Planar additive manufacturing and remanufacturing finite element modeling method based on linear path

Abstract

The invention provides a planar additive manufacturing and remanufacturing finite element modeling method based on a linear path, and aims to solve the problems that a traditional additive manufacturing finite element modeling method based on GUI operation is complex in process, low in efficiency, poor in reliability and inconvenient to digitize and intelligentize, and the model precision is insufficient when a preset weld bead is adopted to simulate an additive process. Parameterized analysis steps are written based on a Python language to create program codes, and the problem that GUI operation is extremely complicated under the large-model and high-precision requirements is solved; based on a Fortran language, DFLUX user subprogram secondary development and a unit life and death technology, the problem of precision deviation caused by neglecting of a welding bead gradual accumulation process in a preset welding bead is solved. By adopting the method, the modeling precision and reliability requirements can be guaranteed to the greatest extent while the finite element modeling efficiency in the additive manufacturing process is improved. Meanwhile, parameterized driving is adopted, the method is applied to additive manufacturing technology development and product full-life-cycle management, and automation and intelligentization are achieved conveniently.

Description

Technical Field

[0001] The present invention relates to the field of additive manufacturing and remanufacturing, and particularly to a finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path. Background Art

[0002] With the continuous development of additive manufacturing technology, planar additive manufacturing and remanufacturing are increasingly widely used in industrial production. However, in the existing planar additive manufacturing and remanufacturing processes, the use of the GUI method to create an analysis step is complex, inefficient, and unreliable, and it is difficult to adapt to the simulation of the additive manufacturing and remanufacturing processes of large components; the method of using pre-placed weld beads ignores the process of gradual bead stacking, resulting in the influence of preheating and structural stress on the previously deposited weld beads / weld layers, leading to a significant decrease in the accuracy of the finite element model, deviating from the engineering reality. For such a finite element modeling method for the additive process without parameter driving based on a straight-line path, it is difficult to adapt to the technological development trend of automated and intelligent control throughout the product life cycle from design, manufacturing, service to remanufacturing. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path in view of the above-mentioned deficiencies of the prior art. This method can establish an accurate and efficient finite element model for straight-line additive manufacturing and remanufacturing, deeply analyze the temperature field, stress field of additive manufacturing and the dynamic evolution law formed by the coupling of the two, which is beneficial to guiding actual production and facilitating the realization of automated and intelligent control throughout the product life cycle.

[0004] In order to achieve the above technical features, the object of the present invention is realized as follows: A finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path, comprising the following steps: Step 1, geometric model construction: According to the engineering actual requirements of planar additive manufacturing, establish the required geometric model by using finite element software; Step 2, material property setting: Set the material physical property parameters for the geometric model established in Step 1 in the finite element software; Step 3, assembly of components: Assemble the geometric model with set parameters in Step 2 into a solid model in the finite element software; Step 4, mesh generation: Use the corresponding module in the finite element software to generate a mesh for the solid model established in Step 3; Step 5, setting analysis steps: Establish a certain number of analysis steps for the solid model after mesh generation; Step 6, load application and boundary condition setting: Apply loads to the finite element model established in Step 5 and set corresponding boundary conditions; Step 7, write and call the heat source subroutine: According to the characteristics of the welding heat source and process parameters, write a user subroutine and solve it by calling the user subroutine; Step 8, result analysis and post-processing: Perform visual analysis on the calculation results in Step 7 and optimize the linear additive manufacturing and remanufacturing process based on the calculation results.

[0005] Preferably, the specific method of Step 1 is: According to the actual situation of planar additive manufacturing and remanufacturing engineering, establish a geometric model containing a planar welding plate and a semi-circular cross-section weld by drawing in the finite element software ABAQUS or importing from other 3D modeling software. The length, width, thickness of the welding plate and the geometric dimensions of the weld are user-defined.

[0006] Preferably, the specific method of Step 2 is: Set the material physical property parameters matching the planar additive manufacturing and remanufacturing process in the ABAQUS Property module. The material physical property parameters include general physical property parameters, mechanical parameters and thermal property parameters; The specific method of Step 3 is: Assemble the geometric model into a solid through the ABAQUS Assembly module.

[0007] Preferably, the specific method of Step 4 is: According to the structural dimensions and calculation accuracy of the established solid model, perform mesh division on it in the ABAQUS Mesh module, and select appropriate mesh strategies and element types according to the structural characteristics of the solid model and the established analysis type to precisely control the mesh size and density; The specific method of Step 5 is: In the ABAQUS Step module, create a certain number of analysis steps according to the weld size and the number of element layers, set the solution parameters, and simulate the weld additive stacking process through element birth and death based on the number of analysis steps and the number of elements in the weld zone.

[0008] Preferably, the specific method of Step 6 is: According to the actual situation of planar additive manufacturing and remanufacturing engineering, apply loads to the established finite element model in the ABAQUS Interaction and Load modules and set corresponding boundary conditions, where the boundary conditions include thermal boundary conditions and displacement boundary conditions; The specific method of Step 7 is: According to the characteristics of the welding heat source and process parameters, a DFLUX user subroutine is written to define the heat source model and the heat source movement trajectory, and the user subroutine is called for solution setting in the ABAQUS Job module.

[0009] Preferably, the specific method of Step Eight is as follows: After the calculation in Step Seven is completed, the temperature field, stress field, and strain field data results are extracted in the ABAQUS Visualization module for visualization analysis, to analyze the thermo-mechanical coupling process of planar additive manufacturing and remanufacturing, reveal the evolution laws of the temperature field and stress field, and optimize the linear additive manufacturing and remanufacturing process based on the relevant results.

[0010] Preferably, the realization of the weld additive build-up process by element birth and death in Step Four is achieved by writing Python code using the "Model change" instruction; The establishment of the analysis steps in Step Five is implemented by GUI operation or by writing Python code. For the step of defining multiple analysis steps according to the weld size and element layer, first, enter the ABAQUS software interface, click the Model button, and successively open Model-Edit keywords-model-1 to enter the analysis step interface, and write the analysis steps through Python code.

[0011] Preferably, the specific steps of writing Python code using the "Model change" instruction in Step 4 include: Step 4.1, initialize variables; Step 4.2, set the model keyword block; Step 4.3, loop to process data; Step 4.4, generate birth and death elements.

[0012] Preferably, in the writing and calling of the heat source subroutine in Step Seven, the heat source is selected as a surface heat source or a volume heat source according to the engineering practice, and the heat source movement is realized through the coordinate transformation of the global coordinates ( x , y , z ) and the local coordinates ( , , ): ; ; ; Among them, Trans is the corresponding translation transformation matrix.

[0013] Preferably, the heat source subroutine code is a FORTRAN subroutine for calculating the heat flux during the welding process. The specific process of the heat source subroutine is as follows: Step 7.1, program header and variable definition; Step 7.2, welding parameter definition and assignment; Step 7.3, numerical values and calculations related to the double ellipsoidal heat source; Step 7.4, calculate the heat flux density according to conditions; Step 7.5, end of the subroutine.

[0014] Advantages of the present invention: 1. Improve the efficiency and reliability of analysis step creation: By using the parameter-driven method to replace the traditional GUI for creating analysis steps, the complexity and low efficiency of the GUI method are avoided. Using this method simplifies the modeling process, improves the efficiency and automation level of analysis step creation, reduces human operation errors, enhances the reliability of modeling, and can better meet the simulation requirements of the additive manufacturing and remanufacturing processes of large components.

[0015] 2. Accurately simulate the gradual stacking process of weld beads and improve the model accuracy: Different from the traditional pre-placed weld bead method, the parameter-driven modeling method can gradually stack weld beads, considering the influence of the previously deposited weld beads on the subsequent weld beads (such as preheating and the accumulation of structural stress). By simulating the stacking process of weld beads layer by layer, the thermo-mechanical coupling effect in additive manufacturing can be more realistically reproduced, improving the accuracy of the finite element model, ensuring compliance with the actual engineering situation, and avoiding the problem of excessive model errors in the traditional method.

[0016] 3. Achieve automated processing and flexibly adjust and optimize the model: In finite element analysis, Python can automate the conventional analysis process, significantly improving the work efficiency and accuracy during the compilation of analysis steps and birth-death elements. The flexibility of Python code allows the operator to quickly adjust and optimize the model and test different algorithms. The integration ability of Python with traditional software (ABAQUS) enables the operator to combine the programming flexibility of Python and the professional algorithms of traditional software for complex simulations.

[0017] 4. Support the automated and intelligent management and control throughout the life cycle: Adopt a parameter-driven modeling method based on a straight-line path, which overcomes the limitations of traditional methods that cannot adapt to full-life cycle management. This method can cover the entire life cycle from design, manufacturing, service to remanufacturing, and adapt to the requirements of automated and intelligent production and control. Through automated and intelligent control, the processes of additive manufacturing and remanufacturing can be optimized in real time, improving production efficiency, reducing costs, and effectively reducing resource waste. Description of the Drawings

[0018] The present invention will be further described below in conjunction with the drawings and embodiments.

[0019] Figure 1 It is the overall flowchart of the present invention.

[0020] Figure 2 It is the case of applying boundary conditions of the present invention.

[0021] Figure 3 It is the case of applying loads of the present invention.

[0022] Figure 4 It is the case of the heat source subroutine of the present invention.

[0023] Figure 5 It is the stress distribution diagram of the present invention. Detailed Embodiments

[0024] The embodiments of the present invention will be further described below in conjunction with the drawings.

[0025] The preferred embodiments of the present invention will be described below in conjunction with the drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0026] Embodiment 1: As Figure 1 shown, a finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path is characterized by including the following steps: Step 1, geometric model construction: According to the actual situation of planar additive manufacturing and remanufacturing engineering, a geometric model including a planar welding plate and a semi-circular cross-section weld is established by drawing in a finite element software (preferably ABAQUS) or importing from other 3D modeling software. The length, width, thickness of the welding plate and the geometric dimensions of the weld are user-defined.

[0027] Step 2, material property setting: In the ABAQUS Property module, set the material physical property parameters that match the processes of planar additive manufacturing and remanufacturing, including general physical property parameters, mechanical parameters, and thermal property parameters, etc.

[0028] Step 3, Assemble components: Assemble the geometric model into a solid through the ABAQUS Assembly module.

[0029] Step 4, Mesh generation: According to the structural dimensions and calculation accuracy of the established model, perform mesh generation on it in the ABAQUS Mesh module, and select appropriate mesh strategies and element types based on the model's structural characteristics and the established analysis type to precisely control the mesh size and density.

[0030] Step 5, Set analysis steps: In the ABAQUS Step module, create a certain number of analysis steps according to the weld size and the number of element layers, set the solution parameters, and simulate the weld additive deposition process through element birth and death based on the number of analysis steps and the number of elements in the weld area.

[0031] Step 6, Load application and boundary conditions: According to the actual situation of planar additive manufacturing and remanufacturing engineering, apply loads to the established finite element model in the ABAQUS Interaction and Load modules and set the corresponding boundary conditions, where the boundary conditions include thermal boundary conditions and displacement boundary conditions, etc.

[0032] Step 7, Write and call the heat source subroutine: According to the characteristics of the welding heat source and process parameters, write the DFLUX user subroutine to define the heat source model and the heat source movement trajectory, and set to call the user subroutine for solution in the ABAQUS Job module.

[0033] Step 8, Result analysis and post-processing: After the calculation is completed, extract data results such as the temperature field, stress field, and strain field in the ABAQUS Visualization module for visual analysis, analyze the thermo-mechanical coupling process of planar additive manufacturing and remanufacturing, reveal the evolution laws of the temperature field and stress field, and optimize the linear additive manufacturing and remanufacturing processes based on the relevant results.

[0034] Furthermore, the establishment of the analysis steps in Step 5 can be achieved through GUI operations or by writing Python code. For the steps of defining multiple analysis steps according to the weld size and the number of element layers, first, enter the ABAQUS software interface, click the Model button, and successively open Model-Edit keywords-model-1 to enter the analysis step interface, and write the analysis steps through Python code. The following is the process of writing the analysis steps with Python code.

[0035] (1) "from abaqus import *": Import all content in the ABAQUS module; (2) "from abaqusConstants import *": Import all content in the ABAQUS constant module; (3)"from caeModules import *": Import all contents in the caeModules module; (4)"maxnum=, minnum=, cnum=": Define the maximum value, minimum value, and the number of layers of the weld elements according to the defined weld size and the number of element layers; "zcnum=(maxnum - minnum + 1) / cnum": The formula for calculating the number of analysis steps, obtained by calculating with the values given in (4); (5)"alltime": Define the total welding simulation time. "dt = alltime / zcnum": The formula for calculating the time step; (6)"mdb.models['Model-1'].CoupledTempDisplacementStep": Create a coupled temperature-displacement analysis step. "name='Step-1'": The step name is Step-1; "previous='Initial'": The previous step is the initial step; "timePeriod, maxNumInc, initialInc, minInc, maxInc, deltmx": They are the time period, the maximum number of increment steps, the initial increment step, the minimum increment step size, the maximum increment step size, and the time step size in sequence; (7)"for j in range(zcnum):": Loop through all integers from 0 to zcnum - 1. The loop is as follows "stepname1='Step-'+str(j + 1), stepnuma2='Step-'+str(j + 2)": Generate the current step name and the next step name, looping up to the maximum analysis step; (8)"mdb.models['Model-1'].CoupledTempDisplacementStep": Create a new coupled temperature-displacement analysis step; "name=stepnuma2": The step name is stepnuma2; "previous=stepname1": The previous step is stepname1; "timePeriod=dt, nlgeom, maxNumInc, initialInc, minInc, maxInc, deltmx": They are the time period, the geometric nonlinearity option, the maximum number of increment steps, the initial increment step, the minimum increment step size, the maximum increment step size in sequence; (9)After generating multiple analysis steps through a loop of Python code, add the compiled Python code to the ABAQUS text box to complete the editing of the analysis steps; Furthermore, the realization of the element birth and death in the fourth step during the weld additive deposition process is achieved by writing Python code using the "Model change" instruction.

[0036] The steps for editing the birth and death elements using Python code are as follows: (1) Initialize variables: ① "maxnum=, minnum=, cnum=": Define the maximum value, minimum value, and the number of elements per layer of the weld elements according to the defined weld size and the number of element layers.

[0037] ② "zcnum=(maxnum - minnum + 1) / cnum": Calculate the number of weld element layers according to the above formula.

[0038] ③ "positionnum=": Set the insertion position.

[0039] (2) Set the model keyword block: ① "mdb.models['Model-1'].keywordBlock.setValues(edited=0)": Set the keyword block of the model'model-1' to the unedited state.

[0040] ② "import job": Import the job model block.

[0041] "mdb.models['Model1'].keywordBlock.synchVersions(storeNodesAndElements=False)": Synchronize the keyword block version of the model'model-1' without storing nodes and elements.

[0042] "mdb.models['Model1'].keywordBlock.insert(positionnum, """*MODELCHANGE,TYPE=ELEMENT,REMOVE Set-NAME""")": Insert an instruction at position positionnum to indicate removing the element set named Set-NAME. The element set name can be customized.

[0043] (3) Process data in a loop: ① "lab1=minnum": Initialize the label lab1 as minnum.

[0044] ② "for j in range(zcnum):": Loop through each group. The loop is as follows, "data = range(cnum)": Initialize the data range as cnum.

[0045] "for i in range(cnum):": Loop through each element in each group.

[0046] " data[i]=lab1+I": Assign a number to each element.

[0047] "initialstr = """*MODEL CHANGE,TYPE=ELEMENT,ADD"""": Initialize the string indicating adding elements.

[0048] "if i%4==3:": If it is the last one among every four elements, then loop as follows. "initialstr = initialstr+'model-1.'+str(data[i])+',\n'": Add the element number and line break.

[0049] "else": Otherwise.

[0050] "initialstr = initialstr+'model-1.'+str(data[i])+','": Add the element number.

[0051] "import job": Import the job module.

[0052] "mdb.models['Model1'].keywordBlock.synchVersions(storeNodesAndElements=False)": Synchronize the keyword block version of model'model-1' without storing nodes and elements.

[0053] "mdb.models['Model-1'].keywordBlock.insert(positionnum+9+j*9,initialstr)": Insert the instruction for adding elements at the specified position.

[0054] "lab1=lab1+cnum": Update the label lab1.

[0055] (4) Generation of birth and death elements: Through these codes, batch addition and removal operations of elements in model'model-1' are achieved. Adding the compiled python code to the ABAQUS text box can generate birth and death elements.

[0056] Furthermore, in the seventh step of writing and calling the heat source subroutine, the heat source can be selected as a surface heat source (preferably a Gaussian surface heat source) or a volume heat source (preferably a double ellipsoid heat source) according to the actual engineering situation. The movement of the heat source can be achieved through coordinate transformation of the global coordinates ( x , y , z ) and local coordinates ( , , ).

[0057] ; ; ; Among them, Trans is the corresponding translation transformation matrix.

[0058] The code of the heat source subroutine is a FORTRAN subroutine used to calculate the heat flux during welding. The description of the heat source subroutine is as follows: (1) Program header and variable definition: ① "SUBROUTINE DFLUX": A subroutine of DFLUX that can accept multiple parameters; "FLUX,SOL,JSTEP,JINC,TIME,NOEL,NPT,COORDS,JLTYP" includes multiple parameters such as heat flux density (FLUX), solution (SOL), time step (JSTEP), etc.

[0059] ② "INCLUDE “ABA_PARAM.INC”": Include an external file named ABA_PARAM.INC. The file defines relevant global variables or constants, and these variables or constants participate in subsequent calculations.

[0060] ③ "DIMENSION COORDS(3),FLUX(2),TIME(2)": Define three arrays. COORDS is a three-dimensional array, and FLUX and TIME are both two-dimensional arrays.

[0061] (2) Definition and assignment of welding parameters: ① Parameter definition and assignment: "wu, welding voltage; wi, welding current; effi, welding efficiency coefficient; q, effective arc thermal power W; v, welding speed m / s; q = wu * wi * effi; d = v * TIME(2)": The code comment of this subroutine defines the meanings of multiple variables, including welding voltage (wu), welding current (wi), welding efficiency coefficient (effi), effective arc thermal power (q), and welding speed (v), and assigns specific values to multiple variables. Some variables can be obtained through formula calculations.

[0062] ② Coordinate variable assignment: "x = COORDS(1), y = COORDS(2), z = COORDS(3)": Assign the three elements of the COORDS array to the x, y, and z variables respectively, representing spatial coordinates. These three variables represent the spatial coordinates of any point during the welding process.

[0063] (3)Numerical values and calculations related to the double-ellipsoid heat source: ① Definition and initialization of double-ellipsoid parameters: "Starting from the coordinates x0, y0, z0, moving along the z direction, x0 = ; y0 = ; z0 = ": Define the starting coordinates of the double-ellipsoid heat source movement 、 、 The moving direction, and the coordinate values are obtained from the defined model.

[0064] "a1, a2, b, c are the shape parameters of the double-ellipsoid, a1 = ; a2 = ; b = ; c =, f1 is the heat source distribution coefficient, f1 = 1.0, PI = 3.1415926": Define the shape parameters of the double-ellipsoid heat source 、 、 b, c And the heat source distribution coefficient 。

[0065] "heat1 = 6.0 * sqrt(3.0) * q / (a1 * b * c * PI * sqrt(PI)) * f1 heat2 = 6.0 * sqrt(3.0) * q / (a2 * b * c * PI * sqrt(PI)) * (2.0 - f1) ": Calculate two heat-related parameters heat1 and heat2 according to the above-defined parameters.

[0066] ② Calculation of the shape function: "shape1 = exp(-3.0 * (x - x0 - d) ** 2 / (a1) ** 2 - 3.0 * (y - y0) ** 2 / b ** 2 $-3.0 * (z - z0) ** 2 / c ** 2) shape2 = exp(-3.0 * (x - x0 - d) ** 2 / (a2) ** 2 - 3.0 * (y - y0) ** 2 / b ** 2 - 3.0 * (z - z0) ** 2 / c ** 2) ": Calculate the shapes of the double-ellipsoid heat sources shape1 and shape2 according to a specific mathematical formula. $-3.0*(z - z0)**2 / c**2)$ ": Calculate the heat flux density according to the conditions:

[0067] (4) Calculate the heat flux density according to the conditions: ① Calculate FLUX(1) based on coordinate conditions: "JLTYP = 1, indicating a volumetric heat source, JLTYP = 1 IF(x.LE.(x0 + d)) THEN FLUX(1) = heat1 * shape1 ": Define JLTYP = 1 (volumetric heat source), and select different formulas to calculate FLUX(1) according to the transformation of the heat source coordinate values.

[0068] ② Adjust the heat flux density based on time: "IF(x.LE.(x0 + d)) THEN FLUX(1) = heat1 * shape1 ELSE FLUX(1) = heat2 * shape2 ENDIF IF (TIME(2).GE.6.25) THEN FLUX(1) = 0 ": Determine FLUX(1) finally by achieving a certain conditional relationship between the two parameters TIME(2) and FLUX(1).

[0069] (5) "ENDIF RETURN END ": The subroutine ends.

[0070] Example 2: The embodiment of the present invention provides a finite element modeling method for planar additive manufacturing and remanufacturing based on a straight path, and the method includes the following steps: Initial model setting: Parameter-driven straight-line additive model and additive layer geometry creation: Import a cuboid planar welding plate with a length of 0.05 m, a width of 0.03 m, and a height of 0.01 m and a semi-circular cross-section weld with a radius of 0.021 m using 3D modeling software (such as SolidWorks, CATIA, Creo, etc.) or draw them in ABAQUS / CAE. The number of layers in the additive layer area is set to 50 layers, and each layer has 22 weld elements.

[0071] Material property setting: In the ABAQUS Property module, set the material physical property parameters that match the planar additive manufacturing and remanufacturing processes. The material properties include conductivity, density, elasticity, thermal expansion, latent heat, specific heat, etc. Specific material parameters are defined through the material library or can be calculated using JMatPro.

[0072] The double ellipsoid heat source model is adopted for the heat source model, where: (1) wu (welding voltage) is 22 (2) wi (welding current) is 196 (3) effi (welding efficiency coefficient) is 0.7 (4) Q (input power) is wu * wi * effi (5) Starting point coordinates ( are = 0.025, = 0, = 0.01 (6) Shape parameters of the double ellipsoid heat source , , b, c are = 0.002, = 0.006, b = 0.006, c = 0.004 (7) Heat source distribution coefficient is 1.0 Assembly of components: Assemble the geometric model into a solid through the ABAQUS Assembly module.

[0073] Mesh generation: According to the process characteristics and requirements, it can be mainly divided into the following regions (hexahedral meshes are used for all mesh types): (1) Additive region: The additive region is the area where materials are gradually added during the linear additive manufacturing and remanufacturing processes. In this region, the mesh needs to be finer to accurately capture the changes in physical quantities such as temperature gradients and stress-strain during the material deposition process.

[0074] (2) Manufactured region: The manufactured region represents the area where additive manufacturing or remanufacturing has been completed. Compared with the additive region, since the changes in physical quantities in this region are relatively gentle, the mesh should be relatively sparse.

[0075] (3) Transition region: The transition region represents the connection between the additive region and the manufactured region. The density of the mesh in this region needs to gradually transition to avoid computational instability or inaccurate results caused by sudden changes in mesh size.

[0076] (4) Heat affected zone: The heat affected zone represents the area where the heat source is used during the additive manufacturing process. The mesh in this area needs to be fine enough to accurately simulate the effect of the heat source on the material and the resulting thermal stress, thermal deformation and other effects.

[0077] Establishment of analysis steps: A certain number of analysis steps are created according to the weld size and the number of element layers, the solution parameters are set, and based on the number of analysis steps and the number of elements in the weld zone, the weld additive deposition process is simulated by element birth and death. Compile the analysis steps using python code as Figure 2 shown, and the parameters are set as follows.

[0078] "maxnum=1100, minnum=1, cnum=22": Define the maximum value of 1100, the minimum value of 1 and the number of weld layers of 22 for the weld elements according to the defined weld size and the number of element layers.

[0079] "alltime=6.25": Define the total welding simulation time as 6.25; "nlgeom=1, maxNumInc=10000, initialInc=0.1; minInc=dt*1e-15, maxInc=dt, deltmx=1500.0": Set the nonlinear geometry (nlgeom) to 1, set the maximum number of time increment steps to 10000 time cycles, set the initial increment step size to 0.1, set the minimum increment step size to dt*1e-15, and set the maximum increment step size to 1500.0.

[0080] Substitute the above parameters into the python code for compilation and input into the ABAQUS text box to generate the analysis steps. Analysis step case: The first part: from abaqus import * from abaqusConstants import * from caeModules import* maxnum=1100 minnum=1 cnum=22 zcnum=(maxnum-minnum+1) / cnum alltime=6.25 dt=altime / zcnum mdb.models['Model-1'].CoupledTempDisplacementStep(name='Step-1', previous=lnitial,timePeriod=1e-8,maxNumlnc=1500,initiallnc=1e-8, minlnc=1e-8,maxlnc=1e-8,deltmx=1000.0) for j in range(zcnum): stepname1='Step-'+str(j + 1) stepnuma2='Step-'+str(j + 2) mdb.models['Model-1'].CoupledTempDisplacementStep(name=stepnuma2, previous=stepname1,timePeriod=dt,nlgeom=1,maxNumlnc=10000,initiallnc=0.1, minlnc=dt*1e-15,maxlnc=dt,deltmx=1500.0); Element birth and death creation: The realization of element birth and death in the process of weld additive deposition is achieved by writing Python code using the "Model change" instruction. Compile the birth and death elements using Python code and set the parameters as follows: "maxnum=1000, minnum=1, cnum=22": Define the maximum value of the weld elements as 1000, the minimum value as 1, and the number of elements per layer of the weld as 22 according to the defined weld size and the number of element layers.

[0081] "zcnum=(maxnum - minnum + 1) / cnum": Calculate the number of element layers of the weld according to the above formula.

[0082] "mdb.models['Model1'].keywordBlock.insert(positionnum, "*MODELCHANGE,TYPE=ELEMENT,REMOVE Set-WZ")": Insert an instruction at position positionnum to indicate removing the element set named Set-WZ. The name of the element set can be customized.

[0083] Substitute the above parameters into the Python code for compilation and input into the ABAQUS text box to generate element birth and death.

[0084] Specific code for the element birth and death case: Second part maxnum = 1100 minnum = 1 cnum = 22 zcnum=(maxnum - minnum + 1) / cnum positionnum = 35 mdb.models['Model-1'].keywordBlock.setValues(edited = 0) importjob mdb.models['Model-1'].keywordBlock.synchVersions(storeNodesAndElements = False) mdb.models['Model-T'].keywordBlock.insert(positionnum, *MODELCHANGE, TYPE = ELEMENT, REMOVE Set-WZ**) lab1 = minnum for j in range(zcnum): data = range(cnum) for i in range(cnum): data[i]=lab1 + i initialstr = 'MODEL CHANGE,TYPE = ELEMENT,ADD for i in range(cnum): if i % 4 == 3: initialstr = initialstr + 'xly-1.'+str(data[i])+',\n' else initialstr = initialstr + 'xly-1.'+str(data[i])+',' importjob mdb.models['Model-1'].keywordBlock.synchVersions(storeNodesAndElements = False) mdb.models['Model-1'].keywordBlock.insert(positionnum+9+j*9,initialstr) lab1 = lab1 + cnum Load application and boundary conditions: According to the actual situation of linear additive manufacturing and remanufacturing engineering, loads are applied to the established finite element model in the ABAQUS Interaction and Load modules, and corresponding boundary conditions are set, such as Figure 2 、 Figure 3 shown

[0085] Writing and calling the heat source subroutine: According to the characteristics of the welding heat source and process parameters, a DFLUX user subroutine is written to define the heat source model and the heat source movement trajectory, and the user subroutine is set to be called for solution in the ABAQUS Job module. FORTRAN code is written according to the following parameters to obtain the heat source subroutine, and the heat source subroutine is as Figure 4 shown

[0086] wu (welding voltage); wi (welding current); effi (welding efficiency coefficient); Q (input power); Starting point coordinates( ; Shape parameters of the double ellipsoidal heat source 、 、b, c; Heat source distribution coefficient 。

[0087] Result analysis and post-processing: After the calculation is completed, in the ABAQUS Visualization module, data results such as the temperature field, stress field, and strain field are extracted according to user-defined requirements for visualization analysis, the thermo-mechanical coupling process of planar additive manufacturing and remanufacturing is analyzed, the evolution laws of the temperature field and stress field are revealed, and the planar additive manufacturing and remanufacturing processes are optimized based on the relevant results

[0088] As Figure 5 shown is the stress distribution during the processing of this model. The von Mises stress (SMises) is used as the evaluation criterion in the figure. The color bar shows the stress range, from blue (low stress) to red (high stress). There is an obvious stress concentration area in the model, located on one side of the model, showing a rainbow gradient change, indicating that the stress value in this area is relatively high. The coordinate axis directions are shown in the lower left corner of the figure

[0089] Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical idea of this invention, and all of them are within the protection scope of this invention. Matters not covered by this invention are common general knowledge to those skilled in the art.

Claims

1. A finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path, characterized in that It includes the following steps: Step 1, geometric model construction: According to the actual engineering requirements of planar additive manufacturing, establish the required geometric model by using finite element software; Step 2, material property setting: Set the material physical property parameters for the geometric model established in Step 1 in the finite element software; Step 3, assembling components: Assemble the geometric model with set parameters in Step 2 into a solid model in the finite element software; Step 4, mesh generation: Use the corresponding module in the finite element software to generate meshes for the solid model established in Step 3; Step 5, setting analysis steps: Establish a certain number of analysis steps for the solid model with completed mesh generation; Step 6, applying loads and setting boundary conditions: Apply loads to the finite element model established in Step 5 and set the corresponding boundary conditions; Step 7, writing and calling the heat source subroutine: According to the characteristics of the welding heat source and process parameters, write a user subroutine and solve it by calling the user subroutine; Step 8, result analysis and post-processing: Conduct visual analysis on the calculation results in Step 7 and optimize the linear additive manufacturing and remanufacturing process based on the calculation results.

2. The finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path according to claim 1, wherein The specific method of Step 1 is as follows: According to the actual situation of planar additive manufacturing and remanufacturing engineering, establish a geometric model including a planar welding plate and a semi-circular cross-section weld by drawing in the finite element software ABAQUS or importing from other 3D modeling software. The length, width, thickness of the welding plate and the geometric dimensions of the weld are user-defined.

3. The finite element modeling method for planar additive manufacturing and remanufacturing based on a straight line path according to claim 1, wherein The specific method of Step 2 is as follows: Set the material physical property parameters matching the planar additive manufacturing and remanufacturing process in the ABAQUS Property module. The material physical property parameters include general physical property parameters, mechanical parameters and thermal property parameters; The specific method of Step 3 is as follows: Assemble the geometric model into a solid through the ABAQUS Assembly module.

4. The finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path according to claim 1, characterized in that The specific method of Step 4 is as follows: According to the structural dimensions and calculation accuracy of the established solid model, generate meshes for it in the ABAQUS Mesh module, and select appropriate mesh strategies and element types according to the structural characteristics of the solid model and the established analysis type to precisely control the mesh size and density; The specific method of Step 5 is as follows: In the ABAQUS Step module, create a certain number of analysis steps according to the weld size and the number of element layers, set the solution parameters, and simulate the weld additive deposition process through element birth and death based on the number of analysis steps and the number of elements in the weld area.

5. The finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path according to claim 1, wherein The specific method of Step 6 is as follows: According to the actual situation of planar additive manufacturing and remanufacturing engineering, apply loads to the established finite element model in the ABAQUS Interaction and Load modules and set the corresponding boundary conditions, where the boundary conditions include thermal boundary conditions and displacement boundary conditions; The specific method of Step 7 is as follows: According to the characteristics of the welding heat source and process parameters, write the DFLUX user subroutine to define the heat source model and the heat source movement trajectory, and set to call the user subroutine for solution in the ABAQUS Job module.

6. The finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path according to claim 1, characterized in that, The specific method of Step 8 is as follows: After the calculation in Step 7 is completed, extract the data results of the temperature field, stress field, and strain field in the ABAQUS Visualization module for visualization analysis, analyze the thermo-mechanical coupling process of planar additive manufacturing and remanufacturing, reveal the evolution laws of the temperature field and stress field, and optimize the linear additive manufacturing and remanufacturing processes based on the relevant results.

7. A finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path according to claim 4, characterized in that The realization of the weld additive deposition process in Step 4 by element birth and death is achieved by writing Python code using the "Model change" instruction. The establishment of the analysis steps in Step 5 is achieved by GUI operation or by writing Python code. According to the weld size and element layer, define multiple analysis steps. First, enter the ABAQUS software interface, click the Model button, and sequentially open Model-Edit keywords-model-1 to enter the analysis step interface, and write the analysis steps through Python code.

8. A finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path according to claim 7, characterized in that, The specific steps for implementing the Python code using the "Model change" instruction in Step 4 include: Step 4.1, initialize variables; Step 4.2, set the model keyword block; Step 4.3, loop through the data; Step 4.4, generate birth and death elements.

9. A finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path according to claim 7, characterized in that, In Step 7 of writing and calling the heat source subroutine, the heat source is selected as a surface heat source or a volume heat source according to the actual engineering situation. The movement of the heat source is realized through the coordinate transformation of the global coordinates ( x , y , z ) and the local coordinates ( , , ): ； ； ； Among them, Trans is the corresponding translation transformation matrix.

10. A finite element modeling method for planar additive manufacturing and remanufacturing based on a straight-line path according to claim 9, characterized in that The heat source subroutine code is a FORTRAN subroutine used to calculate the heat flux during welding. The heat source subroutine specifically includes the following processes: Step 7.1, program header and variable definition; Step 7.2, define and assign welding parameters; Step 7.3, relevant values and calculations for the double ellipsoidal heat source; Step 7.4, calculate the heat flux density according to the conditions; Step 7.5, end of the subroutine.

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