Electric arc additive steel pipe bearing three-dimensional simulation and prediction method

Abstract

The invention relates to an electric arc additive steel pipe bearing three-dimensional simulation and prediction method, which comprises the following steps: carrying out three-dimensional laser scanning geometric measurement on an electric arc additive steel pipe, and setting anisotropic material parameters based on actually measured data; constructing a fluctuating morphology scanning model, and determining an optimal grid size through grid size sensitivity analysis; an ideal surface flat model is constructed, and slenderness ratio parameterization expansion is carried out; and carrying out three-dimensional simulation prediction, comparing and verifying by combining test data, and obtaining a bearing capacity design fitting prediction formula based on a verification result. The method has the beneficial effects that the material anisotropy and the surface fluctuation irregularity of the electric arc additive structural member are considered, and the three-dimensional simulation prediction model of the electric arc additive steel pipe bearing is established through calculation model simplification, grid unit division, boundary condition setting and contact surface setting; the method can be used as a large-scale parameterization performance prediction analysis method, and a novel high-efficiency and high-precision three-dimensional simulation and prediction practical method is provided for the structure.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and more specifically, it relates to a three-dimensional simulation and prediction method for the bearing capacity of arc additive manufactured steel pipes. Background Art

[0002] Wire arc additive manufacturing (WAAM) is an additive manufacturing technology for metal materials, which has the advantages of high deposition efficiency and small size limitations, and is suitable for the intelligent construction requirements of complex metal structures in the construction industry. Therefore, it is urgent to establish a design prediction method applicable to WAAM metal components. The design prediction methods mainly include theoretical prediction, simulation prediction, AI prediction and other methods.

[0003] Steel pipes are an important type of component in building steel structures, mainly including short steel pipes and long steel pipes, and mainly bear axial compression or axial tension. They play a crucial role in the bearing capacity of the overall structure. Combining with the WAAM process can realize the integrated production of complex steel structure components including some steel pipe components, complex curved surfaces or hollowed-out shaped steel pipe components, and avoid the influence of residual stress caused by plate welding on their bearing performance. Therefore, establishing a three-dimensional simulation method for the bearing capacity of arc additive manufactured steel pipes and predicting their bearing capacity is of great significance for the design prediction of WAAM steel structure components.

[0004] The WAAM technology melts metal wire materials through an arc heat source and stacks them layer by layer to form complex metal structure components. Due to the characteristics of the WAAM process, arc additive manufactured steel pipes generally have obvious material anisotropy, surface undulation topography and initial geometric defects, etc. Existing relevant specifications are all for predicting traditional steel pipe components, and it is debatable whether they are applicable to the geometric and mechanical bearing capacities of steel pipes prepared by WAAM printing. And experimental research has adverse factors such as high cost, complex production and error accumulation, and often requires high costs, and is not suitable for large-scale parametric performance prediction analysis. Summary of the Invention

[0005] The purpose of the present invention is to propose a three-dimensional simulation and prediction method for the bearing capacity of arc additive manufactured steel pipes in view of the deficiencies of the existing technology.

[0006] In the first aspect, a three-dimensional simulation and prediction method for the bearing capacity of arc additive manufactured steel pipes is provided, including:

[0007] S1. Geometric measurement and simulation parameter setting: Conduct three-dimensional laser scanning geometric measurement on the arc additive manufactured steel pipe, and set anisotropic material parameters based on the measured data;

[0008] S2. Scanning model construction and sensitivity analysis: Construct a scanning model of the undulation topography, and determine the optimal mesh size through mesh size sensitivity analysis;

[0009] S3. Flat Model Construction and Parametric Extension: Construct an ideal flat surface model and perform parametric extension of the slenderness ratio;

[0010] S4. Simulation Prediction and Fitting Design: Conduct three-dimensional simulation prediction, compare and verify with experimental data, and obtain the bearing capacity design fitting prediction formula based on the verification results.

[0011] Preferably, S1 includes:

[0012] S11. Three-dimensional Scanning Geometric Measurement: Use three-dimensional laser scanning to obtain the complete geometric profiles of the inner and outer surfaces of the arc additive manufactured steel pipe, and use a series of profile samplings to obtain the basic geometric parameters of the cross-sectional profile;

[0013] The basic geometric parameters of the arc additive manufactured steel pipe include height, average outer diameter, average wall thickness, average cross-sectional area, maximum cross-sectional area, and minimum cross-sectional area;

[0014] S12. Anisotropic Parameter Setting: Define the anisotropic yield stress ratio parameter based on the Hill 48 yield criterion.

[0015] Preferably, S2 includes:

[0016] S21. Undulating Topography Scanning Model Construction: Considering the surface undulating topography of the arc additive manufactured steel pipe, establish a scanning finite element model of the arc additive manufactured steel pipe;

[0017] The scanning finite element model uses solid elements for simulation, and the geometric parameters use the measured values of the basic geometric parameters obtained in S11. At the same time, the undulating surface and uneven wall thickness of the arc additive manufactured steel pipe are considered;

[0018] S22. Mesh Size Sensitivity Analysis: Analyze by cutting segments from the arc additive manufactured steel pipe, set different mesh sizes, obtain the normalized ultimate loads at different mesh sizes, analyze the sensitivity of the mesh size, and determine the most suitable mesh size; the mesh size does not exceed the thickness of the arc additive deposition layer.

[0019] Preferably, S3 includes:

[0020] S31. Ideal Surface Flat Model Construction: Without considering the undulating surface of the arc additive manufactured steel pipe, establish a flat finite element model of the arc additive manufactured steel pipe;

[0021] The flat finite element model uses shell elements for simulation, and the geometric parameters use the measured average values of the basic geometric parameters obtained in S11 to improve the calculation efficiency; the mesh size is taken according to the theoretical recommended formula;

[0022] Optionally, the thickness of the shell elements of the flat finite element model can also use S11 to obtain the measured values of the plate thickness at each coordinate position to reflect the uneven wall thickness change of the arc additive manufactured steel pipe; through the coordinate positioning of each shell element, the plate thickness at the measured coordinate position is assigned to the thickness attribute of the corresponding shell element one by one, and the coordinate position of each shell element is taken as the coordinate of the element centroid position;

[0023] S32. Parametric extension of slenderness ratio: Through the simulation of the flat finite element model verified by experiments, data is expanded to cover a larger range of local slenderness ratios, and parametric extension analysis is carried out to obtain the relationship between the normalized bearing capacity and the local slenderness ratio;

[0024] Initial geometric imperfections are introduced, and a series of different wall thicknesses t, outer diameters D, and heights H are set to expand the range of slenderness ratio parameters. The flat finite element model is used for parametric extension analysis to obtain more finite element scatter distribution data results; the slenderness ratio parameter of the short steel pipe is D / (tε 2 ), and the slenderness ratio parameter of the long steel pipe is λ / ε k , where is the material parameter, E is the elastic modulus, f y is the yield strength, λ is the slenderness ratio of the long steel pipe, is the steel grade correction coefficient.

[0025] Preferably, S4 includes:

[0026] S41. Three-dimensional model simulation prediction: A three-dimensional simulation model is established, boundary conditions and contact surfaces are set, and then the bearing performance is predicted through the three-dimensional simulation model; the three-dimensional simulation model includes a flat finite element model and a scanning finite element model;

[0027] End plates and restraint rings are set at both ends of the arc additive manufactured short steel pipe, and reference points are set at the centers of the two end plates; a fixed restraint is set at the bottom reference point; only the vertical translation degree of freedom UZ and the rotational degrees of freedom URX and URY are available at the top reference point, that is, a spherical hinge is simulated; knife edges are set at the two end plates of the arc additive manufactured long steel pipe to form a one-way hinge support restraint, and reference points are set at the centers of the knife edges;

[0028] For the arc additive manufactured short steel pipe, the end plates and restraint rings are modeled using rigid shell elements; the two ends of the short steel pipe are coupled with the reference points of the rigid end plates; the contact between the short steel pipe and the rigid restraint ring is surface-to-surface contact, with the main surface being the arc additive manufactured steel pipe and the slave surface being the rigid restraint ring; for the arc additive manufactured long steel pipe, the end plates are set as deformable bodies and shell elements are used; the end plate thickness is defined according to the sum of the thicknesses of the end welding plates and the knife edges; the area on the knife edge end plate that contacts the triangular prism is divided and coupled with the reference point;

[0029] S42. Experimental Test and Comparative Verification: For the arc additive manufacturing steel pipes, the simulation prediction results of the flat finite element model and the scanning finite element model are compared and verified with the load-displacement curve results and failure modes obtained from the experimental tests to verify the effectiveness and accuracy of the three-dimensional simulation prediction method;

[0030] S43. Bearing Capacity Prediction Fitting Design: Based on the parametric extended simulation data of the flat finite element model verified by experiments, a fitting prediction formula for the bearing capacity design applicable to arc additive manufacturing steel pipes is obtained to consider a wider range of slenderness ratio parameters;

[0031] For short arc additive manufacturing steel pipes, based on the bearing capacity N improved by the CSM method u The fitting design formula for prediction is:

[0032]

[0033] In the formula, is the local slenderness ratio parameter; A is the cross-sectional area; σ 0.2 is the yield stress corresponding to 0.2% plastic strain; is the elastic critical buckling stress; ν is the Poisson's ratio; E is the elastic modulus; D is the outer diameter; t is the wall thickness; ε y is the yield strain, ε csm is the CSM ultimate strain; ε csm / ε y is the strain ratio, reflecting the deformation ability of the cross-section, see Eqs. (2a) - (2b); f csm is the CSM ultimate stress, see Eqs. (3a) - (3b).

[0034]

[0035] In the formula, ε u = 1 - σ 0.2 / σ u is the ultimate strain, σ u is the ultimate strength;

[0036] f csm = σ 0.2 + E sh ε y (ε csm / ε y - 1) for ε csm / ε y ≥ 1 (3a)

[0037] f csm = Eε csm for ε csm / ε y < 1 (3b)

[0038] In the formula, Esh = (σ u - σ 0.2 ) / (0.16ε u - ε y ) is the strain hardening modulus.

[0039] Preferably, in S41, it further includes simplifying the calculation model, and the steps of simplifying the calculation model include:

[0040] Using S11 to obtain the measured average value and measured value of the basic geometric parameters, and establishing a flat finite element model and a scanning finite element model of the arc additive manufacturing steel pipe;

[0041] Setting a constraint ring at the end of the short steel pipe to avoid premature failure at the end before buckling;

[0042] Setting a knife edge at the end of the long steel pipe to simulate a one-way hinged support;

[0043] Coupling the rigid end plate of the arc additive manufacturing steel pipe with its center point, and setting a displacement load at the center point.

[0044] Preferably, in S41, it further includes mesh element division; the scanning finite element model is meshed using hexahedral solid elements, and the scanning finite element model is meshed using hexahedral solid elements; for the arc additive manufacturing steel pipe, a first mesh size is used, while for the end plate and the constraint ring, a second mesh size is used, and the first mesh size is smaller than the second mesh size.

[0045] In a second aspect, an arc additive manufacturing steel pipe bearing three-dimensional simulation and prediction system is provided for performing any of the methods in the first aspect, including:

[0046] A measurement module for geometric measurement and simulation parameter setting: performing three-dimensional laser scanning geometric measurement on the arc additive manufacturing steel pipe, and setting anisotropic material parameters based on the measured data;

[0047] A first construction module for scanning model construction and sensitivity analysis: constructing a scanned model of the undulating topography, and determining the optimal mesh size through mesh size sensitivity analysis;

[0048] A second construction module for flat model construction and parametric expansion: constructing an ideal surface flat model, and performing slenderness ratio parametric expansion;

[0049] A simulation prediction module for simulation prediction and fitting design: performing three-dimensional simulation prediction, comparing and verifying with test data, and obtaining a bearing capacity design fitting prediction formula based on the verification results.

[0050] In a third aspect, a computer storage medium is provided, in which a computer program is stored; when the computer program runs on a computer, the computer is caused to execute the method according to any one of the first aspect.

[0051] In a fourth aspect, an electronic device is provided, including:

[0052] a memory for storing a computer program;

[0053] a processor for executing the computer program to implement the method according to any one of the first aspect.

[0054] The beneficial effects of the present invention are as follows:

[0055] 1. The three-dimensional simulation and prediction method for the load-bearing of arc additive manufacturing steel pipes provided by the present invention realizes the scanning of the undulating morphology profile of arc additive manufacturing steel pipes and the setting of anisotropic parameters through geometric measurement and simulation parameters, realizes the accurate three-dimensional simulation of arc additive manufacturing steel pipes considering undulating morphology and uneven wall thickness and the determination of mesh size through the scanning model and sensitivity analysis, realizes the rapid three-dimensional simulation of arc additive manufacturing steel pipes considering only the average wall thickness and the expansion of the data range of slenderness ratio parameters through the flat model and parameter expansion, and realizes the parametric three-dimensional simulation simulation, load-bearing performance prediction and rapid prediction fitting design application of arc additive manufacturing steel pipes through simulation prediction and experimental verification.

[0056] 2. The three-dimensional simulation and prediction method for the load-bearing of arc additive manufacturing steel pipes provided by the present invention takes into account the material anisotropy and surface undulation irregularity of arc additive manufacturing structural parts, and establishes a three-dimensional simulation prediction model for the load-bearing of arc additive manufacturing steel pipes through calculation model simplification, mesh element division, boundary condition setting and contact surface setting, which can be used as a large-scale parametric performance prediction analysis method, provides a new high-efficiency and high-precision three-dimensional simulation and prediction practical method for this type of structure, and at the same time provides an effective method for rapid prediction fitting design. Description of the Drawings

[0057] Figure 1 is a schematic overall flow chart of the three-dimensional simulation and prediction method for the load-bearing of arc additive manufacturing steel pipes of the present invention;

[0058] Figure 2 is a schematic diagram of the three-dimensional scanning measurement process of WAAM steel pipes;

[0059] Figure 3a is a frequency histogram of the wall thickness distribution of WAAM steel pipes measured by scanning;

[0060] Figure 3b is a frequency histogram of the normalized cross-sectional area distribution of WAAM steel pipes measured by scanning;

[0061] Figure 4It is a schematic diagram of the direction of WAAM and the corresponding tensile part;

[0062] Figure 5 It is a schematic diagram of the scanning finite element model of WAAM steel pipe;

[0063] Figure 6 It is a schematic diagram of different mesh models of the segmented scanning finite element model;

[0064] Figure 7 It is the sensitivity change of the relative ultimate bearing capacity under different mesh sizes;

[0065] Figure 8a It is a schematic diagram of the flat calculation model of WAAM short steel pipe;

[0066] Figure 8b It is a schematic diagram of the flat calculation model of WAAM long steel pipe;

[0067] Figure 8c It is a schematic diagram of the flat finite element model of WAAM steel pipe;

[0068] Figure 9a It is the finite element and experimental comparison of the bearing capacity of short steel pipes after the slenderness ratio is extended;

[0069] Figure 9b It is the finite element and experimental comparison of the bearing capacity of short steel pipes after the slenderness ratio is extended;

[0070] Figure 10 It is the finite element and experimental comparison of the steel pipe load-displacement curve and failure mode of the scanning model;

[0071] Figure 11a It is the finite element and experimental comparison of the load-displacement curve of short steel pipes in the flat model;

[0072] Figure 11b It is the finite element and experimental comparison of the failure mode of short steel pipes in the flat model;

[0073] Figure 12a It is the finite element and experimental comparison of the load-displacement curve of long steel pipes in the flat model;

[0074] Figure 12b It is the finite element and experimental comparison of the failure mode of long steel pipes in the flat model;

[0075] Figure 13a It is the comparison of the normalized bearing capacity-slenderness ratio prediction curves of experiments, finite elements, codes and the prediction formula of the present invention;

[0076] Figure 13b It is the comparison of the bearing capacity test / finite element ratio-slenderness ratio prediction curves of the code and the prediction formula of the present invention.

[0077] Description of the drawing reference numerals: 1 - 3D scanner; 2 - WAAM steel pipe; 3 - geometric scanning model; 4 - scanning data processing software. Specific embodiments

[0078] The present invention will be 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 those of ordinary skill in the art, without departing from the principle of the present invention, several modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0079] Embodiment 1:

[0080] As an embodiment, as Figure 1 shown, this method for three-dimensional simulation and prediction of arc additive manufacturing steel pipes includes:

[0081] S1. Geometric measurement and simulation parameter setting: Perform three-dimensional laser scanning geometric measurement on the arc additive manufacturing steel pipe, and set anisotropic material parameters based on the measured data.

[0082] S1 includes:

[0083] S11. Three-dimensional scanning geometric measurement: Use three-dimensional laser scanning to obtain the complete geometric contour of the inner and outer surfaces of the arc additive manufacturing steel pipe, and use a series of contour samplings to obtain the basic geometric parameters of the cross-sectional contour.

[0084] Due to the process characteristics of arc additive manufacturing, the printed arc additive manufacturing steel pipe has a surface undulating topography, resulting in geometric changes in the overall contour; use a three-dimensional laser scanner to perform geometric scanning on the inner and outer surfaces of the arc additive manufacturing steel pipe, obtain a scanning model of the complete geometric contour, generate a corresponding STL mesh file, and perform post-processing of model repair in three-dimensional scanning processing software.

[0085] Specifically, for the arc additive manufacturing steel pipe, import the scanned model after model repair into Rhino software in the form of an STL mesh file, and perform contour sampling along the axial direction according to the sampling interval d x to obtain the basic geometric parameters of each cross-sectional contour, and use a self-written Rhino Python script to implement the sampling of the cross-sectional contour and the extraction of the basic geometric parameters; perform sensitivity analysis for different contour intervals; calculate the initial geometric defects through the scanning model; among the basic geometric parameters of the arc additive manufacturing steel pipe, H is the height, D is the average outer diameter, t is the average wall thickness, A is the average cross-sectional area, A max is the maximum cross-sectional area, A min is the minimum cross-sectional area. In this embodiment, the wall thickness distribution and the normalized cross-sectional area distribution frequency histogram of the scanned WAAM steel pipe are respectively as Figure 3a , Figure 3b shown.

[0086] As shown in Figure 4 S12, anisotropic parameter setting: Define the anisotropic yield stress ratio parameter based on the Hill 48 yield criterion.

[0087] The arc additive manufactured steel pipe has obvious anisotropy. The anisotropic Hill 48 yield criterion is used for 3D simulation. When establishing the Hill 48 yield function, six anisotropic yield stress ratio parameters are defined, that is, the ratio of the yield stress in a specific direction to the yield stress in the reference direction. Taking the angle θ = 0° between the stress direction and the printing direction as the reference direction, the stress direction of the arc additive manufactured steel pipe is θ = 90°, and the yield stress ratio parameter R 11 = σ 0.2,0° / σ 0.2,0° , R 22 = σ 0.2,90° / σ 0.2,0° , R 33 = R 13 = R 23 = 1, In this embodiment, the arc additive manufactured steel pipe is made of 316L stainless steel material, and the yield stress is the nominal yield stress corresponding to 0.2% strain. The measured average values of the nominal yield stresses in the sampling directions of 0°, 45° and 90° are shown in Table 1, and the values of the six anisotropic yield stress ratio parameters are shown in Table 2.

[0088] Table 1 Nominal yield stress σ in different sampling directions 0.2 Measured average value (unit: MPa)

[0089]

[0090] Table 2 Values of anisotropic yield stress ratio parameters

[0091]

[0092] S2. Scanning model construction and sensitivity analysis: Construct a scanning model of the undulating topography and determine the optimal mesh size through mesh size sensitivity analysis.

[0093] S2 includes:

[0094] S21. Construction of the scanning model of the undulating topography: Considering the surface undulating topography of the arc additive manufactured steel pipe, establish a scanning finite element model of the arc additive manufactured steel pipe.

[0095] The scanned finite element model is simulated using solid element C3D8R. The geometric parameters of the scanned finite element model are the basic geometric parameters measured in step S1.1, and the undulating surface and uneven wall thickness of the arc additive manufactured steel pipe are considered. The STL mesh file obtained by scanning in step S1.1 is imported into the Hypermesh mesh processing software, and the mesh model is regenerated using hexahedral solid elements, and then imported into the finite element software to obtain the scanned finite element model of the undulating surface. Furthermore, a rigid body model of the end plate and the end constraint ring is created.

[0096] As Figure 6 shown, S22, mesh size sensitivity analysis: Analyze a section cut from the arc additive manufactured steel pipe, set different mesh sizes, obtain the normalized ultimate loads at different mesh sizes, analyze the sensitivity of the mesh size, and determine the most suitable mesh size.

[0097] Specifically, a section is cut from the arc additive manufactured steel pipe for mesh size sensitivity analysis to balance calculation efficiency and accuracy; considering that the mesh size should not exceed the thickness of the arc additive deposition layer, the ultimate loads of mesh sizes from 0.1 mm to 1.5 mm are tested; fixed-end boundaries are set at both ends of the structure for unidirectional compression calculation; generally speaking, a larger mesh size will reflect fewer geometric irregularities, making the undulating surface smoother, reducing local geometric defects, thereby reducing the weakening of the resistance of the profile section, that is, the larger the ultimate load.

[0098] As Figure 7 shown, the ultimate load N of the minimum mesh size of 0.1 mm u,0.1 is used to normalize the ultimate load N of each mesh size u to obtain the relationship curve between the normalized ultimate load and the mesh size, and then the most suitable mesh size is obtained by analysis; in this embodiment, the normalized ultimate load increases with the increase of the mesh size, and the most suitable mesh size is 0.4 mm.

[0099] S3. Construction and parametric expansion of the flat model: Construct an ideal surface flat model and perform parametric expansion of the slenderness ratio.

[0100] S3 includes:

[0101] S31. Construction of the ideal surface flat model: Without considering the undulating surface of the arc additive manufactured steel pipe, establish a flat finite element model of the arc additive manufactured steel pipe.

[0102] As Figure 8a 、 Figure 8bAs shown, the flat finite element model is simulated using shell elements, and the geometric parameters of the flat model are the measured average values of the basic geometric parameters measured in step S1.1. By performing finite element simulation on the flat model of shell elements, the complex surface fluctuations of the arc additive manufacturing steel pipe can be ignored, improving the calculation efficiency. The four-node quadrilateral shell element S4R is used for mesh division. The mesh size refers to the theoretical recommended value of 0.1(Dt) 1 / 2 , which is about 8% of the half-wavelength of the axisymmetric elastic local buckling of the steel pipe member, and has good simulation accuracy and high calculation efficiency. In this embodiment, 0.1(Dt) of all the tested arc additive manufacturing steel pipes 1 / 2 is between 2.45 mm and 4.58 mm. Therefore, the mesh size is taken as 3 mm, slightly smaller than the thinnest wall thickness of the steel pipe.

[0103] As Figure 8c shown, for the ideal surface flat model of the steel pipe under axial compression loading, initial geometric defects also need to be introduced. The lowest elastic buckling mode is used as the form of the initial geometric defects, and the measured average value of the geometric defects of the arc additive manufacturing steel pipe obtained in step S1.1 is used as the amplitude of the initial geometric defects. Geometric and material double nonlinear analysis is carried out by the displacement control method.

[0104] For the arc additive manufacturing steel pipe, the thickness of the shell element of the flat finite element model can also adopt the measured values of the plate thickness at each coordinate position measured in step S1.1 to reflect the uneven wall thickness of the arc additive manufacturing steel pipe. Through the coordinate positioning of each shell element, the plate thickness at the measured coordinate position is assigned to the thickness attribute of the corresponding shell element one by one. The coordinate position of each shell element can be taken as the coordinate of the centroid position of the shell element.

[0105] The flat finite element model of the shell element measured on average adopts the measured average value of the wall thickness of the basic geometric parameters to reflect the average wall thickness characteristics. The flat finite element model of the shell element thickness measured adopts the measured values of the wall thickness of the basic geometric parameters to reflect the uneven wall thickness change. The scanned finite element model of the solid element adopts the measured values of the surface geometric parameters to reflect both the surface undulation morphology and the uneven wall thickness change at the same time. The flat finite element model has high calculation efficiency and is suitable for overall response simulation and parameter analysis such as ultimate bearing capacity. The scanned finite element model has high simulation accuracy and is suitable for detailed response simulation such as failure mode.

[0106] The ideal surface flat model of the shell element in S3 and the undulating morphology scanning model of the solid element in step S2 have the same calculation model simplification, material parameters, boundary conditions, and contact surface settings. The contact settings include the interaction between the end plate and the restraint ring, and the restraint ring and the short steel pipe. The material parameters include the anisotropic yield stress ratio parameter. The geometric model assumptions and mesh element divisions of the two types of finite element models are different. The scanning model uses hexahedral solid meshes, and the flat model uses quadrilateral shell meshes.

[0107] As Figure 9a , Figure 9b shown, S32, slender ratio parametric expansion: Data augmentation is carried out through simulation of a flat finite element model verified by experiments to cover a larger range of local slender ratios, and parametric expansion analysis is performed to obtain the relationship between the normalized bearing capacity and the local slender ratio.

[0108] Introduce initial geometric imperfections, set a series of different wall thicknesses, outer diameters and heights to expand the range of slender ratio parameters, and use the flat finite element model to perform parametric expansion analysis to obtain more finite element scatter distribution data; the slender ratio parameter of the short steel pipe is D / (tε 2 ), and the slender ratio parameter of the long steel pipe is λ / ε k , where is the material parameter, E is the elastic modulus, f y is the yield strength, λ is the slender ratio of the long steel pipe, is the steel grade correction coefficient; in this embodiment, the expansion range of the slender ratio parameter of the short steel pipe is D / (tε 2 ) = 40 - 315, and the expansion range of the slender ratio parameter of the long steel pipe is λ / ε k = 12 - 82.

[0109] S4, simulation prediction and fitting design: Perform three-dimensional simulation prediction, compare and verify with test data, and obtain the bearing capacity design fitting prediction formula based on the verification results.

[0110] S4 includes:

[0111] As Figure 5 , Figure 8 shows, S41, three-dimensional model simulation prediction: Establish a three-dimensional simulation model, and the simulation process is successively calculation model simplification, mesh element division, boundary condition setting and contact surface setting, and predict the bearing performance through the simulation model; the three-dimensional simulation model includes a flat finite element model and a scanning finite element model.

[0112] Specifically, S41 includes:

[0113] (1) Calculation model simplification

[0114] To improve the calculation efficiency and convergence of the finite element simulation, simplify the calculation model: 1) Use S11 to obtain the measured average value and measured value of the basic geometric parameters respectively, and establish a flat finite element model and a scanning finite element model of the arc additive manufacturing steel pipe; 2) Set a restraint ring at the end of the short steel pipe to avoid premature end failure before buckling ( Figure 8a ); 3) Set a knife edge at the end of the long steel pipe to simulate a one-way hinged support ( Figure 8b ); 4) Simplify the loading method, that is, couple the rigid end plate of the arc additive manufacturing steel pipe with its center point, and set displacement loading at the center point

[0115] (2) Mesh element division

[0116] The scanned finite element model is meshed using hexahedral solid elements, allowing large deformations and material nonlinearities. Automatic meshing is used to ensure that there are at least 3 or more elements in the thickness direction of the model, and the mesh density of each contact surface is close. A sensitivity analysis of the mesh size is carried out ( Figure 5 ); The flat finite element model is meshed using quadrilateral shell elements, considering both geometric and material nonlinearities. The mesh size can be obtained through sensitivity analysis or theoretically recommended sizes ( Figure 8c ); For the arc additive manufactured steel pipe, a relatively small mesh size is used, while for the end plates and restraint rings, a relatively large mesh size is used.

[0117] (3) Boundary condition setting

[0118] The end plates of the short arc additive manufactured steel pipe are set as fixed constraints, and restraint rings are set at both ends for reinforcement. Reference points RP are set at the centers of the two end plates; At the bottom reference point, all degrees of freedom are constrained, while at the top reference point, only the vertical translation degree of freedom UZ and the rotational degrees of freedom URX and URY are allowed, i.e., simulating a spherical hinge.

[0119] The end plates of the long arc additive manufactured steel pipe are set with knife edges to form a one-way hinge support constraint, and a reference point RP is set at the center of the knife edge.

[0120] (4) Contact surface setting

[0121] For the short arc additive manufactured steel pipe, the end plates and restraint rings are modeled using rigid shell elements; The two ends of the arc additive manufactured steel pipe are coupled with the reference points of the rigid end plates; The contact between the steel pipe and the rigid restraint ring is set as surface-to-surface contact, with the arc additive manufactured steel pipe set as the master surface and the rigid restraint ring set as the slave surface.

[0122] For the long arc additive manufactured steel pipe, the end plate is set as a deformable body, using S4R shell elements, and set as an isotropic ideal elastoplastic steel material; The thickness of the end plate is defined according to the sum of the thicknesses of the end welding plate and the knife edge; The area on the knife edge end plate that contacts the triangular prism is divided and coupled with the reference point.

[0123] As Figure 10 shown in Figures 11 and 12, S42, experimental test comparison and verification: For the arc additive manufactured steel pipe, the simulation prediction results of the flat finite element model and the scanned finite element model are compared and verified with the load-displacement curve results and failure modes of the experimental tests to verify the effectiveness and accuracy of the three-dimensional simulation prediction method.

[0124] Compared with the flat finite element model (Figs. 11 and 12), the scanned finite element model provides more accurate results by retaining the surface irregularities of the arc additive manufactured steel pipe, that is, it is closer to the load-displacement curve and failure mode results of the test tests and has better predictability ( Figure 10 ); however, due to the irregular geometry of the scanned geometric model itself and the large number of non-linear contact calculations involved, the calculation efficiency and convergence are reduced; therefore, when performing three-dimensional simulation and prediction of the bearing capacity of arc additive manufactured steel pipes, the ideal surface flat model is used as the preliminary three-dimensional simulation and prediction method, and the undulating topography scanned model is used as the in-depth three-dimensional simulation and prediction method.

[0125] As shown in Fig. 13, S43, bearing prediction fitting design: Based on the parametric extended simulation data of the flat finite element model verified by tests, a bearing capacity design fitting prediction formula applicable to arc additive manufactured steel pipes is obtained to consider a wide range of slenderness ratio parameters.

[0126] For short arc additive manufactured steel pipes, the prediction fitting design formula for the bearing capacity N u is:

[0127]

[0128] In the formula, is the local slenderness ratio parameter; A is the cross-sectional area; σ 0.2 is the yield stress corresponding to 0.2% plastic strain; is the elastic critical buckling stress; ν is the Poisson's ratio; E is the elastic modulus; D is the outer diameter; t is the wall thickness; ε y is the yield strain, ε csm is the CSM ultimate strain; ε csm / ε y is the strain ratio, reflecting the deformation ability of the cross-section, see Eqs. (2a) to (2b); f csm is the CSM ultimate stress, see Eqs. (3a) to (3b).

[0129]

[0130] In the formula, ε u = 1 - σ 0.2 / σ u is the ultimate strain, σ u is the ultimate strength;

[0131] f csm = σ 0.2 + E sh ε y (ε csm / ε y - 1) for ε csm / εy ≥1(3a)

[0132] f csm = Eε csm for ε csm / ε y <1(3b)

[0133] wherein, E sh = (σ u - σ 0.2 ) / (0.16ε u - ε y ) is the strain hardening modulus.

[0134] Example 2:

[0135] Based on Example 1, this example provides the three-dimensional simulation and prediction method for the load-bearing capacity of the arc additive manufacturing steel pipe proposed in Example 1, and its practical application in the three-dimensional simulation and prediction of the load-bearing performance of the WAAM process integrated manufacturing of arc additive manufacturing steel pipes and other arc additive manufacturing metal structural parts considering material anisotropy, undulating surface characteristics, and initial geometric defect characteristics.

[0136] Example 3:

[0137] Based on Example 1, Example 3 of this application provides a three-dimensional simulation and prediction system for the load-bearing capacity of arc additive manufacturing steel pipes, including:

[0138] A measurement module for geometric measurement and simulation parameter setting: performing three-dimensional laser scanning geometric measurement on the arc additive manufacturing steel pipe, and setting anisotropic material parameters based on the measured data;

[0139] A first construction module for scanning model construction and sensitivity analysis: constructing a scanning model of the undulating topography, and determining the optimal mesh size through mesh size sensitivity analysis;

[0140] A second construction module for flat model construction and parametric expansion: constructing an ideal surface flat model, and performing aspect ratio parametric expansion;

[0141] A simulation prediction module for simulation prediction and fitting design: performing three-dimensional simulation prediction, comparing and verifying with test data, and obtaining a bearing capacity design fitting prediction formula based on the verification results.

[0142] It should be noted that the system provided in this example is the system corresponding to the method provided in Example 1. Therefore, for the parts that are the same or similar in this example and Example 1, reference can be made to each other, and they will not be repeated in this application.

[0143] In summary, the three-dimensional simulation and prediction method for the load-bearing of arc additive manufacturing steel pipes provided by the present invention takes into account the material anisotropy and the irregular surface undulation characteristics of arc additive manufacturing structural parts. Through geometric measurement and simulation parameters, the undulation profile scanning of arc additive manufacturing steel pipes and the setting of anisotropic parameters are realized. Through the scanning model and sensitivity analysis, the accurate three-dimensional simulation of arc additive manufacturing steel pipes considering the undulation profile and uneven wall thickness and the determination of mesh size are achieved. Through the flat model and parameter expansion, the rapid three-dimensional simulation of arc additive manufacturing steel pipes considering only the average wall thickness and the data range expansion of slenderness ratio parameters are realized. Through simulation prediction and experimental verification, the parametric three-dimensional simulation simulation, load-bearing performance prediction, and rapid prediction fitting design application of arc additive manufacturing steel pipes are realized, providing a new high-efficiency and high-precision three-dimensional simulation and prediction practical method for this type of structure, and at the same time providing an effective method for rapid prediction fitting design. And through actual verification, the method of the present invention is effective.

Claims

1. A three-dimensional simulation and prediction method for the bearing capacity of arc additive manufacturing steel pipes, characterized in that Including: S1. Geometric measurement and simulation parameter setting: Conduct three-dimensional laser scanning geometric measurement on the arc additive manufactured steel pipe, and set anisotropic material parameters based on the measured data; S2. Scanning model construction and sensitivity analysis: Construct a scanning model of the undulating topography, and determine the optimal mesh size through mesh size sensitivity analysis; S3. Flat model construction and parametric extension: Construct an ideal surface flat model, and conduct parametric extension of the slenderness ratio; S4. Simulation prediction and fitting design: Conduct three-dimensional simulation prediction, compare and verify with test data, and obtain the bearing capacity design fitting prediction formula based on the verification results.

2. The three-dimensional simulation and prediction method for the bearing of an arc additive manufacturing steel pipe according to claim 1, characterized in that, S1 includes: S11. Three-dimensional scanning geometric measurement: Use three-dimensional laser scanning to obtain the complete geometric profiles of the inner and outer surfaces of the arc additive manufactured steel pipe, and use a series of profile samplings to obtain the basic geometric parameters of the cross-sectional profiles; The basic geometric parameters of the arc additive manufactured steel pipe include height, average outer diameter, average wall thickness, average cross-sectional area, maximum cross-sectional area, and minimum cross-sectional area; S12. Anisotropic parameter setting: Define the anisotropic yield stress ratio parameter of the material based on the Hill 48 yield criterion.

3. The method for three-dimensional simulation and prediction of the bearing capacity of an arc additive manufacturing steel pipe according to claim 2, wherein S2 Including: S21. Undulating topography scanning model construction: Consider the surface undulating topography of the arc additive manufactured steel pipe, and establish a scanning finite element model of the arc additive manufactured steel pipe; The scanning finite element model uses solid elements for simulation, and the geometric parameters use the measured values of the basic geometric parameters obtained from S11. At the same time, the undulating surface and uneven wall thickness of the arc additive manufactured steel pipe are considered; S22. Mesh size sensitivity analysis: Conduct sectional analysis on the arc additive manufactured steel pipe, set different mesh sizes, obtain the normalized ultimate loads at different mesh sizes, analyze the sensitivity of the mesh size, and determine the most suitable mesh size; the mesh size does not exceed the thickness of the arc additive deposition layer.

4. The three-dimensional simulation and prediction method for the bearing of an arc additive manufacturing steel pipe according to claim 3, wherein S3 Including: S31. Ideal surface flat model construction: Without considering the undulating surface of the arc additive manufactured steel pipe, establish a flat finite element model of the arc additive manufactured steel pipe; The flat finite element model uses shell elements for simulation, and the geometric parameters use the measured average values of the basic geometric parameters obtained from S11 to improve the calculation efficiency; the mesh size is taken according to the theoretical recommended formula; The thickness of the shell elements of the flat finite element model can also use the measured values of the plate thickness at each coordinate position obtained from S11 to reflect the uneven wall thickness change of the arc additive manufactured steel pipe; through the coordinate positioning of each shell element, the plate thickness at the measured coordinate position is assigned to the thickness attribute of the corresponding shell element one by one, and the coordinate position of each shell element is taken as the coordinate of the element centroid position; S32. Slenderness ratio parametric extension: Conduct data expansion through flat finite element simulation verified by experiments to cover a larger range of local slenderness ratios, and conduct parametric extension analysis to obtain the relationship between the normalized bearing capacity and the local slenderness ratio; Introduce initial geometric defects, set a series of different wall thicknesses t, outer diameters D, and heights H to expand the range of slenderness ratio parameters, and use a flat finite element model to conduct parametric expansion analysis to obtain more finite element scatter distribution data results; the slenderness ratio parameter of the short steel pipe is D / (tε 2 ), and the slenderness ratio parameter of the long steel pipe is λ / ε k , where ε is the material parameter, E is the elastic modulus, f y is the yield strength, λ is the slenderness ratio of the long steel pipe, and ε k is the steel grade correction coefficient.

5. The three-dimensional simulation and prediction method for the bearing of an arc additive manufacturing steel pipe according to claim 4, wherein S4 Including: S41. Three-dimensional model simulation prediction: Establish a three-dimensional simulation model, conduct boundary condition setting and contact surface setting, and then predict the bearing performance through the three-dimensional simulation model; the three-dimensional simulation model includes a flat finite element model and a scanning finite element model; End plates and restraint rings are provided at both ends of the short steel pipe for arc additive manufacturing. Reference points are set at the centers of the two end plates. A fixed restraint is provided at the bottom reference point. At the top reference point, there are only vertical translation freedom UZ and rotational freedoms URX and URY, that is, simulating a spherical hinge. At both ends of the long steel pipe for arc additive manufacturing, knife edges are provided on the end plates to form a one-way hinge support restraint, and reference points are set at the centers of the knife edges. For the short steel pipe for arc additive manufacturing, the end plates and restraint rings are modeled using rigid shell elements. The two ends of the short steel pipe are coupled with the reference points of the rigid end plates. The contact between the short steel pipe and the rigid restraint ring is surface-to-surface contact, with the main surface being the steel pipe for arc additive manufacturing and the slave surface being the rigid restraint ring. For the long steel pipe for arc additive manufacturing, the end plates are set as deformable bodies and shell elements are used. The thickness of the end plates is defined based on the sum of the thicknesses of the end welding plates and the knife edges. The area on the knife-edge end plates that contacts the triangular prism is divided and coupled with the reference points. S42. Experimental test comparison and verification: For the steel pipe for arc additive manufacturing, compare and verify the simulation prediction results of the flat finite element model and the scanned finite element model, as well as the load-displacement curve results and failure modes of the experimental tests, to verify the effectiveness and accuracy of the three-dimensional simulation prediction method. S43. Bearing capacity prediction fitting design: Based on the parametric extended simulation data of the flat finite element model verified by experiments, obtain a bearing capacity design fitting prediction formula applicable to the steel pipe for arc additive manufacturing to consider a larger range of slenderness ratio parameters. For the short steel pipe fabricated by arc additive manufacturing, the prediction fitting design formula for the bearing capacity N improved based on the CSM method is as follows: u ​ In the formula, is the local slenderness ratio parameter; A is the cross-sectional area; σ 0.2 is the yield stress corresponding to 0.2% plastic strain; σ cr is the elastic critical buckling stress; ε y is the yield strain, ε csm is the CSM ultimate strain; f csm is the CSM ultimate stress.

6. The method for three-dimensional simulation and prediction of the bearing capacity of an arc additive manufacturing steel pipe according to claim 5, characterized in that, In S41, it also includes simplifying the calculation model. The steps for simplifying the calculation model include: Using S11 to obtain the measured average value and measured value of the basic geometric parameters, and establishing a flat finite element model and a scanned finite element model of the steel pipe for arc additive manufacturing. A restraint ring is provided at the end of the short steel pipe to avoid premature failure at the end before buckling. Knife edges are provided at the ends of the long steel pipe to simulate a one-way hinge support. Couple the rigid end plate of the steel pipe for arc additive manufacturing with its center point, and set displacement loading at the center point.

7. The method for three-dimensional simulation and prediction of the bearing capacity of an arc additive manufacturing steel pipe according to claim 6, wherein, In S41, it also includes mesh element division. The scanned finite element model is meshed using hexahedral solid elements. For the steel pipe for arc additive manufacturing, a first mesh size is used, and for the end plates and restraint rings, a second mesh size is used, and the first mesh size is smaller than the second mesh size.

8. The three-dimensional simulation and prediction system for the bearing capacity of arc additive manufacturing steel pipes is characterized in that For implementing the method according to any one of claims 1 to 7, it includes: A measurement module for geometric measurement and simulation parameter setting: Perform three-dimensional laser scanning geometric measurement on the steel pipe for arc additive manufacturing, and set anisotropic material parameters based on the measured data. A first construction module for scanned model construction and sensitivity analysis: Construct a scanned model of the undulating topography, and determine the optimal mesh size through mesh size sensitivity analysis. A second construction module for flat model construction and parametric extension: Construct an ideal surface flat model and perform slenderness ratio parametric extension. A simulation prediction module for simulation prediction and fitting design: Perform three-dimensional simulation prediction, compare and verify in combination with experimental data, and obtain a bearing capacity design fitting prediction formula based on the verification results.

9. A computer storage medium, characterized in that, The computer storage medium stores a computer program; when the computer program runs on a computer, the computer is caused to execute the method according to any one of claims 1 to 7.

10. An electronic device, characterized in that, Comprising: a memory for storing the computer program; a processor for executing the computer program to implement the method according to any one of claims 1 to 7.

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