Electric arc additive T-shaped bolt connection three-dimensional simulation and prediction method

Abstract

The invention relates to an electric arc additive T-shaped bolt connection three-dimensional simulation and prediction method, which comprises the following steps: carrying out three-dimensional laser geometric scanning on an electric arc additive T-shaped part, and carrying out parameter processing on an obtained scanning model; anisotropy constitutive parameters of the electric arc additive T-shaped part are defined, and a material failure criterion is set; constructing an ideal surface flat model and a fluctuating surface scanning model; the bearing performance is predicted through the simulation model and compared with a test result to verify the accuracy of the model. The method has the beneficial effects that the material anisotropy and surface fluctuation irregularity of the electric arc additive structural member are considered, and the three-dimensional simulation prediction model of the electric arc additive T-shaped bolt connection 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 arc additive T-bolt connections. Background Art

[0002] Wire Arc Additive Manufacturing (WAAM) technology is a 3D printing technology for metal materials, which has advantages such as high deposition efficiency and small geometric constraints. It is considered the most suitable metal additive manufacturing technology for the needs of the construction industry, and it also has important value for sustainable development and environmental protection. Therefore, it is urgent to establish a design prediction method applicable to WAAM components.

[0003] The connection nodes in steel structures play a crucial role in the overall performance of the structure. T-bolt connection is a connection method in steel structure connection nodes. Combining with the WAAM process can realize the integrated manufacturing of complex steel structure parts of T-shaped parts or components containing partial T-shaped parts, avoiding the influence of residual stress caused by plate welding on their bearing performance. Therefore, establishing a three-dimensional simulation method for arc additive T-bolt connections and predicting their bearing performance is of great significance for the design prediction of WAAM steel structure parts.

[0004] The WAAM technology melts metal wire materials through an arc heat source and stacks them layer by layer to form complex metal structure parts. Due to the characteristics of the WAAM process, arc additive T-bolt connections generally have obvious material anisotropy, surface undulation morphology, etc. Existing relevant specifications are all for predicting traditional T-bolt connections. Whether they are applicable to the geometric and mechanical bearing performance of T-bolt connections prepared by WAAM printing is debatable. And experimental research has adverse factors such as high cost, complex production, and error accumulation. It 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 arc additive T-bolt connections in view of the deficiencies of the existing technology.

[0006] In the first aspect, a three-dimensional simulation and prediction method for arc additive T-bolt connections is provided, including:

[0007] S1. Geometric scanning and model processing: Conduct three-dimensional laser geometric scanning on the arc additive T-shaped part, and perform parameter processing on the obtained scanning model;

[0008] S2. Material parameter and failure setting: Define the anisotropic constitutive parameters of the arc additive T-shaped part, and set the material failure criterion;

[0009] S3. Establishment of flat model and scanning model: Construct an ideal surface flat model and a surface undulation scanning model;

[0010] S4, Simulation Prediction and Test Verification: Predict the bearing performance through the simulation model and verify the accuracy of the model by comparing with the test results.

[0011] Preferably, S1 includes:

[0012] S11, 3D Laser Geometric Scanning: Use a 3D scanner to perform geometric scanning on the surface undulation topography of the arc additive manufactured T-shaped part, obtain the complete geometric contour, generate an STL mesh model, and import the STL mesh model into the scanning data processing software for model repair;

[0013] S12, Scanning Model Parameter Processing: Import the repaired STL mesh model into Rhino 3D software, divide it into flange and web, and perform contour sampling at the sampling interval respectively to obtain the basic geometric parameters of the cross-sectional contour;

[0014] The basic geometric parameters of the arc additive manufactured T-shaped part include the web thickness, flange thickness, distance between bolt rows, distance from the bolt center to the web edge, and distances from the bolt center along and perpendicular to the force direction to the end of the flange plate.

[0015] Preferably, S2 includes:

[0016] S21, Anisotropic Constitutive Parameters: The arc additive manufactured T-shaped part adopts the Hill 48 yield criterion to introduce anisotropy, define six anisotropic yield stress ratio parameters according to the measured results, and convert the measured engineering stress and engineering strain into true stress and true strain;

[0017] S22, Material Failure Criterion: Define the starting point of material damage as the fracture strain of the material, and set the fracture energy required for material damage evolution; when the equivalent plastic strain of the element reaches the fracture strain of the material, the element stiffness fails, the element is deleted, and the connection fails.

[0018] Preferably, S3 includes:

[0019] S31, Ideal Flat Surface Model: Ignore the undulating surface of the arc additive manufactured T-shaped part and establish a flat finite element model of the arc additive manufactured T-shaped bolt connection;

[0020] The flat finite element model is divided into a flat finite element model of solid elements and a flat finite element model of shell elements; the flat finite element model of solid elements adopts hexahedral solid elements, and the geometric parameters adopt the measured average values of the basic geometric parameters obtained by S12 to reflect the average wall thickness characteristics of the arc additive manufactured T-shaped part;

[0021] The flat finite element model of the shell element adopts shell elements to improve the calculation efficiency. The thickness of the shell element uses S12 to obtain the measured values of the thickness of the plate at each coordinate position, reflecting the uneven wall thickness change of the arc additive manufactured T-shaped part, but it cannot simulate the arc chamfer feature at the connection between the web and the flange of the T-shaped part. By positioning the coordinates of each shell element, the 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.

[0022] S32, Undulating surface scanning model: Considering the undulating surface of the arc additive manufactured T-shaped part, a scanning finite element model of the arc additive manufactured T-shaped bolt connection is established.

[0023] The scanning finite element model is simulated using solid elements. The geometric parameters use S12 to obtain the measured values of the basic geometric parameters, reflecting both the surface undulation morphology and the uneven wall thickness change of the arc additive manufactured T-shaped part. The STL mesh model obtained by S12 is imported into the Hypermesh mesh processing software, and the 2D surface mesh is converted into a 3D solid mesh. The hexahedron solid elements are used for mesh model regeneration and imported into the finite element software to obtain the scanning finite element model.

[0024] The flat model has high calculation efficiency and is used for overall response simulations such as ultimate bearing capacity and parameter analysis; the scanning model has high simulation accuracy and is used for detailed response simulations such as failure modes.

[0025] Preferably, S4 includes:

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

[0027] The reference point RP-1 and the reference point RP-2 are respectively established at the center of the upper surface of the web of the arc additive manufactured T-shaped part and the center of the lower surface of the web of the ordinary T-shaped part. The reference point RP-1 is used as the loading control point at the displacement loading end and is combined with the upper surface of the web of the arc additive manufactured T-shaped part. The reference point RP-2 is coupled with the lower surface of the web of the ordinary T-shaped part and is completely fixed as the fixed constraint end.

[0028] The paired contact surfaces are divided into the lower surface of the flange of the arc additive manufactured T-shaped part and the upper surface of the flange of the ordinary T-shaped part, the lower surface of the high-strength bolt head and the upper surface of the flange of the arc additive manufactured T-shaped part, the upper surface of the high-strength bolt nut and the lower surface of the flange of the ordinary T-shaped part, and the bolt rod and the bolt hole wall. The contact method is surface contact, the main surface is the surface of the T-shaped part, and the slave surface is the surface of the bolt. The tangential attribute of the contact surface uses the friction penalty formula, and the normal attribute is hard contact. A contact tolerance is set at the contact between the bolt rod and the bolt hole wall.

[0029] S42. Test, measurement, comparison, and verification: Considering the arc additive manufacturing of single-row bolt type TS and double-row bolt type TE T-bolt connections, compare and verify the finite element prediction results of the simulation model of the solid element with the load-displacement curve results of the test measurement to verify the effectiveness and accuracy of the three-dimensional simulation method.

[0030] Preferably, in S41, it further includes simplifying the calculation model. The steps for simplifying the calculation model include:

[0031] Using the average value of the basic geometric parameters and the basic geometric parameters measured in S12, establish a flat model and a scanning model of the arc additive manufacturing T-bolt connection;

[0032] Ignore the threads of the bolt rod and establish a bolt model using the effective diameter of the bolt rod;

[0033] Couple the upper surface of the web of the arc additive manufacturing T-piece with its center point and set displacement loading at the center point;

[0034] Assume that when the equivalent plastic strain of a certain unit in the T-piece or bolt piece reaches the fracture strain, it is regarded as the occurrence of failure.

[0035] Preferably, in S41, it further includes mesh element division. The mesh element division includes: using hexahedral solid elements for mesh division; for the arc additive manufacturing T-piece and bolt piece, use the first mesh size, while for the ordinary T-piece, use the second mesh size, and the second mesh size is larger than the first mesh size; use automatic mesh division to ensure that there are at least multiple elements in the thickness direction of the model and the mesh density of each contact surface is close; conduct sensitivity analysis of the mesh size.

[0036] In the second aspect, a three-dimensional simulation and prediction system for arc additive manufacturing T-bolt connections is provided, which is used to execute any of the methods in the first aspect and includes:

[0037] A scanning processing module for geometric scanning and model processing: performing three-dimensional laser geometric scanning on the arc additive manufacturing T-piece and performing parameter processing on the obtained scanning model;

[0038] A setting module for material parameter and failure setting: defining the anisotropic constitutive parameters of the arc additive manufacturing T-piece and setting the material failure criterion;

[0039] A building module for flat model and scanning model building: constructing an ideal surface flat model and a fluctuating surface scanning model;

[0040] A prediction verification module for simulation prediction and test verification: predicting the bearing performance through the simulation model and comparing and verifying the accuracy of the model with the test measurement results.

[0041] 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 enabled to execute the method according to any one of the first aspect.

[0042] In a fourth aspect, an electronic device is provided, including:

[0043] a memory for storing a computer program;

[0044] a processor for executing the computer program to implement the method according to any one of the first aspect.

[0045] The beneficial effects of the present invention are:

[0046] 1. The three-dimensional simulation and prediction method for arc additive manufactured T-bolt connection provided by the present invention realizes the scanning of the undulating surface profile of the arc additive manufactured T-joint and the repair of the geometric model through geometric scanning and model processing, introduces the material anisotropy and failure criterion of the arc additive manufactured T-joint through material parameter and failure setting, realizes the finite element simulation of the arc additive manufactured T-bolt connection without and with considering the undulating surface respectively through the establishment of the flat model and the scanning model, and realizes the parametric three-dimensional simulation, bearing performance prediction and application design of the arc additive manufactured T-bolt connection through simulation prediction and experimental verification.

[0047] 2. The three-dimensional simulation and prediction method for arc additive manufactured T-bolt connection provided by the present invention takes into account the material anisotropy and irregular surface undulation of the arc additive manufactured structural parts, and establishes a three-dimensional simulation prediction model of the arc additive manufactured T-bolt connection 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, providing a new high-efficiency and high-precision three-dimensional simulation and prediction practical method for this type of structure. Description of the Drawings

[0048] Figure 1 is a schematic diagram of the overall steps of the three-dimensional simulation and prediction method for arc additive manufactured T-bolt connection provided by the present invention;

[0049] Figure 2 is a schematic diagram of the three-dimensional geometric scanning measurement process of the arc additive manufactured T-piece;

[0050] Figure 3 is a schematic diagram of the geometric dimensions of the arc additive manufactured T-bolt connection;

[0051] Figure 4 is a schematic diagram of the ideal surface flat model of the solid element of the arc additive manufactured T-bolt connection;

[0052] Figure 5 is a schematic diagram of the ideal surface flat model of the shell element of the arc additive manufactured T-bolt connection;

[0053] Figure 6 It is a schematic diagram of the scanned model of the undulating surface of the solid element of the arc additive manufacturing T-bolt connection;

[0054] Figure 7a It is a schematic diagram for comparing the simulation prediction model of the single-row bolt type TS with the test results;

[0055] Figure 7b It is a schematic diagram for comparing the simulation prediction model of the double-row bolt type TE with the test results.

[0056] Explanation of reference numerals: 1 - Arc additive manufacturing T-piece; 2 - Ordinary T-piece; 3 - High-strength bolt; 4 - Flange of the arc additive manufacturing T-piece; 5 - Web of the arc additive manufacturing T-piece; 6 - Flange of the ordinary T-piece; 7 - Web of the ordinary T-piece; 8 - Reference point RP-1; 9 - Reference point RP-2; 10 - Undulating surface; 11 - Assembly gap; 12 - Displacement loading end; 13 - Fixed constraint end. Specific implementation mode

[0057] The present invention will be further described below in conjunction with embodiments. The description of the following embodiments is only for helping to 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.

[0058] Embodiment 1:

[0059] As an embodiment, as Figure 1 shown, this three-dimensional simulation method for arc additive manufacturing T-bolt connection includes the following steps:

[0060] S1. Geometric scanning and model processing: Perform three-dimensional laser geometric scanning on the arc additive manufacturing T-piece, and perform parameter processing on the obtained scanning model.

[0061] S1 includes:

[0062] As Figure 2 shown, S11. Three-dimensional laser geometric scanning: There is an undulating topography on the surface of the arc additive manufacturing T-piece. Use a three-dimensional scanner to perform surface geometric scanning on the arc additive manufacturing T-piece, obtain a complete geometric contour, generate an STL mesh model, and import the STL mesh model into scanning data processing software for model repair.

[0063] Specifically, due to the characteristics of the arc additive manufacturing process, during the printing and forming process, there is a heat accumulation effect, resulting in an increase in the solidification time of the molten pool. It is difficult to control the shape of the molten pool, which causes the surface undulation morphology of the arc additive T-shaped part, leading to geometric changes in the overall contour. It is difficult to obtain the actual geometric dimensions using traditional measurement methods. A handheld 3D laser scanner is used to perform surface geometry scanning on the arc additive T-shaped part to capture the surface undulation morphology, obtain a scanning model of the complete geometric contour, and generate a corresponding STL mesh model file in the supporting software. During geometric measurement, the arc additive T-shaped part is divided into a web and a flange, and a series of cross-sectional contours are set at a certain spacing. The average measured thickness of each cross-sectional contour in the arc additive T-shaped part is taken as the average wall thickness of each measuring point in this cross-section.

[0064] For the arc additive T-shaped part, the generated STL mesh model file is imported into 3D scanning data processing software for post-processing of model repair, including repairing defects such as small holes, self-intersections, and spikes in the model to obtain a complete and continuous mesh model. In this embodiment, a 3D laser scanner SIMSCAN30 is used for geometric scanning with a scanning accuracy of 0.020 mm, and 3D scanning data processing software Geomagic Wrap is used for post-processing.

[0065] S12. Processing of scanning model parameters: The repaired STL mesh model is imported into Rhino 3D software, divided into a flange and a web, and contour sampling is performed separately at the sampling spacing to obtain the basic geometric parameters of the cross-sectional contour.

[0066] Specifically, for the arc additive T-shaped part, the geometric model processed by the 3D scanning data processing software is imported into Rhino 3D software in the form of an STL mesh model file and divided into two parts, the flange and the web, at the sampling spacing d x Contour sampling is performed on the flange and web models respectively to obtain the basic geometric parameters of each cross-sectional contour. A self-written Rhino Python script is used to achieve the sampling of the cross-sectional contour and the extraction of the contour geometric parameters. Sensitivity analysis is performed for different contour spacings.

[0067] As Figure 3 shown, among the basic geometric parameters of the arc additive T-shaped part, t w is the web thickness, t f is the flange plate thickness, p is the distance between bolt rows, m is the distance from the bolt center to the edge of the web, and n and e are the distances from the bolt center to the end of the flange plate along the force direction and perpendicular to the force direction respectively. In this embodiment, the measured results of the basic geometric parameters of the arc additive T-shaped parts used in the experiment are shown in Table 1. The flange thickness of each arc additive T-shaped part includes two measured values t f1 and t f2 .

[0068] Measured Results of Basic Geometric Parameters of Test Specimens (Unit: mm)

[0069]

[0070] As Figure 4 shown, the arc additive manufactured T-shaped connection bolt consists of an arc additive manufactured T-shaped part 1, a common T-shaped part 2, and a high-strength bolt 3, and is divided into single-row bolt type TS and double-row bolt type TE; the arc additive manufactured T-shaped part 1 consists of the flange 4 of the arc additive manufactured T-shaped part and the web 5 of the arc additive manufactured T-shaped part; the common T-shaped part consists of the flange 6 of the common T-shaped part and the web 7 of the common T-shaped part.

[0071] S2, Material Parameters and Failure Settings: Define the anisotropic constitutive parameters of the arc additive manufactured T-shaped part and set the material failure criterion.

[0072] S2 includes:

[0073] S21, Anisotropic Constitutive Parameters: The Hill 48 yield criterion is adopted for the arc additive manufactured T-shaped part to introduce anisotropy, and the yield stress ratio parameter is defined according to the measured results, and the measured engineering stress and engineering strain are converted into true stress and true strain.

[0074] Specifically, the arc additive manufactured T-shaped part has obvious anisotropy, and the Hill 48 yield criterion is adopted to introduce material anisotropy into the three-dimensional simulation; when establishing the Hill 48 yield function considering anisotropy, 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 longitudinal direction, where R 11 =σ 0.2,0° / σ 0.2,0° , R 22 =σ 0.2,90° / σ 0.2,0° , R 33 =R 12 =σ 0.2,45° / σ 0.2,0° , R 13 =R 23 ; in this embodiment, the arc additive manufactured T-shaped part 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 stress in the sampling directions of 0°, 45°, and 90° are shown in Table 2, and the values of the six anisotropic yield stress ratio parameters are shown in Table 3.

[0075] Table 2 Measured Average Values of Nominal Yield Stress in Different Sampling Directions (Unit: MPa)

[0076]

[0077] Table 3 Values of Anisotropic Yield Stress Ratio Parameters

[0078]

[0079] When assigning material properties to the arc additive manufactured T-shaped part, turn on the electric potential option and input these six anisotropic yield stress parameters. For bolt and high-strength steel materials, use the isotropic von Mises yield criterion; according to the measured stress-strain curves of the arc additive manufactured T-shaped part and high-strength steel materials, convert them into true stress-strain curves.

[0080] σ n = σ(1 + ε) (1)

[0081] ε n = ln(1 + ε) (2)

[0082] Where σ n and ε n are the true stress and true strain respectively, and σ and ε are the engineering stress and engineering strain obtained from experimental measurements; the constitutive relationship of high-strength bolts is simulated by a bilinear elastoplastic constitutive model.

[0083] S22, Material failure criterion: Define the starting point of material damage as the fracture strain of the material, and set the fracture energy J required for material damage evolution.

[0084] Simplify the failure simulation of the arc additive manufactured T-bolt connection. The corresponding failure is mainly controlled by the equivalent plastic strain of each element. When the equivalent plastic strain of a certain element reaches the fracture strain of the material, it is considered that failure occurs; define the starting point of material damage as the fracture strain of the material, and set the fracture energy required for material damage evolution as J. That is, once the fracture strain is reached, the element stiffness drops to failure, the element is deleted, and the connection fails; in this embodiment, the fracture energy for material damage evolution is J = 0.0001.

[0085] S3, Establishment of flat model and scanning model: Construct an ideal surface flat model and a wavy surface scanning model.

[0086] S3 includes:

[0087] S31, Ideal surface flat model: Ignore the wavy surface of the arc additive manufactured T-shaped part and establish a flat finite element model of the arc additive manufactured T-bolt connection.

[0088] As Figure 4 shown, the flat finite element model is simulated using solid elements. The geometric parameters of the flat model are the measured average values of the basic geometric parameters obtained from the measurement in step S1.2, including the flange wall thickness and the web wall thickness; through the flat model of solid elements for finite element simulation, the complex surface fluctuations of the arc additive manufactured T-shaped part can be ignored, improving the calculation efficiency; among various solid elements, hexahedral solid elements are used for mesh division.

[0089] As Figure 5 shown, optionally, for thin-walled structures such as T-bolt connections, the flat finite element model can also be simulated using shell elements to further improve the calculation efficiency; in this case, the thickness of the shell elements in the flat model is the measured value of the thickness of the plate at each coordinate position obtained in step S1.2; through the coordinate positioning of each shell element, the thickness of the plate 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 can be taken as the coordinate of the centroid position of the shell element; the flat model of the shell element can simulate the uneven wall thickness of the T-shaped part, but cannot simulate details such as the rounded chamfer at the connection between the web and the flange of the T-shaped part.

[0090] S32. Undulating surface scanning model: Considering the undulating surface of the arc additive manufacturing T-shaped part, a scanning finite element model of the arc additive manufacturing T-bolt connection is established.

[0091] As Figure 6 shown, the scanning finite element model is simulated using solid elements. The geometric parameters of the scanning model are the basic geometric parameters measured in step S12, and the undulating surface 10 and uneven wall thickness of the T-shaped part are considered; the STL mesh model file obtained by scanning in step S12 is imported into the Hypermesh mesh processing software, and the 2D surface mesh is converted into a 3D solid mesh using the Shrinkwrap function; the mesh model is regenerated using hexahedral solid elements; the regenerated three-dimensional mesh model file is imported into the finite element software to obtain the scanning finite element model of the undulating surface; then, a normal T-shaped part and a high-strength bolt model are created;

[0092] The flat model of the solid element uses the measured average value of the basic geometric parameters to reflect the average wall thickness characteristics; the flat model of the shell element uses the measured values of the basic geometric parameters to reflect the uneven wall thickness changes; the scanning model of the solid element uses the measured values of the surface geometric parameters to reflect the uneven wall thickness changes and the surface undulating morphology; the flat model has high calculation efficiency and is suitable for overall response simulations such as ultimate bearing capacity and parameter analysis; the scanning model has high simulation accuracy and is suitable for detailed response simulations such as failure modes.

[0093] The ideal surface flat model of the solid element in S31 and the undulating surface scanning model of the solid element in S32 have the same calculation model simplification (except for geometric model assumptions), mesh element division, boundary conditions, and contact surface settings; the scanning model uses hexahedral meshes. Due to the complex surface geometry, some meshes will be severely distorted during the direct scanning process, and the scanned model is imported into the Hypermesh software to regenerate a new mesh model.

[0094] S4. Simulation Prediction and Experimental Verification: Predict the bearing performance through the simulation model and verify the accuracy of the model by comparing with the experimental test results.

[0095] S4 includes:

[0096] S41. Three-dimensional Model Simulation Prediction: Establish a simulation model of solid elements. The simulation process includes, in sequence, calculation model simplification, mesh element division, boundary condition setting, and contact surface setting, and then predict the bearing performance through the simulation model; the simulation model of the solid elements includes a flat model and a scanned model.

[0097] Specifically, S41 includes:

[0098] (1) Calculation Model Simplification

[0099] To improve the calculation efficiency and convergence of the finite element simulation, simplify the calculation model: 1) Respectively use the average value of the basic geometric parameters and the basic geometric parameters measured in step S1.2 to establish a flat model and a scanned model of the arc additive manufactured T-bolt connection; 2) Ignore the threads of the bolt rod and use the effective diameter of the bolt rod to establish the bolt model; 3) Simplify the loading method, that is, couple the upper surface of the web of the arc additive manufactured T-piece with its center point and set displacement loading at the center point; 4) Simplify the failure criterion, that is, assume that when the equivalent plastic strain of a certain element in the T-piece or the bolt piece reaches the fracture strain, it is regarded as the occurrence of failure; in this embodiment, the effective diameter of the M14 high-strength bolt is 12.12 mm, and the effective diameter of the M12 high-strength bolt is 10.31 mm.

[0100] (2) Mesh Element Division

[0101] Use hexahedral solid elements for mesh division, allowing large deformations and material nonlinearities, and considering both calculation efficiency and calculation accuracy at the same time; for the arc additive manufactured T-piece and the bolt piece, use relatively small mesh sizes, while for the ordinary T-piece, use relatively large mesh sizes; use automatic mesh division 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 to ensure the accuracy of the simulation results; conduct sensitivity analysis of the mesh size; in this embodiment, the smaller and larger mesh sizes are 2 mm and 3 mm respectively.

[0102] (3) Boundary Condition Setting

[0103] The upper part is an arc additive manufactured T-shaped component, and the lower part is an ordinary T-shaped component; reference points RP-1(8) and RP-2(9) are respectively established at the center of the upper surface of the web of the arc additive manufactured T-shaped component and the center of the lower surface of the web of the ordinary T-shaped component; reference point RP-1 serves as the loading control point of the displacement loading end 12 and is combined with the upper surface of the web of the arc additive manufactured T-shaped component; during displacement loading, the displacements in the X and Z directions and the rotations in the three directions are all constrained, while the vertical displacement in the Y direction is controlled for loading; reference point RP-2 is coupled with the lower surface of the web of the ordinary T-shaped component and completely fixed as the fixed constraint end 13, that is, all 6 degrees of freedom are constrained.

[0104] (4) Contact surface setting

[0105] The paired surfaces in contact are set to include: 1) the lower surface of the flange of the arc additive manufactured T-shaped component and the upper surface of the flange of the ordinary T-shaped component; 2) the lower surface of the high-strength bolt head and the upper surface of the flange of the arc additive manufactured T-shaped component; 3) the upper surface of the high-strength bolt nut and the lower surface of the flange of the ordinary T-shaped component; 4) the bolt rod and the bolt hole wall.

[0106] The contact method is set to surface contact. The surface of the T-shaped component with greater stiffness is set as the master surface, and the surface of the bolt with smaller stiffness is set as the slave surface; the tangential property of the contact surface adopts the friction penalty formula, the friction coefficient is set to 0.3, and the normal property of the contact surface is set to hard contact; in order to improve the convergence of the finite element simulation, a contact tolerance of 1.0 is set at the contact between the bolt rod and the bolt hole wall to consider the assembly gap 11 reserved between the bolt rod and the bolt hole wall during the modeling process.

[0107] As Figure 7a 、 Figure 7b shown, S42. Experimental test and comparison verification: Considering the arc additive manufactured T-shaped bolt connections of single-row bolt type TS and double-row bolt type TE, the finite element prediction results of the simulation model of the solid element are compared with the load-displacement curve results of the experimental test to verify the effectiveness and accuracy of the three-dimensional simulation method.

[0108] Compared with the flat model, the scanning model provides more accurate results by retaining the surface irregularities of the arc additive manufactured T-shaped component, that is, it is closer to the load-displacement curve results of the experimental tests and has better predictability. However, due to the irregular geometry of the scanning model itself and the large number of non-linear contact calculations involved, the computational efficiency and convergence are reduced. Therefore, when performing three-dimensional simulation and prediction of arc additive manufactured T-bolt connections, the ideal surface flat model is used as the preliminary three-dimensional simulation and prediction method, and the undulating surface scanning model is used as the in-depth three-dimensional simulation and prediction method. In this embodiment, the accuracy of the flat model and the scanning model is verified through experimental test results. The load-displacement curve covers three stages: the elastic stage, the plastic yield stage, and the failure stage. The results of the two simulation models are basically consistent with the experimental results. The maximum error effect of the flat model is less than 20% (TS) and 10% (TE), and the maximum error effect of the scanning model is less than 10% (TS) and 5% (TE).

[0109] Embodiment 2:

[0110] Based on Embodiment 1, this embodiment provides the three-dimensional simulation and prediction method for arc additive manufactured T-bolt connections proposed in Embodiment 1, and its practical application in the integrated manufacturing of arc additive manufactured T-bolt connections considering material anisotropy and undulating surface characteristics by WAAM process, as well as the three-dimensional simulation and bearing performance prediction of other arc additive manufactured metal structural components.

[0111] Embodiment 3:

[0112] Based on Embodiment 1, Embodiment 3 of the present application provides a three-dimensional simulation and prediction system for arc additive manufactured T-bolt connections, including:

[0113] A scanning processing module for geometric scanning and model processing: performing three-dimensional laser geometric scanning on the arc additive manufactured T-shaped component and processing the parameters of the obtained scanning model;

[0114] A setting module for material parameter and failure setting: defining the anisotropic constitutive parameters of the arc additive manufactured T-shaped component and setting the material failure criterion;

[0115] A building module for building flat model and scanning model: constructing an ideal surface flat model and an undulating surface scanning model;

[0116] A prediction verification module for simulation prediction and experimental verification: predicting the bearing performance through the simulation model and comparing with the experimental test results to verify the accuracy of the model.

[0117] It should be noted that the system provided in this embodiment is the system corresponding to the method provided in Embodiment 1. Therefore, the parts that are the same or similar to those in Embodiment 1 in this embodiment can be referred to each other and will not be elaborated in this application.

[0118] In summary, the three-dimensional simulation and prediction method for arc additive manufacturing T-bolt connection provided by the present invention takes into account the material anisotropy and irregular surface undulation characteristics of arc additive manufacturing structural parts. The undulating surface profile scanning and geometric model repair of arc additive manufacturing T-joint are realized through geometric scanning and model processing. The material anisotropy and failure criterion of arc additive manufacturing T-joint are introduced through material parameter and failure setting. The finite element simulation of arc additive manufacturing T-bolt connection without and with undulating surface is realized by establishing flat model and scanning model respectively. The parametric three-dimensional simulation, bearing performance prediction and application design of arc additive manufacturing T-bolt connection are realized through simulation prediction and experimental verification, providing a new practical method for three-dimensional simulation and prediction with high efficiency and high precision for this kind of structure. And through actual verification, the method of the present invention is effective.

Claims

1. A three-dimensional simulation and prediction method for arc additive manufacturing T-bolt connection, characterized in that Including: S1. Geometric scanning and model processing: Conduct three-dimensional laser geometric scanning on the arc additive manufactured T-shaped part, and perform parameter processing on the obtained scanning model. S2. Material parameter and failure setting: Define the anisotropic constitutive parameters of the arc additive manufactured T-shaped part, and set the material failure criterion. S3. Establishment of flat model and scanning model: Construct an ideal surface flat model and a fluctuating surface scanning model. S4. Simulation prediction and experimental verification: Predict the bearing performance through the simulation model, and compare with the experimental test results to verify the accuracy of the model.

2. The three-dimensional simulation and prediction method for arc additive manufacturing T-bolt connection according to claim 1, wherein S1 includes: S11. Three-dimensional laser geometric scanning: Use a three-dimensional scanner to conduct geometric scanning on the surface undulation morphology of the arc additive manufactured T-shaped part, obtain a complete geometric contour, generate an STL mesh model, and import the STL mesh model into scanning data processing software for model repair. S12. Scanning model parameter processing: Import the repaired STL mesh model into Rhino 3D software, divide it into a flange and a web, and perform contour sampling respectively according to the sampling interval to obtain the basic geometric parameters of the cross-section contour. The basic geometric parameters of the arc additive manufactured T-shaped part include the web thickness, flange thickness, distance between bolt rows, distance from the bolt center to the web edge, and distances from the bolt center along the stress direction and perpendicular to the stress direction to the end of the flange plate.

3. The three-dimensional simulation and prediction method for arc additive manufacturing T-bolt connection according to claim 2, wherein S2 Including: S21. Anisotropic constitutive parameters: The arc additive manufactured T-shaped part adopts the Hill 48 yield criterion to introduce anisotropy, define six anisotropic yield stress ratio parameters according to the measured results, and convert the measured engineering stress and engineering strain into true stress and true strain. S22. Material failure criterion: Define the starting point of material damage as the fracture strain of the material, and set the fracture energy required for material damage evolution; when the equivalent plastic strain of the element reaches the material fracture strain, the element stiffness fails, the element is deleted, and the connection fails.

4. The three-dimensional simulation and prediction method for arc additive manufacturing T-bolt connection according to claim 3, characterized in that S3 Including: S31. Ideal surface flat model: Ignore the fluctuating surface of the arc additive manufactured T-shaped part and establish a flat finite element model for the arc additive manufactured T-shaped bolt connection. The flat finite element model is divided into a flat finite element model of solid elements and a flat finite element model of shell elements; the flat finite element model of solid elements adopts hexahedron solid elements, and the geometric parameters adopt the measured average values of the basic geometric parameters obtained in S12 to reflect the average wall thickness characteristics of the arc additive manufactured T-shaped part. The flat finite element model of shell elements adopts shell elements to improve the calculation efficiency; the thickness of the shell elements adopts the measured values of the plate thickness at each coordinate position obtained in S12 to reflect the uneven wall thickness change of the arc additive manufactured T-shaped part, but it cannot simulate the arc chamfering characteristics at the connection between the web and the flange of the T-shaped part; through the coordinate positioning of each shell element, the 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 centroid position coordinate of the element. S32. Fluctuating surface scanning model: Consider the fluctuating surface of the arc additive manufactured T-shaped part and establish a scanning finite element model for the arc additive manufactured T-shaped bolt connection. The scanned finite element model is simulated using solid elements. The geometric parameters are measured by S12 to obtain the measured values of the basic geometric parameters, which can simultaneously reflect the surface undulation morphology and uneven wall thickness variation of the arc additive manufactured T-shaped component. The STL mesh model obtained by S12 is imported into the Hypermesh mesh processing software, and the 2D surface mesh is converted into a 3D solid mesh. The hexahedron solid elements are used to regenerate the mesh model, and then imported into the finite element software to obtain the scanned finite element model. The flat model has high computational efficiency and is used for overall response simulations such as ultimate bearing capacity and parameter analysis. The scanned model has high simulation accuracy and is used for detailed response simulations such as failure modes.

5. The three-dimensional simulation and prediction method for arc additive manufacturing T-bolt connection according to claim 4, wherein S4 Including: S41. Three-dimensional model simulation prediction: A simulation model of solid elements is established, boundary conditions and contact surfaces are set, and then the bearing performance is predicted through the simulation model. The simulation model of solid elements includes a flat model and a scanned model. The reference point RP-1 and the reference point RP-2 are respectively established at the center of the upper surface of the web of the arc additive manufactured T-shaped component and the center of the lower surface of the web of the ordinary T-shaped component. The reference point RP-1 serves as the loading control point at the displacement loading end and is combined with the upper surface of the web of the arc additive manufactured T-shaped component. The reference point RP-2 is coupled with the lower surface of the web of the ordinary T-shaped component and is completely fixed as the fixed constraint end. The paired contact surfaces are divided into the lower surface of the flange of the arc additive manufactured T-shaped component and the upper surface of the flange of the ordinary T-shaped component, the lower surface of the high-strength bolt head and the upper surface of the flange of the arc additive manufactured T-shaped component, the upper surface of the high-strength bolt nut and the lower surface of the flange of the ordinary T-shaped component, and the bolt rod and the bolt hole wall. The contact type is surface contact, the main surface is the surface of the T-shaped component, and the slave surface is the surface of the bolt. The tangential property of the contact surface adopts the friction penalty formula, and the normal property is hard contact. A contact tolerance is set at the contact between the bolt rod and the bolt hole wall. S42. Experimental test comparison and verification: Considering the arc additive manufactured T-shaped bolt connections of single-row bolt type TS and double-row bolt type TE, the finite element prediction results of the simulation model of solid elements are compared with the load-displacement curve results of the experimental tests to verify the effectiveness and accuracy of the three-dimensional simulation method.

6. The method for three-dimensional simulation and prediction of arc additive manufacturing T-bolt connection 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 the average value and the basic geometric parameters of the basic geometric parameters measured by S12, a flat model and a scanned model of the arc additive manufactured T-shaped bolt connection are established. Ignoring the threads of the bolt rod, the bolt model is established using the effective diameter of the bolt rod. Coupling the upper surface of the web of the arc additive manufactured T-shaped component with its center point, and setting displacement loading at the center point. Assuming that when the equivalent plastic strain of a certain element in the T-shaped component or the bolt component reaches the fracture strain, it is regarded as the occurrence of failure.

7. The method for three-dimensional simulation and prediction of arc additive manufacturing T-bolt connection according to claim 6, characterized in that In S41, it also includes mesh cell division, and the mesh cell division includes: performing mesh division using hexahedral solid elements; for the arc additive manufactured T-shaped parts and bolt parts, using a first mesh size, while for ordinary T-shaped parts, using a second mesh size, and the second mesh size is larger than the first mesh size; using automatic mesh division to ensure that there are at least multiple elements in the thickness direction of the model and the mesh density of each contact surface is close; performing sensitivity analysis of the mesh size.

8. The three-dimensional simulation and prediction system for T-bolt connection by arc additive manufacturing, characterized in that, For implementing the method according to any one of claims 1 to 7, it includes: A scanning processing module for geometric scanning and model processing: performing three-dimensional laser geometric scanning on the arc additive manufactured T-shaped parts and performing parameter processing on the obtained scanning model; A setting module for material parameter and failure setting: defining the anisotropic constitutive parameters of the arc additive manufactured T-shaped parts and setting the material failure criterion; A building module for building a flat model and a scanning model: constructing an ideal surface flat model and a fluctuating surface scanning model; A prediction verification module for simulation prediction and experimental verification: predicting the bearing performance through the simulation model and comparing with the experimental test results to verify the accuracy of the model.

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

10. An electronic device, characterized in that, It includes: 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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