74 results about "Crystal plasticity" patented technology

The invention relates to the technical field of force sensors, and discloses a nonlinear decoupling method and system for a three-axis force sensor, and the method comprises the steps: collecting multi-dimensional original data, and carrying out the adaptive noise reduction, dynamic selection of a wavelet basis, and construction of a filtering matrix, and obtaining a noise reduction signal through calculation; constructing a dynamic PINN proxy model, fusing material parameters and environment parameters, outputting a stiffness matrix, establishing an online parameter updating mechanism, calculating the obtained optimization parameters, and constructing an enhanced dynamic compensation matrix; the output stiffness matrix and the enhanced dynamic compensation matrix are fused, and a main singular value is reserved; reconstructing to obtain a reconstructed strain field, establishing a multi-physics field coupling model to compensate quantum-thermal coupling errors, and compensating wire inductive coupling under high frequency; constructing a multi-scale graph structure, strengthening a loss function through physical constraint, performing crystal plasticity hysteresis compensation, fusing multi-scale features, and calculating and outputting a decoupling force value; and an intelligent calibration decision is established, the drift trend is predicted, and the calibration period is dynamically adjusted.

The invention discloses a VPSC model construction method based on an ABAQUS sub-model, and belongs to the field of computational material science and engineering.The VPSC model construction method comprises the steps that a global model is established according to the size of a part, and an ABAQUS input file is generated; selecting a local area of a part in the global model, determining a unit number of the area, constructing a crystal plasticity constitutive model through UMAT, and adding a plurality of randomly oriented crystal grains to the local area in an ABAQUS input file to form a reference model; grain nodes and orientation information in the reference model are read through an ABAQUS script, a grain model is created, corresponding orientation is given to sub-models, sub-model boundary conditions consistent with global model deformation are applied to grain geometric boundaries, and a VPSC model is constructed. According to the method, the grain orientation is locally refined through the sub-model technology, and the VPSC sub-model is automatically generated in combination with the script, so that the calculation complexity is remarkably reduced.

The present invention proposes a method for predicting the high-temperature creep life of nickel-based single crystals under the influence of orientation deviation, which relates to the field of reliability technology. The method comprises: establishing a three-dimensional finite element round rod model based on the dimensions of a nickel-based single crystal creep specimen; establishing a constitutive equation for the nickel-based single crystal based on crystal plasticity theory, wherein the constitutive equation for the nickel-based single crystal includes a deformation equation that considers orientation deviation and a damage equation that considers orientation deviation; combining the three-dimensional finite element round rod model and the nickel-based single crystal constitutive equation to perform creep finite element simulation calculations on the round rod model; and establishing a creep time-strain curve and predicting the creep life based on the results of the creep finite element simulation calculations. The present invention can relatively accurately evaluate and predict the high-temperature creep life of nickel-based single crystal turbine blades used in actual industrial manufacturing.

The invention discloses a test-based crystal plasticity and cohesion model coupling hydrogen induced cracking simulation method, which comprises the following steps: carrying out a hydrogen filling mechanical property test on a metal material to obtain a true stress-true strain curve of the metal material in a hydrogen environment; carrying out a hydrogen-filled fracture toughness test on the metal material to obtain a stress intensity factor of the metal material in a hydrogen environment; constructing a cohesion constitutive model; a metal material electron back scattering diffraction microscopic characterization test is carried out, microstructure characteristics are obtained, and a polycrystalline model is constructed; constructing a crystal plastic constitutive model; coupling crystal plasticity constitutive and cohesion constitutive, and calibrating crystal plasticity to-be-determined parameters by adopting a trial-and-error method; and carrying out finite element simulation analysis on hydrogen-induced cracking behaviors with different microstructure characteristics in a hydrogen environment to obtain stress-strain data and crack data of the hydrogen-induced cracking behaviors. According to the invention, high-precision simulation of the hydrogen-induced cracking micromechanism of the metal material in the hydrogen environment is realized.

The invention discloses a welding thermal stress simulation method, device, equipment and medium based on a crystal plasticity finite element, and relates to the technical field of welding thermal stress finite element simulation. The method comprises the steps that a sample is prepared according to a specific multi-phase metal material, and phase distribution and crystal orientation information of a two-dimensional plane of the material are obtained through a metallographic experiment; and a three-dimensional multi-grain model is constructed based on the two-dimensional information. According to the method, a crystal plastic constitutive model is adopted to describe the flowing behavior of the material at high temperature, crystal slippage and polycrystal interaction are considered, the influence on the material performance is reflected from the microstructure evolution level, and the problem that the influence on the macroscopic mechanical performance of a microstructure is difficult to capture in welding multiphase metal material simulation is solved; two-dimensional representation is obtained through a metallographic experiment, the Young modulus and rigidity matrix parameters are accurately calculated by combining forward stretching and shear simulation, the rigidity matrix precision is improved, a temperature field area is divided, stress evolution and residual stress are calculated by combining a thermal-elastic-plastic model, and the welding thermal stress calculation precision is improved.

The invention discloses a method for evaluating a fatigue weak area of a welded joint based on crystal plasticity, which aims at the problem of fatigue failure of the welded joint caused by complex microstructures such as grain orientation difference and uneven grain size distribution, establishes a quantitative correlation model of grain orientation and size evolution through CPFEM, and combines a macro-micro cross-scale analysis method to evaluate the fatigue weak area of the welded joint. And precise prediction of local stress concentration and crack initiation behaviors of the welding joint under a real fatigue load working condition is realized, so that scientific evaluation of a fatigue weak region is completed. According to the method, an innovative framework of fatigue weak area evaluation is constructed through load working condition reduction and grain characteristic multi-scale coupling, so that excessive simplification of a traditional method on real load conditions is made up, the limitation that a traditional model is difficult to couple a microstructure and a real load is overcome, and the fatigue weakening quantization precision is remarkably improved; and a high-precision analysis technology is provided for anti-fatigue design, process optimization and service life evaluation of the engineering welding structure.

The invention relates to the technical field of nuclear reactor fuel element analysis, in particular to an irradiated zirconium alloy plasticity limit prediction method based on a crystal plasticity finite element, which comprises the following steps: establishing a three-dimensional polycrystalline representative body cell model conforming to the actual grain size of zirconium alloy; based on a crystal plasticity theoretical model, zirconium alloy material parameters are obtained through calculation; boundary conditions and load conditions are determined, finite element calculation is executed in combination with material parameters, and an element stiffness matrix of each increment step is output; assembling the unit stiffness matrix, and obtaining a macroscopic stress-strain matrix of the three-dimensional polycrystal cell model through a homogenization method; and substituting the macroscopic stress-strain matrix into the Rice theoretical criterion, traversing the macroscopic stress-strain matrix of each increment step, and determining the plastic strain meeting the judgment critical condition. According to the method, accurate finite element plastic limit analysis can be carried out on the irradiation material, and the plastic limit strain of the zirconium alloy under the irradiation condition can be accurately judged.

The invention provides a method for establishing a nonlinear constitutive model of low-temperature marine steel, and relates to the technical field of ships and materials. A heterogeneous time series data set is provided for model construction through multi-type sample multi-axial load tests and full-field strain acquisition; nonlinear mapping of deformation activation energy about temperature and microscopic state variables is established by taking a crystal plasticity theory as a framework, and the defect that a low-temperature dislocation evolution rule cannot be reflected due to the fact that a traditional model solidifies physical parameters into constants is overcome; a damage evolution operator jointly induced by stress triaxial degree and a principal stress threshold is embedded, Bayesian inference is adopted to carry out parameter joint calibration, model dynamic calibration and parameter continuous optimization are realized through a simulation and experiment closed-loop iteration mechanism, and finally a digital design evaluation model capable of being under untested extreme working conditions is produced. And an engineering tool taking physical interpretability and probabilistic safety margin into consideration is provided for the ice-resistant design of the polar region ship.

The invention discloses a modeling and analysis method for a metal matrix composite crystal plasticity finite element, and particularly relates to the field of metal matrix composites for spaceflight. Comprising the following steps: acquiring EBSD data of a to-be-detected metal-based composite material; identifying a metal matrix phase and a reinforced fiber phase according to the EBSD data; carrying out texture analysis on the to-be-detected metal matrix composite material, and determining grain orientation data; according to the grain orientation data, establishing a finite element model of the to-be-tested metal matrix composite material, and generating a geometric grid; identifying a metal matrix phase and a reinforced fiber phase in the finite element model, and endowing each phase with parameters; according to the crystal plasticity constitutive model, determining the strain of the to-be-measured metal-based composite material; and original crystal plasticity parameters are corrected according to the actually-measured strain and strain, and the metal-based composite material model is obtained. The metal matrix composite model can obtain the grain plastic strain in the plastic deformation process.

The application discloses a method and system for predicting mechanical properties of laser welded particle reinforced welds of aluminum-lithium alloys, and particularly relates to the field of predicting mechanical properties of laser welded joints. A cross-scale parameter transfer path from first principles to crystal plasticity is established. By constructing a unified high-precision machine learning potential function, the mechanical behavior of complex multi-phase interfaces is accurately quantified, providing a solution for understanding the micro-damage mechanism of the weld. Secondly, by establishing an experiment-driven closed-loop self-correction mechanism, the cumulative error problem introduced by the simplification of models at different scales is effectively solved, and the self-optimization and precision improvement of the prediction model are realized. Finally, a high-confidence digital tool is provided for welding process parameter optimization and new material design, significantly shortening the research and development cycle and reducing the test cost, and having important engineering application value in the field of high-end manufacturing such as aerospace.

The invention relates to a fatigue life prediction method based on a physical failure mechanism in a liquid lead bismuth environment, and the method comprises the following steps: building a representative volume element model, and defining elements belonging to a slip band; defining a crystal plasticity constitutive equation; determining parameters in the crystal plasticity constitutive equation; calculating the average shear strain range of the slip band; carrying out a fracture toughness test to obtain specific fracture energy; establishing a fatigue life prediction model based on a physical failure mechanism; carrying out a symmetrically cyclic low-cycle fatigue test on the metal material in a predicted-temperature high-oxygen liquid lead bismuth environment to determine the thickness of an oxide film; and establishing a fatigue life prediction model in the high-oxygen-concentration liquid lead bismuth environment, and predicting the fatigue life of the metal material in the high-oxygen-concentration liquid lead bismuth environment. According to the method, the fatigue life in the liquid lead-bismuth environment can be predicted by carrying out a low-cycle fatigue test for calibrating crystal plasticity constitutive equation parameters in the air at the predicted temperature and a fracture toughness test in the air and liquid lead-bismuth environment.

The present application relates to the technical field of force sensor, disclose a kind of nonlinear decoupling method and system of triaxial force sensor, comprising: acquisition multi-dimensional original data, and carry out adaptive noise reduction, dynamically select wavelet base, construct filter matrix and obtain denoising signal;Dynamic PINN proxy model is constructed, material parameters and environmental variables are fused, and stiffness matrix is output, online parameter updating mechanism is established, and the optimized parameter calculated is constructed enhanced dynamic compensation matrix;The output stiffness matrix and enhanced dynamic compensation matrix are fused and the main singular value is reserved;Reconstruction obtains reconstructed strain field, establishes multi-physical field coupling model compensation quantum-thermal coupling error, and compensates the lead inductance coupling under high frequency;Multi-scale graph structure is constructed, loss function is reinforced by physical constraint, crystal plasticity hysteresis compensation is carried out, multi-scale features are fused, and the decoupling force value is calculated;Establish intelligent calibration decision, predict drift trend and dynamically adjust calibration cycle.

The application discloses a kind of based on crystal plastic finite element and sequence condition generation formula deep learning agent model's oriented electrical steel cold rolling texture fast prediction method, system and medium, with cold rolling process parameter set as input, with ODF slice image as output;Through the crystal plastic finite element model driven by physical mechanism, "process path-ODF" virtual labeling data pair is generated in batch in pre-set cold rolling process design space, and data set is constructed;Then using sequence condition generation formula deep learning agent model realizes the end-to-end nonlinear mapping from cold rolling process path to high-dimensional ODF image, so that the premise of not needing to call crystal plastic finite element model successively, realize the fast prediction, visualization and path regulation of cold rolling texture evolution.This application solves the problem of existing fusion crystal plastic simulation precision advantage and deep learning model high efficient generalization ability, realizes the fast and accurate prediction of cold rolling texture evolution.

The application discloses a kind of gradient nanostructure sliding wear high-efficiency calculation method, comprising: obtaining gradient nanostructure grain size parameter and load parameter, determine the material parameter at different depths;Establish size-dependent crystal plasticity constitutive model and dislocation density evolution model and cluster homogenization model;Establish three-dimensional friction contact finite element model, calibrate constitutive model parameters and friction and wear parameters;In three-dimensional friction contact finite element model, calculate the results such as contact pressure, relative slip, cumulative plastic strain, dislocation density;Based on energy dissipation theory, calculate the wear depth increment of each contact node.The application can be coupled in the same calculation framework gradient grain size, crystal plastic deformation, dislocation density evolution, friction contact and surface wear evolution, obtain the wear depth, contact pressure, cumulative plastic strain, dislocation density of gradient nanostructure under reciprocating sliding load, and can be used for comparing the wear resistance under different surface grain size.

The invention relates to a topological decoupling-based complex component crystal plasticity finite element cross-scale modeling method, which comprises the following steps of: firstly, carrying out macroscopic finite element grid division on a geometric model of a component to be analyzed to export an isolated grid file, and then establishing an RVE voxel grid based on microstructure source data of a material of the component to be analyzed; calculating the geometric centroid coordinate of each unit after macroscopic finite element grid division, and judging the attribution crystal grain ID of each geometric centroid coordinate in the RVE voxel grid through a centroid mapping algorithm to generate a unit set mapping file; then calculating a rotation matrix for each crystal grain ID based on crystal orientation distribution data, combining the rotation matrix with crystal plasticity constitutive model parameters to generate a physical attribute library file, and finally performing semantic analysis and recombination on an isolated grid file to generate a CPFE cross-scale simulation model. According to the method, macroscopic finite elements and microscopic voxel grids are decoupled, the problem that complex geometric expression precision and microstructure fidelity are difficult to consider at the same time is solved, and CPFE cross-scale accurate modeling of complex components is achieved.

The application discloses a spherical tooth tip blade safety evaluation method and system based on data analysis, and relates to the technical field of cutting processing.The application comprises the following steps: collecting blade surface morphology, microscopic lattice structure and cutting dynamic load data through a white light interferometer, EBSD and a dynamometer; establishing a macro finite element model and embedding a microscopic crystal plasticity submodel; matching macro and microscopic stress fields, calculating lattice orientation conversion matrix and Schmid factor, and extracting slip system characteristic parameters; determining crack initiation, calculating an extension path in combination with an anisotropy criterion, and reconstructing three-dimensional crack morphology; calculating a cumulative damage factor, dividing three-level safety threshold values, and outputting a visual report and a life prediction value.The application establishes a coupling equation of macro stress field and microscopic crystal orientation, integrates the mechanical response characteristics of a material at different scales, and improves the physical authenticity of crack initiation and extension prediction.

The invention relates to the technical field of single crystal alloy fatigue life prediction, in particular to a nickel-based single crystal alloy fatigue life prediction method considering second orientation and recrystallization defects. The specific method comprises the following steps: obtaining a plurality of nickel-based single crystal alloys as single crystal alloy samples which have different second orientations and have recrystallization defects partially; establishing a crystal plastic model; acquiring fatigue life and fatigue stress parameters; inputting the fatigue stress parameter into a crystal plastic model to calculate the accumulated plastic shear strain of the dangerous point; 1 / 2 of the product of the cumulative plastic cutting strain and the fatigue load in the crystal plasticity or the cumulative plastic cutting strain is used as a fatigue indication factor; and fitting by taking the fatigue indication factor as a vertical coordinate and the fatigue life as a horizontal coordinate to obtain a fatigue life prediction model. According to the method, the recrystallization defect and the influence of different second orientations are considered, the related fatigue indication factors are introduced to construct the fatigue life prediction model between the fatigue indication factors and the fatigue life, and the accuracy and reliability of the prediction result are improved.

The invention relates to a method for predicting the creep performance of oxide dispersion strengthened (ODS) steel under high temperature and high irradiation conditions. A complex crystal plasticity constitutive model is developed to accurately predict the performance of ODS steel in terms of irradiation hardening and creep behavior, which incorporates the spatial distribution of voids and oxides. This developed model is highly consistent with experimental data at different temperatures and irradiation doses, demonstrating its strong robustness. As the irradiation dose increases, the yield stress of irradiated ODS steel also increases. The yield strength of ODS steel shows a linear relationship with the irradiation dose, which initially increases with the increase of irradiation dose and then decreases. The void size steadily increases, while the void spacing initially decreases and then increases. Therefore, the void hardening effect gradually weakens after the initial enhancement. In contrast, as the irradiation temperature increases, the yield strength decreases due to the expansion of the void spacing at higher temperatures. The creep rate of irradiated ODS steel is nonlinearly related to the irradiation dose. ODS steel irradiated at low or high doses has relatively poor creep performance and exhibits a higher creep rate under low applied stress. In contrast, at moderate doses, the creep performance is better due to the small number of irradiated voids and high strength of oxide particles. And spherical voids exhibit better creep resistance, and the void spacing has a more significant impact on the creep performance than the void size. At low and high doses, the creep performance decreases as the irradiation temperature increases, and in addition, at lower doses, the effect of irradiation temperature on creep performance is not as significant as at higher doses. This invention provides an efficient theoretical method for accurately evaluating the irradiation performance of ODS steel under complex environments.

The invention discloses an additive manufacturing metal crystal plastic constitutive model establishment and parameter determination method, which can realize high-precision physical mechanism driven determination of additive manufacturing metal crystal plastic constitutive model parameters based on a synchronous X-ray diffraction technology and EBSD-RVE modeling. And the description accuracy of the model on the microstructure and the deformation behavior of the material is obviously improved.

The application discloses a method for establishing and determining a metal crystal plasticity constitutive model of additive manufacturing, which can realize high-precision and physical mechanism driven determination of parameters of the metal crystal plasticity constitutive model of additive manufacturing based on a simultaneous X-ray diffraction technology and EBSD-RVE modeling, and significantly improves the description accuracy of the model on microstructure and deformation behavior of materials.

The application relates to the field of power module reliability evaluation, and particularly discloses a crystal plasticity constitutive model construction method based on a density characteristic, which comprises the following steps: S1: modifying the initial value and the saturation value of a critical decomposed shear stress through a correction coefficient; S2: taking the initial value and the saturation value of the corrected critical decomposed shear stress obtained in the step S1 as parameters and substituting the parameters into a hardening law of a crystal plasticity constitutive model to establish the crystal plasticity constitutive model based on the density characteristic; and S3: simulating in finite element software based on the crystal plasticity constitutive model established in the step S2, inputting values of different density characteristic parameters and macroscopic shear strain rates, and calculating and outputting the mechanical performance prediction result of the material. The application effectively quantifies the influence of manufacturing process uncertainty on the mechanical performance of a packaging interconnection material by introducing the density characteristic parameter, and improves the accuracy of simulation analysis.

The invention relates to the field of power module reliability evaluation, and particularly discloses a crystal plasticity constitutive model construction method based on density characteristics, and the method comprises the steps: S1, correcting an initial value and a saturation value of critical decomposition shear stress through a correction coefficient; s2, taking the initial value and the saturation value of the corrected critical decomposition shear stress obtained in the step S1 as parameters, substituting the parameters into a hardening law of a crystal plasticity constitutive model, and establishing the crystal plasticity constitutive model based on density characteristics; and S3, based on the crystal plasticity constitutive model established in the step S2, performing simulation in finite element software, and calculating and outputting a mechanical property prediction result of the material by inputting values of different density characteristic parameters and a macroscopic shear strain rate. According to the method, the influence of the manufacturing process uncertainty on the mechanical property of the packaging interconnection material is effectively quantified by introducing the density characteristic parameters, and the accuracy of simulation analysis is improved.

The invention discloses an oxidation-thermal mechanical fatigue life prediction method based on a crystal plasticity theory. The method comprises the following steps: generating a representative volume unit with a grain boundary characteristic, importing the representative volume unit into abaqus software, and applying a boundary condition; based on a crystal plasticity constitutive theory and an oxygen diffusion control equation under thermal mechanical fatigue, corresponding UMAT and UMATHT subprograms are written; taking the UMAT subprogram and the UMATHT subprogram as abaqus calculation files, combining the abaqus calculation files with representative volume elements with grain boundary characteristics, and carrying out crystal plasticity finite element simulation under thermal mechanical fatigue; according to the finite element simulation result, fatigue damage and oxidative damage parameters under different working conditions are obtained respectively, the obtained parameters are substituted into the thermal mechanical fatigue life prediction model under the heat-force-oxygen coupling effect, and the predicted life is obtained. According to the method, the mechanical damage and the oxidative damage of the turbine disc under the service condition can be accurately simulated, and the prediction precision of the thermal mechanical fatigue life is improved.

The invention discloses a multi-field coupling strength analysis method suitable for a cross-medium projectile under a high-speed water entry condition, which comprises the following steps: establishing a flow field model with water entry angle correction, and completing pressure field solution; an improved JC constitutive equation is used for material setting, and the yield behavior of the material under the high strain rate is accurately represented; transferring the flow field pressure from the fluid grid to the structural grid by adopting an inverse distance weighting method, and performing dynamic response analysis to obtain a projectile stress condition; and a crystal plasticity finite element sub-model is embedded in a high-stress area of the projectile, and the damage condition of a projectile body material is further accurately analyzed. According to the multi-field coupling strength analysis method provided by the invention, high-speed water entry of the cross-medium projectile can be more accurately represented, and the simulation precision is improved.

The invention relates to a multi-scale finite element method and system based on sub-model nesting and a medium, and the method comprises the steps: building a preset macro-scale finite element simulation model of a material or a structural member, determining a pre-extraction first-stage sub-model region of a region of interest, extracting a first-stage sub-model, and obtaining a second-stage sub-model region of the region of interest; determining a pre-extracted second-level sub-model region of the concerned region by using the recorded displacement boundary condition of the first-level sub-model, and carrying out finite element simulation of the second-level sub-model; verifying whether the second-stage sub-model meets the simulation of a micro scale; if yes, based on a Voronoi method, a scanning electron microscope or an electron back scattering diffraction method, a crystal plasticity finite element simulation model is established by utilizing the boundary displacement condition of the level sub-model. According to the invention, simulation of stress, deformation or damage evolution of a material microstructure under a complex load is realized.

The invention discloses a residual stress detection method and system based on dual-scale contour fusion and three-dimensional stress constraint, and belongs to the technical field of material mechanical property testing. The method comprises the following steps: preparing a micro-pit array with a nano-scale corrugated structure and a reinforced coating on the surface of a sample by adopting a femtosecond laser double-beam interference technology as a high-precision reference mark; stress freezing release is achieved through a liquid nitrogen atomization spraying auxiliary low-temperature micro-cutting technology, and cutting heat-force damage is effectively restrained; the white light interferometer and the laser confocal microscope are combined for multi-mode scanning, and high-signal-to-noise-ratio surface topography data are obtained; adopting a deep learning algorithm to realize sub-pixel-level data registration and fusion; a cube is cut from the interior of a sample innovatively through an electrolysis-assisted low-speed wire cutting technology to serve as a three-dimensional stress constraint body, and the accurate geometric contour of the cube serves as a physical calibration reference; and finally, establishing an anisotropic inversion model based on a crystal plasticity theory, training a neural network agent model by taking cube data as a priori constraint condition, carrying out iterative calculation in combination with multi-modal fusion data, and reconstructing a three-dimensional residual stress field with a spatial resolution of 50 microns. According to the method, by introducing the physical calibration reference, the precision and reliability of stress field reconstruction are remarkably improved, and the problems that a traditional method is large in model error and lacks three-dimensional constraint are solved.

The present application relates to a method and device for simulating the crystal plasticity of micro-fatigue of a twin-crystal alloy containing small-angle grain boundaries. The method comprises: performing EBSD characterization on a twin-crystal tenon specimen containing small-angle grain boundaries, generating an inp file from the EBSD results using Dream3d, setting parameters such as grain number and crystal orientation for the inp file using Matlab, importing the input file into ABAQUS to obtain an ABAQUS finite element model, and setting the load, boundary conditions, analysis step, friction and contact conditions. The file is then associated with a Fortran program written based on the crystal plasticity constitutive relation, and the stress, strain and cumulative plastic strain results are simulated. Thus, by establishing a finite element model consistent with the crystal microstructure of the actual specimen, applying the crystal plasticity constitutive relation to each grain, and assigning the true crystal orientation of each grain to each grain, the crystal plasticity simulation of the micro-fatigue specimen is achieved.

The application provides a metal material surface micro-crack positioning method, comprising the following steps: applying a torsional load to a numerical model, calculating stress and strain distribution inside the material, adopting a crystal plasticity constitutive equation to describe crystal deformation behavior, and obtaining dislocation density distribution and slip system activation in each grain; judging a position inside the material prone to forming a micro-crack according to the dislocation density distribution and the slip system activation, and determining that the position is prone to forming the micro-crack when the dislocation density exceeds a preset critical value and multiple activated slip systems exist; judging whether the micro-crack extends according to fracture mechanics parameters and material fracture toughness, and determining that the micro-crack extends when a stress intensity factor exceeds the fracture toughness, and determining a crack propagation path by calculating a maximum release rate direction.

The invention discloses a metal stress regulation and control method based on expanded graphite. The method comprises the following steps that 1, a scanning electron microscope is used for obtaining data such as workpiece morphology; 2, establishing a cavity metal thin-wall part crystal plasticity-finite element model; 3, establishing a macroscopic geometric model and a finite element model of the cavity thin-wall part; step 4, determining a bulging process parameter range; 5, determining the proportion of the expanded graphite in the mixed solid filling structure; 6, purified water and wheat flour are added to form a mixed solid filling structure; 7, the cavity structure of the target regulation and control metal is filled, and heating bulging is carried out to eliminate residual stress; and step 8, performing a sampling experiment, and verifying the residual stress eliminating effect. According to the method, the thermally induced volume deformation characteristic of the expanded graphite-based mixed solid filling structure is utilized, and the cavity metal thin-wall part is induced to complete stress release and relaxation through the controllable bulging force, so that the residual stress is efficiently eliminated. According to the method, key conditions and internal rules of stress release and plastic strengthening of the thin-wall part under the working conditions of heating, filling and bulging can be defined, and the method has important practical significance on residual stress control of the cavity metal thin-wall weak-rigidity structure.

The invention discloses a crystal plasticity constitutive model construction method under an ultrasonic vibration auxiliary processing condition, and relates to the technical field of ultrasonic auxiliary processing, a multi-stage deformation frame is constructed, and a total deformation gradient is decomposed into an elastic deformation gradient, a plastic deformation gradient and a thermal deformation gradient; introducing an ultrasonic softening factor and a thermal softening factor into the classic crystal plastic constitutive model, and correcting a shear strain rate expression; establishing a crystal plasticity constitutive equation considering the ultrasonic vibration and temperature coupling effect; establishing a three-dimensional polycrystalline representative volume element model, and applying an ultrasonic cyclic load and a thermal load in finite element software; and developing a user material subprogram, and integrating the crystal plasticity constitutive equation to a finite element platform for numerical simulation. The method is closer to actual material response, the problem that the ultrasonic thermal coupling effect is difficult to accurately simulate by a crystal plasticity finite element method is solved, and the model prediction precision is improved.