A finite element modeling and simulation method for crystal plasticity

Abstract

The present invention discloses a crystal plasticity finite element modeling simulation method, comprising the following steps: obtaining grain information based on EBSD analysis; importing the ctf format file generated by the EBSD analysis into Dream.3D software to realize automatic reconstruction of the grain structure, and outputting the input file and the geometric orientation data of each grain; then processing the grain geometric orientation data through a Python language script to obtain the average geometric orientation information of each grain; combining the average geometric orientation information of the grain with the input file using a Python script to generate a complete input file with geometric model information and material property information; assigning boundary conditions to the model in ABAQUS finite element analysis software and setting its constitutive relationship using the UMAT subroutine, thereby realizing the entire crystal plasticity finite element analysis process. The present invention realizes the process of crystal plasticity finite element modeling and simulation analysis.

Description

Technical Field

[0001] The present invention relates to a crystal plasticity finite element modeling and simulation method based on electron backscatter diffraction analysis (EBSD), Dream.3D software and ABAQUS finite element analysis software, belonging to the field of mechanical structure strength microscopic modeling and analysis methods. Background Art

[0002] Aero-engine components, especially blades and disk components, are subjected to high-frequency alternating loads and high-temperature working environments during long-term use. These factors lead to serious fatigue failure of aero-engine rotor components. The initiation and propagation of fatigue cracks are closely related to the microscopic grain structure of the material. Therefore, it is necessary to study the initiation and propagation of fatigue cracks at the microscopic grain level.

[0003] At present, domestic and foreign scholars have conducted a lot of research on the mechanical properties of materials at the grain level. However, at the computer simulation level, most of the current research focuses on the setting and assignment of crystal plastic constitutive relations, and there is little research on how to model based on real grain morphology. At the same time, since the input of grain orientation and the determination of grain boundary positions involve massive data processing, if these data are processed manually, it will inevitably consume a lot of time and energy and have a high rate of manual errors. Therefore, it is very important to use a combination of computer software and programs to realize the modeling and grain orientation assignment process based on real grain morphology.

[0004] Among the prior art, patent CN112364535A "A method for predicting creep fatigue life based on crystal plasticity" uses MATLAB software to generate input files and assign material parameters for ABAQUS calculation analysis. Compared with MATLAB, Dream.3D software adopts a functional classification window display method. The code generated when each function is running can be automatically output to a specified file. Compared with MATLAB programming and code display, Dream.3D software is more like a black box operation. Therefore, the operator does not need to have a programming language foundation, has strong operability, better human-computer interaction interface, and its function display is more intuitive. It can reduce noise on EBSD data, change resolution and other secondary operations. Patent CN110222442A "Method for establishing a crystal plastic constitutive model for fatigue process of face-centered cubic materials" uses image processing technology to output grain modeling. Most of its grains are relatively regular polygons, which cannot accurately reflect the true morphology of grains and have a low degree of restoration of real grains. The present invention uses data accurate to pixel level in EBSD files for modeling, which restores the true morphology of grains to the greatest extent. Patent CN111539071A "A method, system and electronic device for establishing a crystal plasticity constitutive model for differentially thick plates" uses EBSD data to draw pole figures and ODF diagrams, and then generates a txt format file that stores grain model information through MATLAB software, and finally uses a Python script to convert the txt file into an input file that can be used for ABAQUS calculation and analysis. This modeling method requires conversion between multiple software and scripts, with many steps and a relatively complex program. The present invention only requires Dream.3D software to directly output input files, greatly reducing the intermediate steps. At the same time, the three patents mentioned above all focus on the setting of constitutive relations in crystal plasticity finite element analysis, and do not involve much on how to simply and quickly realize crystal plasticity modeling based on real structures. The present invention can better fill this gap. Summary of the invention

[0005] The purpose of the present invention is to provide a crystal plasticity finite element modeling and simulation method, which greatly reduces the time loss and high error rate caused by manual input of material property information such as grain orientation by extensively using programming language operation and output.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A crystal plasticity finite element modeling simulation method comprises the following steps:

[0008] (1) Use electron backscatter diffraction analysis technology to scan and process a given material sample, obtain grain information, and output it in ctf file format;

[0009] (2) importing the ctf format file containing the grain information obtained in step (1) into Dream.3D software to realize automatic reconstruction of the grain structure, and outputting an input file containing only the geometric model of the ABAQUS finite element analysis software and the geometric orientation data of each grain;

[0010] (3) Processing the grain geometric orientation data obtained in step (2) by using a Python language script to obtain the average geometric orientation information of each grain, and combining the average geometric orientation information of the grain with the input file obtained in step (2) to generate a complete input file with geometric model information and material property information;

[0011] (4) In the ABAQUS finite element analysis software, boundary conditions are assigned to the model and its constitutive relationship is set using the UMAT subroutine, thereby completing the entire crystal plasticity finite element analysis process.

[0012] Furthermore, in step (1), the grain information includes the surface Euler angles of a given material sample.

[0013] Furthermore, in the step (2), the automatic reconstruction of the grain structure according to the specified grain boundary angle tolerance is achieved through the built-in Filter function combination of the Dream.3D software, and the grid size control is achieved using its built-in function.

[0014] Furthermore, in step (3), the built-in Python script runner of ABAQUS finite element analysis software is used to calculate the arithmetic mean of the grain geometric orientation data according to the grain number and output it.

[0015] Furthermore, in step (3), the input file obtained in step (2) is imported into the ABAQUS finite element analysis software, and then the Python script runner inside the ABAQUS finite element analysis software is used to automatically read and write the material property information into the input file, thereby generating a complete input file for further analysis.

[0016] Furthermore, in step (4), the boundary conditions are determined by actual experimental conditions, and the constitutive relationship is determined by fitting the used materials and their physical models.

[0017] The beneficial effects of the present invention are as follows: the present invention uses a large amount of programming language to complete the crystal plasticity finite element simulation process, which greatly reduces the extremely time-consuming manual operation process of manually inputting material property information such as grain orientation, and realizes the process of crystal plasticity finite element modeling and simulation analysis, thereby bringing great convenience to the simulation prediction of material mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1is a flow chart of the method of the present invention;

[0019] Figure 2 It is a schematic diagram of the structure of electron backscatter diffraction (EBSD);

[0020] Figure 3 It is a schematic diagram of the sample structure and the IPF schematic diagram of the grain structure in a specific area;

[0021] Figure 4 It is a complete grain model diagram containing geometric and material information. DETAILED DESCRIPTION

[0022] The present invention will be further explained below in conjunction with the accompanying drawings and embodiments.

[0023] like Figure 1 As shown, a crystal plasticity finite element modeling and simulation method of the present invention obtains grain information based on EBSD analysis; imports a (ctf format) file containing grain information such as Euler angles generated by EBSD analysis into the open source software Dream.3D to realize automatic reconstruction of the grain structure, and outputs an input file containing only geometric information such as model nodes and units of ABAQUS finite element analysis software and geometric orientation data of each grain; then processes the grain geometric orientation data through a Python language script to obtain the average geometric orientation information of each grain; uses a Python script to combine the average geometric orientation information of the grain with the input file representing the geometric model to generate a complete input file with geometric model information and material property information; finally, in the ABAQUS finite element analysis software, a certain boundary condition is given to the model and its constitutive relationship is set using the UMAT subroutine, thereby realizing the entire crystal plasticity finite element analysis process.

[0024] The specific steps are as follows:

[0025] Step 1: Electron backscatter diffraction analysis (EBSD) is used to analyze the given material sample (such as Figure 3 ) for scanning processing, such as Figure 2 , obtain the grain information such as surface Euler angles, and output it in ctf file format;

[0026] Step 2, import the ctf format file containing the grain information obtained in step 1 into Dream.3D software to realize automatic reconstruction of the grain structure, and output an input file containing only the geometric model of the ABAQUS finite element analysis software and the geometric orientation data of each grain; use the built-in Python script runner of the ABAQUS finite element analysis software to calculate the arithmetic mean of the grain geometric orientation data according to the grain number and output it;

[0027] Step 3, processing the grain geometric orientation data obtained in step 2 through a Python language script to obtain the average geometric orientation information of each grain, and combining the average geometric orientation information of the grain with the input file obtained in step 2 to generate a complete input file with geometric model information and material property information;

[0028] Among them, the built-in Python script runner of ABAQUS finite element analysis software is used to calculate the arithmetic mean of the grain geometric orientation data according to the grain number and output it;

[0029] Among them, the input file obtained in step 2 is imported into the ABAQUS finite element analysis software, and then the internal Python script runner of the ABAQUS finite element analysis software is used to automatically read and write the material property information into the input file to generate a complete input file for further analysis.

[0030] The final model with material properties such as Euler angles is as follows: Figure 4 For comparison, the ctf file was processed using the MTEX ​​toolkit in MATLAB software to obtain the grain distribution map, as shown in Figure 3 As shown in the figure, it can be found that the grain model obtained by using Dream.3D software has a higher degree of restoration and can better reflect the small grains and twin boundaries.

[0031] Step 4, assign boundary conditions to the model in the ABAQUS finite element analysis software and use the UMAT subroutine to set its constitutive relationship, thereby realizing the entire crystal plasticity finite element analysis process; wherein, the boundary conditions are determined by the actual experimental conditions, and the constitutive relationship is determined by fitting the materials used and their physical models.

[0032] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention are within the protection scope of the present invention.

Claims

1. A crystal plasticity finite element modeling and simulation method, characterized in that: The following steps are involved: (1) Use electron backscatter diffraction analysis technology to scan and process a given material sample, obtain grain information, and output it in ctf file format; (2) Importing the ctf format file containing grain information obtained in step (1) into Dream.3D software, automatically reconstructing the grain structure according to the specified grain boundary angle tolerance through the built-in Filter function combination of Dream.3D software, and using its built-in function to control the mesh size, and outputting an input file containing only the geometric model of ABAQUS finite element analysis software and the geometric orientation data of each grain; (3) Processing the grain geometric orientation data obtained in step (2) through a Python language script to obtain the average geometric orientation information of each grain, and combining the average grain geometric orientation information with the input file obtained in step (2) to generate a complete input file with geometric model information and material property information; (4) In the ABAQUS finite element analysis software, boundary conditions are assigned to the model and its constitutive relationship is set using the UMAT subroutine, thereby completing the entire crystal plasticity finite element analysis process.

2. The crystal plasticity finite element modeling simulation method according to claim 1, characterized in that: In the step (1), the grain information includes the surface Euler angles of a given material sample.

3. The crystal plasticity finite element modeling simulation method according to claim 1, characterized in that: In the step (3), the built-in Python script runner of the ABAQUS finite element analysis software is used to calculate the arithmetic mean of the grain geometric orientation data according to the grain number and output it.

4. The crystal plasticity finite element modeling simulation method according to claim 1, characterized in that: In the step (3), the input file obtained in step (2) is imported into the ABAQUS finite element analysis software, and then the internal Python script runner of the ABAQUS finite element analysis software is used to automatically read and write the material property information into the input file, thereby generating a complete input file for further analysis.

5. The crystal plasticity finite element modeling simulation method according to claim 1, characterized in that: In the step (4), the boundary conditions are determined by actual experimental conditions, and the constitutive relationship is determined by fitting the used materials and their physical models.

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