Plasticity finite element modeling method and electronic equipment for shot peening crystal of three-phase TiAl alloy

Abstract

The present application provides a three-phase TiAl alloy shot peening crystal plasticity finite element modeling method and electronic equipment, which establishes a finite element model based on the grain data of the three-phase TiAl alloy sample obtained by electron backscatter diffraction technology and the actual microstructure of the material, integrates the grain data of the real material, the properties of the matrix material and other characteristics into the model, and completes the crystal finite element modeling process through Python and Fortran languages, solves the defects of multiple shot peening models and their time-consuming, improves the accuracy of shot peening of TiAl alloy crystal plasticity finite element model, and helps to accurately predict the mechanical properties of the crystal and thus achieve microstructure optimization.

Description

Technical Field

[0001] The present application relates to the field of modeling technology, and in particular to a three-phase TiAl alloy shot peening crystal plasticity finite element modeling method and electronic equipment. Background Art

[0002] TiAl alloy is widely used in high-tech fields due to its unique properties at high temperatures. Such as high-pressure compressor blades, engine casting low-pressure turbine blades, turbocharger wheels, etc. It is an alloy with the potential to replace the currently used nickel-based high-temperature alloys, mainly due to its lower density, yield strength, and excellent oxidation resistance and creep resistance at high temperatures of 800°C. And TiAl alloy accounts for one-third of the weight of modern aircraft engines, and is the second largest engine material after nickel-based high-temperature alloys. However, modern aircraft engine high-temperature components are mostly made of nickel-based high-temperature alloys, which is not conducive to improving the thrust-to-weight ratio of aircraft engines. Therefore, replacing nickel-based high-temperature alloys with TiAl alloys will not only reduce the structural weight of the components by 20%-30%, but also maintain high specific stiffness at high temperatures. This is very beneficial for the design of lightweight structural parts in aerospace and automotive applications. TiAl alloy is composed of Ti and Al combined in a specific atomic ratio and has a long-range ordered superlattice structure. However, these characteristics lead to fewer slip systems and higher Burgers vectors. But TiAl alloy has poor room temperature plasticity (elongation is only 2% ~4%), and it is easy to crack and cause fracture.

[0003] From a microscopic scale, the plastic deformation modes of metals include slip, twinning, etc. Crystal Plasticity Finite Element Method (CPFEM) is a method based on the crystal plasticity theory coupled with the finite element method to study the plastic behavior of crystals. It uses a variational method in the form of finite element approximation to deal with the anisotropic plastic deformation of crystals under complex external boundary conditions and describe the microscopic slip shear mechanism in the crystallographic direction within the crystal. CPFEM is a computational tool that integrates theoretical and experimental physical knowledge related to dislocations, single crystal deformation, etc. and applies it to continuum mechanics, and can establish a multi-scale physical model based on microstructure, including scale effects and interface mechanisms.

[0004] Shot peening is a surface treatment process used to improve the fatigue resistance of the workpiece surface. Compared with other surface treatment processes, shot peening is simple, effective, and low-cost, so it is widely used, including molds, automobiles, aviation and other important fields. During the shot peening process, a large number of projectiles continuously hit the surface of the workpiece, causing the surface of the workpiece to undergo plastic deformation, forming a surface strengthening layer with a work hardening effect. Studies have shown that the presence of the surface strengthening layer not only improves the hardness and wear resistance of the workpiece surface, but more importantly, forms a residual compressive stress layer on the surface of the workpiece. The residual compressive stress layer can hinder the generation and expansion of fatigue microcracks, thereby greatly improving the surface fatigue resistance of the parts.

[0005] Due to the poor plasticity and complex deformation behavior of TiAl alloy, the research on its deformation mechanism is not in-depth enough. At present, the deformation mechanism of TiAl alloy is explored through microstructure characterization, molecular dynamics simulation, mechanical properties, etc., and the research on TiAl alloy mainly focuses on plastic flow, surface integrity, and microstructure morphology. Crystal plasticity finite element (CPFE) is a very commonly used method for the micro-nano mechanical behavior and deformation mechanism that occurs in the plastic deformation process at the mesoscale. So far, the research on the crystal plasticity of TiAl alloy has mostly focused on a single phase, and the research is not in-depth enough. Summary of the invention

[0006] The purpose of the embodiments of the present application is to provide a three-phase TiAl alloy shot peening crystal plasticity finite element modeling method and electronic equipment to solve the defects of multiple shot peening models and their time-consuming operation, thereby improving the accuracy of shot peening of the TiAl alloy crystal plasticity finite element model.

[0007] In a first aspect, the present invention provides a three-phase TiAl alloy shot peening crystal plasticity finite element modeling method, the method comprising:

[0008] The electron backscatter diffraction technique is used to obtain grain data of the sample, wherein the sample is a three-phase TiAl alloy sample;

[0009] Based on finite element analysis software, the matrix with the shot is given the matrix material properties of each phase of the three-phase TiAl alloy sample, and a script constructed by Python language is used to obtain a shot peening finite element model;

[0010] Inputting the grain data into a subroutine constructed using Fortran language to construct the matrix in the shot peening finite element model into a grain geometry model;

[0011] The crystal plasticity constitutive relation information in the subroutine is coupled to the shot peening finite element model to obtain a shot peening crystal plasticity finite element model.

[0012] In an optional embodiment, the step of assigning the matrix material properties of each phase of the three-phase TiAl alloy sample to the matrix with the shot based on the finite element analysis software, and constructing a shot peening finite element model using a script constructed in Python language, comprises:

[0013] Setting projectile information and substrate information, wherein the projectile information includes the size, quantity, impact speed and angle of the projectile, and the substrate information includes the size of the substrate and the bombardment area;

[0014] Randomly generate projectiles in a bombardment area of ​​the substrate based on the projectile information and the substrate information;

[0015] Based on finite element analysis software, the matrix and the projectile are given the matrix material properties of each phase of the three-phase TiAl alloy sample, and a script constructed in Python language is used to construct a shot peening finite element model.

[0016] In an optional embodiment, the step of assigning the matrix material properties of each phase of the three-phase TiAl alloy sample to the matrix and the projectile based on finite element analysis software, and constructing a shot peening finite element model using a script constructed in Python language, comprises:

[0017] Based on finite element analysis software, the matrix and each of the projectiles are given the matrix material properties of each phase of the three-phase TiAl alloy sample;

[0018] Meshing the substrate;

[0019] The shot peening finite element model was obtained based on the meshed matrix and the script constructed using Python language.

[0020] In an optional embodiment, the grain data includes a grain seed point, a grain size, and a grain Euler angle;

[0021] The step of inputting the grain data into a subroutine constructed using the Fortran language to construct the matrix in the shot peening finite element model into a grain geometry model comprises:

[0022] The grain seed point, grain size and grain Euler angle are input into the SDVINI subroutine of the VUMAT main program constructed in Fortran language;

[0023] The distance between grains is calculated, the direction of grain growth is determined, and the equivalent diameter of the grains is calculated based on a volume method, and the grain division of the matrix in the shot peening finite element model is completed to construct a grain geometry model.

[0024] In an optional embodiment, the step of calculating the distance between grains includes:

[0025] Obtaining the coordinates of a grain seed point, setting the coordinates of an integration point in a VUMAT calculation, and calculating the distance between the grain seed point and the integration point based on the coordinates of the grain seed point and the integration point as a first distance between a first grain and the integration point;

[0026] For each subsequent grain, the distance between each grain and the integration point is calculated, and it is detected whether the distance is less than the first distance. If it is less than the first distance, the distance is updated to the first distance; if it is greater than or equal to the first distance, the distance is maintained.

[0027] In an optional embodiment, the step of calculating the equivalent diameter of the grains based on the volume method comprises:

[0028] The diameter of each of the grains is obtained, and the equivalent diameter of the grain is calculated according to a preset formula corresponding to the volume-based method and based on the diameter.

[0029] In an optional embodiment, the crystal plasticity constitutive relation information in the subroutine is constructed in the following manner:

[0030] Coupled dislocation density slip deformation mechanism, CDM damage criterion, γ-TiAl phase, α 2 -Ti 3 Al phase, 0 -TiAl phase in order to select the initial orientation of the grains, and establish a comprehensive consideration of γ-TiAl, α 2 -Ti 3 Al, 0 - A crystal plasticity finite element constitutive relationship model of TiAl, and the constitutive relationship model is written into the subroutine.

[0031] In an optional embodiment, the step of coupling the crystal plasticity constitutive relationship information in the subroutine to the shot peening finite element model to obtain the shot peening crystal plasticity finite element model comprises:

[0032] Based on the crystal plasticity constitutive relation information in the subroutine, the Taylor cumulative shear strain and dislocation density on all slip and twin systems are obtained, and the damage factor is calculated according to the Taylor cumulative shear strain;

[0033] In each incremental step, the shear stress is corrected by using the damage factor to obtain the effective shear stress, and the cumulative twin crystal volume fraction is calculated based on the effective shear stress of the twin system;

[0034] Each grid in the shot peening finite element model is taken as a unit integration point, and the cumulative twin volume fraction of all twin variants in each unit integration point is calculated according to the number of twin systems opened and the cumulative twin crystal volume fraction. After all incremental steps are completed, the shot peening crystal plasticity finite element model is obtained.

[0035] In an optional embodiment, the method further comprises:

[0036] Simulating the shot peening crystal plasticity finite element model to obtain simulation result data after random shot peening;

[0037] The simulation result data is outputted in a graphical form based on visualization technology.

[0038] In a second aspect, the present invention provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor executes the computer program, the steps of the method described in any one of the aforementioned implementation modes are implemented.

[0039] The embodiment of the present application provides a three-phase TiAl alloy shot peening crystal plasticity finite element modeling method and electronic equipment. The finite element model is established using the actual microstructure of the material based on the grain data of the three-phase TiAl alloy sample obtained based on the electron backscatter diffraction technology, and the grain data of the real material, the properties of the matrix material and other characteristics are integrated into the model. The crystal finite element modeling process is completed through Python and Fortran languages, which solves the defects of multiple shot peening models and their time-consuming defects, improves the accuracy of shot peening of the TiAl alloy crystal plasticity finite element model, and helps to accurately predict the mechanical properties of the crystal and thus achieve microstructure optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 A flow chart of a three-phase TiAl alloy shot peening crystal plasticity finite element modeling method provided in an embodiment of the present application;

[0042] Figure 2 for Figure 1 A flowchart of the sub-steps included in S12;

[0043] Figure 3 for Figure 2 A flowchart of the sub-steps included in S123;

[0044] Figure 4 for Figure 1 A flowchart of the sub-steps included in S13;

[0045] Figure 5 for Figure 4 A flowchart of the sub-steps included in S132;

[0046] Figure 6 for Figure 1 A flowchart of the sub-steps included in S14;

[0047] Figure 7 is the inverse pole figure obtained by the EBSD experiment in this embodiment;

[0048] Figure 8 is a top view of the substrate model after shot peening in this embodiment;

[0049] Fig. 9 is a front view of the substrate model after shot peening in this embodiment;

[0050] Fig.10 It is a surface accumulation diagram simulated in this embodiment;

[0051] Fig.11 Schematic diagram of the distribution of transverse residual stress of the workpiece after shot peening in this embodiment;

[0052] Fig.12 is a distribution curve of residual stress with depth in this embodiment;

[0053] Fig.13 Schematic diagram of total accumulated shear strain in this embodiment;

[0054] Fig.14 This is a structural block diagram of the electronic device provided in this embodiment. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0056] Figure 1 The flowchart of the three-phase TiAl alloy shot peening crystal plasticity finite element modeling method provided in the embodiment of the present application can be performed by an electronic device, which can be a computer, server or other device with data, image and other processing capabilities. Figure 1 As shown, the method comprises the following steps:

[0057] S11, using electron backscatter diffraction technology to obtain grain data of the sample, wherein the sample is a three-phase TiAl alloy sample.

[0058] S12, based on the finite element analysis software, the matrix material properties of each phase of the three-phase TiAl alloy sample are assigned to the matrix with the projectiles, and a script constructed by Python language is used to obtain a shot peening finite element model.

[0059] S13, inputting the grain data into a subroutine constructed using Fortran language, so as to construct the matrix in the shot peening finite element model into a grain geometry model.

[0060] S14, coupling the crystal plasticity constitutive relationship information in the subroutine to the shot peening finite element model to obtain a shot peening crystal plasticity finite element model.

[0061] In this embodiment, the experimental material used is an extruded rod with a nominal chemical composition of Ti-43.5Al-4Nb-1Mo-0.1B (at%). A large sample of a certain size, such as a large sample of 16 mm×16 mm×2 mm, is cut from the middle area of ​​the extruded rod by wire cutting. The sample surface is first ground with a series of SiC sandpapers ranging from 50 mesh to 5000 mesh, and then treated with porous chloroprene rubber with a particle size of 0.06 μm. Finally, an electrolytic polishing solution (5% perchloric acid, 35% n-butanol, 60% methanol) is used at -15° / 25V for 40 seconds to facilitate electron backscatter diffraction EBSD observation.

[0062] The electron backscatter diffraction technique can be used to obtain the crystal orientation map of the sample with a spatial resolution of 1μm. The EBSD measurement can determine the precise grain data of each grain, including grain seed point, grain size, surface Euler angle, phase information, etc.

[0063] In this embodiment, the AZtecCrystal software platform can be used to analyze the grain data obtained by the electron backscatter diffraction technology, and the grain data can be saved in a crc format file. By using the oimA software platform to process the grain data in the crc format file, the matrix material properties of each phase of the required three-phase TiAl alloy sample are obtained, including properties such as crystal orientation, crystal seed point, and grain size.

[0064] Shot peening is performed on the substrate to form a shot on the substrate. On this basis, a finite element analysis software, such as an internal Python script runner of ABAQUS finite element analysis software, can be used to run a script to construct a shot peening finite element model.

[0065] On this basis, the grain data was input into a subroutine constructed in Fortran language, so that the matrix in the shot peening finite element model was constructed as a grain geometry model. In this process, the distance between grains and the equivalent diameter of the grains were considered to complete the division of the grains in the matrix.

[0066] Finally, the grain plasticity constitutive relation information pre-written in the subroutine is coupled to the shot peening finite element model to obtain the shot peening crystal plasticity finite element model.

[0067] In this embodiment, the three-phase TiAl alloy includes γ-TiAl phase, α 2 -Ti 3 Al phase and β 0 -TiAl phase, the slip system in the γ-TiAl phase includes a normal slip system, a super slip system and a twin system, the α 2 -Ti 3 The slip systems in the Al phase include basal slip system, cylindrical slip system and conical slip system. 0 -TiAl contains only common slip systems.

[0068] γ-TiAl has an L10 lattice structure, and the main slip and twin systems are: 4 common slip systems , 8 super-slip systems and 4 twin systems .

[0069] α 2 -Ti 3 Al has a D019 lattice structure, and the main slip systems are: 3 basal slip systems , 3 cylindrical slip systems , 6 conical slip systems .

[0070] β 0 -TiAl has a B2 lattice structure, and the main slip systems are: 12 common slip systems .

[0071] See also Figure 2 In this embodiment, the steps of assigning the matrix material properties of each phase of the three-phase TiAl alloy sample to the matrix with the projectiles based on the finite element analysis software and using the script constructed by Python language to obtain the shot peening finite element model can be achieved in the following way:

[0072] S121, setting projectile information and substrate information, wherein the projectile information includes the size, quantity, impact speed and angle of the projectile, and the substrate information includes the size of the substrate and the bombardment area.

[0073] S122, randomly generating pellets in a bombardment area of ​​the substrate based on the pellet information and the substrate information.

[0074] S123, assigning matrix material properties of each phase of the three-phase TiAl alloy sample to the matrix and the projectile based on finite element analysis software, and obtaining a shot peening finite element model using a script constructed using Python language.

[0075] In this embodiment, the size of the projectile is D, the number of the projectiles is n, the impact speed is V, and the impact angle is Angle. The substrate can also be called a target material, the side length B of the target material can be set to 10 times the diameter of the projectile, the thickness H of the target material is 5 times the distance between the projectiles, and the target material as a whole is a rectangular block. The bombardment area on the target material is a square area with a side length of L.

[0076] In this embodiment, the size D of the projectile can be 0.4 mm, the number of the projectiles can be 15, the impact speed is 50 m / s, and the impact angle is perpendicular to the target. The size of the target is 2 mm 2mm 1mm cuboid, bombardment area is 1mm 1mm square.

[0077] Based on the projectile information and the substrate information, projectiles are randomly generated in the bombardment area of ​​the substrate. The position information of the randomly generated projectiles includes the X coordinate, Y coordinate, and Z coordinate. The X coordinate is randomly generated in the bombardment area of ​​the substrate, and the Y coordinate is randomly generated by the following formula:

[0078] The Y coordinate range of the bombardment area is + (Z coordinate - L / 2) / tan (Angle);

[0079] The Z coordinate of the projectile generates a node at every preset length in the Z-axis direction, wherein the preset length may be 0.05 mm.

[0080] In addition, when randomly generating projectiles, it is necessary to ensure that the coordinates of the center of the randomly generated projectile do not overlap with the spatial positions of the generated projectiles, that is, the distance between the coordinates of the center of the generated (n+1) projectile and the center of the first n projectiles is greater than the radius of the projectile.

[0081] Through the above method, multiple projectiles can be generated in batches, and the projectile information, analysis steps, boundary conditions, interactions, and meshing methods of the projectiles can be written into the Python script inside the ABAQUS finite element analysis software using statements.

[0082] On this basis, see Figure 3The above-mentioned steps of assigning the matrix material properties of each phase of the three-phase TiAl alloy specimen to the matrix and the projectile based on the finite element analysis software, and obtaining the shot peening finite element model by using the script constructed by Python language, can be achieved by the following methods:

[0083] S1231, assigning the matrix material properties to the matrix and each of the projectiles based on finite element analysis software.

[0084] S1232, meshing the substrate.

[0085] S1233, based on the meshed matrix and using the script built in Python language to obtain the shot peening finite element model.

[0086] In this embodiment, based on the finite element analysis software, the matrix material properties can be first assigned to a single projectile, and then copied to all projectiles. In addition, the analysis step and boundary conditions are set, wherein one analysis step includes multiple incremental steps. It can be understood that the time period corresponding to each stage is divided into multiple small time segments, and each time segment is an incremental step.

[0087] The boundary conditions are that the bottom of the target is completely fixed, the shot peening xy axis is fixed, and the z axis gives a speed of 50m / s in the negative direction.

[0088] When dividing the grid, a grid type suitable for the geometric shape of the grain can be selected, such as a hexahedron, a tetrahedron, etc. In this embodiment, specifically, an eight-node linear hexahedral reduced integration unit grid (C3D8R) can be used to divide the target material into multiple grids, and a four-node linear tetrahedron unit can be used to divide the shot peening into grids. In this process, the division can be performed based on the determined grid size.

[0089] On this basis, see Figure 4 , the grain data is input into a subroutine built in Fortarn language to construct the matrix in the shot peening finite element model as a grain geometry model. This step can be achieved in the following ways:

[0090] S131, inputting the grain seed point, grain size and grain Euler angle into the SDVINI subroutine of the VUMAT main program constructed using Fortran language.

[0091] S132, calculating the distance between grains, determining the grain growth direction, and calculating the equivalent diameter of the grains based on a volume method, completing the grain division of the matrix in the shot peening finite element model to construct a grain geometry model.

[0092] In this embodiment, the grain seed point, grain size and grain Euler angle are input into the SDVINI subroutine of the VUMAT main program to complete the real grain growth and obtain the grain geometric model.

[0093] Among them, the grain Euler angle needs to be converted into Miller index and added to the SDVINI subroutine as a grain attribute. Specifically, the grain Euler angle can be recorded as ( ), the grain Euler angle can be converted into Miller index by the following formula:

[0094]

[0095] Crystal orientation is defined as the relative positions of the three crystal axes of the crystal (such as

[100] -

[010] -

[001] ) in the sample coordinate system (such as RD (rolling direction)-TD (lateral or transverse)-ND (normal direction) of rolled plate).

[0096] Miller index = (hkl)[uvw], which means that the (hkl) plane of the unit cell is parallel to the rolling surface of the (sample coordinate system) of the rolled plate, and the [uvw] direction is parallel to the rolling direction.

[0097] The sample coordinate system is the xyz axis where the sample is actually observed, i.e. RD / TD / ND.

[0098] See also Figure 5 , where the distance between grains is calculated and the direction of grain growth is determined, which can be achieved in the following ways:

[0099] S1321, obtain the coordinates of the grain seed point, set the coordinates of the integration point in the VUMAT calculation, and calculate the distance between the grain seed point and the integration point based on the coordinates of the grain seed point and the coordinates of the integration point as the first distance between the first grain and the integration point.

[0100] S1322, for each subsequent grain, calculate the distance between each grain and the integration point, and detect whether the distance is less than the first distance, if it is less than the first distance, execute the following S1323, if it is greater than or equal to the first distance, execute the following S1324.

[0101] S1323: Update the distance to the first distance.

[0102] S1324, maintain the distance.

[0103] In this embodiment, the coordinates of the grain seed point in the grain data obtained by EBSD are a, b, and c, the coordinates of the integration point in the VUMAT calculation can be set to x, y, and z, and the distance between the two is calculated as dis=(xa)^2+(yb)^2+(zc)^2.

[0104] The distance between the seed point of the grain and the integration point is taken as the first distance between the first grain and the integration point, which can be recorded as dis1. For each other grain, such as the second, third, fourth, etc. grains, the distance corresponding to each grain can be recorded as disI (I=2, 3, 4....). During implementation, it is necessary to ensure that disI (I=2, 3, 4.....) is greater than dis1. Therefore, if the obtained distance is less than the first distance, the distance is updated to the first distance. If the obtained distance is greater than or equal to the first distance, the distance can be maintained.

[0105] In addition, the above volume-based method can be used to calculate the equivalent grain diameter in the following ways:

[0106] The diameter of each of the grains is obtained, and the equivalent diameter of the grain is calculated according to a preset formula corresponding to the volume-based method and based on the diameter.

[0107] In this embodiment, the diameter of each grain is recorded as d, and the equivalent grain diameter dgrain is calculated according to the following preset formula in the volume-based method:

[0108] dgrain=(6 d / π)^(1 / 3);

[0109] Through the above method, it can be ensured that there is no overlap and interference between grains, thereby completing the real grain division.

[0110] After completing the construction of the shot peening finite element model and the step of constructing the matrix in the shot peening finite element model as a grain geometry model, the crystal plasticity constitutive relationship information in the subroutine is coupled to the shot peening finite element model to obtain the shot peening crystal plasticity finite element model.

[0111] Among them, the crystal plasticity constitutive relation information in the subroutine is constructed in the following way:

[0112] Coupled dislocation density slip deformation mechanism, CDM damage criterion, γ-TiAl phase, α 2 -Ti 3 Al phase, 0 -TiAl phase in order to select the initial orientation of the grains, and establish a comprehensive consideration of γ-TiAl, α 2 -Ti 3 Al, 0 - A crystal plasticity finite element constitutive relationship model of TiAl, and the constitutive relationship model is written into the subroutine.

[0113] The crystal plasticity constitutive relationship information can be saved in a For file, and the obtained For file is imported into the finite element analysis software for operation. The shot peening finite element model is combined with the crystal plasticity theory represented by the crystal plasticity constitutive relationship information, and the final shot peening crystal plasticity finite element model is obtained through multiple iterative updates.

[0114] Specifically, see Figure 6 , the shot peening crystal plasticity finite element model can be obtained by:

[0115] S141, based on the crystal plasticity constitutive relation information in the subroutine, the Taylor cumulative shear strain and dislocation density on all slip and twin systems are obtained, and the damage factor is calculated according to the Taylor cumulative shear strain.

[0116] S142, in each incremental step, the shear stress is corrected using the damage factor to obtain the effective shear stress, and the cumulative twin crystal volume fraction is calculated based on the effective shear stress of the twin system.

[0117] S143, taking each grid in the shot peening finite element model as a unit integration point, and calculating the cumulative twin volume fraction of all twin variants in each unit integration point according to the number of twin systems opened and the cumulative twin volume fraction, until all incremental steps are completed, the shot peening crystal plasticity finite element model is obtained.

[0118] In this embodiment, the crystal plasticity constitutive relationship information pre-written in the subroutine mainly includes the following information:

[0119] Under the action of the projectile on the substrate surface, the deformation of the crystal material includes elastic deformation and plastic deformation. Therefore, the deformation gradient can be divided into two parts: the elastic part and the plastic part, which are specifically reflected as follows:

[0120] ;

[0121] in, F represents the deformation gradient, represents the elastic deformation gradient, which mainly characterizes the elastic stretching and rigid body rotation characteristics of the lattice. represents the plastic deformation gradient.

[0122] Plastic velocity tensor It can be made of γ-TiAl or α 2 -Shear rates of all 12 slip systems of TiAl The sum is expressed as follows:

[0123] ;

[0124] In the formula, is the sliding direction in global coordinates, is the normal direction of the sliding surface in global coordinates, represents the rate of change of plastic deformation gradient, It means taking the reciprocal of the parameter in brackets. represents the tensor product, and α represents the αth slip system.

[0125] The shear strain rate of the slip system and the shear strain rate of the twin system can be expressed by the power law relationship as follows:

[0126] ;

[0127] in, represents the shear strain rate of the slip system, represents the reference strain rate of the αth slip system, represents the decomposed shear stress of the αth slip system, represents the resistance to slip deformation or shear force, Indicates the strain rate sensitivity index. sgn indicates the sign function, which returns an integer variable indicating the positive or negative sign of the following parameter.

[0128] The evolution of yield strength during strain hardening can be summarized as follows:

[0129] ;

[0130] in, represents the sliding resistance change rate, represents the β-th slip system, represents the hardening modulus, represents the shear strain rate of the β slip system, , is the dimensionless material constant, and are the Burgers vector and shear modulus, respectively, represents the sliding resistance, represents the initial sliding resistance, represents the geometrically required dislocation density along the slip plane.

[0131] In the above equation, the first term can describe the strain hardening caused by statistical storage dislocations (SSD), and the second term describes the strain hardening caused by geometrically necessary dislocations (GND). is the geometrically required dislocation density along the slip plane and can be expressed as follows:

[0132] ;

[0133] in, is the normal slip surface, is the incompatible tensor, which can be expressed by the plastic deformation gradient To calculate, it can be expressed as follows:

[0134] ;

[0135] in, Indicates the compute node load.

[0136] is the hardening modulus, which can be determined by the following formula:

[0137] ;

[0138] in, is the hardening coefficient, when When , it indicates the self-hardening coefficient, that is, the hardening of the α slip system slip pair itself, and q takes the value of 1. It represents the latent hardening coefficient, that is, it represents the hardening of the α slip system by the slip of other slip systems. At this time, the value of q is 1.4. yes The function can be expressed by the following formula:

[0139] ;

[0140] in, , , They are the initial hardening modulus, the initial critical decomposition shear stress, and the breakthrough stress when large plastic flow occurs.

[0141] is the Taylor cumulative shear strain on all slip systems, which can be described by the following formula:

[0142] .

[0143] The damage criterion based on cdm is used to simulate the damage, and the damage factor D is defined as:

[0144] ;

[0145] in, is the maximum shear strain, is the maximum shear strain that causes damage, is the maximum shear strain at which damage reaches its maximum value, and The index that affects the damage curve. In order to make the change of flow stress smoother and improve convergence, in this embodiment, the M index is set to 2.

[0146] In each increment, the shear stress is modified by the damage factor D to act in the crystal plastic framework:

[0147] ;

[0148] in, is the effective shear stress, represents shear stress.

[0149] For the twinning process, since the generation of twins can only be along the positive direction of the twinning plane, it is only necessary to express the relationship when the decomposed shear stress is greater than zero. In this embodiment, a pseudo-slip model between the twinning shear strain rate and the decomposed shear stress is adopted. This model only considers the shear accumulation caused by twinning, and does not consider the redirection and generation process of twinning. It is expressed as follows:

[0150] ;

[0151] in, is the reference shear strain rate of the twin system, is the critical shear stress of the T-th twin system, represents the slip resistance on the Tth twin system.

[0152] In the model, the quantitative expression of the twin volume fraction of the twinning process is particularly important. It is related to the shear rate on the twin system and can be expressed in rate form or increment form as follows:

[0153] or ;

[0154] in, represents the cumulative twin crystal volume fraction, is the twin shear strain rate, It represents the maximum value of the cumulative shear strain, which can be understood as When the integral fraction of the twin crystals on a specific twin system t reaches saturation in n increments, the cumulative value of the twin shear strain reaches a maximum of ; represents the cumulative twin crystal integral score increment, represents the twin shear strain increment.

[0155] In this embodiment, the cumulative twin volume fraction and the like are updated in each incremental step until all incremental steps are completed, thereby obtaining the final shot peening crystal plasticity finite element model.

[0156] On this basis, the modeling method provided in this embodiment also includes the following steps:

[0157] The shot peening crystal plasticity finite element model is simulated to obtain simulation result data after random shot peening; and the simulation result data is output in a graphical form based on visualization technology.

[0158] In this embodiment, material information such as physical phase and grain orientation obtained by real electron backscatter diffraction photography is input into a shot peening crystal plasticity finite element model for simulation, and corresponding stress cloud maps and accumulation maps can be obtained.

[0159] Figure 7 The figure shows the inverse pole figure obtained based on the EBSD experiment, from which the true grain orientation, grain size, grain seed point and other information can be obtained.

[0160] Figure 8 and Fig. 9 The figure shows the substrate model after shot peening, where: Figure 8 is the top view of the base model. Fig. 9 This is the front view of the base model.

[0161] Fig.10 Figure 2 is a simulated surface stacking diagram, from which it can be seen that the phase boundary leads to obvious differences in the stacking pattern.

[0162] The transverse residual stress parallel to the workpiece surface plays a major role in hindering the generation and extension of fatigue cracks on the workpiece surface. Therefore, in this embodiment, the residual stress specifically refers to the transverse residual stress. Fig.11 The distribution of the transverse residual stress of the workpiece after shot peening is shown. Fig.11 It can be clearly seen that a residual compressive stress layer is formed on the surface of the shot peening area. Fig.12 This is the distribution curve of residual stress with depth. It can be clearly seen that with the change of depth, the residual compressive stress first increases and then decreases, and then the residual tensile stress increases and then decreases.

[0163] Fig.13 is the total accumulated shear strain, and simulation results show that their presence greatly affects the stress distribution in the shot peening area. Due to the activation of different slip systems caused by different crystal structures, the plastic deformation of different grains under shot peening is significantly different. These changes in slip behavior lead to significant differences in the direction of plastic deformation, and material accumulation is more prominent in the severe plastic deformation area.

[0164] From the comparison diagram of the above simulation results and the experimental results, it can be seen that the modeling simulation results in this embodiment are consistent with the experimental results, which further shows that the model constructed in this embodiment can help to accurately predict the mechanical properties of crystals and thus achieve microstructure optimization.

[0165] An embodiment of the present invention also provides an electronic device, such as Fig.14As shown, the electronic device may be a computer device, and the electronic device may include a processor and a memory. In addition, the memory stores a computer program, and the processor implements the three-phase TiAl alloy shot peening crystal plasticity finite element modeling method provided in this embodiment by reading and executing the computer program corresponding to the above embodiment in the memory.

[0166] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0167] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0168] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0169] It should be noted that if the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, and other media that can store program codes.

[0170] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0171] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A three-phase TiAl alloy shot peening crystal plasticity finite element modeling method, characterized in that: The method comprises: The electron backscatter diffraction technique is used to obtain grain data of the sample, wherein the sample is a three-phase TiAl alloy sample; Based on finite element analysis software, the matrix with the shot is given the matrix material properties of each phase of the three-phase TiAl alloy sample, and a script constructed by Python language is used to obtain a shot peening finite element model; Inputting the grain data into a subroutine constructed using Fortran language to construct the matrix in the shot peening finite element model into a grain geometry model; coupling the crystal plasticity constitutive relation information in the subroutine to the shot peening finite element model to obtain a shot peening crystal plasticity finite element model; The step of coupling the crystal plasticity constitutive relationship information in the subroutine to the shot peening finite element model to obtain the shot peening crystal plasticity finite element model comprises: Based on the crystal plasticity constitutive relation information in the subroutine, the Taylor cumulative shear strain and dislocation density on all slip and twin systems are obtained, and the damage factor is calculated according to the Taylor cumulative shear strain; In each incremental step, the shear stress is corrected by using the damage factor to obtain the effective shear stress, and the cumulative twin crystal volume fraction is calculated based on the effective shear stress of the twin system; Each grid in the shot peening finite element model is taken as a unit integration point, and the cumulative twin volume fraction of all twin variants in each unit integration point is calculated according to the number of twin systems opened and the cumulative twin crystal volume fraction. After all incremental steps are completed, the shot peening crystal plasticity finite element model is obtained.

2. The three-phase TiAl alloy shot peening crystal plasticity finite element modeling method according to claim 1 is characterized in that: The step of assigning the matrix material properties of each phase of the three-phase TiAl alloy sample to the matrix with the shot based on the finite element analysis software, and using a script constructed in Python language to obtain a shot peening finite element model includes: Setting projectile information and substrate information, wherein the projectile information includes the size, quantity, impact speed and angle of the projectile, and the substrate information includes the size of the substrate and the bombardment area; Randomly generate projectiles in a bombardment area of ​​the substrate based on the projectile information and the substrate information; Based on finite element analysis software, the matrix and the projectile are given the matrix material properties of each phase of the three-phase TiAl alloy sample, and a script constructed by Python language is used to obtain a shot peening finite element model.

3. The three-phase TiAl alloy shot peening crystal plasticity finite element modeling method according to claim 2, characterized in that: The step of assigning the matrix material properties of each phase of the three-phase TiAl alloy sample to the matrix and the projectile based on the finite element analysis software, and obtaining the shot peening finite element model by using a script constructed in Python language, comprises: Based on finite element analysis software, the matrix and each of the projectiles are given the matrix material properties of each phase of the three-phase TiAl alloy sample; Meshing the substrate; The shot peening finite element model was obtained based on the meshed matrix and the script constructed using Python language.

4. The three-phase TiAl alloy shot peening crystal plasticity finite element modeling method according to claim 1, characterized in that: The grain data includes grain seed point, grain size and grain Euler angle; The step of inputting the grain data into a subroutine constructed using the Fortran language to construct the matrix in the shot peening finite element model into a grain geometry model comprises: The grain seed point, grain size and grain Euler angle are input into the SDVINI subroutine of the VUMAT main program constructed in Fortran language; The distance between grains is calculated, the direction of grain growth is determined, and the equivalent diameter of the grains is calculated based on a volume method, and the grain division of the matrix in the shot peening finite element model is completed to construct a grain geometry model.

5. The three-phase TiAl alloy shot peening crystal plasticity finite element modeling method according to claim 4, characterized in that: The step of calculating the distance between the grains comprises: Obtaining the coordinates of a grain seed point, setting the coordinates of an integration point in a VUMAT calculation, and calculating the distance between the grain seed point and the integration point based on the coordinates of the grain seed point and the integration point as a first distance between a first grain and the integration point; For each subsequent grain, the distance between each grain and the integration point is calculated, and it is detected whether the distance is less than the first distance. If it is less than the first distance, the distance is updated to the first distance; if it is greater than or equal to the first distance, the distance is maintained.

6. The three-phase TiAl alloy shot peening crystal plasticity finite element modeling method according to claim 4, characterized in that: The step of calculating the equivalent diameter of grains based on the volume method comprises: The diameter of each of the grains is obtained, and the equivalent diameter of the grain is calculated according to a preset formula corresponding to the volume-based method and based on the diameter.

7. The three-phase TiAl alloy shot peening crystal plasticity finite element modeling method according to claim 1, characterized in that: The crystal plasticity constitutive relation information in the subroutine is constructed in the following way: Coupled dislocation density slip deformation mechanism, CDM damage criterion, γ-TiAl phase, α2-Ti3Al phase, The slip system in the 0-TiAl phase is selected to select the initial orientation of the grains, and a comprehensive consideration of γ-TiAl, α2-Ti3Al, A crystal plasticity finite element constitutive relationship model of 0-TiAl is written into the subroutine.

8. The three-phase TiAl alloy shot peening crystal plasticity finite element modeling method according to any one of claims 1 to 7, characterized in that: The method further comprises: Simulating the shot peening crystal plasticity finite element model to obtain simulation result data after random shot peening; The simulation result data is outputted in a graphical form based on visualization technology.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

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