CN-122021200-A - Phase field stress corrosion cracking simulation method, system and device based on strain rate

CN122021200ACN 122021200 ACN122021200 ACN 122021200ACN-122021200-A

Abstract

The invention provides a phase field stress corrosion cracking simulation method, system and device based on strain rate, and relates to the technical field of phase field stress corrosion cracking simulation. The method comprises the steps of constructing a finite element model based on sample information and boundary conditions to obtain a finite element output file, constructing a phase field model, solving a control equation based on the finite element output file, and obtaining a result file by solving a convergence solution of the variable through the phase field model based on different strain rates, wherein the phase field model comprises variables, input parameters, free energy functional and the control equation. The SCC crack initiation and expansion of the metal can be simulated under the micrometer scale, and the SSRT experimental design of the novel component alloy is guided by comparing crack initiation time, the form during crack expansion and the crack expansion rate value under different strain rates, so that the evaluation efficiency is improved.

Inventors

DONG CHAOFANG
LIU XIAOOU
JI YUCHENG
YAO CHENYANG
QIN WENTAO
CHEN ZHANGHUA

Assignees

北京科技大学

Dates

Publication Date: 20260512
Application Date: 20260414

Claims (10)

1. A method for simulating phase field stress corrosion cracking based on strain rate, comprising: Step 1, constructing a finite element model based on sample information and boundary conditions to obtain a finite element output file; Step 2, constructing a phase field model, wherein the phase field model comprises variables, input parameters, free energy functional and a control equation, and the control equation comprises a Cahn-Hilliard equation controlled by a concentration field, an Allen-Cahn equation controlled by a phase field and a displacement finite element equation controlled by a displacement field; And step 3, solving the control equation based on the finite element output file, and solving a convergence solution of the variable based on different strain rates through a phase field model to obtain a result file.
2. The simulation method according to claim 1, wherein the sample information includes a matrix size and a fracture size, and the fracture size is an average size of pit obtained by an SSRT test.
3. A simulation method according to claim 1, wherein the boundary conditions include a fixed displacement boundary constraint, a specified displacement boundary constraint, and a solid-liquid interface, the solid-liquid interface being provided at a crack.
4. A simulation method according to claim 1, wherein the finite element output file contains node total number, cell total number, degree of freedom, cell type, gaussian point number, node position information at solid-liquid interface, constrained node number, and degree of freedom information at constraint point.
5. A simulation method according to claim 1, wherein the variables of the phase field model include strain energy, stress, concentration And order parameters 。
6. The simulation method of claim 1 wherein the input parameters of the phase field model comprise sample material parameters and time integration parameters, the sample material parameters comprise free energy density curvature, diffusion coefficient, metal atom concentration, saturation concentration of metal ions, elastic modulus of solid phase, virtual elastic modulus of liquid phase, poisson's ratio, interface thickness and interface dynamics parameters, and the time integration parameters comprise total time step and output step.
7. The simulation method according to claim 5, wherein the specific expression of the free energy functional includes: ; Wherein, the Representing the total free energy; Specific expressions that represent chemical free energy and have chemical free energy density include: Wherein, the method comprises the steps of, Representing the local chemical energy density of the solid metal; representing the local chemical energy density of the liquid; Representing a degradation function; specific expressions that represent surface energy and have surface energy density include: Wherein, the method comprises the steps of, A gradient representing an order parameter; The energy coefficient of the gradient is represented, Representing the applied double well barrier height, both of which can be determined by interfacial energy Interface thickness of anodic dissolution model Fitting to obtain; Represents a double well potential, and has: ; Representing strain energy; Representing displacement.
8. A simulation method according to claim 5, further comprising step 4 of performing visualization processing on the result files of different total time steps to obtain variable values at solid-liquid interfaces at corresponding total time steps and performing cracking analysis.
9. The phase field stress corrosion cracking simulation system based on the strain rate is characterized by comprising a data acquisition module, a data processing module and a result generation module; the data acquisition module is used for acquiring sample information; The data processing module comprises a finite element model unit, a phase field model unit and a solving unit; the finite element model unit is used for constructing a finite element model based on sample information and boundary conditions to obtain a finite element output file; The phase field model unit is used for constructing a phase field model, wherein the phase field model comprises a variable, an input parameter, a free energy functional and a control equation, and the control equation comprises a Cahn-Hilliard equation controlled by a concentration field, an Allen-Cahn equation controlled by a phase field and a displacement finite element equation controlled by a displacement field; The solving unit is used for solving the control equation based on the finite element output file, solving the convergence solution of the variable based on different strain rates through a phase field model, and obtaining a result file; the result generation module is used for sending out the processing result of the solving unit.
10. A strain rate based phase field stress corrosion cracking simulation device comprising a processor, a memory and a bus, wherein the memory stores instructions and data read by the processor, the processor is configured to invoke the instructions and data in the memory to perform the simulation method according to any of claims 1-8, and the bus is connected between functional components for transmitting information.

Description

Phase field stress corrosion cracking simulation method, system and device based on strain rate Technical Field The invention relates to the technical field of phase field stress corrosion cracking simulation, in particular to a phase field stress corrosion cracking simulation method, system and device based on strain rate. Background Metals such as aluminum alloys have a high sensitivity to stress corrosion cracking (Stress Corrosion Cracking, SCC), thereby limiting the engineering applicability and service safety of such metals in harsh environments. To evaluate the SCC sensitivity of metals such as aluminum alloys, the test is typically performed using a Slow strain rate tensile (Slow STRAIN RATE TENSILE, SSRT) test. According to specific test standards, aluminum alloys are typically selected to have a single strain rate ±) Tests were performed, however, in order to show the mechanical and electrochemical coupling phenomena during stress corrosion cracking, different strain rates should be selected for the aluminum alloys of different compositions when SSRT tests were performed, and by comparing the SSRT curves of the samples in air and in corrosive media, the strain rate that better shows the SCC process was selected. Meanwhile, different strain rates are also closely related to crack initiation and propagation in the stress corrosion cracking process. With the development of simulation computing technology, the mechanical and electrochemical coupling effect of the SCC process is simulated. However, the existing simulation methods generally describe the hardening effect caused by the strain rate by using the strain hardening rate, and are mainly applied to the fracture field under the single stress, and do not consider the influence of the electrochemical coupling effect. Disclosure of Invention The invention aims to provide a phase field stress corrosion cracking simulation method, system and device based on strain rate, so as to solve at least one of the technical problems in the prior art. In order to solve the above technical problems, the present invention provides a method for simulating phase field stress corrosion cracking based on strain rate, comprising the following steps: And step 1, constructing a finite element model (through a finite element command stream program) based on sample information and boundary conditions to obtain a finite element output file. In one possible embodiment, the sample information includes a matrix size and a fracture size, and the fracture size is an average size of pit obtained by an SSRT test. In a feasible implementation mode, the boundary conditions comprise fixed displacement boundary constraint, specified displacement boundary constraint and a solid-liquid interface, wherein the solid-liquid interface is arranged at a cracking position, so that the problems of metal dissolution caused by electrolyte and material degradation caused by metal damage due to mechanical action are simultaneously considered, and the evolution process driven by electrochemistry and mechanics together at the cracking position of the metal surface in an SSRT test is effectively disclosed. In one possible embodiment, the finite element output file contains the total number of nodes, the total number of units, the number of degrees of freedom, the type of units, the number of gauss points, the node location information at the solid-liquid interface, the number of nodes that are constrained, and the degree of freedom information at the constraint point. And 2, constructing a phase field model, wherein the phase field model comprises variables, input parameters, free energy functional and a control equation, and the control equation comprises a Cahn-Hilliard equation controlled by a concentration field, an Allen-Cahn equation controlled by a phase field and a displacement finite element equation controlled by a displacement field. In one possible embodiment, the phase field model is implemented in MATLAB language. In one possible embodiment, the variables of the phase field model include strain energy, stress, concentrationAnd order parametersWherein when、Corresponding to the solid phase when、Corresponding to the liquid phaseThe specific value range corresponding to the corrosion boundary can beThe concentration ofIs the concentration of the sample material components after normalization treatment. In one possible implementation, the input parameters of the phase field model include sample material parameters including parameters such as free energy density curvature, diffusion coefficient, metal atom concentration, saturation concentration of metal ions, elastic modulus of solid phase, virtual elastic modulus of liquid phase, poisson's ratio, interface thickness, and interface dynamics parameters, which are known or computable, and time integration parameters including a total time step (i.e., total physical time length) and an output step (i.e., time interval). In a possible embodiment