Additive manufacturing process simulation method and system and medium

Abstract

The invention discloses an additive manufacturing process simulation method and system and a medium, and the method comprises the following steps: S1, determining the material attribute and geometry of a to-be-processed workpiece, and determining a processing device and a processing process according to the material attribute and geometry of the to-be-processed workpiece; s2, processing equipment, a processing technology and an inherent strain value under the material attribute of the workpiece to be processed are determined; s3, the simulation model is calibrated through stress-strain analysis of the inherent strain verification piece; the calibrated simulation model is used for analyzing the stress-strain performance of the workpiece to be machined; and optimizing the basic parameters of the to-be-processed workpiece according to the stress-strain performance of the to-be-processed workpiece. According to the additive manufacturing process simulation method and system and the medium, the additive manufacturing process simulation analysis tool is used for conducting simulation analysis on the selective laser melting machining process of actual parts, guidance and reference are provided for product machining scheme design, possible risks are forecasted, and trial and error cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of additive manufacturing process simulation, and in particular to an additive manufacturing process simulation method, system and medium. Background Art

[0002] In manufacturing technology, laser selective melting technology has the characteristics of highly flexible processing and has high application value in the preparation of some complex structures and parts that are difficult to process with traditional processes. However, during the laser selective melting forming process, due to the rapid heating of a specific area of ​​the powder bed by the laser beam and the rapid cooling of the area, it is inevitable that the thermal stress distribution in the processed component will be significantly unbalanced, which may cause the part to warp, deform, or even crack.

[0003] At present, the problem faced by the field of additive manufacturing is that companies try to improve products by improving processes and adjusting parameters during the manufacturing process, and in the actual project implementation process, they consume a lot of raw materials and time costs for blind trial and error. Due to lack of experience, reliance on trial and error, and huge material cost investment, the economic benefits of enterprises are seriously affected. Summary of the invention

[0004] The purpose of the present invention is to provide an additive manufacturing process simulation method, system and medium, and to predict possible risks and reduce trial and error costs.

[0005] The present invention provides an additive manufacturing process simulation method, system and medium, comprising the following steps: S1, determining the material properties and geometry of a workpiece to be processed, and determining a processing device and a processing technology according to the material properties and geometry of the workpiece to be processed; S2, determining the inherent strain value under the processing equipment, processing technology and material properties of the workpiece to be processed; S3. Calibrate the simulation model through stress-strain analysis of the inherent strain calibration piece; Analyze the stress-strain properties of the workpiece to be machined using the calibrated simulation model; The basic parameters of the workpiece to be processed are optimized according to the stress-strain properties of the workpiece to be processed.

[0006] Preferably, in step S1, a geometric model of the workpiece to be processed is loaded, and a support structure of the workpiece to be processed is added; the size of the substrate is determined according to the geometry of the workpiece to be processed, and the thickness of the substrate is obtained.

[0007] Preferably, in step S1, the thickness of the substrate is not less than 40 mm.

[0008] Preferably, in step S2, the surface mesh model of the workpiece to be processed is determined according to the inherent strain value; a volume mesh model is created to obtain the volume fraction of the volume mesh division; the size of the volume mesh in the volume mesh model is adjusted according to the obtained volume fraction; the determined volume mesh model is used to obtain a simulation model of the workpiece to be processed; the simulated model of the workpiece to be processed is obtained, and the surface deviation between the workpiece to be processed and the initially input workpiece to be processed is obtained; the inherent strain value is obtained according to the determined processing equipment and processing technology, and the inherent strain verification part is produced.

[0009] Preferably, in step S2, the volume fraction meets the simulation accuracy requirement.

[0010] Preferably, a system for implementing the additive manufacturing process simulation method as described in any one of claims 1-5.

[0011] Preferably, it includes: a first module for obtaining the performance index requirements of the substrate; a second module, based on the first module, for selecting the material characteristics of the substrate and determining a first design scheme; a third module, for obtaining the substrate engineering schematic diagram in the additive manufacturing substrate design task, and constructing and optimizing the substrate structure model according to the first design scheme; a fourth module, for determining the substrate length and structural form according to the optimized substrate structure model, outputting the substrate pattern and development technical requirements, and completing the additive manufacturing substrate design.

[0012] Preferably, when the computer program is executed by a processor, the steps of the method for designing an additive manufacturing substrate as described in any one of claims 1 to 6 are implemented.

[0013] Therefore, the present invention adopts the above-mentioned additive manufacturing process simulation method, system and medium, and uses the additive manufacturing process simulation analysis tool to simulate and analyze the laser selective melting process of actual parts, which can provide guidance and reference for the design of product processing solutions to a certain extent, and predict possible risks, thereby reducing trial and error costs.

[0014] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of an overall method of an additive manufacturing process simulation method, system and medium of the present invention; Figure 2 A schematic diagram of volume fraction shearing of an additive manufacturing process simulation method, system and medium of the present invention; Figure 3 This is a schematic diagram of the overall system simulation completion of an additive manufacturing process simulation method, system and medium of the present invention. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0017] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0018] Embodiment 1 like Figure 1-3 As shown, the present invention provides an additive manufacturing process simulation method, system and medium, comprising the following steps: S1. Determine the material properties and geometry of the workpiece to be processed, and determine the processing equipment and processing technology according to the material properties and geometry of the workpiece to be processed; S2, determining the inherent strain value under the processing equipment, processing technology and material properties of the workpiece to be processed; S3. Calibrate the simulation model through stress-strain analysis of the inherent strain calibration piece; Analyze the stress-strain properties of the workpiece to be machined using the calibrated simulation model; According to the stress-strain performance of the workpiece to be processed, the basic parameters of the workpiece to be processed are optimized. The geometry of the workpiece to be processed is smaller than the boundary of the substrate. The basic parameters include material influencing factors, including deformation of the substrate and substrate material. The processing procedures are determined according to the workpiece, and deformation analysis: shape and surface deviation rate. The processing procedures include printing stage, separation stage of the workpiece and substrate, support removal stage and heat treatment stage. The geometric component structure of the workpiece is imported, the support structure is created, the substrate parameters are set, the material parameters of the workpiece are set, the laser parameters of the processing procedure are set to divide the grid, the grid parameters are adjusted, and analysis and calculation are performed. The volume fraction of the grid is calculated = geometric body / body unit, and the characterization of the workpiece is calculated.

[0019] When the inherent strain test piece is produced, the energy generated by the laser acts on the metal powder, causing the powder to melt. In the process of temperature drop, the metal material solidifies and shrinks, generating residual stress and causing stress accumulation. Among them, thermal strain, plastic strain, and phase change strain are detected. Elastic strain is not included.

[0020] Different from the accumulation of thermal processes in complex local melting areas, the inherent strain calibration part of this application generates residual stress and inherent strain of deformation inside the structure after a thermal cycle process. The thermal cycle process is not investigated, and an initial strain equal to the inherent strain is applied to the structure, and the deformation of the entire complex structure is solved by elastic finite element. Compared with the thermal elastic-plastic finite element method to solve the stress and strain in the entire thermal processing process, the amount of calculation in the analysis process and the analysis speed of the computer are reduced, which is more suitable for a wide range of applications.

[0021] The inherent strain value includes the definitions of the three directions of X, Y, and Z, which are ε xx, ε yy , ε zz .

[0022] The calculation method of the inherent strain value is the estimation method or the test calibration method. The steps of calibrating the inherent strain value estimation method are as follows: Determine the material properties of the workpiece to be processed and the parameters of the equipment; the parameters of the equipment include laser beam width, laser power, scanning rate, and efficiency.

[0023] The test calibration method steps are as follows: Determine the material properties of the workpiece to be processed and the parameters of the equipment; according to the printed inherent strain calibration piece, cut it in the Z direction and measure the deformation value of its fixed point in the Z direction; The fixed point deformation value is measured and recorded by three standard devices, and the inherent strain fitting calculation is performed using the obtained Z-direction deformation value, and the inherent strain value ε is obtained by fitting iteration. xx , ε yy , ε zz .

[0024] Analyze the deformation of the substrate and the rigid displacement of the workpiece to be processed, design the substrate sample, and correct the Z-direction deviation of the substrate deformation according to the deformation amount calculated by the substrate sample. After obtaining the Z-direction deviation of the substrate deformation, the accuracy comparison of the layout of the workpiece to be processed is analyzed, and the degree data is further corrected; the inherent strain calibration is used to locate the position of the workpiece; the first workpiece is translated 10mm in the X direction and 10mm in the -Y direction; the second workpiece is rotated 90° in the positive direction of the Z axis; The first workpiece and the second workpiece are translated by 10 mm in the -X direction and 10 mm in the Y direction, respectively, and the initial inherent strain value is set for the determined measuring point on the workpiece; a body mesh is created for the workpiece, and the deformation deviation in each direction of the workpiece and the deflection curve of the expected value are analyzed after adjusting the overall mesh size to determine the inherent strain value; the determined inherent strain value is simulated and analyzed, and the body mesh model is a hexahedron; the relationship between the surface mesh parameters and the substrate under the workpiece to be processed, and the deformation parameters of the substrate are adjusted.

[0025] The inherent strain method originally refers to the sum of the compressive strain generated by the temperature rise in the welding process and the tensile plastic strain generated by the temperature drop. The metal additive manufacturing process is consistent with the basic principle of the welding process. In the metal additive manufacturing process, the energy generated by the laser acts on the metal powder, causing the powder to melt. In the process of temperature drop, the metal material solidifies and shrinks, generating residual stress, causing stress accumulation, and finally deforming. Intrinsic strain includes thermal strain, plastic strain, and phase change strain, which includes all strains except elastic strain. The inherent strain theory is introduced into the metal additive manufacturing process to simplify and replace the complex thermal process accumulation of the local melting area. The idea is to generate residual stress and deformation inherent strain inside the structure after a thermal cycle process, without investigating the thermal cycle process, and apply an initial strain equal to the inherent strain in the structure, and solve the deformation of the entire complex structure through elastic finite element. Compared with the thermoelastic-plastic finite element method to solve the stress and strain in the entire thermal processing process, this method greatly reduces the calculation amount of the analysis process and the analysis speed of the computer, and is more suitable for wide application in the engineering field.

[0026] Collect inherent strain values; The inherent strain values ​​in the three directions of XYZ are defined as ε xx , ε yy , ε zz . ; Obtain the inherent strain value by estimation method or test calibration method; Intrinsic strain is equivalent to the mechanical load that reflects the material properties and process parameters. Different materials and different process parameters require different inherent strain values. The inherent strain value can be calibrated through experiments or estimated based on the printing process parameters. The estimation method is to enter material properties and machine parameters in the Build parameters module in Simufact Additive, including laser beam width, laser power, scanning rate, and efficiency to estimate the inherent strain value. After clicking Calculate estimate, the inherent strain value is automatically updated.

[0027] The experimental calibration method is to record the application status of equipment and powder material parameters before printing. After the calibration sample is printed, the cantilever comb sample is linearly cut at a height of 2.9mm from the substrate surface with a cutting depth of 60mm, and the deformation value of the fixed point in the Z direction is measured. After the linear cutting is completed, the deformation value of the fixed point is measured and collected and recorded by using three standard equipment, and the inherent strain fitting calculation is performed using the measured Z-direction deformation value. The inherent strain values ​​EXX, EYY, and EZZ obtained by the fitting iteration are saved in the calculation database for later simulation analysis of specific parts.

[0028] In view of the deformation of the substrate during the analysis process and the rigid body displacement problem caused by the parts, a substrate deformation calibration specimen is designed. Through the printing and deformation measurement of the substrate deformation calibration specimens of large and small equipment, the Z-direction deviation of the substrate deformation in the calculation is corrected. After the calibration test is completed, the calibration test data is corrected and further refined through the trial analysis and accuracy comparison of existing parts.

[0029] Analyze and calibrate inherent strain values; Create a new project and select the simulation type Calibration; The system default process is "Building" and "Cuting" Import the geometry model; After selecting the Calibration type, the system will automatically call a template containing the cantilever geometry model and cutting information. You can also import a custom geometry model.

[0030] Calibrate the two cantilever structures; The number, position and direction of the cantilever structures should be the same as in the experimental process.

[0031] Position the cantilever structure; select "Positioning" on the part Positioning and orienting cantilever structures; Click on the first cantilever to translate it in the +X direction and in the -Y direction; select the second cantilever; change to Rotate mode and rotate the geometry 90° along the positive Z axis; change to Bounding Box Alignment mode and finally return to Translate mode to translate the geometry in the -X direction and in the +Y direction.

[0032] Select powder material; Set build properties and parameters; During the calibration process, each sample needs to have its measurement points, which track the deformation after cutting the sample. Hover the mouse over "Manufacturing&optinization" and double-click to open the build properties. As you can see, only the predefined cantilever beams have the coordinates of the measurement points, while other cantilever beams added manually need to manually define their coordinate positions. Set the Build parameters and click the "Estimation" button to set the initial inherent strain value.

[0033] Create a volume mesh; click the "Analysis" component and double-click "Voxelmesh" to create a volume mesh. You can adjust the size of the volume mesh by yourself. After the volume mesh is created, start the simulation.

[0034] Save the calibrated inherent strain data into the library; Click the "Rusult" component and open "Calibrationresults". "Resultgraph" shows the deflection curve of the cantilever beam deformation deviation and expected value in each direction. In order to facilitate subsequent simulation, the inherent strain results can be saved in the library for easy retrieval.

[0035] Recall the calibrated intrinsic strain data; Click the "Manufacturing&optimization" window, double-click "Build", call the named and saved inherent strain value from the library, and perform simulation calculations.

[0036] Simulation implementation process: Taking an aluminum alloy aircraft component as the object, the additive manufacturing process is simulated and its deformation is evaluated.

[0037] Create a new project: Run Simufact, Additive and select "Newproject".

[0038] Use the default settings, select the save location and define the process and analysis type.

[0039] Import component geometry: Click the "Machine" component box in the toolbar, double-click "Parts" and select "Import" to import the geometry to be calculated. The geometry formats supported by the software are shown below. In the pop-up dialog box, you can adjust the surface mesh parameters yourself. In this example, import according to the default parameters.

[0040] Import and position the geometry. Note that the geometry cannot exceed the boundaries of the substrate.

[0041] Create supports or import other support structures that have already been built.

[0042] Select part material: Double-click "Material" and select "Import" and select ALSi10Mg-powder to confirm.

[0043] Consider substrate deformation: If you want to consider substrate deformation, you need to enter the properties of the substrate and check the "Considerbaseplatedeformation" option, select the substrate material and confirm.

[0044] Define the "Build" properties: Click the "Manufacturing" component box in the toolbar and double-click to open the Build item, select the preset AlSi10Mg-200W from the library (the inherent strain value has been calibrated and verified), or save the inherent strain value that you have calibrated and verified and call it.

[0045] Create a surface mesh: Click the "Analysis" component box, click "surfacemesh", right-click on the component surface, select mesh visibility to display the surface mesh model view, and make sure the mesh is not too coarse.

[0046] Create a volume mesh: Double-click "Voxelmesh" in the "Analysis" component box in the toolbar to open the mesh properties. You can change the mesh division parameters to make the mesh (hexahedral elements) fine enough.

[0047] Check the quality of the volume mesh: After the volume meshing is completed, you can check the quality of the volume meshing by the volume fraction. The volume fraction describes how much of the volume unit is actually filled by the geometry. The larger the volume fraction, the better the quality of the mesh unit. The size of the volume fraction can be judged by the mesh color. Double-click the voxel grid again to activate "Show Volume Fraction".

[0048] A cutaway view of the model's Volume Fraction displayed using the Cut function. If the Volume Fraction within the volume mesh is completely blue, this means the volume fraction is zero and the size of the volume mesh should be reduced.

[0049] Activate option: Make sure the Parallelization option in the solver properties is activated.

[0050] Simulation run: Before the simulation starts, all settings need to be completed, that is, the indicator light below the Component, Build and Analysis windows turns green, indicating that the settings are completed.

[0051] Simulation completed.

[0052] The system includes Process, Components, Manufacturing, Analysis and Results; Process: includes processing steps, including printing stage, separation of parts and substrate, support removal stage, heat treatment stage, etc.; Components: can import related geometric components, generate or import supports, set substrate parameters, set component materials, etc.; Manufacturing: set build properties, laser parameters, etc.; Analysis: divide the grid, adjust grid parameters, and perform analysis and calculation; Results: characterize the analysis results (stress and deformation, etc.).

[0053] Therefore, the present invention adopts the above-mentioned additive manufacturing process simulation method, system and medium, and predicts possible risks, reduces trial and error costs, and achieves one-time printing success.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for simulating an additive manufacturing process, characterized in that: The following steps are involved: S1. Determine the material properties and geometry of the workpiece to be processed, and determine the processing equipment and processing technology according to the material properties and geometry of the workpiece to be processed; S2, determining the inherent strain value under the processing equipment, processing technology and material properties of the workpiece to be processed; S3. Calibrate the simulation model by stress-strain analysis of the inherent strain calibration piece; use the calibrated simulation model to analyze the stress-strain performance of the workpiece to be processed; and optimize the basic parameters of the workpiece to be processed based on the stress-strain performance of the workpiece to be processed.

2. The additive manufacturing process simulation method, system and medium according to claim 1, characterized in that: In step S1, a geometric model of a workpiece to be processed is loaded, and a support structure of the workpiece to be processed is added; a substrate size is determined according to the geometry of the workpiece to be processed, and a thickness of the substrate is obtained.

3. The additive manufacturing process simulation method, system and medium according to claim 2, characterized in that: In step S1 , the thickness of the substrate is not less than 40 mm.

4. The additive manufacturing process simulation method, system and medium according to claim 1, characterized in that: In step S2, the surface mesh model of the workpiece to be processed is determined according to the inherent strain value; a volume mesh model is created to obtain the volume fraction of the volume mesh division; the size of the volume mesh in the volume mesh model is adjusted according to the obtained volume fraction; the determined volume mesh model is used to obtain a simulation model of the workpiece to be processed; the simulated model of the workpiece to be processed is obtained, and the surface deviation between the workpiece to be processed and the initially input workpiece to be processed is obtained; the inherent strain value is obtained according to the determined processing equipment and processing technology, and the inherent strain verification part is produced.

5. The additive manufacturing process simulation method, system and medium according to claim 4, characterized in that: In step S2, the volume fraction meets the simulation accuracy requirement.

6. A system for implementing the additive manufacturing process simulation method according to any one of claims 1 to 5.

7. A system for designing an additive manufacturing substrate, characterized in that: include: The first module is used to obtain the performance index requirements of the substrate; The second module is based on the first module and is used to select the material characteristics of the substrate and determine the first design scheme; The third module is to obtain the engineering schematic diagram of the substrate in the additive manufacturing substrate design task, and to construct and optimize the substrate structure model according to the first design scheme; The fourth module determines the length and structural form of the substrate according to the optimized substrate structure model, outputs the substrate pattern and development technical requirements, and completes the additive manufacturing substrate design.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for designing an additive manufacturing substrate as described in any one of claims 1 to 6 are implemented.

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