Stress simulation variable layer thickness additive manufacturing method, device and equipment and medium

Abstract

The invention relates to a variable-layer-thickness additive manufacturing method, device and equipment for stress simulation and a medium. The method comprises the steps that a structure database is determined according to residual stress sensitivity and easy-deformation geometrical characteristics; performing finite element simulation on the target component according to the structure database to obtain an additive manufacturing stress-strain nephogram under different layer thickness strategies; determining the residual stress strain of the target component according to the stress strain cloud picture, and determining the variable layer thickness strategy design according to the residual stress strain and the geometric feature structure of the target component; and according to the variable-layer-thickness strategy design, variable-layer-thickness additive manufacturing process data are determined, and metal additive manufacturing forming verification is adopted for the variable-layer-thickness additive manufacturing process data. The method has the beneficial effect that the material forming quality and the mechanical property of variable-layer-thickness additive manufacturing are improved.

Description

Technical Field

[0001] This invention belongs to the field of metal additive manufacturing technology, specifically relating to a method, apparatus, equipment and medium for stress simulation in variable layer thickness additive manufacturing. Background Technology

[0002] In recent years, various technologies in the field of metal additive manufacturing have developed rapidly. For example, laser / electron beam powder bed melting and directional energy deposition processes, with their high degree of design freedom and near-net-shape forming capabilities, have been widely used in the forming of complex structures of various alloy materials, especially in precision fields such as lightweight components for aerospace and customized medical implants.

[0003] However, some alloy materials, such as stainless steel, have high solidification shrinkage rates, resulting in significant shrinkage of parts. During the rapid solidification process in additive manufacturing, large temperature gradients can easily lead to the accumulation of residual stress, causing severe dimensional deformation and a significant decrease in forming quality. Furthermore, conventional additive manufacturing processes have low printing efficiency, requiring considerable time for layer-by-layer printing, thus increasing time costs. In addition, for some complex geometric structures (such as thin-walled conical cylinders and process bosses), additive manufacturing with fixed layer thickness is prone to stress concentration in these areas, hindering its large-scale industrial production applications. Therefore, reducing residual stress in complex geometric components and improving their forming quality and mechanical properties have become critical issues that urgently need to be addressed in the field of metal additive manufacturing. Summary of the Invention

[0004] The main objective of this invention is to propose a method, apparatus, equipment, and medium for variable layer thickness additive manufacturing based on stress simulation, which improves the material forming quality and mechanical properties of variable layer thickness additive manufacturing.

[0005] One aspect of the present invention provides a variable layer thickness additive manufacturing method based on stress simulation, comprising: The structural database is determined based on residual stress sensitivity and easily deformable geometric characteristics; Finite element simulation of the target component was performed based on the structural database to obtain stress-strain cloud maps of additive manufacturing under different layer thickness strategies. The residual stress and strain of the target component are determined based on the stress-strain cloud map. Based on the residual stress and strain and the geometric characteristics of the target component, the variable layer thickness strategy design is determined. Based on the variable layer thickness strategy, the variable layer thickness additive manufacturing process data is determined, and the variable layer thickness additive manufacturing process data is verified by metal additive manufacturing forming.

[0006] According to the stress simulation of the variable layer thickness additive manufacturing method, typical residual stress sensitive structures include thin-walled conical cylinder structures, thin-walled annular structures, process boss structures, long cantilever beam structures, honeycomb lattice structures, and suspended curved surface flow channel structures.

[0007] According to the stress simulation-based variable-thickness additive manufacturing method, finite element simulation of the target component is performed based on a structural database to obtain additive manufacturing stress-strain contour maps for different layer thickness strategies, including: Based on the structural database, a three-dimensional model of the target component with typical high residual stress and easily deformable geometric features is determined; The 3D model was meshed with finite element meshes, and the laser energy input was represented by a Gaussian distributed heat source. The additive manufacturing process was simulated based on the constraint conditions and thermal convection boundary conditions. Elastic-plastic thermal stress simulation and nonlinear deformation simulation analysis were performed on the additive manufacturing process to obtain stress-strain cloud maps of additive manufacturing under different layer thickness strategies.

[0008] According to the stress simulation-based variable layer thickness additive manufacturing method, the residual stress and strain of the target component are determined based on the stress-strain contour plot. Based on the residual stress and strain and the geometric features of the target component, a variable layer thickness strategy design is determined, including: Finite element simulations of various fixed and variable layer thickness strategies are performed based on residual stress, strain, and the geometric characteristics of the target component to obtain residual stress and deformation. The design of the variable layer thickness strategy is then determined based on the residual stress and deformation.

[0009] According to the stress simulation-based variable layer thickness additive manufacturing method, the metal additive manufacturing adopts a laser powder bed melting process.

[0010] According to the stress simulation-based variable layer thickness additive manufacturing method, the forming verification includes: Based on the variable layer thickness strategy and orthogonal process, determine the additive manufacturing process window that is compatible with the layer thickness; Based on the preset variable layer thickness process parameters, a corresponding slice model file is generated, and the slice model file is subjected to metal additive manufacturing processing for the sample and target component. Microstructure analysis and mechanical property testing were performed on the formed specimens, and roughness and residual stress were measured on the target components.

[0011] According to the stress simulation-based variable layer thickness additive manufacturing method, the additive manufacturing process window is a laser powder bed melting process parameter adapted to the layer thickness parameters involved in the variable layer thickness. The laser powder bed melting process parameter includes laser power, scanning speed, and scanning spacing.

[0012] Another aspect of the present invention provides a variable layer thickness additive manufacturing apparatus for stress simulation, comprising: The first module is used to determine the structural database based on residual stress-sensitive and easily deformable geometric features; The second module is used to perform finite element simulation of the target component based on the structural database to obtain additive manufacturing stress-strain cloud maps for different layer thickness strategies. The third module is used to determine the residual stress and strain of the target component based on the stress-strain cloud map, and to determine the variable layer thickness strategy design based on the residual stress and strain and the geometric characteristics of the target component. The fourth module is used to design and determine the variable layer thickness additive manufacturing process data based on the variable layer thickness strategy, and to verify the variable layer thickness additive manufacturing process data using metal additive manufacturing forming.

[0013] Another aspect of the present invention provides an electronic device, including a processor and a memory; The memory is used to store programs; The processor executes the program to implement the method as described above.

[0014] This invention also discloses a computer-readable storage medium storing a program that is executed by a processor to implement the stress simulation-based variable layer thickness additive manufacturing method.

[0015] The beneficial effects of this invention are as follows: by finite element simulation of the additive manufacturing process, residual stress-strain cloud maps under different layer thickness strategies are calculated, thereby obtaining an optimized variable layer thickness strategy, which improves forming efficiency and quality and enhances the mechanical properties of metal parts; based on printing examples that are prone to accumulating residual stress and large deformation, the variable layer thickness strategy is optimized for printing examples, and verified by laser powder bed melting forming, so as to achieve low residual stress and high performance fabrication of complex components. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the variable layer thickness additive manufacturing method for stress simulation according to an embodiment of the present invention.

[0017] Figure 2 These are stress cloud diagrams (before and after optimization) for three typical geometric feature structures with different layer thickness strategies in this embodiment of the invention. Figures (a) and (b) are stress cloud diagrams of the thin-walled conical cylinder structure before and after optimization, respectively. Figures (c) and (d) are stress cloud diagrams of the thin-walled ring structure before and after optimization, respectively. Figures (e) and (f) are stress cloud diagrams of the process boss before and after optimization, respectively.

[0018] Figure 3These are deformation cloud maps of three typical geometric feature structures under different layer thickness strategies (before and after optimization) according to embodiments of the present invention. Figures (a) and (b) are deformation cloud maps of the thin-walled conical cylinder structure before and after optimization, respectively; Figures (c) and (d) are deformation cloud maps of the thin-walled ring structure before and after optimization, respectively; and Figures (e) and (f) are deformation cloud maps of the process boss before and after optimization, respectively.

[0019] Figure 4 These are roughness reconstruction morphologies of three typical geometric feature structures under different layer thickness strategies (before and after optimization) according to embodiments of the present invention. Figures (a) and (b) show the roughness reconstruction morphologies of the thin-walled conical cylinder structure before and after optimization, respectively. Figures (c) and (d) show the roughness reconstruction morphologies of the thin-walled annular structure before and after optimization, respectively. Figures (e) and (f) show the roughness reconstruction morphologies of the process boss before and after optimization, respectively.

[0020] Figure 5 These are GND diagrams corresponding to the EBSD orientation diagrams under different layer thickness strategies (before and after optimization) for three typical geometric feature structures in this invention. Figures (a) and (b) are the GND diagrams of the thin-walled conical cylinder structure before and after optimization with a fixed layer thickness of 40 μm, respectively. Figures (c) and (d) are the GND diagrams of the thin-walled annular structure before and after optimization with a fixed layer thickness of 60 μm, respectively. Figures (e) and (f) are the GND diagrams of the process boss before and after optimization with a fixed layer thickness of 40-60 μm, respectively.

[0021] Figure 6 These are the stress-strain curves of room temperature mechanical properties tested under different layer thickness strategies (before and after optimization) for three typical geometric features of the present invention. Figure 6 (a) shows the stress-strain curves of the thin-walled conical cylinder structure before and after optimization at room temperature with a fixed layer thickness of 40 μm. Figure 6 (b) shows the stress-strain curves of the thin-walled circular ring structure before and after optimization, with a fixed layer thickness of 60 μm. Figure 6 (c) shows the room temperature mechanical property test stress-strain curves of the process boss before and after the optimization of the variable layer thickness of 40-60μm.

[0022] Figure 7 This is a schematic diagram of a variable layer thickness additive manufacturing apparatus for stress simulation according to an embodiment of the present invention. Detailed Implementation

[0023] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. Throughout the description, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the purpose of illustrative purposes and have no specific meaning in themselves. Therefore, "module," "part," or "unit" can be used interchangeably. Terms such as "first," "second," etc., are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the sequential relationship of the indicated technical features. In the following description, the consecutive reference numerals for method steps are for ease of review and understanding. Adjusting the implementation order of steps, in conjunction with the overall technical solution of the present invention and the logical relationship between the various steps, will not affect the technical effect achieved by the technical solution of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0024] refer to Figure 1 , Figure 1 This is a schematic diagram of a variable-thickness additive manufacturing method based on stress simulation, which includes, but is not limited to, steps S100-S400: In some embodiments, stress simulation of variable-thickness additive manufacturing is achieved through a variable-thickness additive manufacturing preprocessing method based on geometric features and their stress states.

[0025] S100, the structural database is determined based on residual stress sensitivity and easily deformable geometric characteristics.

[0026] In some embodiments, based on the geometric regions in metal additive manufacturing that are prone to accumulating residual stress and undergoing severe deformation, three typical geometric feature structures are summarized, including thin-walled conical cylinder structure, thin-walled ring structure, process boss structure, long cantilever beam structure, honeycomb lattice structure, and overhanging curved surface flow channel structure, and digital modeling of the three structures of thin-walled conical cylinder, thin-walled ring and process boss is performed.

[0027] S200 uses a structural database to perform finite element simulation on the target component, obtaining stress-strain cloud maps of additive manufacturing under different layer thickness strategies.

[0028] In some embodiments, a digital three-dimensional model of a typical structure with high residual stress accumulation and easily deformable geometric features is established, and non-uniform adaptive meshing and finite element discretization are performed. A Gaussian distributed heat source model is used to characterize the laser energy input, and mechanical constraints and thermal convection boundary conditions are applied. Based on the material constitutive model and phase transformation dynamics theory, the metal additive manufacturing process is simulated through transient thermo-mechanical coupling of layer-by-layer deposition. Elastic-plastic thermal stress simulation and nonlinear deformation simulation analysis are performed to obtain the transient thermal stress field and deformation field distribution cloud map of the entire additive manufacturing process, and the maximum equivalent residual stress (VonMises stress) and strain data of key areas are extracted.

[0029] S300: Determine the residual stress and strain of the target component based on the stress-strain cloud map, and determine the variable layer thickness strategy design based on the residual stress and strain and the geometric characteristics of the target component.

[0030] In some embodiments, based on the geometric features of the target component, finite element simulations of various fixed and variable layer thickness strategies are performed to obtain residual stress and deformation, and the variable layer thickness strategy design is determined based on the residual stress and deformation.

[0031] In some embodiments, for various typical geometric features, a library of multiple layer thickness strategies is designed, including multiple fixed layer thickness strategies {d, 2d, 3d…} and variable layer thickness strategies {d-2d, d-3d, 2d-3d…} (d is the single-layer base layer thickness parameter). Finite element simulation analysis of the additive manufacturing process is performed on each strategy, and the optimized variable layer thickness strategy is obtained based on the calculated cumulative residual stress and deformation.

[0032] In some embodiments, the optimized variable layer thickness strategy design includes: (a) The variable layer thickness strategy for the thin-walled conical structure is a transition from 60 μm to 40 μm; (b) The variable layer thickness strategy for the thin-walled annular structure is a transition from 60 μm to 40 μm; (c) The variable layer thickness strategy for the process boss structure is a transition from 60 μm to 40 μm; (d) The variable layer thickness strategy for long cantilever beam structures is a transition from 40 μm to 60 μm; (e) The variable layer thickness strategy of the cellular lattice structure is to transition from 80 μm to 40 μm and then to 80 μm; (f) The variable layer thickness strategy of the overhanging curved flow channel structure is to transition from 80 μm to 60 μm and then to 80 μm.

[0033] In some embodiments, multiple layer thickness strategies are designed, including three fixed layer thickness strategies ({40μm, 60μm, 80μm}) and three variable layer thickness strategies ({40μm-60μm, 40μm-80μm, 60μm-80μm}). Finite element simulation analysis of the additive manufacturing process is performed on each strategy. Based on the calculated cumulative residual stress and deformation, an optimized variable layer thickness strategy is obtained: {layer thickness transitioning from 60μm to 40μm}. S400, based on the variable layer thickness strategy, determines the variable layer thickness additive manufacturing process data, and verifies the variable layer thickness additive manufacturing process data using metal additive manufacturing forming.

[0034] In some embodiments, forming verification includes: determining an additive manufacturing process window adapted to the layer thickness based on a variable layer thickness strategy and orthogonal process; generating a corresponding slice model file based on preset variable layer thickness process parameters; performing metal additive manufacturing processing on the slice model file for the sample and the target component; performing microstructure analysis and mechanical property testing on the formed sample; and measuring the roughness and residual stress on the target component.

[0035] In some embodiments, metal additive manufacturing is specifically a laser powder bed fusion molding process.

[0036] In some embodiments, the additive manufacturing process window adapted to the layer thickness is specifically the laser powder bed melting process parameters such as laser power, scanning speed, and scanning spacing that are adapted to the layer thickness parameters involved in the variable layer thickness. It can be understood that different layer thicknesses correspond to different adaptation parameters.

[0037] In some embodiments, based on the layer thickness parameters of 60μm and 40μm involved in the optimized variable layer thickness strategy {layer thickness transition from 60μm to 40μm}, and based on orthogonal process experimental research, a suitable laser powder bed melting process window is obtained: {(laser power 260W, scanning speed 900mm / s, layer thickness 60μm, scanning spacing 0.1mm); (laser power 240W, scanning speed 1000mm / s, layer thickness 40μm, scanning spacing 0.09mm)}; the slice model file designed according to the process parameters is imported, and the laser powder bed melting forming verification of 316L stainless steel samples and thin-walled conical cylinder components is carried out; the microstructure analysis and mechanical property testing of the samples are performed, and the roughness measurement and residual stress measurement of the thin-walled conical cylinder components are performed.

[0038] Figure 2 (ab) are residual stress cloud diagrams of the thin-walled conical cylinder structure under different layer thickness strategies provided in the embodiments of this application. The obtained stress cloud diagrams are... Figure 2 b) and the stress cloud diagram obtained before optimization ( Figure 2a) It can be seen that the designed variable layer thickness strategy can improve the residual stress of thin-walled conical structures during additive manufacturing.

[0039] Figure 3 (ab) are deformation cloud diagrams of the thin-walled conical cylinder structure under different layer thickness strategies provided in the embodiments of this application, showing the obtained deformation amounts ( Figure 3 b) and the deformation obtained before optimization ( Figure 3 a) It can be seen that the designed variable layer thickness strategy can improve the deformation of thin-walled conical structures during additive manufacturing.

[0040] Figure 4 (ab) shows the roughness reconstruction morphology of the thin-walled conical cylinder structure under different layer thickness strategies provided in the embodiments of this application, and the resulting roughness ( Figure 4 b) and the roughness obtained before optimization ( Figure 4 a) It can be seen that the designed variable layer thickness strategy can improve the forming quality of additive manufacturing of thin-walled conical cylinder structures.

[0041] Figure 5 (ab) are the GND map results corresponding to the EBSD orientation maps under different layer thickness strategies provided in the embodiments of this application. The obtained GND maps ( Figure 5 b) and the GND diagram obtained before optimization ( Figure 5 a) It can be seen that the designed variable layer thickness strategy can improve the residual stress in additive manufacturing, which is consistent with the simulation results.

[0042] Figure 6 (a) Stress-strain curves of room temperature mechanical properties under different layer thickness strategies provided in the embodiments of this application. The obtained engineering stress changes show that the designed variable layer thickness strategy can improve the mechanical properties of the manufactured components.

[0043] In another embodiment, the variable layer thickness additive manufacturing method flow is shown in (1) to (4): (1) Based on the structural characteristics of areas prone to residual stress accumulation and deformation, a digital three-dimensional model of the thin-walled circular ring structure is established; (2) Establish a three-dimensional model of a typical geometric feature structure with high residual stress and easy deformation, divide it into finite element meshes, use a Gaussian distributed heat source to characterize the laser energy input, apply constraint conditions and thermal convection boundary conditions to simulate the additive manufacturing process; then perform elastoplastic thermal stress simulation and nonlinear deformation simulation analysis to obtain the corresponding stress-strain cloud map.

[0044] (3) Design multiple layer thickness strategies, including three fixed layer thickness strategies of {40μm, 60μm, 80μm} and three variable layer thickness strategies of {40μm-60μm, 40μm-80μm, 60μm-80μm}. Perform finite element simulation analysis of the additive manufacturing process respectively. Based on the calculated cumulative residual stress and deformation, obtain the optimized variable layer thickness strategy: {layer thickness transitions from 60μm to 40μm}. (4) Based on the layer thickness parameters of 60μm and 40μm involved in the optimized variable layer thickness strategy {layer thickness transition from 60μm to 40μm}, and based on orthogonal process experiment research, the process windows of laser powder bed melting that are compatible are obtained: {(laser power is 260W, scanning speed is 900mm / s, layer thickness is 60μm, scanning spacing is 0.1mm); (laser power is 240W, scanning speed is 1000mm / s, layer thickness is 40μm, scanning spacing is 0.09mm)}; import the slice model file designed according to the process parameters, and verify the laser powder bed melting forming of 316L stainless steel samples and thin-walled ring components; perform microstructure analysis and mechanical property testing on the samples, and measure the roughness and residual stress of the thin-walled ring components.

[0045] A fixed layer thickness strategy (40 μm) and a matching laser powder bed melting process window were adopted: laser power 240 W, scanning speed 1000 mm / s, layer thickness 40 μm, and scanning interval 0.09 mm. The slice model file designed according to the process parameters was imported to verify the laser powder bed melting forming of 316L stainless steel samples and thin-walled ring components. Microstructure analysis and mechanical property testing were performed on the samples, and roughness and residual stress were measured on the thin-walled ring components.

[0046] Figure 2 (cd) shows the residual stress cloud diagrams under different layer thickness strategies for the thin-walled ring structure provided in the embodiments of this application. The obtained stress cloud diagrams ( Figure 2 d) and the stress cloud diagram obtained before optimization ( Figure 2 c) It can be seen that the designed variable layer thickness strategy can improve the residual stress of thin-walled ring structures during additive manufacturing.

[0047] Figure 3 (cd) is a deformation cloud map of the thin-walled ring structure under different layer thickness strategies provided in the embodiments of this application, and the obtained deformation amount ( Figure 3 d) and the deformation obtained before optimization ( Figure 3 c) It can be seen that the designed variable layer thickness strategy can improve the deformation of thin-walled ring structures during additive manufacturing.

[0048] Figure 4(cd) represents the roughness reconstruction morphology of the thin-walled annular structure under different layer thickness strategies provided in the embodiments of this application, and the resulting roughness ( Figure 4 d) and the roughness obtained before optimization ( Figure 4 c) It can be seen that the designed variable layer thickness strategy can improve the forming quality of additive manufacturing of thin-walled ring structures.

[0049] Figure 5 (cd) represents the GND map results corresponding to the EBSD orientation map under different layer thickness strategies provided in the embodiments of this application. The obtained GND map ( Figure 5 d) and the GND map obtained before optimization ( Figure 5 c) It can be seen that the designed variable layer thickness strategy can improve the residual stress in additive manufacturing, which is consistent with the simulation results.

[0050] Figure 6 (b) The room temperature mechanical property test stress-strain curves under different layer thickness strategies provided in the embodiments of this application show that the engineering stress changes can improve the mechanical properties of the manufactured components.

[0051] In another embodiment, the variable layer thickness additive manufacturing method flow is shown in (1) to (4): (1) Based on the structural characteristics of areas prone to residual stress accumulation and deformation, a digital three-dimensional model of the process boss structure is established; (2) Establish a three-dimensional model of a typical geometric feature structure with high residual stress and easy deformation, divide it into finite element meshes, use a Gaussian distributed heat source to characterize the laser energy input, apply constraint conditions and thermal convection boundary conditions to simulate the additive manufacturing process; then perform elastoplastic thermal stress simulation and nonlinear deformation simulation analysis to obtain the corresponding stress-strain cloud map.

[0052] (3) Design multiple layer thickness strategies, including three fixed layer thickness strategies of {40μm, 60μm, 80μm} and three variable layer thickness strategies of {40μm-60μm, 40μm-80μm, 60μm-80μm}. Perform finite element simulation analysis of the additive manufacturing process respectively. Based on the calculated cumulative residual stress and deformation, obtain the optimized variable layer thickness strategy: {layer thickness transitions from 60μm to 40μm}. (4) Based on the layer thickness parameters of 60μm and 40μm involved in the optimized variable layer thickness strategy {layer thickness transition from 60μm to 40μm}, and based on orthogonal process experiment research, the process windows of laser powder bed melting that are compatible are obtained: {(laser power is 260W, scanning speed is 900mm / s, layer thickness is 60μm, scanning spacing is 0.1mm); (laser power is 240W, scanning speed is 1000mm / s, layer thickness is 40μm, scanning spacing is 0.09mm)}; import the slice model file designed according to the process parameters, and verify the laser powder bed melting forming of 316L stainless steel samples and process boss components; perform microstructure analysis and mechanical property testing on the samples, and measure the roughness and residual stress of the process boss components.

[0053] In some embodiments, a fixed layer thickness strategy (layer thickness of 60 μm) and a matching laser powder bed melting process window are adopted: (laser power of 260 W, scanning speed of 900 mm / s, layer thickness of 60 μm, and scanning interval of 0.1 mm). The slice model file designed according to the process parameters is imported to verify the laser powder bed melting forming of 316L stainless steel samples and process boss components. Microstructure analysis and mechanical property testing are performed on the samples, and roughness and residual stress are measured on the process boss components.

[0054] Figure 2 (ef) is a residual stress cloud diagram under different layer thickness strategies for the process boss structure provided in the embodiments of this application. The obtained stress cloud diagram ( Figure 2 f) and the stress cloud diagram obtained before optimization ( Figure 2 e) It can be seen that the designed variable layer thickness strategy can improve the residual stress of the process boss structure in the additive manufacturing process.

[0055] Figure 3 (ef) is a deformation cloud diagram of the process boss structure under different layer thickness strategies provided in the embodiments of this application, and the obtained deformation amount ( Figure 3 f) and the deformation obtained before optimization ( Figure 3 e) It can be seen that the designed variable layer thickness strategy can improve the deformation of the process boss structure during additive manufacturing.

[0056] Figure 4 (ef) represents the roughness reconstruction morphology of the process boss structure under different layer thickness strategies provided in the embodiments of this application, and the resulting roughness ( Figure 4 f) and the roughness obtained before optimization ( Figure 4 e) It can be seen that the designed variable layer thickness strategy can improve the forming quality of additive manufacturing of process boss structures.

[0057] Figure 5(ef) represents the GND diagrams corresponding to EBSD under different layer thickness strategies provided in the embodiments of this application. The resulting GND diagrams ( Figure 5 f) and the GND map obtained before optimization ( Figure 5 d) It can be seen that the designed variable layer thickness strategy can improve the residual stress in additive manufacturing, which is consistent with the simulation results.

[0058] Figure 6 In (ac), blue represents the optimized state, gray represents the unoptimized state, and red represents the intermediate optimization process. Figure 6 (c) The room temperature mechanical property test stress-strain curves under different layer thickness strategies provided in the embodiments of this application show that the engineering stress changes can improve the mechanical properties of the manufactured components.

[0059] Figure 7 This is a diagram of a variable-thickness additive manufacturing analysis device for stress simulation according to an embodiment of the present invention. The device includes a first module 710, a second module 720, a third module 730, and a fourth module 740.

[0060] The system comprises four modules: the first module determines the structural database based on the residual stress sensitivity and easily deformable geometric characteristics; the second module performs finite element simulation on the target component based on the structural database to obtain additive manufacturing stress-strain cloud maps for different layer thickness strategies; the third module determines the residual stress and strain of the target component based on the stress-strain cloud maps, and determines the variable layer thickness strategy design based on the residual stress and strain and the geometric characteristics of the target component; and the fourth module determines the variable layer thickness additive manufacturing process data based on the variable layer thickness strategy design, and verifies the variable layer thickness additive manufacturing process data using metal additive manufacturing.

[0061] Exemplarily, with the cooperation of the first to fourth modules in the device, the embodiment device can implement any of the aforementioned stress simulation-based variable layer thickness additive manufacturing methods, namely, determining a structural database based on residual stress sensitivity and easily deformable geometric characteristics; performing finite element simulation on the target component based on the structural database to obtain additive manufacturing stress-strain cloud maps under different layer thickness strategies; determining the residual stress and strain of the target component based on the stress-strain cloud maps; determining the variable layer thickness strategy design based on the residual stress and strain and the geometric characteristics of the target component; determining the variable layer thickness additive manufacturing process data based on the variable layer thickness strategy design; and verifying the variable layer thickness additive manufacturing process data using metal additive manufacturing forming. The beneficial effects of this invention are: by simulating the additive manufacturing process through finite element simulation, calculating the residual stress-strain cloud maps under different layer thickness strategies, and thus obtaining an optimized variable layer thickness strategy, the forming efficiency and quality are improved, and the mechanical properties of metal parts are enhanced; based on printing examples that are prone to accumulating residual stress and large deformation, the variable layer thickness strategy is optimized for printing examples, supplemented by laser powder bed melting forming verification, to achieve low residual stress and high-performance fabrication of complex components.

[0062] This invention also provides an electronic device, which includes a processor and a memory; The memory stores the program; The processor executes a program to perform the aforementioned stress simulation-based variable-thickness additive manufacturing method; the electronic device has the function of carrying and running the stress simulation-based variable-thickness additive manufacturing software system provided in the embodiments of the present invention, such as a personal computer, minicomputer, mainframe, workstation, network or distributed computing environment, standalone or integrated computer platform, or communicating with charged particle tools or other imaging devices, etc.

[0063] This invention also provides a computer-readable storage medium storing a program that is executed by a processor to implement the variable layer thickness additive manufacturing method with stress simulation as described above.

[0064] In some alternative embodiments, the functions / operations mentioned in the block diagrams may not occur in the order shown in the operation diagrams. For example, depending on the functions / operations involved, two consecutively shown blocks may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order. Furthermore, the embodiments presented and described in the flowcharts of this invention are provided by way of example to provide a more comprehensive understanding of the technology. The disclosed methods are not limited to the operations and logic flows presented herein. Alternative embodiments are contemplated in which the order of various operations is altered and sub-operations described as part of a larger operation are executed independently.

[0065] This invention also discloses a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device can read the computer instructions from the computer-readable storage medium and execute the computer instructions, causing the computer device to perform the aforementioned stress simulation-based variable-thickness additive manufacturing method.

[0066] Furthermore, although the invention has been described in the context of functional modules, it should be understood that, unless otherwise stated, one or more of the described functions and / or features may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the invention. Rather, given the properties, functions, and internal relationships of the various functional modules in the apparatus disclosed herein, the actual implementation of the module will be understood within the scope of conventional skill of an engineer. Therefore, those skilled in the art can implement the invention as set forth in the claims using ordinary techniques without excessive experimentation. It is also understood that the specific concepts disclosed are merely illustrative and not intended to limit the scope of the invention, which is determined by the full scope of the appended claims and their equivalents.

[0067] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0068] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-including system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0069] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0070] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0071] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0072] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0073] The above is a detailed description of the preferred embodiments of the present invention, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A variable-thickness additive manufacturing method based on stress simulation, characterized in that, include: The structural database is determined based on residual stress sensitivity and easily deformable geometric characteristics; Finite element simulation of the target component was performed based on the structural database to obtain stress-strain cloud maps of additive manufacturing under different layer thickness strategies. The residual stress and strain of the target component are determined based on the stress-strain cloud map. Based on the residual stress and strain and the geometric characteristics of the target component, the variable layer thickness strategy design is determined. Based on the variable layer thickness strategy, the variable layer thickness additive manufacturing process data is determined, and the variable layer thickness additive manufacturing process data is verified by metal additive manufacturing forming.

2. The variable layer thickness additive manufacturing method based on stress simulation according to claim 1, characterized in that, The residual stress sensitivity includes thin-walled conical cylinder structures, thin-walled annular structures, process boss structures, long cantilever beam structures, honeycomb lattice structures, and suspended curved surface flow channel structures.

3. The variable layer thickness additive manufacturing method based on stress simulation according to claim 1, characterized in that, The step of performing finite element simulation on the target component based on a structural database to obtain additive manufacturing stress-strain contour maps for different layer thickness strategies includes: Based on the structural database, a three-dimensional model of the target component with typical high residual stress and easily deformable geometric features is determined; The 3D model was meshed with finite element meshes, and the laser energy input was represented by a Gaussian distributed heat source. The additive manufacturing process was simulated based on the constraint conditions and thermal convection boundary conditions. Elastic-plastic thermal stress simulation and nonlinear deformation simulation analysis were performed on the additive manufacturing process to obtain stress-strain cloud maps of additive manufacturing under different layer thickness strategies.

4. The variable layer thickness additive manufacturing method based on stress simulation according to claim 1, characterized in that, The process of determining the residual stress and strain of the target component based on the stress-strain cloud map, and determining the variable layer thickness strategy design based on the residual stress and strain and the geometric characteristics of the target component, includes: Finite element simulations of various fixed and variable layer thickness strategies are performed based on residual stress, strain, and the geometric characteristics of the target component to obtain residual stress and deformation. The design of the variable layer thickness strategy is then determined based on the residual stress and deformation.

5. The variable layer thickness additive manufacturing method based on stress simulation according to claim 1, characterized in that, The metal additive manufacturing process employs laser powder bed fusion molding.

6. The variable layer thickness additive manufacturing method based on stress simulation according to claim 1, characterized in that, The forming verification includes: Based on the variable layer thickness strategy and orthogonal process, determine the additive manufacturing process window that is compatible with the layer thickness; Based on the preset variable layer thickness process parameters, a corresponding slice model file is generated, and the slice model file is subjected to metal additive manufacturing processing for the sample and target component. Microstructure analysis and mechanical property testing were performed on the formed specimens, and roughness and residual stress were measured on the target components.

7. The variable layer thickness additive manufacturing method based on stress simulation according to claim 6, characterized in that, The additive manufacturing process window is a laser powder bed melting process parameter that is adapted to the layer thickness parameters involved in the variable layer thickness. The laser powder bed melting process parameter includes laser power, scanning speed, and scanning spacing.

8. A variable-thickness additive manufacturing apparatus for stress simulation, characterized in that, include: The first module is used to determine the structural database based on residual stress-sensitive and easily deformable geometric features; The second module is used to perform finite element simulation of the target component based on the structural database to obtain additive manufacturing stress-strain cloud maps for different layer thickness strategies. The third module is used to determine the residual stress and strain of the target component based on the stress-strain cloud map, and to determine the variable layer thickness strategy design based on the residual stress and strain and the geometric characteristics of the target component. The fourth module is used to design and determine the variable layer thickness additive manufacturing process data based on the variable layer thickness strategy, and to verify the variable layer thickness additive manufacturing process data using metal additive manufacturing forming.

9. An electronic device, characterized in that, Including the processor and memory; The memory is used to store programs; The processor executes the program to implement the variable layer thickness additive manufacturing method with stress simulation as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The storage medium stores a program that is executed by a processor to implement the variable layer thickness additive manufacturing method for stress simulation as described in any one of claims 1-7.

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