set; substitute this data set into the base material hardening model to obtain all the undetermined coefficients in the model. The number of data sets is not less than 3, and the specific number can be determined according to the test requirements, which is not limited here.

[0066] Furthermore, the expression for the parent material hardening model in this step is: .in σ true The true stress of the parent material can be obtained from the stress-strain curve in step S2. The true strain can be obtained from the stress-strain curve in step S2. These are the weighting coefficients. For the undetermined coefficients in the Swift criteria, These are the undetermined coefficients of the Hockett-Sherby criterion.

[0067] Furthermore, step S4 also includes: substituting the actual stress-strain data set obtained in step S3 into the expression of the base material hardening model in sequence, and combining the least squares method to fit all the undetermined coefficients in the base material hardening model, including α.

[0068] S5, based on the hardening curve obtained in step S4 and the weld mesh established in step S2, establish as follows: Figure 3 The finite element model of the lap-type welded specimen is shown. In this case, the welding finite element model includes two base materials and a weld mesh, but the weld mesh is not assigned any parameters and exists only as a model element.

[0069] Specifically, in the welding finite element model, the weld mesh can exist as an individual element, placed between base material one and base material two. Further, as... Figure 3 As shown, the connection point between unit A and unit B in the weld mesh is located at the end of the first base material near the second base material, that is, unit A is completely located between the first base material and the second base material, while unit B protrudes from the end of the first base material and is connected to the second base material; the bottom of unit A is connected to the second base material.

[0070] S6. Tensile and bending tests were performed on the lap-type welded specimens to obtain the displacement-force curves of the lap-type welded specimens.

[0071] Furthermore, the tensile test of the lap-welded specimen specifically includes:

[0072] S61, a speckled coating is sprayed onto the surface of the lap-type welded specimen, and the two ends of the lap-type welded specimen are clamped by a testing machine;

[0073] S62, the testing machine is started, causing one end of the lap-type welded specimen to move away from its other end at a uniform speed until the weld on the lap-type welded specimen breaks and then stops; at this time, the welding finite element model appears as follows. Figure 4 The state shown in part (a) of the document;

[0074] S63, uses a testing machine to collect displacement and force data, and generates data for tensile tests, such as... Figure 4 The displacement-force curve of the lap-type welded specimen is shown in part (b) of the figure.

[0075] The bending test of the lap-type welded specimen specifically includes:

[0076] S61', Spraying speckle coating onto the surface of the lap-type welded specimen, and fixing both ends of the lap-type welded specimen by a testing machine;

[0077] S62', Start the testing machine, causing the pressure head on the testing machine to move at a constant speed towards the surface of the lap-type welded specimen and apply force to the lap-type welded specimen until the weld on the lap-type welded specimen breaks; at this time, the welding finite element model appears as follows. Figure 5 The state shown in part (a) of the document;

[0078] S63', uses a testing machine to collect displacement and force data, and generates data for bending tests, such as... Figure 5 The displacement-force curve of the lap-type welded specimen is shown in part (b) of the figure.

[0079] S7. Input the welding finite element model established in step S5 and the displacement-force curve obtained in step S6 into the optimization platform for calculation, and output the weld hardening curve and weld fracture curve.

[0080] Specifically, the optimization platform in this step determines the weld hardening curve according to the following formula: ;

[0081] In the hardening model expression σ true This represents the actual stress in the base material; To respond to real situations; These are weighting coefficients; For the undetermined coefficients in the Swift criteria, These are the undetermined coefficients of the Hockett-Sherby criterion. That is, in this step, according to the formula... ;

[0082] Determine all the undetermined coefficients in the formula, generate the weld hardening curve model, and generate the corresponding weld hardening curve based on the weld hardening curve model.

[0083] Furthermore, the specific steps for generating the weld hardening curve are as follows: Figure 5 As shown:

[0084] S71, obtain the undetermined coefficients in the welding finite element model described in step S5, and conduct experiments on all the undetermined coefficients to design a Latin hypercube sampling method to form a set of sampling points. In this invention, the preferred sample size is 100, i.e., the number of sampling points is 100. Of course, in other embodiments, the sample size can be adjusted according to actual needs.

[0085] S72, using a known finite element solver in the prior art, the simulated displacement-force curve of the welding finite element model under the simulated tensile test is calculated;

[0086] S73, obtain the displacement-force curve corresponding to each sampling point in step S71 through the simulated displacement-force curve in step S72; that is, obtain the displacement-force curve of a set of sampling points in step S1.

[0087] S74. Based on the displacement-force curve obtained in step S73, establish the displacement-force curve element model corresponding to the undetermined coefficients in the welding finite element model.

[0088] S75. Based on the displacement-force curve of the lap-type welded specimen obtained in step S6, the undetermined coefficients in the welding finite element model are back-calculated using the displacement-force curve element model established in step S74, and the determined undetermined coefficients are obtained.

[0089] S76, Determine the hardening curve of the weld based on the undetermined coefficients obtained in step S75.

[0090] Furthermore, the optimization platform described in this step also needs to determine the weld fracture curve using the following formula: ;

[0091] in, These are the undetermined coefficients in the Swift-HS hardening criterion; Undetermined coefficients for the improved Hosford-Coulomb fracture model; For fracture equivalent strain; For stress triaxiality; Here are the nominal Rhodes angle parameters; ;

[0092] In this step, all undetermined coefficients are determined according to the above formula, a weld fracture curve model is generated, and a corresponding weld fracture curve is generated based on the weld fracture curve model.

[0093] Since the specific steps for generating the weld fracture curve are the same as those for generating the weld hardening curve, they will not be repeated here. The only difference between the weld fracture curve and the weld hardening curve is that in step S72, the simulated displacement-force curve of the welding finite element model under simulated bending test is calculated using a known finite element solver in the prior art. The remaining steps are the same, so that the weld fracture curve is finally obtained in step S76.

[0094] In the weld hardening model and the fracture model described in this invention The optimal value range is set between -1000 and 1000. This ensures that the range of all undetermined coefficients is relatively wide and not concentrated in a certain local area, thereby guaranteeing a more accurate meta-model of the maximum force and laying the foundation for the accuracy of subsequent simulation model establishment.

[0095] S8. The weld hardening curve and weld fracture curve obtained in step S7 are applied to the weld mesh established in step S2 to form a weld simulation finite element model. That is, various parameters of the weld can be obtained through the weld hardening curve and the weld fracture curve, thereby establishing a finite element model of the weld.

[0096] Tensile tests were conducted on the base material specimens to obtain their stress-strain curves. These curves were then input into a hardening model to obtain the hardening curves. A welding finite element model was established based on these hardening curves and the weld mesh created by observing the lap-type welded specimens. Tensile and bending tests were conducted on the lap-type welded specimens to obtain displacement-force curves. The optimization platform obtained the weld hardening curve and weld fracture curve based on the displacement-force curves and the welding finite element model. These two curves were then assigned to the weld mesh to achieve accurate simulation and predict crack initiation tendency, effectively improving the digitalization level of vehicle manufacturing, ensuring structural safety from the design stage, and reducing R&D costs.

[0097] Furthermore, the weld simulation modeling method disclosed in this invention is not only applicable to the modeling of lap welds but also to the modeling of T-welds. Since the modeling method of T-welds is basically the same as the above method, it will not be described in detail here.

[0098] This invention has many other embodiments, and all technical solutions formed by equivalent transformation or equivalent transformation fall within the protection scope of this invention.

Claims

1. A weld simulation modeling method, characterized in that: Includes the following steps: S1, Obtain base material specimens and lap-type welded specimens; S2, establish a weld mesh according to the weld size on the lap-type welded specimen; the weld mesh includes unit A and unit B arranged side by side along the setting direction of the base material; the upper nodes of unit A and unit B are connected to base material one; the lower nodes of unit A and unit B are connected to base material two. S21, extend the upper surface of the base material in the lap-type welded specimen to form an extension line; observe the intersection of the extension line and the outer surface of the weld through a magnifying glass, and determine the intersection point as point a; S22. Observe the root position of the weld connecting the two base materials with a magnifying glass. Draw a perpendicular line from the root of the weld towards the base material. The intersection of this perpendicular line and the coincident line of the two base materials is determined as point b. S23, observe the landing point of the weld on the upper surface of the second base material using a magnifying glass; this landing point is point c. S24, determine the length of unit A based on the distance between point a and point b; determine the length of unit B based on the distance between point a and point c; S25, determine the height of unit A and unit B according to the distance between the transverse axes of the two parent materials, and determine the width of unit A and unit B according to the smaller width of the two parent materials; S3, Perform a tensile test on the base material specimen to obtain the true stress-strain curve of the base material; S4, Substitute the data set on the true stress-strain curve obtained in step S3 into the initial base material hardening model to calculate all the undetermined coefficients in the base material hardening model, and then calibrate the base material hardening model of the current base material to determine the hardening curve of the current base material. The expression for the initial matrix hardening model is as follows: ; in σ true The actual stress of the parent material can be obtained from the stress-strain curve in step S2; The true strain can be obtained from the stress-strain curve in step S2; These are weighting coefficients; For the undetermined coefficients in the Swift criteria, These are the undetermined coefficients of the Hockett-Sherby criterion; S5. Based on the hardening curve obtained in step S4 and the weld mesh established in step S2, establish a welding finite element model of the lap-type welding specimen. S6, Perform tensile and bending tests on the lap-type welded specimen to obtain the displacement-force curve of the lap-type welded specimen; S7. Input the welding finite element model established in step S5 and the displacement-force curve obtained in step S6 into the optimization platform for calculation, and output the weld hardening curve and weld fracture curve. S8. Assign the weld hardening curve and the weld fracture curve described in step S7 to the weld mesh established in step S2 to form a weld simulation finite element model.

2. The weld simulation modeling method according to claim 1, characterized in that: Step S4 further includes: substituting the data set composed of the actual stress-strain data obtained in step S3 into the expression of the base material hardening model in sequence, and combining the least squares method to fit the expression of the base material hardening model. α All undetermined coefficients, including those in the range of [unspecified coefficients].

3. The weld simulation modeling method according to claim 2, characterized in that: The welding finite element model in step S5 includes the base material and the weld mesh; the unit A is located entirely between the base material one and the base material two, and is connected to the base material one and the base material two by a tie; the unit B protrudes from the end of the base material one and is connected to the base material two by a tie; the tie connection point between the unit A and the unit B is located at the end of the base material one near the base material two.

4. The weld simulation modeling method according to claim 1, characterized in that: The tensile test in step S6 specifically includes: S61, a speckled coating is sprayed onto the surface of the lap-type welded specimen, and the two ends of the lap-type welded specimen are clamped by a testing machine; S62, Start the testing machine so that one end of the lap-type welded specimen moves away from its other end at a uniform speed until the weld on the lap-type welded specimen breaks and then stops. S63, the displacement and force data are collected by the testing machine, and the displacement-force curve of the lap-type welded specimen under tensile test is generated.

5. The weld simulation modeling method according to claim 1, characterized in that: The bending test in step S6 specifically includes: S61', Spraying speckle coating onto the surface of the lap-type welded specimen, and fixing both ends of the lap-type welded specimen by a testing machine; S62', Start the testing machine so that the pressure head on the testing machine moves at a constant speed toward the surface of the lap-type welded specimen and applies force to the lap-type welded specimen until the weld on the lap-type welded specimen breaks and stops. S63': Displacement and force data are collected using a testing machine, and displacement-force curves of the lap-type welded specimen under bending test are generated.

6. The weld simulation modeling method according to claim 1, characterized in that: The optimization platform in step S7 determines the weld hardening curve according to the following formula: ; in, σ true-f This represents the actual stress in the base material; To respond to real situations; These are weighting coefficients; For the undetermined coefficients in the Swift criteria, These are the undetermined coefficients of the Hockett-Sherby criterion.

7. The weld simulation modeling method according to claim 6, characterized in that: In step S7, the optimization platform determines the weld fracture curve according to the following formula: ; in, These are the undetermined coefficients in the Swift-HS hardening criterion; Undetermined coefficients for the improved Hosford-Coulomb fracture model; For fracture equivalent strain; For stress triaxiality; Here are the nominal Rhodes angle parameters; .

8. The weld simulation modeling method according to claim 7, characterized in that: In both the base material hardening model and the fracture model, the values ​​of all undetermined coefficients range from -1000 to 1000.

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