A method for determining the starting point of laser sealing welding based on temperature and stress simulation

Abstract

The present invention discloses a method for determining the starting point of laser sealing welding based on temperature and stress simulation, which includes constructing a solid model of the housing; dividing the solid model of the housing according to the influence of heat and force on the housing during laser sealing welding, and constructing a finite element model of the housing based on the division result; obtaining the temperature field and stress of the housing during the sealing welding process under different starting point conditions of the sealing welding by using the finite element model; and determining the starting point of the sealing welding of the housing among different starting points of the sealing welding according to the temperature field and stress. The present invention can accurately and quickly determine the optimal starting point of laser sealing welding, improve the qualified rate of product quality, and meet the current research and development requirements of short cycle and batch production of aerospace payload products.

Description

Technical Field

[0001] The present invention relates to a method for determining the starting point of laser sealing based on temperature and stress simulation, belonging to the technical field of laser sealing in electronic packaging. Background Art

[0002] At present, with the increasing trend of short-cycle and quantitative development of communication satellites in key models such as low-orbit and constellation networking in China, batch production, high reliability, and high efficiency requirements are also put forward for the production of microwave aerospace products such as active phased array antennas and radar T / R components. To ensure that microwave payload components for aerospace applications have good microwave performance and high reliability both in space and on the ground, it is necessary to hermetically package the microwave components, and hermetic packaging plays a crucial role in the long-term stability of the circuit operation of the payload module.

[0003] A large number of packaging shells for aerospace satellite-borne microwave modules use lightweight silicon-aluminum alloy shells. Due to the high silicon content in the material and the complex shell structure, according to the actual working conditions, the thermal distribution and thermal stress in the laser beam sealing process have different degrees of influence on the shell (such as cracks appearing at 1.5 mm on the side wall of the shell), and the product often leaks airtight due to the side wall of the shell being cracked by tensile stress. After adjusting the starting point of the sealing welding, it is found that the side wall cracks have improved, but different starting points of laser sealing welding have different force and thermal effects on the silicon-aluminum alloy shell during the sealing welding process. It is necessary to determine the optimal starting point of laser sealing welding to minimize the stress on the silicon-aluminum shell during the sealing welding process. Therefore, the determination of the optimal starting point of laser sealing welding is of great significance in improving the yield and reliability of laser sealing of silicon-aluminum shells. Currently, a method for determining the optimal starting point of laser sealing welding is urgently needed. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above defects, provide a method for determining the starting point of laser sealing based on temperature and stress simulation, and solve the technical problem that it is difficult to determine the optimal starting point of laser sealing in the prior art. The method for determining the starting point of laser sealing based on temperature and stress simulation of the present invention has high accuracy, improves the simulation efficiency at the same time, and provides a guiding direction for the optimization of the sealing process.

[0005] To achieve the above invention purpose, the present invention provides the following technical solutions:

[0006] A method for determining the starting point of laser sealing based on temperature and stress simulation, comprising:

[0007] Construct a solid model of the shell according to the two-dimensional structure diagram of the shell;

[0008] Divide the solid model of the shell based on the influence of heat and force on the shell during the laser sealing process, and construct a finite element model of the shell based on the division result;

[0009] Perform temperature field analysis using a finite element model, optimize the finite element model according to the temperature field analysis results to obtain a first optimized finite element model; use the first optimized finite element model to obtain the temperature field of the outer shell during the sealing process under different sealing start point conditions.

[0010] Based on the temperature field, perform stress analysis using the first optimized finite element model, optimize the first optimized finite element model according to the stress analysis results to obtain a second optimized finite element model; use the second optimized finite element model to obtain the stress of the outer shell during the laser sealing process under different sealing start point conditions.

[0011] Determine the sealing start point of the outer shell according to the temperature field and stress of the outer shell during the laser sealing process under different sealing start points.

[0012] Further, in the side wall of the solid model of the outer shell, the part with a perpendicular distance ≤ d to the sealing surface is used as the key area; d is any value in the range of 1 to 2 mm.

[0013] The temperature field analysis result is the temperature field analysis result of the key area. According to the first optimized finite element model, obtain the temperature field of the key area of the outer shell during the sealing process under different sealing start point conditions. The temperature field is the temperature change curve of the calculation nodes in the key area; the calculation nodes are the grid nodes of the finite element model.

[0014] The stress analysis result is the stress analysis result of the key area. According to the second optimized finite element model, obtain the stress of the key area of the outer shell during the laser sealing process under different sealing start point conditions, and obtain the stress safety factor change curve of the key area according to the stress of the key area.

[0015] Further, the sealing surface is a rounded rectangle.

[0016] The method for determining different sealing start points is as follows:

[0017] Select different sealing start points at least on two adjacent sides of the sealing surface.

[0018] The sealing start points selected on a single side at least include the midpoint of the side. On the premise that the side length is sufficient, it also includes several sealing start points selected at intervals of 10 to 15 mm from the midpoint along the side.

[0019] Further, according to the influence of heat and force on the outer shell during the laser sealing process, the method for partitioning the solid model of the outer shell and constructing the finite element model of the outer shell based on the partitioning result is as follows:

[0020] According to the influence of heat and force on the housing during the laser seam welding process, the solid model of the housing is partitioned to obtain the weld influence zone, the transition zone, and the heat source - remote zone. Among them, the weld influence zone is centered on the weld center (i.e., the welding position between the cover plate and the housing), and the depth decreases from the weld center to both sides, presenting a bowl - dish shape. The width at the top of the weld influence zone is 0.6 - 1.0 mm, the depth at the weld center is 0.6 - 1.0 mm, preferably 0.8 mm. The transition zone extends from the boundary of the weld influence zone in the direction away from the weld influence zone, and the width at the top of the transition zone is 0.3 - 0.4 times the width at the top of the weld influence zone. The heat source - remote zone is the remaining part of the solid model of the housing except for the weld influence zone and the transition zone.

[0021] The division principles of the above - mentioned weld influence zone, transition zone, and heat source - remote zone can be understood as being divided according to Figure 4 the distribution of each region in the schematic diagram of the temperature distribution at the starting point of the simulated heat source. Taking the weld influence zone as the center, the temperatures of the weld influence zone and the transition zone show a gradient decline. The area where T≥1083 °C is the weld influence zone, the area where 657≤T≤1083 °C is the transition zone, and the area where T≤657 °C is the heat source - remote zone.

[0022] Define the mesh sizes of the weld influence zone, transition zone, and heat source - remote zone, and perform mesh division on the solid model. The mesh size of the weld influence zone is smaller than that of the heat source - remote zone, and the transition zone is used to realize the transition of the mesh sizes between the weld influence zone and the heat source - remote zone.

[0023] According to the mesh division result of the solid model, construct the finite - element model of the housing.

[0024] Furthermore, when performing temperature - field analysis using the finite - element model, apply the temperature - field analysis boundary conditions to the finite - element model. When optimizing the finite - element model according to the temperature - field analysis results, the optimization goal is to make the temperature - field analysis results converge or conform to the actual working conditions. The methods for optimizing the finite - element model according to the temperature - field analysis results include removing mesh distortion or densifying the mesh.

[0025] When performing stress analysis using the finite - element model according to the temperature field, apply the temperature field as a load to the finite - element model, and at the same time apply the stress - analysis boundary conditions to the finite - element model. When optimizing the finite - element model according to the stress - analysis results, the optimization goal is to make the stress - analysis results converge and conform to the actual working conditions. The methods for optimizing the finite - element model according to the stress - analysis results include removing mesh distortion or densifying the mesh.

[0026] Furthermore, the temperature - field analysis boundary conditions include: simulating the input of the laser heat source by a moving heat source and simulating the heat output of the housing to the surrounding environment by surface convection heat transfer.

[0027] The moving heat source is a combination of a Gaussian surface heat source and a cone heat source. The descriptions of the Gaussian surface heat source and the cone heat source are as follows:

[0028] Gaussian heat source:

[0029] Cone Heat Source:

[0030] Among them, x, y, z are the coordinates of the calculation point relative to the heat source point, r s 、r V is the equivalent radius of the heat source, α is the surface heat source concentration coefficient, H and β are the depth and attenuation coefficient of the body heat source, Q s is the input heat flux density of the surface heat source, Q V is the input heat flux density of the body heat source;

[0031] The stress analysis boundary conditions include restricting the shell's rotation and translation without restricting its thermal expansion.

[0032] Furthermore, the method for performing temperature field analysis on the finite element model is:

[0033] S3.1 Given the welding speed, welding starting point, initial heat source moving direction and heat source moving path of the laser welding process; each welding point along the heat source moving path is denoted as p i , i≥0, p0 represents the sealing starting point;

[0034] S3.2 in p i At the point where the heat source moves, find the next solder point p along the heat source moving path according to the heat source moving direction. i+1 , and update the heat source moving direction according to the welding speed;

[0035] S3.3 Repeat step S3.2 until returning to the sealing starting point;

[0036] In step S3.2, at point p0, the next soldering point p1 is searched along the heat source moving path according to the given initial heat source moving direction;

[0037] In step S3.2, based on the known direction of heat source movement and the current weld point, the arc segment of the heat source movement path is equivalent to a discrete straight line segment; in the arc segment of the heat source movement path, an equivalent heat source based on the current time is generated according to the component of the welding speed along the coordinate axis.

[0038] Furthermore, the method of using the finite element model to perform stress analysis is:

[0039] Divide the finite element model into m blocks, m ≥ 4;

[0040] In each sub-block, the mesh sizes in the weld heat-affected zone, transition zone, and the zone far from the heat source are refined to 0.3 mm, 0.5 mm, and 3 mm, respectively.

[0041] In the refined mesh of the weld heat-affected zone, birth-death elements are determined. At the start of the laser sealing welding process, the birth-death elements are killed. When the temperature of a birth-death element first exceeds the melting temperature, the birth-death element is activated. After all birth-death elements are activated, the laser sealing welding is completed.

[0042] Parallel simulation is performed on m blocks, and the transient stress during the laser sealing welding process is output.

[0043] Furthermore, the range of the birth-death elements is the entire area of the weld heat-affected zone.

[0044] The mesh elements within the depth range d1 - d2 in the depth direction are treated as bonded; where d1 represents the depth at the center of the weld, and d2 is the thickness of the cover plate. As Figure 11 shown, the cover plate is butt-jointed with the shell. Except for the part welded together in the upper molten pool, the lower part and other areas are not welded, but this part is treated as bonded during the simulation.

[0045] The method for optimizing the finite element model according to the stress analysis results also includes adjusting the range or material properties of the birth-death elements.

[0046] Furthermore, the method for determining the sealing welding start point of the shell among different sealing welding start points according to the temperature field and stress during the laser sealing welding process is as follows:

[0047] Sort the temperature fields of different sealing welding start points in ascending or descending order;

[0048] Determine the laser sealing welding stress safety factors for different sealing welding start points according to the stress of different sealing welding start points, and sort the stress safety factors of different sealing welding start points in ascending or descending order;

[0049] Determine the sealing welding start point of the shell according to the sorting result of the temperature field and the sorting result of the stress safety factor;

[0050] The method for determining the laser sealing welding start point based on temperature and stress simulation is implemented using the ANSYS platform.

[0051] The present invention has at least one of the following beneficial effects compared with the prior art:

[0052] (1) Based on the characteristics of the silicon-aluminum shell of aerospace microwave module products, the characteristics of laser welding, and engineering practice, the present invention applies the simulation calculation method to analyze the temperature field and stress field in laser welding under different welding starting points, realizing a method for identifying and determining the optimal welding starting point. During the design stage, the weak positions of the shell can be understood and avoided, greatly reducing the probability of appearance defects such as cracks on the side wall of the silicon-aluminum shell, improving the product quality qualification rate. This application has a substantial improvement in this field and also meets the current research and development requirements of short cycle and batch production for aerospace payload products;

[0053] (2) The present invention proposes a method for automatically applying heat sources to the complex laser welding path (including arc angles and straight lines) of silicon-aluminum alloy shells. The complex path is equivalent to a discrete path, taking into account both simple and complex paths, with high applicability. Traditional methods only perform static simulations on straight-line laser welding paths. The present invention conducts force and heat simulations of transient processes for straight and circular arc laser welding paths;

[0054] (3) The present invention proposes a technology for block-by-block analysis of the welding stress field of laser welding paths, realizing a multi-block parallel simulation method. Compared with the traditional continuous calculation by steps, the method of the present invention has higher efficiency, can shorten the simulation calculation time, and has a substantial improvement;

[0055] (4) The present invention forms multi-scale grids for actual working conditions, effectively improving the calculation efficiency on the basis of ensuring the accuracy of simulation results. Brief Description of the Drawings

[0056] Figure 1 are (a) Gaussian heat source model and (b) conical heat source model;

[0057] Figure 2 is a three-dimensional structure schematic diagram of a silicon-aluminum alloy shell;

[0058] Figure 3 is the laser welding calculation pulse waveform of the present invention;

[0059] Figure 4 is the temperature distribution of the current simulated heat source starting point of the present invention;

[0060] Figure 5 is the equivalent schematic diagram of the complex heat source path of the present invention;

[0061] Figure 6 is the temperature change curve of different starting points during welding of the present invention;

[0062] Figure 7 is the block diagram during stress analysis of the present invention;

[0063] Figure 8Schematic diagram of grid stress sub-block division of the silicon-aluminum alloy housing of the present invention; where (a), (b), (c), and (d) respectively correspond to Figure 7 sub-block 1, sub-block 2, sub-block 3, and sub-block 4 in the middle;

[0064] Figure 9 Schematic diagram of the extreme value distribution law of the safety factor during the welding process of the present invention;

[0065] Figure 10 Distribution law diagram of the extreme value of the safety factor during the welding process with different starting welding points of the present invention;

[0066] Figure 11 Schematic diagram of the weld heat-affected zone, transition zone, and heat source-remote zone of the present invention. Detailed implementation manners

[0067] The present invention will be described in detail below, and the features and advantages of the present invention will become clearer and more definite with these descriptions.

[0068] The special term "exemplary" here means "serving as an example, embodiment, or illustration". Any embodiment described as "exemplary" here does not have to be interpreted as superior to or better than other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings do not have to be drawn to scale unless otherwise specified.

[0069] The present invention relates to the laser sealing welding process of a lightweight silicon-aluminum housing for an aerospace satellite-borne microwave module. Due to the high silicon content in the housing material and the complex housing structure, the thermal distribution and the generated thermal stress during the laser sealing welding process have different degrees of influence on the housing, especially the effect of the welding starting point is more obvious. However, for different structures (including special-shaped structures), the starting point cannot be accurately determined. The present invention proposes a method for determining the laser sealing welding starting point based on temperature and stress simulation, aiming to determine the safest sealing welding starting point for silicon-aluminum housings with different structures in the laser sealing welding link. By simulating the laser sealing welding process of different silicon-aluminum tube housings with different sealing welding starting points using the ansys platform, the transient temperature field distribution and variation law, stress distribution and variation law, and weak links of the silicon-aluminum housing during the laser sealing welding process under different sealing welding starting points are obtained, thereby finding the safest sealing welding starting point to guide process optimization.

[0070] The variation law of the transient temperature field and stress field during the laser sealing welding process generally refers to the temperature and stress changes at a certain longitudinal distance on the side wall of the silicon-aluminum housing, preferably in the range of 0 - 1.5 mm. The present invention takes the sealing welding surface (the same as the cover plate surface) of the silicon-aluminum housing as the reference, and the range of 0 - 1.5 mm longitudinally on the side wall is the key area for simulating the distribution and variation law of the temperature field and stress field.

[0071] The selection method for different sealing welding starting points is as follows: for those with a unilateral length less than 15 mm, the midpoint can be selected as the starting point; for those with a length meeting the requirements, several points can be selected on the straight edge of the silicon-aluminum alloy shell, including key points, with a spacing of 10-15 mm between adjacent points, and the number of points on one side is preferably ≥3; select points according to this method and perform simulation calculations.

[0072] In a preferred embodiment, taking 6 points as an example, one point is taken at the midpoint in the length direction and the width direction respectively, and then one point is selected at 10-15 mm to the left and right of the midpoint, for a total of 6 different positions as the sealing welding starting points ( Figure 2 , the three points on the long side are defined as L1, L2, and L3, and the three points on the short side are defined as S1, S2, and S3), compare the temperature and stress changes in the range of 0-1.5 mm from the top down on the side wall of the silicon-aluminum alloy shell under different starting points, and finally determine the optimal sealing welding starting point.

[0073] A method for determining the starting point of laser sealing welding based on temperature and stress simulation according to the present invention is as follows:

[0074] Step 1: According to the CAD two-dimensional structure diagram of the silicon-aluminum shell, on this basis, appropriately simplify the model, take the range of 0-1.5 mm from the top down on the side wall as the key area, and establish a solid model of the high silicon-aluminum shell for the area outside the simplified range.

[0075] Step 2: Construct a finite element model according to the solid model. The establishment of the finite element model mainly includes two parts: the segmentation of the solid model and the meshing. The segmentation of the solid model mainly considers a more reasonable configuration of the finite element mesh. Considering the characteristics of laser sealing welding, the heat and force influence areas are very small. The solid model is segmented into three parts: the weld influence area, the transition area, and the area far from the heat source, and different mesh sizes are defined. On the basis of the segmentation of the solid model, combined with the characteristics of the laser sealing welding process, different mesh sizes are defined for different regions, and the solid model is meshed. After the meshing is completed, the material of the unit is defined according to the entity where the unit is located, and the establishment of the finite element model is completed.

[0076] Step 3: After determining the solid model and the finite element model, perform temperature field analysis processing. On the basis of the finite element model, apply the boundary conditions for temperature field analysis, perform temperature field analysis, and obtain the temperature field. The boundary conditions of the temperature field mainly include: simulating the input of the laser heat source with a moving heat source and simulating the heat output of the shell to the surrounding environment with surface convective heat transfer.

[0077] In this step, the finite element model is optimized according to the temperature field analysis results. Specifically, during the temperature field analysis, if the results do not converge or the local temperature gradient is too large, it is largely due to mesh distortion or relatively coarse meshes in the weld-affected areas. Therefore, the finite element model needs to be adjusted, mainly by improving or densifying the meshes, and then re-performing the temperature field analysis until the results meet the expectations. Thus, the temperature field is analyzed for different starting points, and by comparing the variation patterns, the minimum temperature is determined. The results meeting the expectations mean they conform to the actual working conditions. Specifically, in the actual working conditions, after laser sealing welding, at a depth of 1.5 mm from the outer shell, the temperature reaches around 280 - 330 °C. If the temperature value obtained after calculating with the temperature field mesh division is close to 280 - 330 °C, it is considered to meet the expectations.

[0078] Step 4: Perform stress and strain analysis based on the results of the temperature field. The temperature is applied as a load to the structure, and at the same time, the structural analysis boundary conditions are applied to analyze the structure to obtain its stress or strain.

[0079] In this step, the finite element model is optimized according to the stress or strain analysis results. Similar to the temperature field analysis, during the stress and strain analysis, the results may also not converge or the local stress gradient may be large. The finite element model needs to be improved or densified, and then the stress and strain analysis is re-performed. If the results converge, the stress and strain results of the weld and its surrounding areas can be obtained. Based on the analysis results, it is mainly judged whether the maximum stress area at 1.5 mm from the side wall of the outer shell in the simulation model coincides with the crack area observed in the actual working conditions. If they coincide, the results are reasonable; if not, the settings of the sealing welding area need to be adjusted, mainly adjusting the range of the birth and death elements and the material properties of the birth and death elements, etc., until the results are reasonable or meet the expectations. Thus, the stress distribution is analyzed for multiple different sealing welding starting points (such as Figure 2 ) selected, and by comparing the variation patterns, the minimum stress is determined.

[0080] Step 5: Combine the temperature field and the stress or strain analysis calculation results of different sealing welding starting points to obtain the optimal sealing welding starting point for avoiding quality defect problems such as cracks on the side wall of the outer shell.

[0081] In step 3 above, considering the characteristics that the laser sealing welding energy of the silicon-aluminum outer shell is applied in the form of pulses and the morphology of the welding penetration depth, it is determined to use a combination of a Gaussian surface heat source and a conical heat source. The superposition of the two models is more in line with the shape of the laser sealing welding molten pool and the temperature distribution. The descriptions of the two heat sources are as follows:

[0082] Gaussian heat source

[0083] Conical heat source

[0084] where x, y, and z are the coordinates of the calculation point relative to the heat source point, rs , r V is the equivalent radius of the heat source effect, α is the concentration coefficient of the surface heat source, H and β are the action depth and attenuation coefficient of the volume heat source, and x is x0 + v x *t, and y is y0 + v y *t (x0 and y0 are the positions of the heat source at the starting moment of the welding simulation time step; v x , v y are the velocity components of the heat source movement within the time step, and t is the time). The movement of the heat source is mainly controlled by load steps (the load step refers to a setting of boundary conditions and load options, and can be solved once or multiple times during simulation calculation).

[0085] In step 3 above, according to the structural characteristics of the silicon-aluminum shell (including straight edges and arcs), in the analysis of the temperature field, a laser sealing welding heat source application simulation technology with a complex path containing arc angles is used to obtain the temperature field distribution and maximum and minimum values. Specifically:

[0086] (a) According to the rectangular silicon-aluminum alloy shell simulation object ( Figure 2 ), a finite element simulation is carried out on the laser sealing welding process. Among them, it is edited using the APDL platform. Under the parameters of the given welding speed, initial welding position, initial heat source movement direction, and the position array of each node on the heat source movement path, APDL searches for the next welding point along the heat source path according to the given initial heat source movement direction. Then, according to the given path, the heat source movement direction for the next time is updated, thus realizing the automatic application of the heat source and simulation calculation.

[0087] (b) On the basis of knowing the heat source movement direction and the current welding point, APDL can automatically calculate the equivalent heat source according to the rounded corners in the sealing welding path of the silicon-aluminum shell using the above given parameters. Compared with the previous laser sealing welding numerical simulation, the traditional method only calculates the straight path (without arc angles) and has a single heat source function. However, the method of the present invention realizes the equivalent heat source processing for the circular arc welding path based on the ansys platform. Specifically, the present invention equivalently converts the path of the arc segment into multiple straight line segments, and can automatically adjust the heat source direction according to the path, replacing manual work. The automatic application of the heat source in this method is achieved by changing the velocity components v x , v y in the heat source formula through the slope of each straight line segment. Therefore, this method can realize the application of the heat source for the complex sealing welding path of the silicon-aluminum alloy shell (with both straight lines and arcs), making the calculated values more in line with the actual working conditions, thereby obtaining the transient change law and maximum and minimum values of the temperature field during the laser sealing welding process. This method takes into account both simple and complex paths and improves the generality of program application.

[0088] In step 4 above, for stress-strain analysis, the structural analysis boundary (stress analysis boundary condition) refers to the fixation of the bottom surface, mainly restricting the inversion and translation of the outer shell while not restricting its thermal expansion. During the laser sealing welding process, the molten bonding of two parts of materials, namely the shell and the cover plate, is involved. In structural analysis, this phenomenon is simulated through birth and death elements. A part of the elements in the weld affected area is defined as birth and death elements. At the beginning of the analysis, all of them are killed, i.e., simulating the separated state of the two parts. Then, when the element temperature first exceeds a specific value (melting temperature), they are activated to represent the re-fusion of the two parts. Until all elements are activated, the fusion process of the two parts of materials is completed.

[0089] In step 4 above, in order to determine the welding stress field of the long-path laser sealing welding of the high-silicon aluminum outer shell, the segmented analysis technology is used to obtain the stress field distribution and the maximum and minimum values. The specific implementation content is as follows:

[0090] (a) According to multiple trials, it is found that the silicon-aluminum alloy outer shell has a long sealing welding path (the path perimeter is 216 mm and it contains 4 arc corners). If the same analysis strategy as the temperature field is adopted and the load is applied step by step in time, the time required for the stress-strain field analysis of the same mesh is about 10 times that of the temperature field solution! Considering the characteristic that the thermal stress influence domain of laser sealing welding is relatively small, therefore, the plastic deformation of the silicon-aluminum outer shell is concentrated in a very small area around the weld. In addition, according to the fact that each solder joint in the laser sealing welding process has little temperature influence on the welded area within a certain distance during welding, considering the efficiency and calculation duration of the comprehensive simulation, in the present invention, the stress-strain field analysis of the rectangular silicon-aluminum alloy outer shell is carried out by means of block parallel segmented analysis.

[0091] (b) Under the block parallel processing method, the model is processed into 4 parts. The criterion for block division is that the model structure is centrosymmetric. Each part is separately divided to separate the weld affected area, the transition area and the area far from the heat source. The corresponding mesh sizes are refined to 0.3 mm, 0.5 mm and 3 mm, respectively, so that the mesh division in the weld affected area is relatively dense and the mesh in the far area is relatively sparse, taking into account both the accuracy and efficiency of the simulation.

[0092] (c) In order to more realistically reflect the structural characteristics of the weld fusion, the present invention uses the "birth and death element" technology to simulate the adhesion process of the cover plate material and the outer shell material in the weld area. Therefore, the transient stress field and the maximum and minimum values during the laser sealing welding process of the silicon-aluminum outer shell at different welding starting points are obtained.

[0093] In step 5 above, by combining the temperature and stress analysis results and processing, the safest welding starting point is obtained and determined. The specific content is as follows:

[0094] (a) Based on the development and application of the simulation method for the temperature field, in order to screen out the temperature field distribution and the minimum temperature value at 1.5 mm from the side wall of the outer shell during the sealing welding process for different sealing welding starting points, therefore, the present invention selects 6 different starting welding points L1, L2, L3, S1, S2, S3 on the rectangular silicon-aluminum outer shell (such as Figure 1 ) and selects the temperature change curves of one week at 1.5 mm deep from the side wall of the outer shell during the sealing welding process for each starting point.

[0095] (b) By comparing the change rules of the temperature curves under 6 different sealing welding starting points, in order of the maximum temperature from high to low, the corresponding sealing welding starting points are S3, S2, L1, L2, S1, L3. Among them, when S3, S2, and L1 are used as the sealing welding starting points, the overall transient temperature during the sealing welding process is relatively high. When L2, L3, and S1 are selected as the starting points, the overall temperature value of the outer shell is relatively low. This shows that in actual sealing welding, it is safer to select L2, L3, and S1 as the sealing welding starting points with the lowest temperature field distribution.

[0096] (c) After obtaining the change rule of the temperature field, in order to analyze the stress distribution and the minimum value during the sealing welding process for different starting welding points, the present invention selects the same 6 starting points L1, L2, L3, S1, S2, S3 for simulation calculation. Considering that the yield fracture characteristics of the material also change with temperature, the stress safety factor is taken as n = σ s (T) / σ (σ s is the material yield stress, and σ is the calculated stress) to judge the stress during the sealing welding process. The higher this coefficient, the safer the structure.

[0097] (d) According to the obtained minimum value of the safety factor, it can be known that the largest value among the minimum values of the safety factor during the sealing welding process is the starting welding point S1, and S3 is the second. According to the average value of the safety factor comparison, the value is the largest when L3 or S3 is used as the starting welding point. Combining the temperature field, the peak value of the maximum temperature with L2, L3, and S1 as the starting welding points is relatively low. Considering the comprehensive results of the temperature and stress fields, it is analyzed that using S1 as the starting welding point, the sealing welding process of the silicon-aluminum alloy outer shell is the safest. Therefore, combining the results of the temperature and stress fields, the optimal sealing welding starting point is determined.

[0098] Using the ANSYS simulation platform, this invention simulates and calculates the stress, temperature field distribution rules and maximum and minimum values during the laser sealing welding process under different sealing welding starting points. The starting point when the minimum value of the shell thermal stress occurs is taken as the safest sealing welding starting point. By comparing and fitting with the results of the laser sealing welding test, the safest sealing welding starting point is determined, further improving the qualified rate of the product appearance quality and significantly reducing the manufacturing and quality costs. This invention is particularly suitable for simulating and calculating the temperature field of laser sealing welding of complex paths containing arc corners. At the same time, according to the welding stress of the long-path laser sealing welding of the silicon-aluminum shell, this invention adopts a segmented parallel analysis method to calculate the variation rules of the temperature field and stress field of the silicon-aluminum shell during the laser sealing welding process under different sealing welding starting points, predict the force, heat distribution and weak links, and determine the safest sealing welding starting point. The calculation period of the method of this invention is shorter than that of the traditional calculation method, determining the influence rule of the sealing welding starting point on the shell during the laser sealing welding process, and it is also an innovative method for determining the laser sealing welding starting point, providing an optimized guiding direction for the sealing welding process.

[0099] Example:

[0100] In this example, the rectangular silicon-aluminum shell of the aerospace microwave component product is taken as an example for simulation calculation, and a method for determining the laser sealing welding starting point based on temperature and stress simulation is proposed. By using the ANSYS software platform to simulate the laser sealing welding process of different structural silicon-aluminum tube shells under different sealing welding starting points, the temperature, stress distribution and weak links of the silicon-aluminum shell under different sealing welding starting points are obtained, and thus the safest sealing welding starting point is found to guide the process optimization.

[0101] In this example, the specifications of the high silicon-aluminum shell are 65mm×43mm×16mm (the arc angle between the straight edges is R2), which is composed of two parts: a shell and a cover plate, and the joint surface between the two is subjected to the laser sealing welding process. The high silicon-aluminum shell has double-sided cavities (including double-sided outer cover plates). The material of the high silicon-aluminum shell is 50% Si 50% Al silicon-aluminum alloy, and the material of the cover plate is 27% Si 73% Al silicon-aluminum alloy.

[0102] The method for determining the laser sealing welding starting point based on temperature and stress simulation of this invention is implemented as follows:

[0103] (1) Establish a solid model according to the two-dimensional design drawing of the silicon-aluminum shell, and then construct a finite element model and perform mesh division. The mesh division is carried out according to the characteristics of the laser sealing welding process. The energy of the laser sealing welding is applied in the form of pulses, such as Figure 3As shown. When analyzing the present invention, a pulse period T is used as the basic calculation unit. During the pulse time, a heat source is applied (the heat source is turned on) to the shell structure during the heating period, and the heat source is removed (the heat source is turned off) during the remaining time within one period T for calculation. Therefore, the affected areas of heat and force during laser sealing welding are very small. The solid model is divided into three parts: the weld affected area, the transition area, and the area far from the heat source, as Figure 11 shown, a’ is the weld affected area, a” is the transition area, and different mesh sizes are defined. Since the heat flow is relatively concentrated in the weld affected area, resulting in large temperature and stress gradients, it is necessary to divide finer meshes. The area far from the affected area only serves as a support, and the mesh can be relatively rough. The transition area is mainly to enable the elements to smoothly transition from the coarse mesh area to the fine mesh area.

[0104] (2) Based on the finite element model, the boundary conditions for temperature field analysis are applied to conduct temperature field analysis to obtain the temperature field. According to the morphology of the seal weld penetration, the simulated heat source for laser sealing welding is determined in the form of a combination of a Gaussian surface heat source and a cone heat source. The superposition of the two heat source models is more in line with the shape of the laser sealing welding molten pool and the temperature distribution ( Figure 4 ). The parameters required for the heat source model are as follows:

[0105] (a) According to the shell structure, the items provided by the laser sealing welding process parameters include heat source power (W, watt), heat source efficiency, laser pulse frequency (Hz, hertz), pulse width (ms, millisecond), welding speed (mm / s, millimeter per second), and the molten depth of the solder joint (mm, millimeter).

[0106] (b) The corresponding simulated Gaussian heat source parameters include the heat source action radius (mm, millimeter), heat source concentration coefficient, and heat source component coefficient.

[0107] (c) The corresponding simulated cone heat source parameters include the heat source action depth (mm, millimeter), heat source equivalent radius (mm, millimeter), heat source loss coefficient, and heat source component coefficient.

[0108] In this step, according to the determined heat source model, the transient change of the temperature field during the laser sealing welding process of the silicon-aluminum alloy shell is simulated and analyzed. Since the target shell for simulation contains straight lines and arc angles, it is a complex sealing welding path for the laser sealing welding path. Using the finite element simulation APDL program for editing, according to the given sealing welding process, such as welding speed, initial welding position, initial heat source movement direction, and the array conditions of each node position on the heat source movement path, the calculation program searches for the next solder joint along the path according to the given initial heat source movement direction, and at the same time updates the next movement direction according to the given path, obtaining the simulation technology for automatic heat source application.

[0109] On the other hand, for the heat source calculation at the rounded corners in the sealing welding path of the silicon-aluminum shell, according to the known sealing welding direction and the current welding point, the present invention uses the finite element APDL program to calculate the components of the heat source moving speed along the coordinate axes (such as the x, y, and z axes defined in Figure 2 ) at the rounded corners in the sealing welding path. When changing the heat source parameters (x, y), an equivalent heat source based on the current time is generated (as shown in Figure 5 ). On this basis, combined with the laser sealing welding pulse period ( Figure 3 ), within one period, the heat source is turned on during the pulse heating section and turned off during the remaining time. This method of applying the heat source and equivalent processing of the circular arc corner laser sealing welding path is different from the previous method of calculating the straight line path (without circular arc corners) in laser sealing welding simulation. This method is more in line with the reality of the laser sealing welding path.

[0110] Therefore, this method can realize the application of the heat source for the complex sealing welding path of the silicon-aluminum alloy shell (with both straight lines and circular arcs), making the calculated values more in line with the actual working conditions, so as to obtain the transient change law and maximum value of the temperature field during the laser sealing welding process. This method takes into account both simple and complex paths, reduces the subsequent use difficulties, and improves the application versatility.

[0111] According to the heat source calculation of the laser sealing welding path, as shown in Figure 2 , the present invention takes 6 selected starting welding points as examples for analysis. Six different starting welding points L1, L2, L3, S1, S2, and S3 are selected on the silicon-aluminum shell. The temperature change curves of one week of the box body at a depth of 1.5 mm from the side wall of the shell are selected for each starting point's sealing welding process, as shown in Figure 6 . By comparing the temperature field distribution laws, the temperature change curves of one week of the box body at a depth of 1.5 mm are selected as the preferred scheme here. The reason is that in the key area, the temperature change curves of one week at a depth of 1.5 mm are the most representative, so there is no need to analyze the temperature change curves of the whole key area. By comparing the maximum values of the temperature (Table 1), the maximum temperature values are sorted from high to low, and the corresponding sealing welding starting points are S3, S2, L1, L2, S1, and L3 in turn. When S3, S2, and L1 are used as the sealing welding starting points, the transient temperature during the sealing welding process is generally higher. When L2, L3, and S1 are selected as the starting points, the overall shell temperature value is lower. This shows that in actual sealing welding, it is safer to select L2, L3, and S1 as the sealing welding starting points with the lowest temperature field distribution. According to this method, the temperature field distribution analysis can be carried out for any point.

[0112] Table 1 Maximum shell temperature under different sealing welding starting points

[0113] Sealing starting point L1 L2 L3 S1 S2 S3 Maximum temperature / °C 458.89 442.53 423.04 437.31 449.22 460.40

[0114] (3) Analyze the stress and strain distribution based on the obtained temperature field distribution law and simulation results. In order to obtain the welding stress field results of long-path laser sealing of high-silicon aluminum shells, the segmented analysis technique is used to obtain the stress field distribution and extreme values. Specifically as follows:

[0115] For the long sealing welding path of the silicon-aluminum alloy shell (the path perimeter is 216 mm and contains 4 arc corners), if the same analysis strategy as the temperature field is adopted and the load is applied step by step in time, the time required for the same mesh stress and strain field analysis is about 10 times that of the temperature field solution! The main reasons are as follows: First, when performing stress and strain analysis, the degrees of freedom of a single node are 3 times that of temperature analysis. In the simulation method of the present invention, the transient temperature field at each time point is imported into the stress analysis model in the form of a file, and then the temperature of each node in the stress and strain analysis mesh is obtained by interpolation based on this basic temperature field. Second, the too large temperature gradient in the local area causes local plastic deformation of the structure, and more iteration times are taken when solving the equilibrium equation. Third, in order to ensure the convergence of the solution, a smaller load step is often required during stress and strain analysis.

[0116] According to the characteristics that the thermal stress influence domain of laser sealing welding is small, and in addition, the plastic deformation of the structure of the simulation object is also concentrated in a very small area around the weld. On the other hand, relative to the current solder joint, the subsequent solder joints of laser sealing welding have little influence on the temperature of the welded area within a certain distance during welding. Considering the efficiency and calculation duration of the comprehensive simulation, in the present invention, the block parallel segmented ( Figure 7 ) analysis method is used to analyze the stress and strain field of the rectangular silicon-aluminum alloy shell.

[0117] As Figure 7 shown, the method of segmented analysis is as follows: The weld area (weld influence area) is divided into 4 blocks for calculation ( Figure 7 ), and each block has its own refined area. The starting point and the ending point in each block are spliced into a complete welding area. However, considering the influence of the thermal influence area of the nearby solder joints, the calculation starting point (i.e., the starting point of sealing welding) should be advanced compared with the block starting point. Therefore, when processing each block, the calculation starting point is moved forward compared with the block starting point. In this method, the advance amount is ≥ 30T (i.e., 30 pulse periods). The calculation starting point is the starting point for calculating the thermal stress, that is, the position where the heat source starts to be applied when calculating the stress. When dividing the mesh for a single block, only the mesh in the refined area is refined, and other areas are not refined. During calculation, it is also necessary to perform a closing process on the "disconnection" between the starting solder joint and the calculation starting point to simulate the effect of laser sealing welding.

[0118] Under the block parallel processing method, the model is processed into 4 parts, and each part is separately segmented to isolate the weld influence area, the transition area, and the area far from the heat source. The corresponding mesh sizes are refined to 0.3 mm, 0.5 mm, and 3 mm respectively, making the mesh division in the weld area denser and the mesh in the far area relatively sparse, taking into account both the accuracy and efficiency of the simulation. The mesh division of each part of the silicon-aluminum alloy shell is as shown in Figure 8 shown.

[0119] When performing stress analysis, in order to more realistically reflect the structural characteristics of weld fusion, the present invention uses the "birth and death element" technology to simulate the adhesion process of the cover plate material and the shell material in the weld area. The technical key point is that before analysis, a part near the weld (i.e., the weld influence area unit within 0 - 0.8 mm in the weld depth direction) is selected and defined as a birth and death element, and the element is killed during pulse cooling; other contact parts of the weld surface (depth direction 0.8 - 1.5 mm, assuming the cover plate thickness is 1.5 mm and the weld center depth is 0.8 mm) are treated as bonded. During analysis, the nodes connected to the birth and death elements that also experience the process of heating to melting and cooling are activated, and the corresponding elements enter the analysis until the analysis is completed and all elements are activated.

[0120] (4) Taking 6 points as an example, according to the temperature field distribution results of 6 different sealing welding starting points and the stress segment parallel processing technology, the stress field distribution and the minimum value of the stress safety factor of the selected 6 different sealing welding starting points are calculated to obtain the safest sealing welding starting point. Specifically as follows:

[0121] (a) The same as the sealing welding starting points selected during temperature field analysis, 6 starting points L1, L2, L3, S1, S2, S3 are also selected for simulation calculation. Considering that the yield fracture characteristics of the material also change with temperature, the stress safety factor is taken as n = σ s (T) / σ (where σ s is the material yield stress and σ is the calculated stress) to judge the stress during the sealing welding process. The higher this coefficient, the safer the structure. Figure 9 Shown is the stress safety factor change curve during the sealing welding process when the sealing welding starting point is S1. It is found that the safety factor in the last 1 / 4 segment of the sealing welding process is less than 1, indicating that the stress of the material is lower than the sealing welding stress at this time, and the sealing welding process is relatively dangerous and prone to defects such as appearance cracks. In order to efficiently obtain the thermal stress differences of different starting welding points, combined with the stress analysis segment parallel processing method, only the thermal stress in the last 1 / 4 welding process of different starting welding points is analyzed during stress analysis. According to this method, stress and strain analysis can be performed on any point.

[0122] Due to the general change law of the last 1 / 4 dangerous segment during the sealing welding process of the silicon-aluminum alloy shell, therefore, the stress safety factor change curves of the last 1 / 4 segments during the sealing welding processes of 6 different sealing welding starting points are as shown inFigure 10 As can be seen from the results, when 6 starting welding points are used for welding in the latter 1 / 4 section, the safety factors at 1.5 mm on the side wall are all lower than 1.

[0123] Table 2 Statistics of Stress Safety Factors in the Latter 1 / 4 Section after Welding with Different Starting Welding Points

[0124] Soldering starting point L1 L2 L3 S1 S2 S3 Minimum value 0.8858 0.8803 0.8874 0.8961 0.8890 0.8913

[0125] From the minimum value of the safety factor in Table 2, it can be seen that the largest among the minimum values of the safety factor during the sealing welding process is the starting welding point S1, followed by S3. From the perspective of the average safety factor, this value is the largest when L3 or S3 is used as the starting welding point. Considering that the peak values of the maximum temperatures with L2, L3, and S1 as the starting welding points are relatively low, through comprehensive analysis, it is considered that using S1 as the starting welding point, the sealing welding process of the silicon-aluminum alloy shell is the safest. Therefore, combining the results of the temperature and stress fields, the optimal starting point for sealing welding is determined.

[0126] This embodiment is established using the ansys platform, and a method for determining the starting point of laser sealing welding based on temperature and stress simulation is proposed. It can accurately determine the safest starting point for laser sealing welding of the silicon-aluminum shell, predict the weak links of laser sealing welding at the front end of the production of the silicon-aluminum alloy shell of the product, avoid design defects, and can determine the optimal starting point for laser sealing welding, greatly reducing the probability of appearance defects such as cracks on the side wall of the silicon-aluminum shell and improving the product quality qualification rate. This application has a substantial improvement in this field and also meets the research and development requirements of short cycle and batch production of microwave load products in the current Xi'an Branch.

[0127] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limitations on the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications, or improvements can be made to the technical solutions and their implementation manners of the present invention, and all of these fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

[0128] The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A method for determining the starting point of laser sealing welding based on temperature and stress simulation, characterized in that Including: Construct a solid model of the housing according to the two-dimensional structure diagram of the housing; Divide the solid model of the housing based on the influence of heat and force on the housing during laser sealing welding, and construct a finite element model of the housing based on the division results; Perform temperature field analysis using the finite element model, and optimize the finite element model according to the temperature field analysis results to obtain the first optimized finite element model; Use the first optimized finite element model to obtain the temperature field of the housing during the sealing welding process under different sealing welding starting point conditions; Based on the temperature field, perform stress analysis using the first optimized finite element model, and optimize the first optimized finite element model according to the stress analysis results to obtain the second optimized finite element model; Use the second optimized finite element model to obtain the stress of the housing during laser sealing welding under different sealing welding starting point conditions; Determine the sealing welding starting point of the housing according to the temperature field and stress of the housing during laser sealing welding under different sealing welding starting points; The method for performing temperature field analysis on the finite element model is: S3.1 Given the welding speed, welding start point, initial heat source movement direction, and heat source movement path of the laser sealing welding process; denote each solder joint along the heat source movement path as p i , i≥0, p0 represents the welding start point; S3.2 At p i , search for the next solder joint p i+1 along the heat source movement path in the heat source movement direction, and update the heat source movement direction according to the welding speed; S3.3 Repeat step S3.2 until the sealing welding starting point is returned; In step S3.2, at p0, find the next welding point p1 along the heat source movement path in the given initial heat source movement direction; In step S3.2, based on the known heat source movement direction and the current welding point, equivalent the arc segment of the heat source movement path to discrete straight line segments; On the arc segment of the heat source movement path, generate an equivalent heat source based on the component of the welding speed along the coordinate axis according to the current time; The method for performing stress analysis using the finite element model is: Divide the finite element model into m blocks, where m ≥ 4; In each block, refine the mesh sizes of the weld influence zone, transition zone, and area far from the heat source to 0.3 mm, 0.5 mm, and 3 mm respectively; Determine the birth and death elements in the refined mesh of the weld influence zone. At the beginning of the laser sealing welding process, kill the birth and death elements. When the temperature of the birth and death elements first exceeds the melting temperature, activate the birth and death elements until all birth and death elements are activated, and then complete the laser sealing welding; Perform parallel simulation on the m blocks and output the transient stress during the laser sealing welding process.

2. The method for determining the starting point of laser sealing welding based on temperature and stress simulation according to claim 1, wherein, Regard the part of the side wall of the solid model of the housing with a perpendicular distance ≤ d from the sealing welding surface as the key area; d is any value in the range of 1 - 2 mm; The temperature field analysis result is the temperature field analysis result of the key area. According to the first optimized finite element model, obtain the temperature field of the key area of the housing during the sealing welding process under different sealing welding starting point conditions; The stress analysis result is the stress analysis result of the key area. According to the second optimized finite element model, obtain the stress of the key area of the housing during laser sealing welding under different sealing welding starting point conditions, and obtain the stress safety factor change curve of the key area according to the stress of the key area.

3. A method for determining the starting point of laser sealing welding based on temperature and stress simulation according to claim 2, characterized in that, The sealing welding surface is a rounded rectangle; The method for determining different sealing welding starting points is: Select different sealing welding starting points at least on two adjacent sides of the sealing welding surface; The sealing welding starting points selected on a single side at least include the midpoint of the side. On the premise that the length of the single side is sufficient, it also includes several sealing welding starting points selected at intervals of 10 - 15 mm starting from the midpoint along the single side.

4. A method for determining the starting point of laser sealing welding based on temperature and stress simulation according to claim 1, characterized in that The method of partitioning the solid model of the outer shell according to the influence of heat and force during laser sealing welding and constructing the finite element model of the outer shell based on the partitioning results is as follows: According to the influence of heat and force during laser sealing welding on the outer shell, the solid model of the outer shell is partitioned to obtain the weld influence zone, the transition zone, and the heat source - remote zone. Among them, the weld influence zone is centered on the weld center, and the depth decreases from the weld center to both sides, presenting a bowl - dish shape. The width at the top of the weld influence zone is 0.6 - 1.0 mm, and the depth at the weld center is 0.6 - 1.0 mm. The transition zone extends from the boundary of the weld influence zone in the direction away from the weld influence zone, and the width at the top of the transition zone is 0.3 - 0.4 times the width at the top of the weld influence zone. The heat source - remote zone is the remaining part of the solid model of the outer shell except the weld influence zone and the transition zone; Define the mesh sizes of the weld influence zone, the transition zone, and the heat source - remote zone, and perform mesh division on the solid model. The mesh size of the weld influence zone is smaller than that of the heat source - remote zone, and the transition zone is used to realize the transition of the mesh sizes between the weld influence zone and the heat source - remote zone; Construct the finite element model of the outer shell according to the mesh division results of the solid model.

5. A method for determining the starting point of laser sealing welding based on temperature and stress simulation according to claim 4, characterized in that When performing temperature field analysis using the finite element model, apply the temperature field analysis boundary conditions to the finite element model. When optimizing the finite element model according to the temperature field analysis results, the optimization goal is to make the temperature field analysis results converge or conform to the actual working conditions; The method of optimizing the finite element model according to the temperature field analysis results includes removing mesh distortion or densifying the mesh; When performing stress analysis using the finite element model according to the temperature field, apply the temperature field as a load to the finite element model, and at the same time apply the stress analysis boundary conditions to the finite element model; When optimizing the finite element model according to the stress analysis results, the optimization goal is to make the stress analysis results converge and conform to the actual working conditions; The method of optimizing the finite element model according to the stress analysis results includes removing mesh distortion or densifying the mesh.

6. A method for determining the starting point of laser sealing welding based on temperature and stress simulation according to claim 5, characterized in that The temperature field analysis boundary conditions include: simulating the input of the laser heat source with a moving heat source and simulating the heat output of the outer shell to the surrounding environment with surface convective heat transfer; The moving heat source is a combination of a Gaussian surface heat source and a conical heat source. The descriptions of the Gaussian surface heat source and the conical heat source are as follows: Gaussian heat source: Cone heat source where x, y, and z are the coordinates of the calculation point relative to the heat source point, r s , r V are the equivalent radii of the heat source action, α is the concentration coefficient of the surface heat source, H and β are the action depth and attenuation coefficient of the volume heat source, Q s is the input heat flux density of the surface heat source, Q V is the input heat flux density of the volume heat source; The stress analysis boundary conditions include restricting the inversion and translation of the shell on the premise of not restricting the thermal expansion of the shell.

7. A method for determining the starting point of laser sealing welding based on temperature and stress simulation according to claim 1, characterized in that, The range of the birth - death elements is the entire area of the weld influence zone; The mesh elements within the depth range of d1 - d2 are processed as bonded; where d1 represents the depth at the weld center and d2 is the cover plate thickness; The method of optimizing the finite element model according to the stress analysis results also includes adjusting the range of the birth - death elements or the material properties.

8. A method for determining the starting point of laser sealing welding based on temperature and stress simulation according to claim 1, characterized in that, The method of determining the laser sealing welding starting point of the outer shell among different sealing welding starting points according to the temperature field and stress of the outer shell during laser sealing welding is as follows: Sort the temperature fields of different sealing welding starting points in ascending or descending order; Determine the laser sealing welding stress safety factors of different sealing welding starting points according to the stresses of different sealing welding starting points, and sort the stress safety factors of different sealing welding starting points in ascending or descending order; Determine the laser sealing welding starting point of the outer shell according to the sorting result of the temperature field and the sorting result of the stress safety factor; The method for determining the starting point of laser sealing welding based on temperature and stress simulation is implemented using the ANSYS platform.

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