Electric arc additive real-time simulation and model prediction method based on event sequence

Abstract

The invention relates to an arc additive real-time simulation and model prediction method based on an event sequence, and the method comprises the steps: activating a unit in real time through the event sequence, and guiding a heat source in real time in the real-time process of arc additive manufacturing of a metal structure; heat source model parameters, thermal simulation parameters and mechanical simulation parameters are set, and electric arc additive manufacturing thermal-mechanical coupling real-time simulation is carried out; and establishing a residual stress field simplified calculation theoretical model, and correcting calculation model prediction. The method has the advantages that real-time simulation of the electric arc additive manufacturing process is carried out in an event sequence mode, the modeling difficulty is remarkably reduced, unit activation does not depend on a large number of analysis steps any more, unit activation can be carried out along with the event sequence in a single analysis step, and the operation complexity is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and more specifically, to an event sequence-based arc additive real-time simulation and model prediction method. Background Art

[0002] With the continuous advancement of modern intelligent manufacturing technology, wire arc additive manufacturing (WAAM), as an innovative process that combines traditional welding technology and modern additive manufacturing technology, has gradually become a research hotspot in the field of metal additive manufacturing due to its high material utilization rate and good workpiece forming ability.

[0003] WAAM technology uses arc heat source to melt metal wire and deposit it layer by layer to form complex metal structures. In the WAAM process, due to the movement of heat source and rapid heating and cooling of materials, complex thermo-mechanical behaviors will be generated, which will affect the forming quality and mechanical properties of the structure. At present, the mechanical properties of formed structures are generally improved by heat treatment and high-pressure rolling. However, due to the high cost and complex process of these methods, there are still many challenges when they are applied to the preparation of large-scale complex metal structures. Therefore, how to effectively control the defects of formed structures in the WAAM process is particularly critical. The high heat input in the WAAM process often leads to various temperature-related defects in the formed metal structures, such as pores, microcracks, residual stress and shape distortion. The generation of residual stress and deformation of the formed structure is mainly caused by the constraint of thermal expansion and contraction of the additive part, which is directly related to the mechanical properties of the final formed structure. Therefore, it is of great significance to study and predict the thermo-mechanical behavior of the WAAM process to improve the forming quality and reduce the influence of defects.

[0004] Existing studies on the thermo-mechanical behavior of the WAAM process are mainly based on experiments, including residual stress and deformation measurements, fatigue crack growth behavior, etc. However, experimental studies are usually time-consuming and laborious, and it is difficult to extract stress at certain special locations, and it is impossible to monitor the changes in stress distribution in real time during the WAAM process. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and to propose an arc additive real-time simulation and model prediction method based on event sequence.

[0006] In the first aspect, a real-time simulation and model prediction method of arc additive based on event sequence is provided, including:

[0007] S1. In the real-time process of arc additive manufacturing of metal structures, the unit is activated in real time through an event sequence, and the heat source is guided in real time; the event sequence is used to set the virtual block to move in three-dimensional space along a pre-set path and time, and exert a three-dimensional field on the path passed by the virtual block;

[0008] S2, setting heat source model parameters, thermal simulation parameters and mechanical simulation parameters based on the event sequence method in S1, and performing arc additive manufacturing thermal-mechanical coupling real-time simulation;

[0009] S3. Based on the stress diffusion distribution and normal stress interface correction deviation obtained from the real-time simulation of thermal-mechanical coupling in S2, a simplified calculation theoretical model of the residual stress field is established, and the calculation model prediction is corrected.

[0010] Preferably, S1 comprises:

[0011] S101, using the event sequence to restore the real-time process of arc additive manufacturing, and activating the units on the path swept by the virtual block of the event sequence one by one;

[0012] S102, guiding the position of the virtual block in the event sequence as the position of the mobile heat source, using the Goldak double ellipsoid heat source model.

[0013] Preferably, S2 comprises:

[0014] S201, setting thermal simulation parameters and mechanical simulation parameters to construct a thermal-mechanical coupling simulation model; the thermal simulation parameter settings include thermal boundary conditions, phase change latent heat, thermal conductivity and specific heat settings; the mechanical simulation parameter settings include thermal expansion coefficient, material mechanical parameters, and boundary mechanical constraint settings;

[0015] S202, constructing a linear deposition simulation model to simulate a multi-layer multi-channel arc additive manufacturing deposition process, and obtaining the stress diffusion distribution of the deposition layer according to the deposition stress simulation results.

[0016] Preferably, in S202, the straight line deposition simulation model includes single straight line, double straight line and triple straight line deposition simulation models. In the single straight line deposition simulation model, the additive deposition layer is placed in the middle of the substrate; in the double straight line deposition simulation model, the additive deposition layer is placed on both longitudinal edges of the substrate; in the triple straight line deposition simulation model, the additive deposition layer is placed on both longitudinal edges and in the middle.

[0017] Preferably, S3 includes:

[0018] S301, establishing a simplified calculation theoretical model, wherein the simplified calculation theoretical model is composed of a substrate and an additive part in an arc additive manufacturing process, including a stress field distribution before and after the release of the fixture constraint; at the junction of the additive part and the substrate, there is a diffusion effect of the deposited stress before and after the release of the fixture constraint, and it presents a semicircular shape;

[0019] S302, correcting the calculation model prediction, including:

[0020] S3021. For a T-shaped cross-section integral component consisting of a substrate and an additive part, calculate the centroid height y of the substrate, the deposition wall and the integral component. s ,y d and 0 ;

[0021] S3022. Calculate the moment of inertia I of the T-shaped cross section xx ;

[0022] S3023. Calculate the deposition stress σ on the substrate during arc additive manufacturing before the fixture constraint on the substrate is released. zz The equivalent concentrated force F d and the pressure F in the substrate s ;

[0023] S3024, before the clamp constraint on the substrate is released, calculate the equivalent concentrated force F d and the pressure F in the substrate s The bending moment M about the neutral axis caused by the position offset;

[0024] S3025, after the clamp constraint on the substrate is released, calculating the deformation curvature κ of the model;

[0025] S3026. After the clamp constraint on the substrate is released, calculate the modified residual stress field σ considering the normal stress interface deviation Δy′ during the entire arc additive manufacturing process. zz,res (y);

[0026]

[0027] In the formula, y=0 is located on the neutral axis y 0 At the height; Δy′ is the correction deviation of the normal stress interface caused by the stress diffusion of the deposited layer. The correction deviation is only for the "positive" part of the longitudinal stress, that is, the tensile stress area, and the compressive stress area of ​​the substrate remains unchanged;

[0028] S3027, Calculate the descending gradient of the residual stress field

[0029] In a second aspect, a real-time simulation and model prediction system for arc additive based on an event sequence is provided, which is used to execute any method described in the first aspect, including:

[0030] An activation guidance module is used to activate the unit and guide the heat source in real time during the real-time process of arc additive manufacturing through an event sequence; the event sequence is used to set the virtual block to move in three-dimensional space along a preset path and time, and exert a three-dimensional field influence on the path passed by the virtual block;

[0031] A simulation module, used for inputting heat source model parameters, thermal simulation parameters and mechanical simulation parameters corresponding to the activation guidance module, for performing real-time thermo-mechanical simulation of arc additive manufacturing;

[0032] The prediction module is used to input the stress diffusion distribution and normal stress interface correction deviation obtained by the simulation module, to establish a simplified calculation theory model, and to correct the calculation model prediction.

[0033] According to a third aspect, a computer storage medium is provided, wherein a computer program is stored in the computer storage medium; when the computer program is executed on a computer, the computer executes any method described in the first aspect.

[0034] In a fourth aspect, an electronic device is provided, including:

[0035] Memory, used to store computer programs;

[0036] A processor is used to execute the computer program to implement any method as described in the first aspect.

[0037] The beneficial effects of the present invention are:

[0038] 1. The present invention adopts an event sequence method to perform real-time simulation of the arc additive manufacturing process, which significantly reduces the difficulty of modeling. Unit activation no longer relies on a large number of analysis steps, but can be performed in a single analysis step along with the event sequence, effectively reducing the complexity of the operation. Through the definition of the event sequence, only the position coordinates and time information need to be given to perform complex path planning, making it easier to achieve the simulation of the arc additive manufacturing process of curved welds or special-shaped structural parts.

[0039] 2. The present invention takes into account the stress diffusion distribution caused by repeated heat input at the junction of the additive part and the substrate, and makes a correct prediction on the theoretical calculation of residual stress in the arc additive manufacturing process, thereby effectively improving the real-time prediction accuracy of the model.

[0040] 3. The present invention activates units and guides heat sources through event sequences to achieve high-temperature and high-speed multi-layer and multi-channel deposition simulation in arc additive manufacturing application scenarios; through real-time thermomechanical simulation of arc additive manufacturing, the stress diffusion effect caused by repeated heat input at the interface between the additive parts and the substrate of different materials is obtained; through theoretical calculation and correction prediction of residual stress of arc additive manufacturing integral components with T-shaped cross-sections considering stress diffusion effect, efficient, real-time and accurate prediction of deposition stress and deformation in the arc additive manufacturing process is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the overall process of the arc additive real-time simulation and model prediction method based on event sequence of the present invention;

[0042] Figure 2 is a schematic diagram of the simulation of the event sequence control unit activation and moving heat source;

[0043] Figure 3a It is a schematic diagram of the molten pool morphology of the double ellipsoid heat source model;

[0044] Figure 3b It is a schematic diagram of the geometric parameters of the molten pool of the double ellipsoid heat source model;

[0045] Figure 4 It is a schematic diagram of thermal boundary conditions of the T-section integral component model;

[0046] Figure 5a It is a schematic diagram of the cross-sectional stress field of the single straight line deposition simulation model;

[0047] Figure 5b It is a schematic diagram of the cross-sectional stress field of the double straight line deposition simulation model;

[0048] Figure 5c It is a schematic diagram of the cross-sectional stress field of the three-line deposition simulation model;

[0049] Figure 6a It is a schematic diagram of the fixture constraints of the single-line deposition simulation model;

[0050] Figure 6b It is a schematic diagram of the middle narrow channel constraint of the single straight line deposition simulation model;

[0051] Figure 7 It is a schematic diagram of the temperature field of the single-line deposition simulation model during the printing process (unit: °C);

[0052] Figure 8 It is a schematic diagram of residual stress development before and after the fixture constraint is released during arc additive manufacturing;

[0053] Fig. 9It is a schematic diagram of stress diffusion in the deposited layer of the T-section integral component model before and after the clamp constraint is released;

[0054] Fig.10 It is a comparison curve of theoretical stress and simulated stress of three integral component models after deviation correction;

[0055] Fig.11 It is a schematic diagram of geometric parameters of a T-shaped cross-section integral component composed of a substrate and an additive part;

[0056] Explanation of the reference numerals: 1 - substrate; 2 - WAAM additive part; 3 - additive path; 4 - previous layer; 5 - current layer; 6 - mobile heat source; 7 - unit to be activated. DETAILED DESCRIPTION

[0057] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0058] Embodiment 1:

[0059] With the continuous improvement of computer performance, three-dimensional transient thermal-mechanical coupling numerical models are gradually being applied to the simulation research of arc welding process, which has certain similarities with arc additive process. Numerical models can be used as an effective supplementary tool for obtaining thermo-mechanical parameter information in actual arc additive experiments, and by expanding the range of parameter values, a large amount of data results that are difficult to obtain in experiments can be obtained. Therefore, it is very important to develop accurate and fast real-time simulation and model prediction methods for multi-layer and multi-channel deposition stress in combination with the arc additive manufacturing thermo-mechanical theoretical model.

[0060] In this regard, Example 1 of the present application provides an event sequence-based arc additive real-time simulation and model prediction method, which can realize real-time simulation of high-temperature and high-speed multi-layer and multi-pass deposition in arc additive manufacturing application scenarios, as well as efficient and accurate prediction of deposition stress and deformation.

[0061] Specifically, Figure 1 As shown, the method includes:

[0062] S1. In the real-time process of arc additive manufacturing of metal structures, units are activated in real time through event sequences, and heat sources are guided in real time. The event sequence is used to define a three-dimensional field that changes with time and space, which is equivalent to setting a virtual block to move in three-dimensional space along a preset path and time, and exerting a three-dimensional field on the path passed by the virtual block. Therefore, the event sequence method can be conveniently applied to the real-time simulation of arc additive manufacturing process.

[0063] S1 includes:

[0064] S101, using the event sequence to restore the real-time process of arc additive manufacturing, activating the units on the path swept by the virtual block of the event sequence one by one. The size of the virtual block is definable, and is used to control the range of the units to be activated.

[0065] like Figure 2 As shown, during the real-time simulation process, multi-layer printing and deposition of the WAAM additive part 2 is performed on the substrate 1 along the additive path 3, the completed deposition layer below is the previous layer 4, the deposition layer being printed above is the current layer 5, and the adjacent unit in front of the mobile heat source 6 of the current layer 5 is the unit to be activated 7; because the temperature fields of different simulation models are also different, the temperature field values ​​can be normalized in the temperature field cloud map, with the highest temperature set to 1 and the lowest temperature set to 0; in this embodiment, the event sequence function module of the ABAQUS software is used to perform real-time activation simulation of the unit.

[0066] S102, guiding the position of the virtual block in the event sequence as the position of the mobile heat source, using the Goldak double ellipsoid heat source model, without the need to specially write user subroutines, and significantly reducing the workload of building the heat source model guidance.

[0067] Through S101 and S102, the additive effect and heat source movement in the entire arc additive manufacturing process can be achieved using the event sequence method.

[0068] like Figure 3a , Figure 3b As shown in the figure, the Goldak double ellipsoid heat source model is a body heat source model that takes into account the laser penetration effect. It is more accurate and practical in simulating the melting phenomenon in the arc additive manufacturing process. In the Goldak double ellipsoid heat source model, the heat source is described in a non-axisymmetric manner, and its power density is Gaussian distributed in the combined double ellipsoid. The temperature gradient in front of the heat source is much steeper than that at the trailing edge of the molten pool, and the power density in the area in front of the arc center and the area behind the arc center are defined respectively.

[0069] Power density distribution q in the positive quadrant of the Z axis f for:

[0070]

[0071] Power density distribution q in the negative quadrant of the Z axis r for:

[0072]

[0073] In the formula, a 1 、a 2are the lengths of the front ellipsoid and the rear ellipsoid, respectively; b is the width of the heat source; c is the depth of the heat source; Q is the energy input considering the efficiency factor; f f and f r is the parameter for allocating the power before and after the heat source, and the two satisfy f f +f r =2.

[0074] like Figure 3b As shown in the Goldak double ellipsoid heat source model, different arc additive manufacturing processes can be simulated by adjusting the model parameters, and the parameters corresponding to the size and shape of the molten pool can be obtained; parameter a 1 、a 2 , b and c can be converted from the cross-sectional metallographic data and the corrugation marks on the molten pool surface. Different parameter values ​​represent the front and rear quadrant data of different molten pools to simulate different heat sources.

[0075] S2. Based on the event sequence method in S1, the heat source model parameters, thermal simulation parameters and mechanical simulation parameters are set to perform real-time simulation of arc additive manufacturing thermal-mechanical coupling.

[0076] S2 includes:

[0077] S201. Perform thermal simulation parameter settings and mechanical simulation parameter settings to construct a thermal-mechanical coupling simulation model; the thermal simulation parameter settings include thermal boundary conditions, phase change latent heat, thermal conductivity and specific heat settings; the mechanical simulation parameter settings include thermal expansion coefficient, material mechanical parameters, and boundary mechanical constraint settings.

[0078] During the real-time simulation process, the thermal simulation parameters that need to be set include thermal boundary conditions, latent heat of phase change, thermal conductivity and specific heat, etc., and then the event sequence method is used to calculate the three-dimensional temperature field changes in real time; when calculating the three-dimensional stress-strain field changes in real time, the real-time three-dimensional temperature field results are input as known conditions, and the mechanical simulation parameter change curves such as thermal expansion coefficient, material mechanical parameters and boundary mechanical constraints that change with the temperature field are determined, so as to calculate the three-dimensional stress-strain field results of the policy model before and after the fixture constraint is released in real time;

[0079] In the arc additive manufacturing process, in order to control the deformation of the formed structural parts, boundary mechanical constraints are imposed on the structural parts before the start of the additive manufacturing process. This constraint is usually achieved by installing a fixture on the substrate, and the fixture constraint is removed after the additive manufacturing process is completed and cooling is completed. At the same time, the thermal conductivity and specific heat, thermal expansion coefficient, and material mechanical parameters (Young's modulus, Poisson's ratio, yield strength) of the formed structural parts will change with the change of the temperature field.

[0080] like Figure 4As shown in the figure, in the thermal boundary condition setting of the T-section integral component, the thermal emissivity of the integral component surface is set to ε, and the thermal convection coefficient of the surface of the additive part and the free part of the substrate is set to h 1 , the thermal convection coefficient of the bottom surface of the substrate is set to h 2 In this embodiment, the thermal emissivity ε = 0.2, and the thermal convection coefficient h of the surface of the additive part and the free part of the substrate is 1 =5.7W / (m 2 K), the thermal convection coefficient h of the bottom surface of the substrate 2 =300W / (m 2 K).

[0081] S202, constructing a linear deposition simulation model to simulate a multi-layer multi-channel arc additive manufacturing deposition process, and obtaining the stress diffusion distribution of the deposition layer according to the deposition stress simulation results.

[0082] In S202, Figure 5a , Figure 5b , Figure 5c As shown, the linear deposition simulation model includes single-linear, double-linear and triple-linear deposition simulation models, and the three simulation models are all set as additive parts of multi-layer and multi-channel deposition, and the additive parts have the same geometric dimensions. In the single-linear deposition simulation model, the additive deposition layer is placed in the middle of the substrate; in the double-linear deposition simulation model, the additive deposition layer is placed on both longitudinal edges of the substrate; in the triple-linear deposition simulation model, the additive deposition layer is placed on both longitudinal edges and in the middle.

[0083] like Figure 6a , Figure 6b As shown in the figure, the three simulation models all use the same fixture constraint method and grid division method; taking the single straight line deposition simulation model as an example, the fixture constraint has a significant effect on the final deformation of the single straight line deposition; in order to effectively simulate the actual printing situation, a rigid support plate is added under the substrate, wherein the top surface of the support plate is the main surface, and the bottom surface of the substrate is the secondary surface, and the two are in rigid contact; this ensures that during the entire printing process, the overall component can only move along the positive direction of the Y axis; in the actual operation process, the substrate needs to be clamped to fix it on the printing platform; this condition is simulated by fixing the position of the red dot area on the upper surface of the substrate, and the fixture constraint is released at the end of the simulation process; since the deformation of this type of simulation model is mostly warping deformation at both ends, after the final fixture constraint is released, the narrow section unit in the middle of the substrate is selected and its displacement is constrained without constraining the rotation angle, so as to obtain the stress and deformation results of the simulation model.

[0084] like Figure 7As shown in the figure, in the arc additive manufacturing process, the first layer of multi-pass interlayer printing is first carried out, and after the first layer is printed, the interlayer cooling is carried out, and then the second layer is printed, and so on; for the single straight line deposition simulation model, the transient method in the ABAQUS software is used to solve the temperature field and stress-strain field of the arc additive manufacturing process; in the actual printing process, the temperature is controlled to achieve the effect of only the temperature of the newly printed part reaching the melting point, which can effectively reduce the adverse effects of material collapse on the molding quality in additive manufacturing.

[0085] S3. Based on the stress diffusion distribution and normal stress interface correction deviation obtained from the real-time simulation of thermal-mechanical coupling in S2, a simplified calculation theoretical model of the residual stress field is established, and the calculation model prediction is corrected.

[0086] Embodiment 2:

[0087] Based on Example 1, Example 2 of the present application provides a more specific arc additive real-time simulation and model prediction method based on event sequence, including:

[0088] S1. In the real-time process of arc additive manufacturing of metal structures, units are activated in real time and heat sources are guided in real time through event sequences; the event sequences are used to set a virtual block to move in three-dimensional space along a preset path and time, and to exert a three-dimensional field influence on the path passed by the virtual block.

[0089] S2. Based on the event sequence method in S1, the heat source model parameters, thermal simulation parameters and mechanical simulation parameters are set to perform real-time simulation of arc additive manufacturing thermal-mechanical coupling.

[0090] S3. Based on the stress diffusion distribution and normal stress interface correction deviation obtained from the real-time simulation of thermal-mechanical coupling in S2, a simplified calculation theoretical model of the residual stress field is established, and the calculation model prediction is corrected.

[0091] S3 includes:

[0092] S301. Establish a simplified calculation theoretical model, wherein the simplified calculation theoretical model is composed of a substrate and an additive part in an arc additive manufacturing process, including a stress field distribution before and after the clamp constraint is released.

[0093] It should be noted that at the junction of the additive part and the substrate, there is a diffusion effect of the deposition stress before and after the clamp constraint is released, and it is semicircular. This application analyzes the scenarios when the diffusion effect of the deposition stress is not considered and when the diffusion effect of the deposition stress is considered. S301 includes:

[0094] S3011. When the diffusion effect of the deposited stress is not considered, the development and redistribution of the residual stress field remain unchanged along the longitudinal length L, and any edge effect is not considered; e.g. Figure 8 As shown in the figure, before releasing the clamp constraint on the substrate, there is a tensile stress on the deposition wall caused by the arc additive manufacturing process, and a compressive stress is generated on the substrate to balance it. It is assumed that the stress on the substrate and the deposition wall is uniformly distributed in their respective parts, and there is a sudden change at the junction. The equivalent concentrated forces of the stress on the substrate and the deposition wall are F s and F d , acting on the centroid of the base plate and the wall, and at a height y from the centroid of the cross section of the overall component 0 There is a certain distance between the neutral axis height and the position.

[0095] After releasing the clamp constraint on the substrate, the ends of the overall component are in a free state, the two equivalent concentrated forces are released and an internal bending moment M is generated, the internal stress of the structure is redistributed, and becomes the final residual stress of the component; the tensile stress above the neutral axis decreases linearly, and if the height of the deposition wall is sufficient, compressive stress appears at the top of the deposition wall after stress redistribution.

[0096] S3012. When considering the diffusion effect of deposition stress, Fig. 9 As shown in the figure, before the clamp constraint is released, the deposition positive stress is not limited to the deposition wall, and it has a radial diffusion tendency in the substrate part under the interface; this is because the substrate under the interface is close to the deposition layer and is also affected by thermal expansion and contraction, and this part is cyclically subjected to the secondary effects of heating-cooling-heating during the printing process, which also produces a large deposition stress, and the deposition stress is also diffused to the substrate. The stress on the deposition wall and the substrate is roughly semicircular in the transition diffusion area, and its radius is approximately equal to the deposition width. This diffusion effect still exists after the constraint is released.

[0097] In addition, if Fig. 9 , Fig.10 As shown, the correction deviation Δy′ reflects the deviation value of the curve parallel between the theoretical model result and the simulation stress result of the deposition layer after the clamp constraint is released, which can be obtained from the stress diffusion distribution of the deposition layer in the deposition simulation calculation result of step S2.2; the correction deviation Δy′ is mainly due to the diffusion effect of the deposition layer stress, which makes the starting point of the change of the positive stress of the deposition layer drop from the interface (i.e., the longitudinal position is 0) to a certain point on the substrate after the clamp constraint is released. The stress at this position before the clamp constraint is released is equal to the stress of the deposition layer; a schematic diagram comparing the stress results of the corrected deposition simulation model and the theoretical model is drawn. The corrected theoretical model is closer to the simulation result and can more accurately predict the residual stress in the arc additive process; in this embodiment, the diffusion area is about 5mm, and Δy′=2.55mm is obtained by stress extraction and interpolation calculation.

[0098] For different deposition models, the coordinates of the deviation position are also different, and are related to many factors such as model geometry, heat source parameters and deposition materials. The corrected deviation Δy′ of the residual stress can be calculated and observed from the deposition simulation model results.

[0099] S302, correcting the calculation model prediction, including:

[0100] S3021, such as Fig.11 As shown in the figure, for a T-shaped cross-section integral component composed of a substrate and an additive part, the centroid height y of the substrate, the deposition wall and the integral component is calculated. s ,y d and 0 , the calculation formula is:

[0101] y s =t / 2 (3)

[0102] y d =W H / 2+t (4)

[0103]

[0104] Where W W is the width of the sediment wall, W H is the deposition wall height, t is the substrate thickness, and b is the substrate width.

[0105] S3022. Calculate the moment of inertia I of the T-shaped cross section xx .

[0106] Specifically, the metal wire material used in the additive part is the same as that of the substrate, and the centroid height y of the overall component is 0 It is also the neutral axis position of the T-shaped section, and the moment of inertia of the cross section I xx The calculation formula is:

[0107]

[0108] S3023. Calculate the deposition stress σ on the substrate during arc additive manufacturing before the fixture constraint on the substrate is released. zz The equivalent concentrated force F d and the pressure F in the substrate s .

[0109] Specifically, before releasing the fixture constraint on the substrate, the deposition stress σ on the substrate during arc additive manufacturing is zz The equivalent concentrated force F d It can be calculated by formula (7), and the pressure F in the substrate s Should meet F s =F d , in order to ensure the balance of internal forces.

[0110] F d =F s = -∫∫σ zz (x,y)×dA(W W ,W H )=σ zz ×W W ×W H (7)

[0111] Since the residual stress of the substrate and the deposition wall is assumed to be uniformly distributed on their respective rectangular cross sections, the corresponding equivalent concentrated force acts at the centroid of their respective rectangular cross sections, that is, F d 、F s Act on y d ,y s At height position.

[0112] S3024, before the clamp constraint on the substrate is released, calculate the equivalent concentrated force F d and the pressure F in the substrate s The bending moment M around the neutral axis caused by the position offset is calculated as follows:

[0113] M=F d (y d -y 0 )+F s (y 0 -y s )=F(y d -y s )=F(t / 2+W H / 2) (8)

[0114] S3025. After the clamp constraint on the substrate is released, the deformation curvature κ of the model is calculated.

[0115] Specifically, after the clamp constraint on the substrate is released, the deformation curvature of the model can be calculated by formula (9), where the parameters for calculating the curvature are regrouped into two categories: the material and deposition factor S determined by the deposition stress and the material elastic modulus E; and the geometric factor K determined by the geometric dimensions of the component.

[0116]

[0117] Where κ is the deformation curvature, ρ is the radius of curvature, and the unit of the material and deposition factor S is The unit of the geometric factor K is

[0118] S3026. After the clamp constraint on the substrate is released, calculate the modified residual stress field σ considering the normal stress interface deviation Δy′ during the entire arc additive manufacturing process. zz,res (y).

[0119] After the clamp constraint on the substrate is released, the stress field is redistributed, and the initial deposition stress field and the stress caused by the bending moment M are superimposed, and finally the modified residual stress field σ considering the normal stress interface deviation Δy′ in the entire arc additive manufacturing process is obtained. zz,res (y) can be calculated by formula (10):

[0120]

[0121] In the formula, y=0 is located on the neutral axis y 0 height; Δy′ is the correction deviation of the positive stress interface caused by the stress diffusion of the deposited layer. The correction deviation is only for the "positive" part of the longitudinal stress, that is, the tensile stress area, and the compressive stress area of ​​the substrate remains unchanged; for the same model, M and I xx They are all constant in the y direction, so the residual stress after the fixture constraint is released changes linearly along the y-axis direction.

[0122] S3027, Calculate the descending gradient of the residual stress field The calculation formula is:

[0123]

[0124] This embodiment also demonstrates the real-time simulation and model prediction method of arc additive based on event sequence, and its analytical application in single-line, double-line and triple-line deposition models.

[0125] like Fig.11 As shown, the shape of the single straight line deposition model is relatively regular, and the geometric dimensions of the model are: the height of the deposition wall W H =10mm, width W W =5mm, substrate width b = 60mm, thickness t = 12mm; deposition length and substrate length are both l = 250mm, deposition height h = 2.5mm, and there are 4 deposition layers in total. The additive part of the model uses a cubic unit with a side length of 1.25mm, and the substrate uses a cubic unit of 2.75×2.4×1.25mm; the moving heat source speed is 4mm / s, the interlayer cooling time is 200s, and the calculation is ended 300s after the printing is completed to ensure that the deposition model cools to the normal temperature. The total time is 1500s. The dimensions of the double-line and triple-line deposition models are the same as those of the single-line model, and the position of the additive part is shown in Figure 5.

[0126] According to equations (3) to (11), the longitudinal stress drop gradients of the single-line, double-line, and triple-line deposition models are calculated to be: 39.9Mpa / mm, 50.5Mpa / mm; the stress diffusion distribution of the deposited layer obtained by simulation calculation is as follows Fig. 9 As shown;

[0127] Considering the diffusion effect of the sediment layer, according to Fig. 9 As shown in the results, the diffusion area is about 5 mm. After stress extraction and interpolation calculation, the correction deviation Δy′=2.55 mm is substituted into formula (10) to calculate the residual stress distribution curve of the single straight line deposition model as follows: Fig.10 shown.

[0128] It should be noted that the parts in this embodiment that are the same or similar to those in Embodiment 1 can be referenced to each other and will not be described in detail in this application.

[0129] Embodiment 3:

[0130] Based on Examples 1 and 2, Example 3 of the present application provides an arc additive real-time simulation and model prediction system based on event sequence, including:

[0131] An activation guidance module is used to activate the unit and guide the heat source in real time during the real-time process of arc additive manufacturing through an event sequence; the event sequence is used to set the virtual block to move in three-dimensional space along a preset path and time, and exert a three-dimensional field influence on the path passed by the virtual block;

[0132] A simulation module, used for inputting heat source model parameters, thermal simulation parameters and mechanical simulation parameters corresponding to the activation guidance module, for performing real-time thermo-mechanical simulation of arc additive manufacturing;

[0133] The prediction module is used to input the stress diffusion distribution and normal stress interface correction deviation obtained by the simulation module, to establish a simplified calculation theory model, and to correct the calculation model prediction.

[0134] Specifically, the system provided in this embodiment is a system corresponding to the method provided in Embodiments 1 and 2. Therefore, the parts in this embodiment that are the same or similar to Embodiments 1 and 2 can be referenced to each other and will not be repeated in this application.

[0135] In summary, the real-time simulation and model prediction method of arc additive manufacturing based on event sequence provided by the present invention can realize high-temperature and high-speed multi-layer and multi-channel deposition simulation in the arc additive manufacturing application scenario through event sequence activation unit and guiding heat source; through arc additive manufacturing thermo-mechanical real-time simulation, the stress diffusion effect caused by repeated heat input at the junction of the additive part and the substrate of different materials can be obtained; through the residual stress theoretical calculation correction prediction of the arc additive manufacturing integral component of the T-shaped cross-section considering the stress diffusion effect, the deposition stress and deformation in the arc additive manufacturing process can be predicted efficiently, in real time and accurately. And it has been verified that the method of the present invention is effective.

Claims

1. Arc additive real-time simulation and model prediction method based on event sequence, characterized in that: include: S1. In the real-time process of arc additive manufacturing of metal structures, the unit is activated in real time through the event sequence and the heat source is guided in real time; The event sequence is used to set the virtual block to move in three-dimensional space along a preset path and time, and to exert a three-dimensional field influence on the path passed by the virtual block; S2, setting heat source model parameters, thermal simulation parameters and mechanical simulation parameters based on the event sequence method in S1, and performing arc additive manufacturing thermo-mechanical real-time simulation; S3. Based on the stress diffusion distribution and normal stress interface correction deviation obtained from the real-time simulation of thermal-mechanical coupling in S2, a simplified calculation theoretical model of the residual stress field is established, and the calculation model prediction is corrected.

2. The method for real-time simulation and model prediction of arc additive based on event sequence according to claim 1, characterized in that: S1 includes: S101, using the event sequence to restore the real-time process of arc additive manufacturing, and activating the units on the path swept by the virtual block of the event sequence one by one; S102, guiding the position of the virtual block in the event sequence as the position of the mobile heat source, using the Goldak double ellipsoid heat source model.

3. The method for real-time simulation and model prediction of arc additive based on event sequence according to claim 2, characterized in that S2 include: S201, setting thermal simulation parameters and mechanical simulation parameters, and building a thermal-mechanical coupling simulation model; The thermal simulation parameter settings include thermal boundary conditions, latent heat of phase change, thermal conductivity and specific heat settings; the mechanical simulation parameter settings include thermal expansion coefficient, material mechanical parameters, and boundary mechanical constraint settings; S202, constructing a linear deposition simulation model to simulate a multi-layer multi-channel arc additive manufacturing deposition process, and obtaining the stress diffusion distribution of the deposition layer according to the deposition stress simulation results.

4. The method for real-time simulation and model prediction of arc additive based on event sequence according to claim 3, characterized in that: In S202, the straight line deposition simulation model includes single straight line, double straight line and triple straight line deposition simulation models. In the single straight line deposition simulation model, the additive deposition layer is placed in the middle of the substrate; in the double straight line deposition simulation model, the additive deposition layer is placed on both longitudinal edges of the substrate; in the triple straight line deposition simulation model, the additive deposition layer is placed on both longitudinal edges and in the middle.

5. The method for real-time simulation and model prediction of arc additive based on event sequence according to claim 4, characterized in that S3 include: S301, establishing a simplified calculation theoretical model, wherein the simplified calculation theoretical model is composed of a substrate and an additive part in an arc additive manufacturing process, including a stress field distribution before and after the release of the fixture constraint; at the junction of the additive part and the substrate, there is a diffusion effect of the deposited stress before and after the release of the fixture constraint, and it presents a semicircular shape; S302, correcting the calculation model prediction, including: S3021. For a T-shaped cross-section integral component consisting of a substrate and an additive part, calculate the centroid height y of the substrate, the deposition wall and the integral component. s ,y d and y0; S3022. Calculate the moment of inertia I of the T-shaped cross section xx ; S3023. Calculate the deposition stress σ on the substrate during arc additive manufacturing before the substrate fixture constraint is released. zz The equivalent concentrated force F d and the pressure F in the substrate s ; S3024, before the clamp constraint on the substrate is released, calculate the equivalent concentrated force F d and the pressure F in the substrate s The bending moment M about the neutral axis caused by the position offset; S3025, after the clamp constraint on the substrate is released, calculating the deformation curvature κ of the model; S3026. After the clamp constraint on the substrate is released, calculate the modified residual stress field σ considering the normal stress interface deviation Δy′ during the entire arc additive manufacturing process. zz,res (y); Where y=0 is at the height of the neutral axis y0; Δy′ is the correction deviation of the normal stress interface caused by the stress diffusion of the deposited layer. The correction deviation is only for the "positive" part of the longitudinal stress, that is, the tensile stress area, and the compressive stress area of ​​the substrate remains unchanged; S3027, Calculate the descending gradient of the residual stress field 6. Arc additive real-time simulation and model prediction system based on event sequence, characterized in that: The method for executing any one of claims 1 to 5 comprises: An activation guidance module is used to activate the unit and guide the heat source in real time during the real-time process of arc additive manufacturing through an event sequence; the event sequence is used to set the virtual block to move in three-dimensional space along a preset path and time, and exert a three-dimensional field influence on the path passed by the virtual block; A simulation module, used for inputting heat source model parameters, thermal simulation parameters and mechanical simulation parameters corresponding to the activation guidance module, for performing real-time thermo-mechanical simulation of arc additive manufacturing; The prediction module is used to input the stress diffusion distribution and normal stress interface correction deviation obtained by the simulation module, to establish a simplified calculation theory model, and to correct the calculation model prediction.

7. A computer storage medium, characterized in that: The computer storage medium stores a computer program; when the computer program is executed on a computer, the computer executes any one of the methods described in claims 1 to 5.

8. An electronic device, characterized in that: include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the method according to any one of claims 1 to 5.

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