A method, system, electronic device and product for analyzing residual stress of a forged print

Abstract

This invention belongs to the field of additive manufacturing technology, and its purpose is to provide a method, system, electronic device, and product for residual stress analysis in laser forging printing. This invention introduces a strengthening laser into the additive manufacturing process by setting a continuous laser heat source model and a strengthened laser shock wave pressure model in the CFD model. The CFD model accurately simulates the molten pool dynamics during the laser-powder interaction process. Subsequently, a FEM model is constructed based on node coordinates, and the CFD model and FEM model are sequentially coupled, allowing the accurate transfer of real temperature field and material state information to the FEM model. Finally, thermo-coupled finite element analysis is performed using the FEM model to obtain the residual stress distribution results. This achieves high-precision prediction of the residual stress evolution during laser forging printing, avoiding systematic errors introduced by simplification of molten pool morphology and material state. This invention is applicable to forging printing processes and offers high accuracy in residual stress analysis.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a method, system, electronic device, and product for analyzing residual stress in forging printing. Background Technology

[0002] Selective Laser Melting (SLM) is a commonly used metal additive manufacturing technique that uses a laser to melt metal powder layer by layer to create complex three-dimensional parts. In the SLM process, the metal powder undergoes rapid heating and cooling cycles. When the laser irradiates the metal powder, the material locally melts to form a molten pool, which then rapidly solidifies. This extremely fast thermal cycle (cooling rate can reach 10⁻⁶) is crucial. 6 -10 8 The temperature (℃ / s) causes uneven thermal expansion and contraction within the material. At the same time, due to the constraints of the substrate and surrounding solid materials, this thermal deformation is limited, leading to the accumulation of plastic strain and the formation of residual stress. These residual stresses can cause deformation, warping, or even cracking of parts after manufacturing or during subsequent processing.

[0003] To overcome the problem of residual stress, a new composite manufacturing technology called forging printing technology has been proposed in recent years, which combines the "free forming" of additive manufacturing with the "plastic deformation" of forging technology. After the metal powder is melted by laser scanning, a controllable forging pressure (transient impact pressure) is immediately applied to the cladding layer or a specific area. By utilizing the good plasticity of the metal material at high temperature, it causes micro-plastic deformation, thereby rolling together the internal pores, breaking up the coarse columnar crystals, and significantly releasing thermal stress.

[0004] At the numerical analysis level, residual stress analysis in the SLM process typically employs two methods: experimental measurement and numerical simulation. Experimental measurement methods, such as X-ray diffraction and nanoindentation, can directly measure residual stress, but they are costly and struggle to capture the dynamic changes in residual stress throughout the process. Numerical simulation methods include the Finite Element Method (FEM) and Computational Fluid Dynamics (CFD). The FEM is widely used for predicting temperature and stress fields, but it often uses simplified heat source models and heat transfer mechanisms, making it difficult to accurately reflect the true molten pool morphology and fluid dynamics behavior. In contrast, CFD methods can more accurately simulate the molten pool morphology, temperature field, and flow behavior, but its Eulerian meshes are unsuitable for structural mechanics analysis, and it consumes significant computational resources, making it difficult to apply to macroscopic parts.

[0005] Therefore, existing technologies have developed CFD-FEM coupled residual stress analysis methods, which can improve the accuracy of residual stress prediction. However, in using existing technologies, the inventors have discovered at least the following problems: Existing CFD-FEM residual stress analysis methods are not applicable to forging printing processes. Specifically, forging printing processes introduce intensifying laser shock loads, and the material undergoes instantaneous alternation and coupling of multiple physical processes such as laser melting, molten pool flow, solidification shrinkage, and forging plastic deformation. However, most existing CFD-FEM residual stress analysis methods are designed for conventional SLM processes and fail to comprehensively consider the plastic strain introduced by the intensifying laser shock pressure and its feedback effect on the subsequent thermal stress evolution, making it difficult to accurately model and predict this complex process.

[0006] Therefore, it is necessary to study a CFD-FEM residual stress analysis scheme suitable for forging printing process. Summary of the Invention

[0007] The present invention aims to solve the above-mentioned technical problems to at least a certain extent. The present invention provides a method, system, electronic device and product for analyzing residual stress in forging printing.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for analyzing residual stress in forging printing, comprising: Construct a CFD model of the forging and printing process of a specified alloy; A continuous laser heat source model and an enhanced laser shock wave pressure model are set in the CFD model, and transient CFD calculations are performed to obtain the CFD calculation results. The node coordinates, node temperatures, and node volume fractions corresponding to each time step are extracted from the CFD calculation results. Based on the node coordinates, an FEM model is constructed, and a mapping relationship is established between the mesh nodes of the CFD model and the mesh nodes of the FEM model. The node temperature is transmitted to the FEM model via node mapping. In the FEM model, the nodal material state is dynamically identified based on the nodal temperature and the nodal volume fraction, and the enhanced laser shock wave pressure corresponding to the enhanced laser shock wave pressure model is applied to perform thermo-mechanical coupled finite element calculations to obtain the residual stress distribution results.

[0009] In one possible design, a CFD model of the specified alloy forging printing process is constructed, including: Obtain the geometric dimensional parameters of the powder layer, substrate and their relative positional relationship during the forging and printing process of a specified alloy, as well as the thermal properties of the specified alloy in powder and solid states; Based on the geometric parameters and the thermal property parameters, a three-dimensional computational domain containing the powder layer and the substrate is constructed to generate an initial CFD model; The initial CFD model is meshed to generate a CFD model that can be used for numerical solution.

[0010] In one possible design, the continuous laser heat source model adopts a Gaussian body heat source model; in the enhanced laser shock wave pressure model, the peak value of the shock wave pressure generated by the enhanced laser is calculated by the Fabbro formula.

[0011] In one possible design, the node coordinates, node temperature, and node volume fraction corresponding to each time step are extracted from the CFD calculation results, including: Extract the original node data corresponding to each time step from the CFD calculation results; wherein, the original node data includes the initial node coordinates, the initial node temperature, and the initial node volume fraction; The original node data is processed for data alignment, unit unification, and outlier correction to generate standardized original node data; The standardized raw node data is organized according to a time series to obtain the node coordinates, node temperature, and node volume fraction corresponding to each time step.

[0012] In one possible design, when the node temperature is transmitted to the FEM model through node mapping, the nearest neighbor interpolation algorithm built into the FEM software is used.

[0013] In one possible design, the nodal material state is dynamically identified in the FEM model based on the nodal temperature and the nodal volume fraction, and a strengthening laser shock wave pressure corresponding to the strengthening laser shock wave pressure model is applied. A thermo-coupling finite element analysis is then performed to obtain the residual stress distribution results, including: In the FEM model, the nodal material state of each node is dynamically identified based on the nodal temperature and the nodal volume fraction; wherein the nodal material state is gaseous, liquid, or solid. For different nodal material states, the corresponding material constitutive model is invoked; wherein, the material constitutive model is an elastoplastic constitutive model corresponding to the solid region or a fluid model corresponding to the liquid region; A reinforced laser shock wave pressure corresponding to the reinforced laser shock wave pressure model is applied to the node region identified as liquid, and thermo-mechanical coupled finite element calculation is performed to obtain the residual stress distribution results.

[0014] In one possible design, after obtaining the residual stress distribution results, the method further includes: The residual stress distribution results were compared with experimental measurements to verify the accuracy of the results.

[0015] Secondly, the present invention provides a forging printing residual stress analysis system, comprising: The CFD model building module is used to build a CFD model of a specified alloy forging printing process; The CFD calculation module is communicatively connected to the CFD model construction module. It is used to set up a continuous laser heat source model and an enhanced laser shock wave pressure model in the CFD model, and to perform transient CFD calculations to obtain CFD calculation results. The CFD calculation module is also used to extract the node coordinates, node temperature and node volume fraction corresponding to each time step from the CFD calculation results. The FEM model building module is communicatively connected to the CFD calculation module and is used to build an FEM model based on the node coordinates and establish a mapping relationship between the grid nodes of the CFD model and the grid nodes of the FEM model. The FEM model building module is also used to transfer the node temperature to the FEM model through node mapping. The FEM calculation module is communicatively connected to the FEM model construction module. It is used to dynamically identify the nodal material state in the FEM model based on the nodal temperature and the nodal volume fraction, and to load the enhanced laser shock wave pressure corresponding to the enhanced laser shock wave pressure model to perform thermo-mechanical coupled finite element calculations to obtain the residual stress distribution results.

[0016] Thirdly, the present invention provides an electronic device, comprising: Memory, used to store computer program instructions; and, A processor is configured to execute the computer program instructions to perform the operation of a forging printing residual stress analysis method as described in any of the preceding claims.

[0017] Fourthly, the present invention provides a computer program product, including a computer program or instructions, wherein the computer program or instructions, when executed by a computer, implement a forging printing residual stress analysis method as described in any of the above.

[0018] The beneficial effects of this invention are as follows: This invention discloses a method, system, electronic device, and product for residual stress analysis in laser forging printing, applicable to the forging printing process, and offering high accuracy in residual stress analysis. Specifically, in implementation, firstly, by setting a continuous laser heat source model and a reinforced laser shock wave pressure model in the CFD model, a reinforced laser is introduced into the additive manufacturing process. The CFD model accurately simulates the molten pool dynamics during the laser-powder interaction process, achieving a high-precision description of the molten pool dynamics. Subsequently, an FEM model is constructed based on the node coordinates, and the CFD model and FEM model are sequentially coupled, ensuring that the actual temperature field and material state information during laser melting, molten pool flow, and solidification are accurately transferred to the FEM model. Finally, thermo-coupled finite element analysis is performed using the FEM model to obtain the residual stress distribution results, thereby achieving high-precision prediction of the residual stress evolution during laser forging printing and avoiding systematic errors introduced by simplification of molten pool morphology and material state. In this process, by introducing enhanced laser shock wave load in the FEM analysis stage and combining it with the dynamic identification mechanism of material state, this invention can accurately describe the transient plastic deformation caused by shock wave in the forging printing process and its influence on the evolution of residual stress, making the residual stress prediction results closer to the actual forming state, thereby significantly improving the accuracy and engineering applicability of residual stress analysis.

[0019] Other beneficial effects of the present invention will be further explained in the specific embodiments. Attached Figure Description

[0020] Figure 1 This is a flowchart of a method for analyzing residual stress in forging printing, as described in the embodiment. Figure 2 This is a block diagram of a forging printing residual stress analysis system in one embodiment; Figure 3 This is a block diagram of an electronic device in one embodiment. Detailed Implementation

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0022] Example 1: This embodiment discloses a method for analyzing residual stress in forging printing, which can be executed, but is not limited to, by a computer device or virtual machine with certain computing resources, such as an electronic device like a personal computer, smartphone, personal digital assistant, or wearable device, or by a virtual machine.

[0023] like Figure 1 As shown, a method for analyzing residual stress in forging printing may include, but is not limited to, the following steps: S1. Construct a CFD model for the specified alloy forging and printing process.

[0024] In step S1, a CFD model of the specified alloy forging printing process is constructed, including: S101. Obtain the geometric dimensional parameters of the powder layer, substrate, and their relative positional relationship during the forging and printing process of the specified alloy, as well as the thermal properties of the specified alloy in the powder state and solid state; specifically, in this embodiment, the specified alloy is an AlSi10Mg alloy; correspondingly, the thermal properties include different thermal properties of the AlSi10Mg alloy in the powder state and solid state, including the relationship between thermal conductivity, specific heat capacity, density, etc., and temperature, especially the characteristic parameter of laser energy absorption rate changing with temperature.

[0025] S102. Based on the geometric parameters and the thermal property parameters, construct a three-dimensional computational domain containing the powder layer and the substrate, and generate an initial CFD model; S103. The initial CFD model is meshed to generate a CFD model that can be used for numerical solution.

[0026] Specifically, in this embodiment, the computational domain is set to 800×500×500μm, the initial temperature is set to a preheating temperature of 100℃, the input pressure on the top surface is atmospheric pressure, and the rest are set as wall conditions. The material parameters use the parameters of the corresponding materials in the database, and it is confirmed that the parameters to be analyzed are complete. The initial CFD model is a three-dimensional geometric model corresponding to the three-dimensional computational domain. During implementation, a hexahedral mesh with a global size of 5μm is used to mesh the initial CFD model, and the mesh is refined in a preset laser scanning area to improve the computational accuracy.

[0027] It should be noted that in this embodiment, by simultaneously introducing material thermal property parameters of both powder and solid states during the CFD modeling stage, and setting the powder layer and substrate structure within a unified three-dimensional computational domain, the influence of material state differences on heat transfer behavior during laser forging printing can be realistically reflected, avoiding thermal field calculation deviations caused by equating the powder region with a dense solid. Furthermore, meshing the initial CFD model allows for subsequent node-based description, which improves the accuracy of subsequent residual stress analysis.

[0028] S2. A continuous laser heat source model and a reinforced laser shock wave pressure model are set in the CFD model, and transient CFD calculations are performed to obtain the CFD calculation results. Specifically, the CFD calculation results include the temperature field, melt pool morphology, and volume fraction distribution that vary with time. It should be noted that the continuous laser heat source model is used to apply a continuous laser, which is used to melt the powder (additive manufacturing), and the reinforced laser shock wave pressure model is used to apply a reinforcing laser to generate a shock wave to apply forging pressure (modification).

[0029] In step S2, the continuous laser heat source model adopts the Gaussian body heat source model; in the enhanced laser shock wave pressure model, the peak value of the shock wave pressure generated by the enhanced laser is calculated by the Fabbro formula.

[0030] During implementation, a three-dimensional Gaussian volume heat source model is used to describe the energy distribution of additive continuous laser and its heat flux density. q ( r The formula for calculating ) is:

[0031] In the formula, P It is the power of the additive continuous laser. r It is the distance from the center of the additive continuous laser. r 0 is the beam radius of the additive continuous laser.

[0032] It should be noted that by using a three-dimensional Gaussian volume heat source model to describe the energy distribution of additive continuous laser, compared with traditional surface heat source or simplified volume heat source models, it can more realistically reflect the energy attenuation and spatial distribution characteristics of laser within the powder layer, thereby improving the accuracy of predicting the temperature field and geometric morphology of the molten pool.

[0033] In this embodiment, the shock wave pressure generated by the enhanced laser exhibits a pulsed transient change in time and a non-uniform distribution in space related to the laser spot and propagation direction. Therefore, it can be expressed as a pressure function that depends on both spatial coordinates and time variables. The peak value of the shock wave pressure generated by the enhanced laser... P max The calculation formula is:

[0034] In the formula, α It enhances the efficiency of the interaction between the laser and the specified alloy. Z It is the combined impedance. , z 1 represents the target impedance, which is the acoustic impedance of the powder layer or substrate as the laser target. z2 represents the preset constraint layer impedance, which is the acoustic impedance of the constraint layer (usually a transparent medium such as water or glass) covering the material surface. I 0 represents the power density of the enhanced laser. , β It is a preset energy correction coefficient used to characterize the proportion of effective energy actually involved in the generation of the shock wave in the energy of the enhanced laser single pulse. A It enhances the effective area of ​​the laser. E It enhances the single-pulse energy of the laser. τ It enhances the pulse width of the laser.

[0035] It should be noted that in this embodiment, the Fabbro formula based on physical mechanisms is used to model the shock wave pressure generated by the enhanced laser, which can accurately reflect the transient loading characteristics of the shock wave and avoid the uncertainty brought about by empirical values, thereby improving the simulation accuracy of the impact-induced plastic strain and stress release process.

[0036] It should be noted that the enhanced laser effect has a significant impact on the flow pattern of the molten pool during the additive manufacturing process, and the force effect of the shock wave generated by it significantly changes the distribution of residual stress inside the material. Based on this, this embodiment considers the influence of the enhanced laser force effect on the flow and morphology of the molten pool, which can make the final residual stress prediction result closer to the actual forming state.

[0037] In this embodiment, by simultaneously considering the continuous laser heat input and the thermodynamic effects of the enhanced laser shock load in the CFD model, the transient evolution behavior of the molten pool during the forging printing process can be accurately simulated, overcoming the shortcomings of traditional CFD models that only focus on heat input and ignore the impact effect.

[0038] S3. Extract the node coordinates, node temperature, and node volume fraction corresponding to each time step from the CFD calculation results. The node volume fraction is used to characterize the filling ratio of material (such as liquid metal) within the computational cell.

[0039] In step S3, the node coordinates, node temperature, and node volume fraction corresponding to each time step are extracted from the CFD calculation results, including: S301. Extract the original node data corresponding to each time step from the CFD calculation results; wherein, the original node data includes the initial node coordinates, the initial node temperature, and the initial node volume fraction; S302. Perform data alignment, unit unification, and outlier correction on the original node data (for example, correct values ​​exceeding the material vaporization temperature to the vaporization temperature) to generate standardized original node data; S303. Organize the standardized raw node data according to the time series to obtain the node coordinates, node temperature and node volume fraction corresponding to each time step.

[0040] It should be noted that in this embodiment, by performing standardized preprocessing on the original node data before coupling the CFD module and the FEM module, the impact of problems such as abnormally high temperatures and inconsistent data formats on the stability of subsequent finite element solutions can be effectively avoided, thereby significantly improving the numerical reliability of the coupled calculation. Simultaneously, the time-series processing of the node-level data allows the temperature field and volume fraction field to be transferred to the FEM model in the form of a complete thermal history, providing continuous and consistent load input for subsequent thermo-mechanical coupling analysis.

[0041] S4. Construct an FEM model based on the node coordinates, and establish a mapping relationship between the grid nodes of the CFD model and the grid nodes of the FEM model.

[0042] S5. The node temperature is transmitted to the FEM model through node mapping.

[0043] In step S5, when the node temperature is transmitted to the FEM model through node mapping, the nearest neighbor interpolation algorithm built into the FEM software is used.

[0044] Specifically, in this embodiment, the FEM model supports the import of high-precision temperature field data from the CFD model through various methods such as predefined fields, user subroutines, or a combination of amplitude curves. This allows the transient temperature field, volume fraction field, and node coordinates calculated by the CFD model to be mapped to the FEM mesh without loss or with high fidelity, serving as the data basis for thermo-mechanical coupling analysis.

[0045] Before importing the data into the FEM model, data standardization preprocessing is required. During implementation, a dedicated conversion script can be used to organize the data into a format that the FEM model can directly read.

[0046] The following are several ways to import data into the FEM model: Direct import of predefined fields: In the "Loads" module of the FEM model, create a predefined field of type "Temperature". Select "From Results or Output Database File" as the distribution type, and then specify the preprocessed file containing the temperature field data. The FEM model will automatically match the node coordinates and assign the temperature values ​​to the corresponding FEM nodes. This method supports complete time series import and is suitable for static and transient thermal analysis.

[0047] User-defined subroutine dynamic interface: By writing user-defined subroutines, more flexible temperature field loading logic can be implemented. Subroutines can read external data files or internal arrays in each incremental step, dynamically calculate and return the node temperature value based on information such as the current analysis time and node number. This method is suitable for advanced scenarios requiring complex interpolation or coupling with other field variables (such as phase transitions).

[0048] Combining amplitude curves and distribution: For simplified cases where the spatiotemporal variation of the temperature field is clear, a "analytical field" can be used to define the spatial distribution, and an "amplitude curve" can be used to define the temporal variation. The temperature load is applied by multiplying the two. This method is computationally efficient, but it is difficult to reproduce the complex irregular molten pool morphology in the FEM model calculation.

[0049] In this embodiment, a direct mapping relationship is established between the CFD model and the FEM model through the node coordinates, which avoids the development of complex spatiotemporal interpolation algorithms and significantly reduces human error and implementation difficulty during data transmission. Simultaneously, relying on the nearest neighbor interpolation algorithm built into the FEM software, computational efficiency is significantly improved while ensuring the accuracy of temperature field transmission, providing practical feasibility for large-scale engineering simulations.

[0050] In this embodiment, after importing the node temperature into the FEM model, a complete coupled thermal stress analysis model needs to be set up in the FEM model in order to realize the subsequent forging printing residual stress analysis. The specific steps are as follows: a. Based on the node coordinate file of the FEM model, reconstruct the component geometry within the FEM model, or directly import a mesh file that matches the CFD model. To ensure data transfer accuracy, the node coordinates of the FEM model should be as consistent as possible with the node coordinates of the CFD model. The node element type of the FEM model should be selected to support thermal coupling, such as an eight-node coupled temperature-displacement hexahedral element (C3D8T). Subsequently, instantiate the component into an assembly.

[0051] b. Material Property Definition and State Assignment: Considering the multi-state changes of materials during shock wave forging printing (gas, liquid, solid), it is necessary to define material constitutive models for different states, as follows: Solid AlSi10Mg: Defines temperature-dependent elastoplastic properties, including Young's modulus, Poisson's ratio, yield strength, and coefficient of thermal expansion.

[0052] Liquid metal: imparts extremely low shear modulus (simulating fluid behavior) and a Poisson's ratio close to 0.49 (simulating incompressibility).

[0053] Gaseous environment: imparts extremely low stiffness, its role is only to maintain numerical convergence, and it does not participate in the main mechanical response.

[0054] The dynamic allocation of material states is achieved through a user subroutine. This subroutine uses the imported volume fraction field and temperature field as the main criteria, combined with thermal history variables, to determine the state of matter (gas, liquid or solid) at each integration point in real time in each incremental step, and drives the FEM model to call the corresponding material definition by modifying the field variable values.

[0055] c. Create a “coupled temperature-displacement” analysis step; specifically, to accurately capture the transient processes of laser scanning and shock wave loading, a small initial increment step needs to be set and automatic time increment needs to be enabled; the geometric nonlinearity option needs to be enabled in the analysis step; due to the involvement of drastic changes in material state and impact loads, in this embodiment, the complete Newton method is used to solve the problem to improve convergence.

[0056] d. Set the loads and boundary conditions as follows: Temperature load: The node temperature is applied to the entire FEM model as a "predefined field" at the beginning of the analysis step as a thermal load.

[0057] Mechanical load: The shock wave pressure load is applied to the upper surface area of ​​the molten pool in the form of "pressure" load; its time history is defined by the "amplitude curve", which is usually described by a modified half sine wave or other forms to describe the instantaneous impact characteristics of the pressure; its spatial distribution can be defined as a uniform distribution, or a more complex Gaussian distribution can be implemented through user subroutines.

[0058] Boundary conditions: Constrain all degrees of freedom of the bottom surface of the substrate. Other free surfaces in the model are typically set as adiabatic or convective heat transfer boundaries.

[0059] S6. In the FEM model, the nodal material state is dynamically identified based on the nodal temperature and the nodal volume fraction. By defining shock wave pressure parameters including pressure amplitude, waveform, timing of action, and area of ​​action, a strengthening laser shock wave pressure corresponding to the strengthening laser shock wave pressure model is applied, and thermo-mechanical coupled finite element calculation is performed to obtain the residual stress distribution results during the forging and printing process and after the forming is completed for the specified alloy. Specifically, in this embodiment, during the thermo-mechanical coupled finite element calculation, multiple analysis steps are set to simulate the layer-by-layer manufacturing process. All time steps are calculated iteratively, and the material state and stress distribution are dynamically updated to output the final residual stress distribution results. This allows the system to analyze the influence of shock wave parameters on residual stress. The residual stress distribution results include residual stress (such as Mises stress) distribution data, deformation results, etc., which are not limited here.

[0060] In step S6, the nodal material state is dynamically identified in the FEM model based on the nodal temperature and the nodal volume fraction, and a strengthening laser shock wave pressure corresponding to the strengthening laser shock wave pressure model is applied. A thermo-mechanical coupled finite element calculation is performed to obtain the residual stress distribution results during and after the forging and printing of the specified alloy, including: S601. In the FEM model, based on the node temperature and the node volume fraction, the node material state corresponding to each node is dynamically identified; wherein, the node material state is gaseous, liquid, or solid. S602. For different nodal material states, call the corresponding material constitutive model; wherein, the material constitutive model is an elastoplastic constitutive model corresponding to the solid region or a fluid model corresponding to the liquid region; S603. Apply the enhanced laser shock wave pressure corresponding to the enhanced laser shock wave pressure model to the node region identified as liquid, and perform thermo-mechanical coupled finite element calculation to obtain the residual stress distribution results.

[0061] In this embodiment, by introducing a multi-criteria material state identification mechanism based on volume fraction and temperature, it is possible to accurately distinguish between unmelted powder, molten metal, and solidified material, overcoming the limitation of traditional methods that rely solely on temperature thresholds, thereby significantly improving the physical rationality of stress calculations. Simultaneously, by applying the enhanced laser shock wave pressure only to the liquid region that meets the physical state conditions, the location and timing of the impact load can be made closer to the actual process, effectively improving the reliability of residual stress prediction results.

[0062] In step S6, after obtaining the residual stress distribution results during and after the forging and printing of the specified alloy, the method further includes: S7. Compare the residual stress distribution results with the experimental measurement results to verify the accuracy of the results.

[0063] Specifically, in this embodiment, the stress values ​​in the residual stress distribution results can be extracted along a specific path, and compared point-to-point with the residual stress data measured by experiments such as X-ray diffraction or drilling. The average error and correlation coefficient between the two are calculated to quantitatively verify the prediction accuracy of the CFD-FEM model composed of the CFD model and the FEM model in this embodiment.

[0064] In this embodiment, by quantitatively comparing the simulation results with the experimental measurement results, the predictive capability of the CFD-FEM model is verifiable, so that residual stress analysis is no longer limited to the theoretical level, but has the credibility for engineering applications.

[0065] Furthermore, in this embodiment, the optimal process parameter window for laser forging printing can be determined based on the residual stress distribution results, so as to optimize the forging printing process parameters. Based on this, a low residual stress process window can be quickly screened without a large number of experiments, significantly reducing process development costs and shortening the R&D cycle.

[0066] This embodiment is applicable to forging printing processes and offers high accuracy in residual stress analysis. Specifically, in the implementation process, firstly, by setting a continuous laser heat source model and a reinforced laser shock wave pressure model in the CFD model, a reinforced laser is introduced into the additive manufacturing process. The CFD model is used to accurately simulate the molten pool dynamics during the laser-powder interaction process, thereby achieving a high-precision description of the molten pool dynamics. Subsequently, an FEM model is constructed based on the node coordinates, and the CFD model and the FEM model are sequentially coupled, allowing the real temperature field and material state information during laser melting, molten pool flow, and solidification to be accurately transferred to the FEM model. Finally, thermo-coupled finite element analysis is performed using the FEM model to obtain the residual stress distribution results, thereby achieving high-precision prediction of the residual stress evolution during laser forging printing and avoiding systematic errors introduced by simplification of molten pool morphology and material state. In this process, by introducing enhanced laser shock wave load in the FEM analysis stage and combining it with the dynamic identification mechanism of material state, this embodiment can accurately describe the transient plastic deformation caused by shock wave in the forging printing process and its influence on the evolution of residual stress, making the residual stress prediction results closer to the actual forming state, thereby significantly improving the accuracy and engineering applicability of residual stress analysis.

[0067] As an example, the following discloses a residual stress analysis scheme for laser forging printing when the specified alloy is AlSi10Mg: A1. CFD Model Establishment and Solution: First, a three-dimensional CFD model of the shock wave forging printing process of AlSi10Mg alloy was established. The CFD model includes a substrate and a powder layer, discretized using a hexahedral mesh, with mesh refinement performed in the laser scanning area. A three-dimensional Gaussian heat source model was set up, defining process parameters such as laser power and scanning speed. The calculations considered the relationship between the material's thermophysical parameters and temperature, including thermal conductivity, specific heat capacity, and density; and also considered the influence of the enhanced laser force effect on the molten pool flow and morphology.

[0068] A2. Data Transmission and Processing: The CFD calculation results are imported into the data processing program to extract nodal coordinates, nodal temperatures, and nodal volume fractions. Based on the nodal coordinates, a corresponding FEM hexahedral mesh is generated, establishing a mapping relationship between the CFD model and the FEM model mesh. Temperature data is filtered to correct anomalous temperature values, ensuring the data is suitable for subsequent stress analysis calculations.

[0069] A3. Shock wave pressure loading and FEM solution: A thermo-mechanical coupling analysis model was established in FEM software. Shock wave pressure parameters were defined, including pressure amplitude, pressure waveform, timing of impact, and impact area. A custom subroutine was used to dynamically determine the node state, distinguishing between solid, liquid, and gaseous nodes based on volume fraction and temperature, and assigning corresponding material properties. Boundary conditions were set, including substrate constraints and thermal boundary conditions.

[0070] A4. Solution, Calculation, and Result Analysis: The FEM solver was used to simulate the entire laser forging printing process. After the calculation was completed, the residual stress distribution results were extracted, and the influence of shock wave parameters on residual stress was analyzed. By comparing the calculation results of different parameter combinations, the optimal process window was determined.

[0071] A5. Model Validation: The accuracy of the simulation results is verified by experimental measurement methods. The measured residual stress data are compared with the simulation results to evaluate the prediction accuracy of the model.

[0072] Example 2: This embodiment discloses a forging printing residual stress analysis system for implementing the forging printing residual stress analysis method in Embodiment 1; such as Figure 2 As shown, the forging printing residual stress analysis system includes: The CFD model building module is used to build a CFD model of a specified alloy forging printing process; The CFD calculation module is communicatively connected to the CFD model construction module. It is used to set up a continuous laser heat source model and an enhanced laser shock wave pressure model in the CFD model, and to perform transient CFD calculations to obtain CFD calculation results. The CFD calculation module is also used to extract the node coordinates, node temperature and node volume fraction corresponding to each time step from the CFD calculation results. The FEM model building module is communicatively connected to the CFD calculation module and is used to build an FEM model based on the node coordinates and establish a mapping relationship between the grid nodes of the CFD model and the grid nodes of the FEM model. The FEM model building module is also used to transfer the node temperature to the FEM model through node mapping. The FEM calculation module is communicatively connected to the FEM model construction module. It is used to dynamically identify the nodal material state in the FEM model based on the nodal temperature and the nodal volume fraction, and to load the enhanced laser shock wave pressure corresponding to the enhanced laser shock wave pressure model to perform thermo-mechanical coupled finite element calculations to obtain the residual stress distribution results.

[0073] It should be noted that the working process, working details and technical effects of the forging printing residual stress analysis system provided in this embodiment 2 can be found in embodiment 1, and will not be repeated here.

[0074] Example 3: Based on Embodiment 1 or 2, this embodiment discloses an electronic device, which may be a smartphone, tablet computer, laptop computer, or desktop computer, etc. The electronic device may be referred to as a user terminal, portable terminal, desktop terminal, etc. Figure 3 As shown, the electronic device includes: Memory, used to store computer program instructions; and, A processor is used to execute the computer program instructions to perform the operation of a forging printing residual stress analysis method as described in any of Embodiment 1.

[0075] Specifically, processor 301 may include one or more processing cores, such as a quad-core processor or an octa-core processor. Processor 301 may be implemented using at least one hardware form of DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), or PLA (Programmable Logic Array). Processor 301 may also include a main processor and a coprocessor. The main processor, also known as a CPU (Central Processing Unit), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, processor 301 may integrate a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content required to be displayed on the screen.

[0076] The memory 302 may include one or more computer-readable storage media, which may be non-transitory. The memory 302 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In some embodiments, the non-transitory computer-readable storage media in the memory 302 are used to store at least one instruction, which is executed by the processor 301 to implement the forging printing residual stress analysis method provided in Embodiment 1 of this application.

[0077] In some embodiments, the terminal may also optionally include a communication interface 303 and at least one peripheral device. The processor 301, memory 302, and communication interface 303 can be connected via a bus or signal line. Each peripheral device can be connected to the communication interface 303 via a bus, signal line, or circuit board. Specifically, the peripheral device includes at least one of a radio frequency circuit 304, a display screen 305, and a power supply 306.

[0078] The communication interface 303 can be used to connect at least one I / O (Input / Output) related peripheral device to the processor 301 and the memory 302. In some embodiments, the processor 301, the memory 302, and the communication interface 303 are integrated on the same chip or circuit board; in some other embodiments, any one or two of the processor 301, the memory 302, and the communication interface 303 can be implemented on separate chips or circuit boards, which is not limited in this embodiment.

[0079] The radio frequency (RF) circuit 304 is used to receive and transmit RF (Radio Frequency) signals, also known as electromagnetic signals. The RF circuit 304 communicates with communication networks and other communication devices via electromagnetic signals.

[0080] Display screen 305 is used to display the UI (User Interface). The UI may include any combination of graphics, text, icons, and video.

[0081] Power supply 306 is used to supply power to various components in electronic devices.

[0082] Example 4: Based on any one of Embodiments 1 to 3, this embodiment discloses a computer program product, including a computer program or instructions, which, when executed by a computer, implements a forging printing residual stress analysis method as described in any one of Embodiments 1. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.

[0083] Obviously, those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device, or fabricating them separately as individual integrated circuit modules, or fabricating multiple modules or steps as a single integrated circuit module. Thus, the present invention is not limited to any particular hardware and software combination.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for analyzing residual stress in forging printing, characterized in that, include: Construct a CFD model of the forging and printing process of a specified alloy; A continuous laser heat source model and an enhanced laser shock wave pressure model are set in the CFD model, and transient CFD calculations are performed to obtain the CFD calculation results. The node coordinates, node temperatures, and node volume fractions corresponding to each time step are extracted from the CFD calculation results. Based on the node coordinates, an FEM model is constructed, and a mapping relationship is established between the mesh nodes of the CFD model and the mesh nodes of the FEM model. The node temperature is transmitted to the FEM model via node mapping. In the FEM model, the nodal material state is dynamically identified based on the nodal temperature and the nodal volume fraction, and the enhanced laser shock wave pressure corresponding to the enhanced laser shock wave pressure model is applied to perform thermo-mechanical coupled finite element calculations to obtain the residual stress distribution results.

2. The method for analyzing residual stress in forging printing according to claim 1, characterized in that, Construct a CFD model of the forging and printing process of a specified alloy, including: Obtain the geometric dimensional parameters of the powder layer, substrate and their relative positional relationship during the forging and printing process of a specified alloy, as well as the thermal properties of the specified alloy in powder and solid states; Based on the geometric parameters and the thermal property parameters, a three-dimensional computational domain containing the powder layer and the substrate is constructed to generate an initial CFD model; The initial CFD model is meshed to generate a CFD model that can be used for numerical solution.

3. The method for analyzing residual stress in forging printing according to claim 1, characterized in that, The continuous laser heat source model adopts the Gaussian body heat source model; in the enhanced laser shock wave pressure model, the peak value of the shock wave pressure generated by the enhanced laser is calculated by the Fabbro formula.

4. The method for analyzing residual stress in forging printing according to claim 1, characterized in that, The node coordinates, node temperature, and node volume fraction corresponding to each time step are extracted from the CFD calculation results, including: Extract the original node data corresponding to each time step from the CFD calculation results; wherein, the original node data includes the initial node coordinates, the initial node temperature, and the initial node volume fraction; The original node data is processed for data alignment, unit unification, and outlier correction to generate standardized original node data; The standardized raw node data is organized according to a time series to obtain the node coordinates, node temperature, and node volume fraction corresponding to each time step.

5. The method for analyzing residual stress in forging printing according to claim 1, characterized in that, When the node temperature is transmitted to the FEM model through node mapping, the nearest neighbor interpolation algorithm built into the FEM software is used.

6. The method for analyzing residual stress in forging printing according to claim 1, characterized in that, In the FEM model, the nodal material state is dynamically identified based on the nodal temperature and the nodal volume fraction. A strengthening laser shock wave pressure corresponding to the strengthening laser shock wave pressure model is applied, and thermo-mechanical coupled finite element calculations are performed to obtain the residual stress distribution results, including: In the FEM model, the nodal material state of each node is dynamically identified based on the nodal temperature and the nodal volume fraction; wherein the nodal material state is gaseous, liquid, or solid. For different nodal material states, the corresponding material constitutive model is invoked; wherein, the material constitutive model is an elastoplastic constitutive model corresponding to the solid region or a fluid model corresponding to the liquid region; A reinforced laser shock wave pressure corresponding to the reinforced laser shock wave pressure model is applied to the node region identified as liquid, and thermo-mechanical coupled finite element calculation is performed to obtain the residual stress distribution results.

7. The method for analyzing residual stress in forging printing according to claim 1, characterized in that, After obtaining the residual stress distribution results, the method further includes: The residual stress distribution results were compared with experimental measurements to verify the accuracy of the results.

8. A forging printing residual stress analysis system, characterized in that, include: The CFD model building module is used to build a CFD model of a specified alloy forging printing process; The CFD calculation module is communicatively connected to the CFD model construction module. It is used to set up a continuous laser heat source model and an enhanced laser shock wave pressure model in the CFD model, and to perform transient CFD calculations to obtain CFD calculation results. The CFD calculation module is also used to extract the node coordinates, node temperature and node volume fraction corresponding to each time step from the CFD calculation results. The FEM model building module is communicatively connected to the CFD calculation module and is used to build an FEM model based on the node coordinates and establish a mapping relationship between the grid nodes of the CFD model and the grid nodes of the FEM model. The FEM model building module is also used to transfer the node temperature to the FEM model through node mapping. The FEM calculation module is communicatively connected to the FEM model construction module. It is used to dynamically identify the nodal material state in the FEM model based on the nodal temperature and the nodal volume fraction, and to load the enhanced laser shock wave pressure corresponding to the enhanced laser shock wave pressure model to perform thermo-mechanical coupled finite element calculations to obtain the residual stress distribution results.

9. An electronic device, characterized in that, include: Memory is used to store computer program instructions; as well as, A processor is configured to execute the computer program instructions to perform the operation of a forging printing residual stress analysis method as described in any one of claims 1 to 7.

10. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or the instructions are executed by the computer, they implement a forging printing residual stress analysis method as described in any one of claims 1 to 7.

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