CN-117594162-B - Polycrystal plastic finite element simulation method and device

CN117594162BCN 117594162 BCN117594162 BCN 117594162BCN-117594162-B

Abstract

The application relates to a polycrystalline plasticity finite element simulation method and device, wherein the method comprises the steps of obtaining an original file by utilizing a polycrystalline model, importing the file into a first preset script for operation, generating the first file according to numbers and actual crystal orientations, importing the first file into a preset program, obtaining a second file according to the polycrystalline model of a cohesive grain boundary unit, importing the second file into a second preset script for operation, obtaining a complete polycrystalline model, importing the complete polycrystalline model into finite element software, generating a polycrystalline plasticity finite element model containing the cohesive grain boundary unit and grids, invoking a crystal plasticity subroutine to calculate at least one mechanical behavior in the polycrystalline plasticity finite element model, and simulating and calculating crack crystal plasticity of the complete polycrystalline model. Therefore, the problems that the influence of back stress of cyclic load and grain boundary damage are less considered in the related technology, errors exist in finite element results, and the accuracy and reliability of finite element simulation are reduced are solved.

Inventors

ZHAO QIUYU
HAN QINAN
CUI HAITAO

Assignees

南京航空航天大学

Dates

Publication Date: 20260512
Application Date: 20231109

Claims (10)

1. A method of polycrystalline plasticity finite element simulation, comprising the steps of: Acquiring original crystal grain direction data, and generating a polycrystal model according to the crystal grain direction data so as to obtain an original file by utilizing the polycrystal model; Importing the file into a first preset script for operation so as to number each crystal grain in the polycrystalline model, endowing each crystal grain with actual crystal orientation, and generating a first file according to the number and the actual crystal orientation; The first file is imported into a preset program, the preset program is inserted into a cohesive force grain boundary unit model simulating a grain boundary, so that a polycrystal model with cohesive force grain boundary units simulating the grain boundary is obtained, and a second file is obtained according to the polycrystal model of the cohesive force grain boundary units; importing the second file into a second preset script for operation to delete at least one element in redundant grids and models to obtain a complete polycrystal model; importing the complete polycrystalline model into finite element software to generate a polycrystalline plastic finite element model containing cohesive grain boundary units and grids; Writing a crystalline plastic constitutive relation of back stress evolution as a crystalline plastic subroutine, and importing the polycrystalline plastic finite element model into the finite element software to invoke the crystalline plastic subroutine to calculate at least one mechanical behavior in the polycrystalline plastic finite element model, and And on the basis of the at least one mechanical behavior, carrying out file association on the polycrystalline plasticity finite element model and the crystal plasticity subprogram, simulating and calculating crack crystal plasticity of the complete polycrystalline model, and obtaining at least one result of stress and damage variables after crack initiation and expansion according to the crack crystal plasticity.
2. The method of claim 1, further comprising, prior to writing the back stress evolving crystalline plastic constitutive relationship as a crystalline plastic subroutine and importing the polycrystalline plastic finite element model into the finite element software: setting at least one constraint condition of load, boundary condition and analysis step for the polycrystalline model; and obtaining the cae file of the polycrystalline model according to the constraint condition.
3. The method of claim 1, wherein the obtaining raw grain orientation data and generating a polycrystalline model from the grain orientation data comprises: performing global Electron Back Scattering Diffraction (EBSD) scanning shooting on the metal easily damaged area to obtain the original crystal grain orientation data; And importing the original crystal orientation data into stream 3D to obtain the polycrystal model containing at least one piece of crystallographic information of grids, crystal orientations of the crystal grains, crystal sizes of the crystal grains and crystal morphology of the crystal grains.
4. The method of claim 1, wherein the polycrystalline plasticity finite element model is the same shape as an actual polycrystalline test piece, and the polycrystalline plasticity finite element model contains at least one crystallographic information of the grain orientation, grain boundaries, grain size, and grain morphology.
5. The method of claim 2, further comprising, prior to setting at least one of a load, a boundary condition, and a constraint for the polycrystalline model in the analyzing step: And defining an initial criterion of damage of the cohesive grain boundary unit by adopting a maximum nominal stress criterion, wherein when the stress of the crack tip of the cohesive area is smaller than a damage initial critical value, the cohesive grain boundary unit is in a linear elastic deformation stage, and when the normal traction force is increased, the material of the cohesive grain boundary unit is degraded and continuously damaged until the cohesive grain boundary unit is completely damaged.
6. The method of claim 5, wherein the material of the cohesive grain boundary element degenerates and continues to be damaged as the normal traction increases until the cohesive grain boundary element is completely damaged, comprising: And introducing a damage variable to represent the change of material degradation of the cohesive grain boundary unit, wherein when the damage variable is 0, the cohesive grain boundary unit is not damaged, when the cohesive grain boundary unit is subjected to external load, the damage variable value is continuously increased when the crack tip is damaged in a cumulative manner, and until the damage variable value is 1, the cohesive grain boundary unit is completely failed.
7. The method of claim 1, wherein the back stress is calculated by the formula: Wherein ζ (α) and r (α) are material dependent constants, Is the strain rate on the alpha-th slip train.
8. A polycrystalline plastic finite element simulation device, comprising: the acquisition module is used for acquiring original crystal grain direction data and generating a polycrystal model according to the crystal grain direction data so as to obtain an original file by utilizing the polycrystal model; The first generation module is used for importing the file into a first preset script for operation so as to number each crystal grain in the polycrystalline model, endow the actual crystal orientation of each crystal grain, and generate a first file according to the number and the actual crystal orientation; The importing module is used for importing the first file into a preset program, inserting the preset program into a cohesive force grain boundary unit model simulating a grain boundary so as to obtain a polycrystal model with cohesive force grain boundary units simulating the grain boundary, and obtaining a second file according to the polycrystal model of the cohesive force grain boundary units; The deleting module is used for importing the second file into a second preset script to run so as to delete at least one element in redundant grids and models and obtain a complete polycrystal model; the second generation module is used for importing the complete polycrystalline model into finite element software to generate a polycrystalline plasticity finite element model containing the cohesive grain boundary units and the grids; a calculation module for writing the back stress evolving crystal plasticity constitutive relation into a crystal plasticity subroutine, and importing the polycrystal plasticity finite element model into the finite element software to call the crystal plasticity subroutine to calculate at least one mechanical behavior in the polycrystal plasticity finite element model, and And the simulation module is used for carrying out file association on the polycrystalline plasticity finite element model and the crystal plasticity subprogram based on the at least one mechanical behavior, simulating and calculating crack crystal plasticity of the complete polycrystalline model, and obtaining at least one result of stress and damage variables after crack initiation and expansion according to the crack crystal plasticity.
9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor executing the program to implement the polycrystalline plastic finite element simulation method of any one of claims 1 to 7.
10. A computer readable storage medium having stored thereon a computer program, the program being executable by a processor for implementing the polycrystalline plasticity finite element simulation method according to any one of claims 1-7.

Description

Polycrystal plastic finite element simulation method and device Technical Field The application relates to the technical field of material performance characterization, in particular to a polycrystalline plasticity finite element simulation method and device. Background The finite element simulation of crystal plasticity is an effective means for researching the damage and sliding behaviors of the crystal material, and particularly has a good prospect in the aspects of crack initiation, expansion behavior exploration and the like of the crystal material. In the related technology, the finite element research aiming at the damage and sliding behavior of the polycrystalline material is mainly a macroscopic research method, the macroscopic research method obtains a finite element model through macroscopic modeling, the macroscopic modeling method is further optimized through finite element analysis software, the established finite element model is divided into a plurality of parts through means such as segmentation, and then crystal properties are independently given to each part, so that the model contains more crystal information, and the finite element analysis is performed through the steps such as load setting, contact setting, analysis step and the like, so that the accuracy of a finite element analysis result is improved. However, in the related art, the current crystal plasticity constitutive model is less considering the back stress influence of cyclic load, so that it is difficult to describe the mechanical behavior of materials under cyclic load such as fatigue, and many metals and alloys are polycrystalline, so that the single crystal finite element model is not applicable any more, the finite element model considering the polycrystal needs to be developed, and in addition, the current polycrystal modeling method does not consider the damage effect of the grain boundary, so that the grain boundary crack initiation and propagation behavior cannot be simulated, and improvement is needed. Disclosure of Invention The application provides a polycrystalline plasticity finite element simulation method and device, which are used for solving the problems that the related technology is limited to a monocrystalline finite element model and a crystal plasticity constitutive model, the back stress influence of cyclic load is less considered, the damage effect of a grain boundary is not considered, the finite element result has errors, the accuracy and the reliability of finite element simulation are reduced, and the like. An embodiment of the first aspect of the present application provides a method for finite element simulation of polycrystalline plasticity, comprising the steps of obtaining original crystal orientation data of crystal grains, generating a polycrystalline model based on the crystal orientation data of crystal grains, obtaining an original file by using the polycrystalline model, importing the file into a first preset script, numbering each crystal grain in the polycrystalline model, assigning an actual crystal orientation to each crystal grain, generating a first file based on the numbering and the actual crystal orientation, importing the first file into a preset program, inserting the preset program into a cohesive grain boundary unit model simulating grain boundaries, obtaining a polycrystalline model simulating the cohesive grain boundary unit, obtaining a second file based on the polycrystalline model simulating the cohesive grain boundary unit, importing the second file into the second preset script, deleting at least one element of redundant grids and models, obtaining a complete polycrystalline model, importing the complete polycrystalline model into a finite element software, generating a first file based on the numbering and the actual crystal orientation, importing the first file into the finite element software, and the crystal model into the finite element software, and calculating a plastic crack based on the complete polycrystalline model, and compiling the complete polycrystalline model into the complete polycrystalline model based on the complete polycrystalline model, and calculating the complete plastic crack, at least one of the expanded stress and damage variables results. Optionally, in one embodiment of the present application, before writing the back stress evolving crystal plastic constitutive relation as a crystal plastic subroutine and importing the polycrystalline plastic finite element model into the finite element software, the method further comprises setting at least one constraint condition of load, boundary condition and analysis step for the polycrystalline model, and obtaining a cae file of the polycrystalline model according to the constraint condition. Optionally, in one embodiment of the present application, the obtaining the original grain orientation data and generating the polycrystalline model according to the grain orientation data includes performin