Polycrystalline plastic finite element simulation method and device
By introducing cohesive grain boundary units and the polycrystalline plastic finite element simulation method based on back stress evolution, the problem of neglecting back stress and grain boundary damage in polycrystalline material simulation is solved, enabling more accurate simulation of crack initiation and propagation. This method is applicable to tensile, fatigue, and fretting fatigue analysis of polycrystalline metallic materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
- Filing Date
- 2023-11-09
- Publication Date
- 2026-05-12
AI Technical Summary
In the existing technology, the finite element simulation method for polycrystalline materials fails to effectively consider the back stress effect of cyclic loading and the grain boundary damage effect, resulting in inaccurate and unreliable simulation results.
The polycrystalline plasticity finite element simulation method is adopted. By introducing cohesive grain boundary elements and back stress evolution, a corresponding calculation program is written to simulate the crack crystal plasticity of the polycrystalline model. The file association is combined with the crystal plasticity subroutine to calculate the crack initiation and propagation of polycrystalline materials.
It improves the accuracy and reliability of finite element simulation, accurately simulating the crack initiation and propagation behavior of polycrystalline materials, especially the grain boundary effects under actual tensile, fatigue, and fretting fatigue loads.
Smart Images
Figure CN117594162B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of material property characterization technology, and in particular to a polycrystalline plastic finite element simulation method and apparatus. Background Technology
[0002] Finite element simulation of crystal plasticity is an effective means of studying damage and slip behavior in crystalline materials, especially in the study of crack initiation and propagation behavior.
[0003] In related technologies, current finite element studies on damage and slip behavior of polycrystalline materials mainly use macroscopic research methods. Macroscopic research methods obtain finite element models through macroscopic modeling, and then further optimize the macroscopic modeling methods using finite element analysis software. The established finite element model is divided into multiple parts by means of segmentation, and each part is assigned crystal properties individually, so that the model contains more crystal information. Finite element analysis is performed by giving loads and contacts, setting analysis steps, etc., to improve the accuracy of finite element analysis results.
[0004] However, current crystal plastic constitutive models in related technologies rarely consider the back stress effect of cyclic loading, making it difficult to describe the mechanical behavior of materials under cyclic loading such as fatigue. Furthermore, many metals and alloys are polycrystalline, which renders single-crystal finite element models no longer applicable. Finite element models that consider polycrystalline structures need to be developed. In addition, current polycrystalline modeling methods do not consider the damage effect of grain boundaries, and therefore cannot simulate the initiation and propagation behavior of grain boundary cracks, which urgently needs to be improved. Summary of the Invention
[0005] This application provides a polycrystalline plastic finite element simulation method and apparatus to address the problems of related technologies being limited to single-crystal finite element models and crystal plastic constitutive models, rarely considering the back stress effect of cyclic loads, and not considering the damage effect of grain boundaries, which leads to errors in finite element results and reduces the accuracy and reliability of finite element simulation.
[0006] The first aspect of this application provides a polycrystalline plastic finite element simulation method, comprising the following steps: acquiring original grain orientation data, and generating a polycrystalline model based on the grain orientation data, thereby obtaining an original file using the polycrystalline model; importing the file into a first preset script for execution, thereby numbering each grain in the polycrystalline model and assigning an actual crystal orientation to each grain, and generating a first file based on the numbering and the actual crystal orientation; importing the first file into a preset program, and inserting the preset program into a cohesive grain boundary unit model simulating grain boundaries, thereby obtaining a polycrystalline model with cohesive grain boundary units simulating grain boundaries, and obtaining a second file based on the polycrystalline model with cohesive grain boundary units; importing the second file into a second preset script for execution, thereby deleting... After removing redundant meshes and at least one element from the model, a complete polycrystalline model is obtained. The complete polycrystalline model is imported into the finite element software to generate a polycrystalline plastic finite element model containing the cohesive grain boundary elements and meshes. The crystal plastic constitutive relation of back stress evolution is written as a crystal plasticity subroutine, and the polycrystalline plasticity finite element model is imported into the finite element software to call the crystal plasticity subroutine to calculate at least one mechanical behavior in the polycrystalline plasticity finite element model. Based on the at least one mechanical behavior, the polycrystalline plasticity finite element model is associated with the crystal plasticity subroutine to simulate and calculate the crack crystal plasticity of the complete polycrystalline model. Based on the crack crystal plasticity, at least one of the stress and damage variables after crack initiation and propagation is obtained.
[0007] Optionally, in one embodiment of this application, before writing the crystal plastic constitutive relation of back stress evolution into a crystal plasticity subroutine and importing the polycrystalline plasticity finite element model into the finite element software, the method further includes: setting at least one constraint condition in the load, boundary conditions, and analysis steps for the polycrystalline model; and obtaining the CAE file of the polycrystalline model based on the constraint condition.
[0008] Optionally, in one embodiment of this application, obtaining the original grain orientation data and generating a polycrystalline model based on the grain orientation data includes: performing a global electron backscatter diffraction (EBSD) scan on the vulnerable metal region to obtain the original grain orientation data; importing the original grain orientation data into Dream3D to obtain the polycrystalline model containing at least one crystallographic information among the following: mesh, grain orientation, grain size, and grain morphology.
[0009] Optionally, in one embodiment of this application, the polycrystalline plastic finite element model has the same shape as the actual polycrystalline specimen, and the polycrystalline plastic finite element model includes at least one crystallographic information among the crystal orientation of each grain, the grain boundary of each grain, the size of each grain, and the morphology of each grain.
[0010] Optionally, in one embodiment of this application, before setting at least one constraint condition in the load, boundary conditions, and analysis step for the polycrystalline model, the method further includes: defining the initiation criterion for damage of cohesive grain boundary units using the maximum nominal stress criterion; when the stress at the crack tip in the cohesive region is less than the damage initiation critical value, the cohesive grain boundary unit is in the linear elastic deformation stage; when the normal traction force increases, the material of the cohesive grain boundary unit degrades and continues to be damaged until the cohesive grain boundary unit is completely damaged.
[0011] Optionally, in one embodiment of this application, the step of the material of the cohesive grain boundary unit degrading and continuously damaging when the normal traction force increases, until the cohesive grain boundary unit is completely damaged, includes: introducing a damage variable to characterize the change in the material degradation of the cohesive grain boundary unit; when the damage variable is 0, the cohesive grain boundary unit has not been damaged; when the cohesive grain boundary unit is subjected to an external load and the crack tip accumulates damage, the damage variable value continuously increases until the damage variable value is 1, at which point the cohesive grain boundary unit completely fails.
[0012] Optionally, in one embodiment of this application, the formula for calculating the back stress is:
[0013]
[0014] Where, ζ (α) and r (α) These are material-related constants. Let be the strain rate on the α-th slip system.
[0015] A second aspect of this application provides a polycrystalline plastic finite element simulation device, comprising: an acquisition module for acquiring original grain orientation data and generating a polycrystalline model based on the grain orientation data, thereby obtaining an original file using the polycrystalline model; a first generation module for importing the file into a first preset script for execution, thereby numbering each grain in the polycrystalline model and assigning an actual crystal orientation to each grain, and generating a first file based on the numbering and the actual crystal orientation; an import module for importing the first file into a preset program and inserting the preset program into a cohesive grain boundary unit model simulating grain boundaries, thereby obtaining a polycrystalline model with cohesive grain boundary units simulating grain boundaries, and obtaining a second file based on the polycrystalline model with cohesive grain boundary units; and a deletion module for importing the second file into a second preset script for execution, thereby obtaining a first file using the first file; and a second file for deleting the second file into a second preset script for execution, thereby obtaining a second file using the second file; and a third module for deleting the second file into a second preset script for execution, thereby obtaining a second file using the second file; and a fourth module for deleting the second file into a second preset script for execution, thereby obtaining a second file using the second file; and a fifth module for deleting the second file into a second preset script for execution, thereby obtaining a second file using the second file; and a sixth module for deleting the second file into a second preset script for execution, thereby obtaining a second file using the second file; and a seventh ... seventh module for deleting the second file into a second preset script for execution, thereby obtaining a second file using the second file; and a seventh module for deleting the second file into a second The system employs a multi-component modeling module, which removes redundant meshes and at least one element from the model to obtain a complete polycrystalline model. A second generation module imports the complete polycrystalline model into the finite element software to generate a polycrystalline plastic finite element model containing the cohesive grain boundary elements and meshes. A calculation module writes the crystal plastic constitutive relation of back stress evolution into a crystal plasticity subroutine and imports the polycrystalline plastic finite element model into the finite element software to call the crystal plasticity subroutine to calculate at least one mechanical behavior in the polycrystalline plastic finite element model. A simulation module associates the polycrystalline plastic finite element model with the crystal plasticity subroutine based on the at least one mechanical behavior, simulates and calculates the crack crystal plasticity of the complete polycrystalline model, and obtains at least one result from the stress and damage variables after crack initiation and propagation based on the crack crystal plasticity.
[0016] Optionally, in one embodiment of this application, it further includes: a setting module, used to set at least one constraint condition in the load, boundary conditions, and analysis step for the polycrystalline model before writing the crystal plastic constitutive relation of back stress evolution into a crystal plasticity subroutine and importing the polycrystalline plasticity finite element model into the finite element software; and a third generation module, used to obtain the CAE file of the polycrystalline model according to the constraint conditions.
[0017] Optionally, in one embodiment of this application, the acquisition module includes: a scanning unit, used to perform global electron backscatter diffraction (EBSD) scanning on the vulnerable areas of the metal to obtain the original grain orientation data; and an acquisition unit, used to import the original grain orientation data into Dream3D to obtain the polycrystalline model containing at least one crystallographic information among the mesh, each grain orientation, each grain size, and each grain morphology.
[0018] Optionally, in one embodiment of this application, the polycrystalline plastic finite element model has the same shape as the actual polycrystalline specimen, and the polycrystalline plastic finite element model includes at least one crystallographic information among the crystal orientation of each grain, the grain boundary of each grain, the size of each grain, and the morphology of each grain.
[0019] Optionally, in one embodiment of this application, it further includes: a definition module, used to define the initiation criterion of damage of cohesive grain boundary units using the maximum nominal stress criterion before setting at least one constraint condition in the load, boundary conditions and analysis step for the polycrystalline model. When the stress at the crack tip of the cohesive region is less than the damage initiation critical value, the cohesive grain boundary unit is in the linear elastic deformation stage. When the normal traction force increases, the material of the cohesive grain boundary unit degrades and continues to be damaged until the cohesive grain boundary unit is completely damaged.
[0020] Optionally, in one embodiment of this application, the definition module includes: a definition unit, used to introduce a damage variable to characterize the change in material degradation of the cohesive grain boundary unit. When the damage variable is 0, the cohesive grain boundary unit has not been damaged. When the cohesive grain boundary unit is subjected to an external load, and damage accumulates at the crack tip, the damage variable value continuously increases until the damage variable value is 1, at which point the cohesive grain boundary unit completely fails.
[0021] Optionally, in one embodiment of this application, the formula for calculating the back stress is:
[0022]
[0023] Where, ζ (α) and r (α) These are material-related constants. Let be the strain rate on the α-th slip system.
[0024] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the polycrystalline plastic finite element simulation method as described in the above embodiments.
[0025] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the polycrystalline plastic finite element simulation method described above.
[0026] This application's embodiments can introduce cohesive grain boundary units and back stress evolution, and write corresponding calculation programs to calculate and simulate a polycrystalline plastic finite element model. The polycrystalline plastic finite element model is linked to a crystal plasticity subroutine to simulate the crack crystal plasticity of the complete polycrystalline model, thereby ensuring the accuracy and reliability of the finite element simulation. This ensures more accurate research on crack initiation and propagation behavior in polycrystalline materials and better simulates the influence of grain boundaries on the plastic deformation and damage behavior of polycrystalline alloys under actual tensile, fatigue, and fretting fatigue loads. Therefore, it solves the problems of related technologies being limited to single-crystal finite element models and crystal plasticity constitutive models, rarely considering the back stress effect of cyclic loading, and neglecting the damage effect of grain boundaries, resulting in errors in the finite element results and reducing the accuracy and reliability of the finite element simulation.
[0027] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0028] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:
[0029] Figure 1 This is a flowchart of a polycrystalline plasticity finite element simulation method provided according to an embodiment of this application;
[0030] Figure 2 This is a schematic diagram of a polycrystalline model containing cohesive elements according to an embodiment of the polycrystalline plastic finite element simulation method of this application;
[0031] Figure 3 Stress cloud diagram of the crack propagation stage of a polycrystalline plastic finite element simulation method according to an embodiment of this application;
[0032] Figure 4 This is a damage variable diagram of the crack propagation stage of a polycrystalline plastic finite element simulation method according to an embodiment of this application;
[0033] Figure 5 This is a flowchart of a polycrystalline plastic finite element simulation method according to an embodiment of this application;
[0034] Figure 6 This is a schematic diagram of a polycrystalline plastic finite element simulation device provided according to an embodiment of this application;
[0035] Figure 7 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of this application. Detailed Implementation
[0036] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.
[0037] The following describes, with reference to the accompanying drawings, a method and apparatus for finite element simulation of polycrystalline plasticity according to embodiments of this application. To address the issues mentioned in the background art, which are limited to single-crystal finite element models and crystal plastic constitutive models, rarely consider the influence of back stress under cyclic loading, and fail to consider the damage effect of grain boundaries, leading to errors in finite element results and reducing the accuracy and reliability of finite element simulations, this application provides a polycrystalline plastic finite element simulation method. This method introduces cohesive grain boundary elements and back stress evolution, and develops corresponding calculation programs to simulate the polycrystalline plastic finite element model. By associating the polycrystalline plastic finite element model with the crystal plasticity subroutine, the complete polycrystalline model's crack crystal plasticity is simulated, thereby ensuring the accuracy and reliability of the finite element simulation. This allows for more accurate research on crack initiation and propagation behavior in polycrystalline materials and better simulation of the influence of grain boundaries on the plastic deformation and damage behavior of polycrystalline alloys under actual tensile, fatigue, and fretting fatigue loads. Thus, this method solves the problems of related technologies being limited to single-crystal finite element models and crystal plastic constitutive models, rarely considering the influence of back stress under cyclic loading, and failing to consider the damage effect of grain boundaries, resulting in errors in finite element results and reducing the accuracy and reliability of finite element simulations.
[0038] Specifically, Figure 1 This is a schematic flowchart of a polycrystalline plastic finite element simulation method provided in an embodiment of this application.
[0039] like Figure 1 As shown, the polycrystalline plastic finite element simulation method includes the following steps:
[0040] In step S101, the original grain orientation data is obtained, and a polycrystalline model is generated based on the grain orientation data, so as to obtain the original file using the polycrystalline model.
[0041] It is understood that the polycrystalline model in the embodiments of this application can be established based on the original grain orientation data.
[0042] In actual implementation, the embodiments of this application can obtain the original grain orientation CTF data. Based on the original grain orientation CTF data, a polycrystalline model with the same shape as the actual specimen can be established. The original .inp file can be obtained using the polycrystalline model, ensuring the accuracy and reliability of the finite element simulation.
[0043] Optionally, in one embodiment of this application, obtaining the original grain orientation data and generating a polycrystalline model based on the grain orientation data includes: performing a global electron backscatter diffraction (EBSD) scan on the vulnerable metal region to obtain the original grain orientation data; importing the original grain orientation data into Dream3D to obtain a polycrystalline model containing at least one crystallographic information among the grid, each grain orientation, each grain size, and each grain morphology.
[0044] In actual implementation, this embodiment can first perform a global EBSD (Electron Backscatter Diffraction) scan on the easily damaged areas of the metal to obtain the original grain orientation CTF data, thereby providing support for the subsequent establishment of a polycrystalline model consistent with the shape of the actual specimen; this embodiment can also generate a Dream3D self-written script to import the original grain orientation CTF data into the Dream3D software to obtain a polycrystalline model containing crystallographic information such as mesh, crystal orientation of each grain, size of each grain, and morphology of each grain, thereby providing support for obtaining the original inp file.
[0045] The embodiments of this application can obtain a polycrystalline model containing detailed crystallographic information such as mesh, crystal orientation of each grain, size of each grain, and morphology of each grain, further ensuring the accuracy and reliability of finite element simulation.
[0046] In step S102, the file is imported into the first preset script and run to number each grain in the polycrystalline model and assign an actual crystal orientation to each grain, and generate the first file based on the number and the actual crystal orientation.
[0047] It is understood that the first preset script in the embodiments of this application can be a self-written Matlab script 1, and the first file can be the inp file processed for the first time.
[0048] In actual execution, the embodiments of this application can import the file into the first preset script for execution. That is, the embodiments of this application can import the original inp file into the self-compiled Matlab script 1 for execution, so as to number each grain in the polycrystalline model and assign each grain an actual crystal orientation. Based on the number and the actual crystal orientation, the first file is generated, that is, the inp file of the first processing is generated.
[0049] This application embodiment can import the file into the first preset script for execution, thereby making the inp file more complete, including both assigning physical properties to the grains and numbering each grain in the polycrystalline model.
[0050] It should be noted that the first preset script can be set by those skilled in the art according to the actual situation, and no specific restrictions are imposed here.
[0051] In step S103, the first file is imported into a preset program, and the preset program is inserted into the cohesive grain boundary unit model simulating grain boundaries to obtain a polycrystalline model with cohesive grain boundary units simulating grain boundaries. The second file is obtained based on the polycrystalline model of the cohesive grain boundary units.
[0052] It is understood that the preset program in the embodiments of this application can be a self-written Python program, and the second file can be an inp file processed for the second time.
[0053] In actual execution, the embodiments of this application can import the first file into a preset program and insert the preset program into the cohesive grain boundary unit model simulating grain boundaries. That is, the embodiments of this application can import the inp file after the first processing into a self-written Python file, run the program to automatically insert the cohesive grain boundary unit model simulating grain boundaries, so as to obtain a polycrystalline model with cohesive grain boundary units simulating grain boundaries, and obtain the second file based on the polycrystalline model of cohesive grain boundary units, that is, obtain the inp file after the second processing.
[0054] The embodiments of this application can automatically identify grain boundaries in a polycrystalline finite element model and insert cohesive grain boundary damage elements at the grain boundary locations. Because there are cohesive elements simulating grain boundaries, grain boundary damage can be simulated, as well as crack initiation and propagation at the grain boundary locations.
[0055] It should be noted that the preset program can be set by those skilled in the art according to the actual situation, and no specific restrictions are imposed here.
[0056] In step S104, the second file is imported into the second preset script and run to delete redundant meshes and at least one element in the model to obtain a complete polycrystalline model.
[0057] It is understood that the second preset script in the embodiments of this application can be a self-written Matlab script 2.
[0058] In actual execution, the embodiments of this application can import the second file into the second preset script to run, so as to delete redundant meshes and at least one element in the model. That is, the embodiments of this application can import the inp file after the second processing into the self-written Matlab script 2 for running, and delete redundant meshes, model and other elements to obtain the fully processed polycrystalline model inp file.
[0059] Since the inp file processed by Python may contain multiple inserted cohesive grain boundary units, this embodiment of the application can import the second file into a second preset script to run, thereby deleting redundant meshes and at least one element in the model, ensuring the integrity and accuracy of the inp file.
[0060] It should be noted that the second preset script can be set by those skilled in the art according to the actual situation, and no specific restrictions are imposed here.
[0061] In step S105, the complete polycrystalline model is imported into the finite element software to generate a polycrystalline plastic finite element model containing cohesive grain boundary elements and a mesh.
[0062] As one possible approach, embodiments of this application can import the complete polycrystalline model inp file into ABAQUS to generate a polycrystalline plastic finite element model containing cohesive grain boundary units and meshes, making the finite element results calculated in this application more accurate and reliable. At the same time, the technology in this application is applicable to various polycrystalline metal materials.
[0063] Optionally, in one embodiment of this application, before setting at least one constraint in the load, boundary conditions, and analysis step for the polycrystalline model, the method further includes: defining the initiation criterion for damage of cohesive grain boundary units using the maximum nominal stress criterion; when the stress at the crack tip in the cohesive region is less than the damage initiation critical value, the cohesive grain boundary unit is in the linear elastic deformation stage; when the normal traction force increases, the material of the cohesive grain boundary unit degrades and continues to be damaged until the cohesive grain boundary unit is completely damaged.
[0064] In actual implementation, the relevant parameters of the cohesive grain boundary unit damage in this embodiment are as follows: The damage initiation criterion adopted is the maximum nominal stress criterion. When the stress at the crack tip in the cohesive region is less than the critical value for damage initiation, the cohesive grain boundary unit is in the linear elastic deformation stage. When the normal traction force increases, the material of the cohesive grain boundary unit degrades and continues to be damaged until the cohesive grain boundary unit is completely damaged. By introducing cohesive grain boundary units, this embodiment makes the simulated crack propagation path closer to reality, thus improving the accuracy of polycrystalline crack simulation.
[0065] Optionally, in one embodiment of this application, when the normal traction force increases, the material of the cohesive grain boundary unit degrades and continues to be damaged until the cohesive grain boundary unit is completely damaged. This includes: introducing a damage variable to characterize the change in the material degradation of the cohesive grain boundary unit; when the damage variable is 0, the cohesive grain boundary unit has not been damaged; when the cohesive grain boundary unit is subjected to an external load, and damage accumulates at the crack tip, the damage variable value continuously increases until the damage variable value is 1, at which point the cohesive grain boundary unit completely fails.
[0066] In actual implementation, in order to characterize the degradation law of cohesive grain boundary unit material, the embodiments of this application can introduce a damage variable. When the damage variable is 0, it means that the cohesive grain boundary unit has not been damaged. As the cohesive grain boundary unit is continuously subjected to external load, the crack tip gradually accumulates damage, and the damage variable value continues to increase until the damage variable value is 1, at which point the cohesive grain boundary unit completely fails and the crack continues to propagate forward.
[0067] The embodiments of this application can further improve the accuracy of polycrystalline crack simulation by introducing damage variables to characterize the degradation law of cohesive grain boundary unit materials.
[0068] Optionally, in one embodiment of this application, before writing the crystal plastic constitutive relation of the back stress evolution into a crystal plasticity subroutine and importing the polycrystalline plasticity finite element model into the finite element software, the method further includes: setting at least one constraint condition in the load, boundary conditions, and analysis step for the polycrystalline model; and obtaining the CAE file of the polycrystalline model based on the constraint condition.
[0069] As one possible approach, embodiments of this application can set constraints such as loads, boundary conditions, and analysis steps for a polycrystalline model of an actual metallic material specimen, and finally obtain the CAE file of the polycrystalline model based on the constraints, thereby ensuring that this application is applicable to various polycrystalline metallic materials.
[0070] Optionally, in one embodiment of this application, the polycrystalline plastic finite element model has the same shape as the actual polycrystalline specimen, and the polycrystalline plastic finite element model includes at least one crystallographic information among the crystal orientation of each grain, the grain boundary of each grain, the size of each grain, and the morphology of each grain.
[0071] In actual implementation, the polycrystalline plastic finite element model in this application embodiment has the same shape as the actual polycrystalline specimen, and the polycrystalline plastic finite element model includes crystallographic information such as the crystal orientation, grain boundaries, grain size, and grain morphology of each grain, such as... Figure 2 As shown, the polycrystalline plastic finite element model includes detailed crystal information such as the crystal orientation and grain size of the actual metal structure, ensuring that the finite element results calculated in this application are more accurate and reliable, and also ensuring that this application is applicable to various polycrystalline metal materials.
[0072] In step S106, the crystal plastic constitutive relation of back stress evolution is written as a crystal plasticity subroutine, and the polycrystalline plasticity finite element model is imported into the finite element software to call the crystal plasticity subroutine to calculate at least one mechanical behavior in the polycrystalline plasticity finite element model.
[0073] In actual implementation, the embodiments of this application can write the crystal plastic constitutive relation considering the evolution of back stress as a crystal plasticity subroutine, that is, write it as a Fortran subroutine, and import the polycrystalline plasticity finite element model into the finite element software. This allows the polycrystalline model containing cohesive grain boundary units with actual crystal orientation and grain size to be imported into ABAQUS and the UMAT subroutine to be called for calculation. The crystal plasticity subroutine is then called to calculate the mechanical behaviors such as tension, compression, fatigue and fretting fatigue in the polycrystalline plasticity finite element model.
[0074] This application's embodiments can introduce the back stress evolution equation into the crystal plastic constitutive model and incorporate it into the UMAT material subroutine (UMAT) written in Fortran. This enables the application to simulate the mechanical behavior of crystalline materials under cyclic loading, calculate a more accurate mechanical response under cyclic loading, and make the study of crack initiation and propagation behavior of polycrystalline materials more accurate. It realizes the polycrystalline plastic finite element simulation of crack initiation and propagation in polycrystalline metal materials under tensile, fatigue, and fretting fatigue processes, and can better simulate the influence of grain boundaries on the plastic deformation and damage behavior of polycrystalline alloys under actual tensile, fatigue, and fretting fatigue loads.
[0075] Optionally, in one embodiment of this application, the formula for calculating back stress is:
[0076]
[0077] Where, ζ (α) and r (α) These are material-related constants. Let be the strain rate on the α-th slip system.
[0078] Specifically, the main part of the crystal plastic constitutive relation in the embodiments of this application is the crystallographic description of the plastic behavior. The crystallographic description of the back stress evolution behavior in this scheme is as follows:
[0079] The formula for calculating back stress is:
[0080]
[0081] Where, ζ (α) and r (α) These are material-related constants. Let be the strain rate on the α-th slip system.
[0082] in, Let denot be the strain rate on the α-th slip system, and its plastic flow equation is:
[0083]
[0084] in, G represents the relative strain rate. (α) τ represents the current intensity, n represents the rate exponent, and τ represents the current intensity. (α) This represents the decomposed shear stress on the α-th slip system.
[0085] According to the calculation formula in this application, the back stress can be accurately obtained, which facilitates the crystallographic description of the back stress evolution behavior and thus ensures more accurate research on the crack initiation and propagation behavior of polycrystalline materials.
[0086] In step S107, based on at least one mechanical behavior, the polycrystalline plasticity finite element model is associated with the crystal plasticity subroutine to simulate and calculate the crack crystal plasticity of the complete polycrystalline model, and at least one of the stress and damage variables after crack initiation and propagation is obtained based on the crack crystal plasticity.
[0087] In actual implementation, this application embodiment can associate the polycrystalline plasticity finite element model with the crystal plasticity subroutine based on at least one mechanical behavior. That is, this application embodiment can associate the ABAQUS finite element model with the aforementioned established Fortran subroutine to simulate and calculate the crack crystal plasticity of the complete polycrystalline model, and obtain the stress after crack initiation and propagation based on the crack crystal plasticity. Figure 3 ) and damage variables ( Figure 4 Results such as )
[0088] The embodiments of this application can use ABAQUS to visualize and analyze the results. The results can show the dangerous locations of stress, damage variables, etc., providing a valid basis for the crack initiation and propagation of polycrystalline materials, thereby studying the influence of microstructures such as crystal orientation, grain boundaries, and grain geometry on the fracture behavior of polycrystalline alloys.
[0089] Specifically, it can be combined with Figure 5 As shown, the working principle of the polycrystalline plastic finite element simulation method in this application is explained in detail with a specific embodiment.
[0090] like Figure 5 As shown, embodiments of this application may include the following steps:
[0091] Step S501: Method 1: Use EBSD to photograph the polycrystalline material to obtain grain orientation data, and import the EBSD data into Dream3D to obtain a polycrystalline model.
[0092] In this embodiment, the metal vulnerable area can be scanned globally using EBSD to obtain the original grain orientation CTF data, generate a Dream3D self-written script, and import the CTF file obtained in the first step into the Dream3D software to obtain an actual polycrystalline model containing crystallographic information such as mesh, grain orientation, grain size, and grain morphology.
[0093] Step S502: Method 2: Use Dream3D to generate a simulated polycrystalline model.
[0094] The second method in this application embodiment uses Dream3D to generate a simulated polycrystalline model to ensure the accuracy and reliability of the simulation.
[0095] Step S503: Assign properties to each grain of the polycrystalline model in Matlab.
[0096] In this embodiment of the application, the original inp file can be imported into a self-written Matlab script 1 for execution, which can number each grain in the generated crystal model and assign each grain an actual crystal orientation.
[0097] Step S504: Write a Python program to insert cohesive units for simulating grain boundaries.
[0098] In this embodiment, the inp file after the first processing can be imported into a self-written Python file, and the program can be run to automatically insert the cohesive grain boundary unit model of the simulated grain boundary, thereby obtaining a polycrystalline model containing the cohesive grain boundary unit of the simulated grain boundary.
[0099] Step S505: Delete redundant unit models and generate a polycrystalline model containing cohesive units.
[0100] In this embodiment, the inp file after the second processing can be imported into a self-written Matlab script 2 for execution, and redundant mesh, model and other elements can be deleted to generate a polycrystalline model containing cohesive units.
[0101] Step S506: Write the UMAT crystal plasticity subroutine.
[0102] In this embodiment of the application, a UMAT crystal plasticity subroutine can be written to provide support for subsequent calculations by calling the UMAT subroutine.
[0103] Step S507: Import the model into ABAQUS and call the UMAT subroutine for calculation.
[0104] In this embodiment of the application, the model can be imported into ABAQUS and the UMAT subroutine can be called for calculation. By importing the complete polycrystalline model inp file into ABAQUS, a polycrystalline plastic finite element model containing cohesive grain boundary elements and a mesh can be generated.
[0105] The embodiments of this application can be based on EBSD technology, combined with Dream3D, Matlab, and Python software, and the crystal plasticity UMAT subroutine written in Fortran language, combined with ABAQUS software, to realize the polycrystalline plasticity finite element simulation of crack initiation and propagation in polycrystalline metal materials under tensile, fatigue, and fretting fatigue processes. It can better simulate the influence of grain boundaries on the plastic deformation and damage behavior of polycrystalline alloys under actual tensile, fatigue, and fretting fatigue loads.
[0106] The polycrystalline plasticity finite element simulation method proposed in this application introduces cohesive grain boundary elements and back stress evolution, and writes corresponding calculation programs to simulate the polycrystalline plasticity finite element model. The polycrystalline plasticity finite element model is then linked with a crystal plasticity subroutine to simulate the crack crystal plasticity of the complete polycrystalline model. This ensures the accuracy and reliability of the finite element simulation, making the study of crack initiation and propagation behavior in polycrystalline materials more accurate and better simulating the influence of grain boundaries on the plastic deformation and damage behavior of polycrystalline alloys under actual tensile, fatigue, and fretting fatigue loads. This solves the problem that related technologies are limited to single-crystal finite element models and crystal plasticity constitutive models, rarely considering the back stress effect of cyclic loading and neglecting the damage effect of grain boundaries, leading to errors in the finite element results and reducing the accuracy and reliability of the finite element simulation.
[0107] Next, the polycrystalline plastic finite element simulation apparatus proposed according to the embodiments of this application is described with reference to the accompanying drawings.
[0108] Figure 6 This is a schematic diagram of the structure of the polycrystalline plastic finite element simulation device according to an embodiment of this application.
[0109] like Figure 6 As shown, the polycrystalline plastic finite element simulation device 10 includes: an acquisition module 100, a first generation module 200, an import module 300, a deletion module 400, a second generation module 500, a calculation module 600, and a simulation module 700.
[0110] Specifically, the acquisition module 100 is used to acquire the original grain orientation data and generate a polycrystalline model based on the grain orientation data, so as to obtain the original file using the polycrystalline model.
[0111] The first generation module 200 is used to import the file into the first preset script for execution, so as to number each grain in the polycrystalline model, assign an actual crystal orientation to each grain, and generate the first file according to the number and the actual crystal orientation.
[0112] Import module 300 is used to import the first file into a preset program and insert the preset program into the cohesive grain boundary unit model of the simulated grain boundary to obtain a polycrystalline model with cohesive grain boundary units of the simulated grain boundary, and obtain the second file based on the polycrystalline model of the cohesive grain boundary units.
[0113] The deletion module 400 is used to import the second file into the second preset script and run it to delete redundant meshes and at least one element in the model to obtain a complete polycrystalline model.
[0114] The second generation module 500 is used to import the complete polycrystalline model into the finite element software and generate a polycrystalline plastic finite element model containing cohesive grain boundary elements and mesh.
[0115] The calculation module 600 is used to write the crystal plastic constitutive relation of back stress evolution into a crystal plasticity subroutine and import the polycrystalline plasticity finite element model into the finite element software to call the crystal plasticity subroutine to calculate at least one mechanical behavior in the polycrystalline plasticity finite element model.
[0116] The simulation module 700 is used to associate a polycrystalline plasticity finite element model with a crystal plasticity subroutine based on at least one mechanical behavior, simulate and calculate the crack crystal plasticity of the complete polycrystalline model, and obtain at least one result from the stress and damage variables after crack initiation and propagation based on the crack crystal plasticity.
[0117] Optionally, in one embodiment of this application, the polycrystalline plastic finite element simulation device 10 further includes a setting module and a third generation module.
[0118] The setting module is used to set loads, boundary conditions, and at least one constraint condition in the analysis step for the polycrystalline model before writing the crystal plastic constitutive relation of back stress evolution into a crystal plasticity subroutine and importing the polycrystalline plasticity finite element model into the finite element software.
[0119] The third generation module is used to obtain the CAE file of the polycrystalline model based on the constraints.
[0120] Optionally, in one embodiment of this application, the acquisition module 100 includes a scanning unit and an acquisition unit.
[0121] The scanning unit is used to perform global electron backscatter diffraction (EBSD) scanning of the easily damaged areas of the metal to obtain the original grain orientation data.
[0122] The acquisition unit is used to import the original grain orientation data into Dream3D to obtain a polycrystalline model containing at least one crystallographic information among the mesh, each grain orientation, each grain size, and each grain morphology.
[0123] Optionally, in one embodiment of this application, the polycrystalline plastic finite element model has the same shape as the actual polycrystalline specimen, and the polycrystalline plastic finite element model includes at least one crystallographic information among the crystal orientation of each grain, the grain boundary of each grain, the size of each grain, and the morphology of each grain.
[0124] Optionally, in one embodiment of this application, the polycrystalline plastic finite element simulation device 10 further includes a definition module.
[0125] The definition module is used to define the initiation criterion of damage to cohesive grain boundary units using the maximum nominal stress criterion before setting loads, boundary conditions, and at least one constraint condition in the analysis step for the polycrystalline model. When the stress at the crack tip in the cohesive region is less than the critical value for damage initiation, the cohesive grain boundary unit is in the linear elastic deformation stage. When the normal traction force increases, the material of the cohesive grain boundary unit degrades and continues to be damaged until the cohesive grain boundary unit is completely damaged.
[0126] Optionally, in one embodiment of this application, the definition module includes: a definition unit.
[0127] The defined unit is used to introduce damage variables to characterize the changes in the degradation of the cohesive grain boundary unit material. When the damage variable is 0, the cohesive grain boundary unit has no damage. When the cohesive grain boundary unit is subjected to external load, the damage variable value increases continuously until the damage variable value is 1, at which point the cohesive grain boundary unit completely fails.
[0128] Optionally, in one embodiment of this application, the formula for calculating back stress is:
[0129]
[0130] Where, ζ (α) and r (α) These are material-related constants. Let be the strain rate on the α-th slip system.
[0131] It should be noted that the foregoing explanation of the polycrystalline plastic finite element simulation method embodiment also applies to the polycrystalline plastic finite element simulation device of this embodiment, and will not be repeated here.
[0132] The polycrystalline plasticity finite element simulation device proposed in this application can introduce cohesive grain boundary elements and back stress evolution, and write corresponding calculation programs to calculate and simulate the polycrystalline plasticity finite element model. The polycrystalline plasticity finite element model is linked with the crystal plasticity subroutine to simulate the crack crystal plasticity of the complete polycrystalline model, thereby ensuring the accuracy and reliability of the finite element simulation. This ensures more accurate research on crack initiation and propagation behavior of polycrystalline materials and better simulates the influence of grain boundaries on the plastic deformation and damage behavior of polycrystalline alloys under actual tensile, fatigue, and fretting fatigue loads. Therefore, it solves the problem that related technologies are limited to single-crystal finite element models and crystal plasticity constitutive models, rarely considering the back stress effect of cyclic loading, and failing to consider the damage effect of grain boundaries, resulting in errors in the finite element results and reducing the accuracy and reliability of the finite element simulation.
[0133] Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include:
[0134] The memory 701, the processor 702, and the computer program stored on the memory 701 and executable on the processor 702.
[0135] When the processor 702 executes the program, it implements the polycrystalline plastic finite element simulation method provided in the above embodiments.
[0136] Furthermore, electronic devices also include:
[0137] Communication interface 703 is used for communication between memory 701 and processor 702.
[0138] The memory 701 is used to store computer programs that can run on the processor 702.
[0139] The memory 701 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.
[0140] If the memory 701, processor 702, and communication interface 703 are implemented independently, then the communication interface 703, memory 701, and processor 702 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of representation, Figure 7 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.
[0141] Optionally, in a specific implementation, if the memory 701, processor 702, and communication interface 703 are integrated on a single chip, then the memory 701, processor 702, and communication interface 703 can communicate with each other through an internal interface.
[0142] The processor 702 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.
[0143] This embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described polycrystalline plastic finite element simulation method.
[0144] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0145] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0146] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.
[0147] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.
[0148] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.
[0149] Those skilled in the art will understand that all or part of the steps of the methods described in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it includes one or a combination of the steps of the method embodiments.
[0150] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.
[0151] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.
Claims
1. A finite element method for simulating polycrystalline plasticity, characterized in that, Includes the following steps: Obtain the original grain orientation data and generate a polycrystalline model based on the grain orientation data, so as to obtain the original file using the polycrystalline model; The file is imported into a first preset script and run to number each grain in the polycrystalline model and assign an actual crystal orientation to each grain, and to generate a first file based on the number and the actual crystal orientation. The first file is imported into a preset program, and the preset program is inserted into the cohesive grain boundary unit model simulating grain boundaries to obtain a polycrystalline model with cohesive grain boundary units simulating grain boundaries. The second file is obtained based on the polycrystalline model of the cohesive grain boundary units. Import the second file into the second preset script and run it to delete redundant meshes and at least one element in the model to obtain a complete polycrystalline model; Import the complete polycrystalline model into the finite element software to generate a polycrystalline plastic finite element model containing the cohesive grain boundary units and the mesh; The crystal plastic constitutive relation of back stress evolution is written as a crystal plasticity subroutine, and the polycrystalline plasticity finite element model is imported into the finite element software to call the crystal plasticity subroutine to calculate at least one mechanical behavior in the polycrystalline plasticity finite element model; as well as Based on the at least one mechanical behavior, the polycrystalline plasticity finite element model is associated with the crystal plasticity subroutine to simulate and calculate the crack crystal plasticity of the complete polycrystalline model, and at least one of the stress and damage variables after crack initiation and propagation is obtained based on the crack crystal plasticity.
2. The method according to claim 1, characterized in that, Before writing the crystal plastic constitutive relation of back stress evolution into a crystal plasticity subroutine and importing the polycrystalline plasticity finite element model into the finite element software, the following steps are also included: Set at least one constraint from the load, boundary conditions, and analysis step for the polycrystalline model; The CAE file of the polycrystalline model is obtained based on the constraints.
3. The method according to claim 1, characterized in that, The step of obtaining the original grain orientation data and generating a polycrystalline model based on the grain orientation data includes: Global electron backscatter diffraction (EBSD) scanning was performed on the vulnerable areas of the metal to obtain the original grain orientation data. The original grain orientation data is imported into Dream3D to obtain the polycrystalline model containing at least one crystallographic information among the mesh, grain orientation, grain size, and grain morphology.
4. The method according to claim 1, characterized in that, The polycrystalline plastic finite element model has the same shape as the actual polycrystalline specimen, and the polycrystalline plastic finite element model contains at least one crystallographic information among the crystal orientation of each grain, the grain boundary of each grain, the size of each grain, and the morphology of each grain.
5. The method according to claim 2, characterized in that, Before setting at least one constraint in the load, boundary conditions, and analysis step for the polycrystalline model, the method further includes: The maximum nominal stress criterion is used to define the initiation criterion of damage to cohesive grain boundary units. When the stress at the crack tip in the cohesive region is less than the critical value for damage initiation, the cohesive grain boundary unit is in the linear elastic deformation stage. When the normal traction force increases, the material of the cohesive grain boundary unit degrades and continues to be damaged until the cohesive grain boundary unit is completely damaged.
6. The method according to claim 5, characterized in that, As the normal traction force increases, the material of the cohesive grain boundary unit degrades and continues to be damaged until the cohesive grain boundary unit is completely damaged, including: A damage variable is introduced to characterize the changes in the degradation of the cohesive grain boundary unit material. When the damage variable is 0, the cohesive grain boundary unit does not produce damage. When the cohesive grain boundary unit is subjected to external load, the damage variable value increases continuously as damage accumulates at the crack tip. When the damage variable value is 1, the cohesive grain boundary unit completely fails.
7. The method according to claim 1, characterized in that, The formula for calculating the back stress is: Where, ζ (α) and r (α) These are material-related constants. Let be the strain rate on the α-th slip system.
8. A finite element simulation device for polycrystalline plasticity, characterized in that, include: The acquisition module is used to acquire the original grain orientation data and generate a polycrystalline model based on the grain orientation data, so as to obtain the original file using the polycrystalline model; The first generation module is used to import the file into a first preset script for execution, so as to number each grain in the polycrystalline model and assign an actual crystal orientation to each grain, and generate a first file according to the number and the actual crystal orientation; The import module is used to import the first file into a preset program and insert the preset program into the cohesive grain boundary unit model of the simulated grain boundary to obtain a polycrystalline model with cohesive grain boundary units of the simulated grain boundary, and obtain the second file according to the polycrystalline model of the cohesive grain boundary units. The deletion module is used to import the second file into the second preset script and run it to delete redundant meshes and at least one element in the model to obtain a complete polycrystalline model; The second generation module is used to import the complete polycrystalline model into the finite element software and generate a polycrystalline plastic finite element model containing the cohesive grain boundary units and the mesh. The calculation module is used to write the crystal plastic constitutive relation of back stress evolution into a crystal plasticity subroutine and import the polycrystalline plasticity finite element model into the finite element software to call the crystal plasticity subroutine to calculate at least one mechanical behavior in the polycrystalline plasticity finite element model; as well as The simulation module is used to associate the polycrystalline plasticity finite element model with the crystal plasticity subroutine based on the at least one mechanical behavior, simulate and calculate the crack crystal plasticity of the complete polycrystalline model, and obtain at least one of the stress and damage variables after crack initiation and propagation based on the crack crystal plasticity.
9. An electronic device, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the polycrystalline plastic finite element simulation method as described in any one of claims 1-7.
10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the polycrystalline plastic finite element simulation method as described in any one of claims 1-7.