Laser fusion forging multi-physics field integrated numerical simulation method and laser fusion forging multi-physics field integrated numerical simulation system

Abstract

The invention discloses a laser fusion forging multi-physics field integrated numerical simulation method and system, and belongs to the technical field of additive manufacturing. The numerical simulation method comprises the steps that a three-dimensional geometric computational domain is established; based on the computational domain, a mass source item is introduced into a mass conservation equation to simulate the coaxial powder feeding laser cladding process; based on the mass source item, phase fraction field distribution is solved, and then a metal and gas interface is determined; determining temperature field distribution of the computational domain based on the phase fraction field; based on the phase fraction field and the temperature field, dynamically updating the material attribute of each region of the computational domain; calculating a flow field of the liquid metal based on a fluid momentum conservation equation under the constraint of the updated material attributes; and based on the phase fraction field and the temperature field, solving a solid momentum conservation equation, and determining a stress field of the solid region. According to the method, a unified multi-physics field solving framework is established, the problem of heat-flow and heat-force model separation in a traditional method is avoided, and the integrity and accuracy of defect prediction are effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, and specifically relates to a multi-physics integrated numerical simulation method and system for laser melting and forging. Background Technology

[0002] Laser melting and forging is an advanced manufacturing process that combines laser additive manufacturing with localized plastic deformation technology. For example... Figure 1 As shown, this process simultaneously achieves material deposition and performance enhancement through the synergistic effect of two lasers: a pre-laser cladding laser melts and deposits the material, while a subsequent pulsed laser acts on the solidified region, inducing localized plastic deformation, thereby reducing porosity and residual stress, and improving forming quality and mechanical properties. With the increasing demands for reliability and extended service life repair of key metal components in high-end manufacturing, traditional welding and thermal spraying processes are insufficient in ensuring repair quality and performance stability. Laser forging, by simultaneously achieving material reconstruction and performance enhancement, is suitable for high-quality repair of high-value-added components such as aero-engines and energy pipelines, effectively extending service life, reducing replacement costs, and demonstrating significant engineering application value.

[0003] Laser cladding and laser shock annealing involve the coupling and dynamic interaction of multiple physical mechanisms, including heat conduction, molten pool flow, residual stress accumulation and release, and microstructure evolution, requiring numerical simulation for analysis. However, existing numerical simulation methods for laser cladding and laser shock annealing processes have shortcomings. Specifically, simulations of laser cladding and laser shock annealing are typically performed independently using different software, making it difficult to achieve integrated simulation of the thermo-fluid-mechanical multiphysics fields within a single numerical framework. In particular, cladding simulations often employ Computational Fluid Dynamics (CFD) software, focusing on the flow field (e.g., publication CN108193204B) and the melting and solidification process, neglecting the influence of the solid stress field. Shock annealing simulations, on the other hand, rely on the Finite Element Method (FEM) software, focusing on stress response analysis but ignoring the dynamic flow behavior of the molten pool. This separation in modeling and solution methods leads to fragmented simulations of the multiphysics fields in the overall laser cladding and annealing process, making it difficult to fully represent the true physical processes. Therefore, there is an urgent need to develop a new integrated numerical simulation method and system for laser melting and forging using multiple physics fields. Summary of the Invention

[0004] To address the above problems, this invention discloses a multiphysics-integrated numerical simulation method for laser melting and forging, comprising: Establish a three-dimensional geometric computational domain; Based on the computational domain, the coaxial powder feeding laser cladding process is simulated by introducing a mass source term into the mass conservation equation; Solving the phase fraction field distribution based on the mass source term, and then determining the metal and gas interface; Determining the temperature field distribution of the calculation domain based on the phase fraction field; Based on the phase fraction field and the temperature field, dynamically updating the material properties of each region of the calculation domain; Under the constraint of the updated material properties, calculating the flow field of the liquid metal based on the fluid momentum conservation equation; Based on the phase fraction field and the temperature field, solving the solid momentum conservation equation to determine the stress field of the solid region.

[0005] Further, the establishment of the three-dimensional geometric calculation domain includes the following steps: Based on the actual laser forging workpiece and the processing area, a three-dimensional geometric calculation domain is established, the calculation domain is meshed, and initial conditions and boundary conditions are set.

[0006] Further, the mass conservation equation is determined by the following formula:

[0007] wherein, p the density, t time, the gradient operator, the fluid velocity, the mass source.

[0008] Further, the phase fraction field is determined by the following formula:

[0009] wherein, the mass source rate, the phase fraction.

[0010] Further, the determination of the temperature field distribution of the calculation domain based on the phase fraction field includes the following steps: Based on the phase fraction field, a laser heat source model is introduced into the energy conservation equation to determine the temperature field distribution of the calculation domain, and the temperature evolution characteristics of the metal material under the action of the laser are obtained.

[0011] Further, the energy conservation equation is as follows:

[0012]

[0013] wherein, T temperature, heat capacity, k thermal conductivity, S L solid-liquid phase change latent heat, is the evaporative heat loss, is the radiative heat loss, is the laser heat source input, is the energy distribution coefficient, A is the absorption rate of the powder to the heat beam, P is the cladding laser power, x is the spatial x coordinate of the laser heat source, y is the spatial y coordinate of the laser heat source, is the radius of the cladding laser beam.

[0014] Further, the fluid momentum conservation equation is determined by the following formula:

[0015] wherein, p is the pressure, g is the gravitational acceleration, is the dynamic viscosity, is the buoyancy, is the drag force, is the surface tension, is the Marangoni force, is the recoil pressure.

[0016] Further, the solid momentum conservation equation is determined by the following formula:

[0017] wherein, D is the displacement vector, is the Cauchy stress, is the laser impact pressure.

[0018] Further, after the stress field of the solid region is determined based on the phase fraction field and the temperature field, solving the solid momentum conservation equation, the method further comprises the following steps: updating the time step, repeating the solving of the multiple physical fields in the above steps until a preset simulation termination time step is reached.

[0019] The application also discloses a laser forging multi-physical field integrated numerical simulation system, comprising: a building unit configured to build a three-dimensional geometric calculation domain; a simulation unit configured to simulate the coaxial powder feeding laser cladding process based on the calculation domain and the mass conservation equation; a phase fraction field unit configured to solve the phase fraction field distribution based on the mass conservation equation, and further determine the metal-gas interface; a temperature field unit configured to determine the temperature field distribution of the calculation domain based on the phase fraction field; a material property unit, configured to dynamically update material properties of each region of the calculation domain based on the phase fraction field and the temperature field; a flow field unit, configured to calculate a flow field of the liquid metal based on a fluid momentum conservation equation under the constraint of the updated material properties; a stress field unit, configured to solve a solid momentum conservation equation based on the phase fraction field and the temperature field to determine a stress field of the solid region.

[0020] Compared with the prior art, the embodiments of the present application have at least the following advantages: (1) The present application establishes a unified multi-physical field solving framework, integrates heat conduction, molten pool flow and thermal response modules in the same calculation platform, avoids the problem of splitting of heat-flow and heat-force models in traditional methods, and effectively improves the integrity and accuracy of defect prediction.

[0021] (2) The present application can provide complete temperature field, flow field and stress / strain field and other key data outputs, provide theoretical support for revealing the evolution mechanism of manufacturing defects, the formation of residual stress and the influence law of process parameters, and help the optimization of repair process of complex components such as aero-engine and energy pipeline and the landing of engineering application.

[0022] (3) The present application is developed based on the OpenFOAM (Open Field Operation and Manipulation) open source platform, has good modularity and openness, is convenient for users to flexibly modify control equations, boundary conditions and constitutive relations according to different material systems and laser parameters, supports subsequent extension of organization evolution, crack prediction and other functions, and meets the needs of simulation depth and expandability of various engineering applications.

[0023] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the structures indicated in the specification and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0025] Figure 1 An engineering diagram of double laser synergy in laser forging process is shown; Figure 2A flow chart of the laser fusion forging multi-physical field integrated numerical simulation method according to the embodiment of the present application is shown. Figure 3 A typical scanning path and fusion forging area grid division schematic diagram according to the embodiment of the present application is shown. Figure 4 A Gaussian heat source energy distribution schematic diagram according to the embodiment of the present application is shown. DETAILED DESCRIPTION

[0026] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0027] The present application aims to overcome the problem of fragmented multi-physical field solution and insufficient calculation accuracy in the existing laser fusion forging process simulation, and proposes a laser fusion forging multi-physical field integrated numerical simulation method. The method realizes modeling of the whole process of cladding and impact strengthening in a unified framework, completely describes the multi-physical field behavior of the whole process of laser fusion forging, and provides reliable technical support for process optimization, quality improvement and engineering application.

[0028] As shown in Figure 2 A laser fusion forging multi-physical field integrated numerical simulation method proposed by the embodiment of the present application includes the following steps: Step 1: Geometric modeling: establish a three-dimensional geometric calculation domain; Based on the actual laser fusion forging workpiece and processing area, a three-dimensional geometric calculation domain containing complete laser scanning path and its surrounding heat affected zone is established in the OpenFOAM calculation platform, which has the ability to adapt to complex scanning paths and multi-layer multi-pass forming processes. As shown in Figure 3As shown, the calculation domain mainly includes two parts of the lower metal substrate area and the upper argon protection area. The OpenFOAM self-provided grid generation tool is used for finite volume grid division of the calculation domain: firstly, the basic hexahedral structure grid is generated; then, according to the laser scanning track and the expected molten pool position, hierarchical encryption is implemented in the key area, so that the grid size of the molten pool and the heat affected zone is accurately controlled in the order of 2-10 μm, meeting the accuracy requirement of multi-physical field coupling calculation; at the same time, the progressive coarse grid strategy is adopted for the peripheral area, which significantly reduces the calculation cost on the premise of ensuring the accurate implementation of boundary conditions. Then, the initial conditions and boundary conditions required for multi-physical field calculation are applied in the calculation domain, laying a foundation for subsequent multi-physical field numerical solution. The grid division supports full three-dimensional unstructured grid layout, and can implement fine grid arrangement in key areas (such as molten pool, heat affected zone, etc.) according to the physical characteristics of the region combined with multi-scale local encryption strategy, so as to balance the requirements of calculation efficiency and accuracy, and lay a foundation for high-precision solution of subsequent heat-flow-force multi-physical field.

[0029] The initial condition setting includes: the initial value of the temperature field is set as the ambient temperature, to reflect the thermal state of the workpiece before being affected by the laser; the velocity field is initially set as a static state, which meets the physical conditions that the powder is not sent in and the molten pool has not been formed; the phase fraction field is set according to the initial state of the workpiece, the substrate area is a pure solid metal phase (phase fraction is 1), and the gas phase area is a pure gas phase (phase fraction is 0), to ensure the clear interface between the solid substrate and the surrounding gas.

[0030] The boundary condition setting includes: the outer surface of the calculation domain can be applied with zero gradient or adiabatic temperature boundary condition, to simulate the natural heat exchange or adiabatic state between the system and the outside world; the pressure field and the phase fraction field are applied with zero gradient condition at the boundary, to ensure the continuous transmission of physical field variables and the consistency of molten pool dynamic evolution; the displacement field is applied with zero gradient condition at the free boundary or unconstrained surface, to truly simulate the mechanical response of the workpiece during the cladding process. Through the continuous setting of the above initial conditions and boundary conditions, a reasonable calculation basis can be provided for the multi-physical field coupling solution, and the physical field variables in the simulation process are ensured to evolve stably and continuously. The boundary conditions include velocity boundary, temperature boundary, pressure boundary and displacement boundary.

[0031] This step provides unified spatial and boundary constraint conditions for the whole simulation, which is the premise of all subsequent steps.

[0032] Step 2: Coaxial powder feeding modeling: according to the current tAt the moment, the calculation domain and initial conditions and boundary conditions established in step 1 are used to start the simulation of the laser cladding process. In the coaxial powder feeding laser cladding process, metal powder is fed coaxially with the laser beam from the nozzle and is melted and deposited under the action of laser heating to form a dense cladding layer. In numerical modeling, the mass in the molten pool increases continuously due to powder injection, so the coaxial powder feeding laser cladding process is simulated by introducing a mass source term in the mass conservation equation. This mass source term can be simplified based on the powder feeding rate and the spatial coupling characteristics of the laser beam and the carrier gas flow, thereby improving the realism of the cladding process simulation. The specific expression is: (1) In the formula, p is the density, t is the time, is the gradient operator, is the fluid velocity, is the mass source.

[0033] Step 3: Multiphase flow solution: Start the simulation of the laser scanning process and scan along the set path on the substrate. Based on the mass source input in step 2, use the Volume of Fluid (VOF, Fluid Volume Method) multiphase flow model to solve the phase fraction field distribution and determine the metal-gas interface. The control equation of the VOF multiphase flow model is as follows: (2) In the formula, is the mass source rate, is the gradient operator, is the volume fraction of the metal phase (i.e. phase fraction), which represents its proportion in the grid element. When , it means that the current grid is all metal phase; when , the grid is all gas phase; and when , the metal phase and gas phase coexist in the grid element, which is called "interface element" and represents the dispersion interface region between the two phases.

[0034] This model describes the occupation proportion of the metal phase and the gas phase through the phase fraction function, thereby realizing the explicit tracking and dynamic evolution simulation of the liquid metal-gas phase interface. The phase fraction field obtained not only reflects the real-time changes of the molten pool morphology with time, but also provides the solidification track interface geometry.

[0035] To improve the accuracy of the interface tracking, the initial distribution of the phase fraction function in the VOF model should match the initial state of the molten pool, and the boundary region can be set to zero gradient form. During the simulation, a small time step is preferred, and local grid refinement is performed on the interface region to enhance the ability to capture the dynamic evolution of the metal / gas interface and ensure the continuity and stability of the interface topography.

[0036] Step 4, temperature field solution: based on the phase fraction field, determine the temperature field distribution of the calculation domain; Based on the phase fraction field obtained in step 3, introduce the laser heat source model into the energy conservation equation to obtain the transient temperature distribution (temperature field distribution) in the calculation domain, and obtain the temperature evolution characteristics of the metal material under the action of the laser. The expression of the energy conservation equation is: (3) In the formula, T T is the temperature, Cp is the heat capacity, k k is the thermal conductivity, S L L is the solid-liquid phase change latent heat, q is the evaporation loss heat, q is the radiation loss heat, Q is the laser heat source input.

[0037] Specifically, as shown in Figure 4 , the laser heat source model can be selected as a Gaussian surface heat source model, and its expression is: (4) Where, α represents the energy distribution coefficient, A β represents the absorption rate of the powder to the heat beam, P represents the laser heat source power, x r represents the spatial x axis coordinate of the heat source, y z represents the spatial y axis coordinate of the heat source (the laser beam focus is located on the x - y plane), R represents the radius of the cladding laser beam.

[0038] The temperature field result provides input conditions for material property updating in step 5 and thermal load input for stress field solution in step 7.

[0039] In the temperature field calculation, mechanisms such as heat conduction, heat radiation, phase change latent heat release, and laser heat source input are mainly considered to dynamically simulate the temperature field changes in laser scanning. The laser heat source model can be selected as a surface Gaussian heat source, and each heat source model parameter (such as energy absorption rate, energy distribution coefficient, spot radius, scanning speed, etc.) can be reasonably calibrated and optimized according to experimental or literature data.

[0040] Step 5, updating material properties: according to the current time, the phase fraction field obtained in step 3 and the temperature field distribution result obtained in step 4, the material properties in each element in the calculation domain are dynamically adjusted and updated. Specifically, it includes: density, thermal conductivity, specific heat capacity, viscosity, Young's modulus, Poisson's ratio, yield strength and other key thermophysical and thermomechanical parameters.

[0041] The thermophysical parameters (such as thermal conductivity, specific heat capacity, density, etc.) and thermomechanical parameters (such as Young's modulus, yield strength, Poisson's ratio, etc.) of the material are set as temperature-dependent functions, so as to accurately reflect the performance evolution of the material in the melting, solidification and thermal cycle stages.

[0042] Further, in the solid, liquid and gas phase regions, the material properties of each phase are predefined as temperature-dependent functions, so that the property values can dynamically respond to local temperature changes. In the grid elements in the phase transition region (such as the solid-liquid interface region), the proportion of each phase is calculated through the comprehensive information of the phase fraction function and the temperature field, and the weighted average method is used to determine the equivalent material properties of the grid element, so as to realize the continuous transition of the solid-liquid-gas three-phase material performance.

[0043] Through this step, the material parameters used in the flow field solving (step 6) and stress field solving (step 7) can reflect the temperature distribution and phase change of the material in the cladding process in real time, so as to ensure the accuracy and physical reality of the multi-physical field coupling simulation.

[0044] Step 6, flow field solving: based on the fluid momentum conservation equation, the flow field of the liquid metal is calculated under the constraint of the updated material properties; Solve the fluid momentum conservation equation (incompressible Navier-Stokes equation) to calculate the transient velocity field of the liquid metal in the molten pool, which accurately describes the internal flow behavior. The expression of the fluid momentum conservation equation is as follows: (5) In the formula, p is the pressure, g is the gravitational acceleration, is the dynamic viscosity, is the buoyancy, is the drag force, is the surface tension, is the Marangoni force, is the recoil pressure.

[0045] To balance the simulation accuracy and computational efficiency, the molten pool can be simplified as an incompressible Newtonian fluid model. Considering the small size of the molten pool and low Reynolds number in the laser scanning process, the laminar flow assumption can be further introduced to simplify the calculation of fluid flow in the molten pool, improve the simulation efficiency and stability. On the driving force of the molten pool flow, the main consideration is gravity, drag force, surface tension, Marangoni effect and recoil pressure.

[0046] Step 7, stress field solution: combining the phase fraction field calculated from step 3 and the temperature field calculated from step 4, and combining the laser impact load model, the stress field and strain field distribution of the solid region (i.e. solidified metal region) are calculated by solving the solid momentum conservation equation, which is expressed as follows: (6) In the formula, D is the displacement vector, is the Cauchy stress, is the laser impact pressure.

[0047] Specifically, when solving the solid momentum conservation equation, all fluid phases (liquid and gas phases) are regarded as "pseudo-solid" materials. That is, artificially giving them a very small yield stress, a Poisson's ratio close to 0.5 and a smaller Young's modulus, then the mechanical parameters of the solid and fluid interface region material (such as yield strength, Poisson's ratio and Young's modulus) can be calculated according to the phase fraction and liquid metal volume fraction : (7) In the formula, represents the mechanical parameters of the pure solid phase; represents the mechanical parameters of the liquid phase; represents the mechanical parameters of the gas phase. Among them, the mechanical parameters of the material are determined by formula (7), and the stress field is solved by formula (6).

[0048] The liquid metal volume fraction can be determined by the error function related to the temperature: (8) In the formula, is the arithmetic mean of the solidification temperature and the liquefaction temperature .

[0049] Specifically, when simulating the laser shock peening process, the spatial distribution of the shock wave (shock pressure) adopts a Gaussian function distribution form, as shown in the following formula: (9) In the formula, is the radius of the laser spot; x is x the axial coordinate, y is y the axial coordinate; is the laser shock pressure distribution over time t is the laser shock pressure distribution over time, where, is the peak plasma shock pressure, expressed as: (10) where, is the laser shock power density; is the ratio of thermal energy to internal energy within the plasma, which is generally taken as 0.1; Z is the damping impedance between the material and the confinement medium; is the unit directional vector. represents a normalized time function used to describe the change of the laser shock pressure pulse over time t. The laser shock pressure pulse adopts a triangular, half-sine wave or exponential decay time-dependent function form to accurately reflect the dynamic characteristics of the shock pressure.

[0050] In the simulation of the laser melt-forging process, the mechanical response of the solid region after cooling and solidification needs to consider the thermal stress effect caused by the temperature field distribution and thermal load caused by laser scanning. In order to accurately describe the mechanical behavior of the material under the action of significant temperature gradient and thermal cycle, the elastic-plastic constitutive model or damage mechanics model is preferably introduced to characterize the nonlinear response characteristics of the material under the condition of thermal-mechanical coupling.

[0051] Step 8, enter the next time step, repeat the solution of the multi-physical field in the above steps until the preset termination time step is reached. Specifically, it is judged whether the time t is greater than the termination time t end , if yes, end, if no, repeat the solution of the multi-physical field in the above steps. δt is the time step.

[0052] As an open-source finite volume method (FVM) computing platform, OpenFOAM has the ability of multi-physical field co-modeling and parallel computing, which is suitable for the unified numerical solution of thermal-fluid-mechanical behavior in laser fusion forging. Based on this platform, an integrated numerical simulation method can accurately predict the temperature field, stress field and flow behavior, which provides reliable support for laser fusion forging process optimization and defect control, and improves the repair efficiency and forming quality of key components of aero-engine and energy pipeline, and has significant engineering application value. The numerical simulation method realizes the integrated solution of thermal-fluid-mechanical behavior in the same OpenFOAM computing framework, avoiding the fragmentation of multi-physical fields caused by using different software to simulate the cladding and impact strengthening processes independently, so as to more accurately and efficiently reflect the physical behavior of the whole process of laser fusion forging process.

[0053] The present application can provide complete key data output such as temperature field, flow field and stress / strain field, provide theoretical support for revealing the evolution mechanism of manufacturing defects, the formation of residual stress and the influence law of process parameters, and help the optimization of repair process of complex components such as aero-engine and energy pipeline and the landing of engineering application.

[0054] The present application is developed based on the OpenFOAM open-source platform, has good modularity and openness, is convenient for users to flexibly modify the control equation, boundary condition and constitutive relation according to different material systems and laser parameters, supports subsequent extension of functions such as crack prediction, and meets the needs of simulation depth and expandability of various engineering applications.

[0055] The present application also discloses a laser fusion forging multi-physical field integrated numerical simulation system, comprising: A building unit is used to build a three-dimensional geometric calculation domain; A simulation unit is used to simulate the coaxial powder feeding laser cladding process by the mass conservation equation based on the calculation domain; A phase fraction field unit is used to solve the phase fraction field distribution based on the mass conservation equation, and then determine the metal and gas interface; A temperature field unit is used to determine the temperature field distribution of the calculation domain based on the phase fraction field; A material property unit is used to dynamically update the material properties of each region of the calculation domain based on the phase fraction field and the temperature field; A flow field unit is used to calculate the flow field of liquid metal based on the fluid momentum conservation equation under the constraint of the updated material properties; A stress field unit is used to solve the solid momentum conservation equation based on the phase fraction field and the temperature field, and determine the stress field of the solid region.

[0056] The application further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the laser forging multi-physical field integrated numerical simulation method when executing the computer program.

[0057] The application further provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the laser forging multi-physical field integrated numerical simulation method.

[0058] The application further provides a computer program product, comprising computer instructions, and the computer instructions are executed by a processor to implement the laser forging multi-physical field integrated numerical simulation method.

[0059] Although the application is described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A method for numerical simulation of laser fusion forging and multi-physical field integration, characterized in that, The method comprises the following steps: establishing a three-dimensional geometric calculation domain; simulating the coaxial powder feeding laser cladding process based on the calculation domain and a mass source term introduced in a mass conservation equation; solving a phase fraction field distribution based on the mass source term, and determining a metal-gas interface; determining a temperature field distribution of the calculation domain based on the phase fraction field; dynamically updating material properties of each region of the calculation domain based on the phase fraction field and the temperature field; calculating a flow field of liquid metal based on a fluid momentum conservation equation under the constraint of the updated material properties; solving a solid momentum conservation equation based on the phase fraction field and the temperature field, and determining a stress field of a solid region. 2.The method according to claim 1, wherein, The step of establishing the three-dimensional geometric calculation domain comprises the following steps: based on an actual laser forging workpiece and a processing region, establishing a three-dimensional geometric calculation domain, performing mesh division on the calculation domain, and setting initial conditions and boundary conditions. 3.The laser deposition welding multi-physical field integrated numerical simulation method according to claim 1 or 2, characterized in that, The mass conservation equation is determined by the following formula: wherein, The phase fraction field is determined by the following formula: is the density, t is the time, is the gradient operator, is the fluid velocity, is the mass source. 4.The method according to claim 1, wherein, The step of determining the temperature field distribution of the calculation domain based on the phase fraction field comprises the following steps: wherein is the mass source rate, is the phase fraction.

5. The method of claim 1, wherein, based on the phase fraction field, introducing a laser heat source model in an energy conservation equation, determining the temperature field distribution of the calculation domain, and obtaining temperature evolution characteristics of the metal material under the action of the laser. The energy conservation equation is as follows:

6. The method of claim 5, wherein, The fluid momentum conservation equation is determined by the following formula: wherein, T T is the temperature, C is the heat capacity, k K is the thermal conductivity, S L L is the latent heat of solid-liquid phase change, Qe is the evaporation loss heat, Qr is the radiation loss heat, Ql is the laser heat source input, f is the energy distribution coefficient, A a is the absorption rate of the powder to the heat beam, P is the cladding laser power, x is the spatial x coordinate of the laser heat source, y is the spatial y coordinate of the laser heat source, is the radius of the cladding laser beam.

7. The method of claim 1, wherein, The solid momentum conservation equation is determined by the following formula: wherein, p is the pressure, g is the acceleration of gravity, is the dynamic viscosity, is the buoyancy force, is the drag force, is the surface tension, is the Marangoni force, is the back pressure.

8. The method of claim 1, wherein, After the step of solving the solid momentum conservation equation based on the phase fraction field and the temperature field, and determining the stress field of the solid region, the following step is included: wherein, D is the displacement vector, is the Cauchy stress, is the laser shock pressure. 9.The method according to claim 1, wherein, updating a time step, repeating the solving of the multiple physical fields in the above steps, and repeating until a preset simulation termination time step is reached. The method comprises the following steps:

10. A laser fusion forging multi-physical field integrated numerical simulation system, characterized in that, a establishing unit for establishing a three-dimensional geometric calculation domain; a simulation unit for simulating the coaxial powder feeding laser cladding process based on the calculation domain and a mass conservation equation; a phase fraction field unit for solving a phase fraction field distribution based on the mass conservation equation, and determining a metal-gas interface; a temperature field unit for determining a temperature field distribution of the calculation domain based on the phase fraction field; a material property unit for dynamically updating material properties of each region of the calculation domain based on the phase fraction field and the temperature field; a flow field unit for calculating a flow field of liquid metal based on a fluid momentum conservation equation under the constraint of the updated material properties; a stress field unit for solving a solid momentum conservation equation based on the phase fraction field and the temperature field, and determining a stress field of a solid region. ​

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