18 results about "Viscoplasticity" patented technology

This invention discloses a method, medium, and equipment for determining creep parameters of fractured rock masses based on the equivalent medium theory. The method includes: constructing a random fracture network model of fractured rock masses containing multiple sets of structural planes, and generating numerical models of fractured rock masses of different sizes; embedding the viscoelastic-plastic constitutive model of the structural planes into discrete element numerical calculation software; applying constant loads to the numerical models of fractured rock masses of different sizes, conducting numerical creep tests on the fractured rock masses, and obtaining the creep deformation time history curves of each numerical model; performing parameter inversion on the creep curves of fractured rock mass models of different sizes to determine the size range of the CREV (Crew Characterization Equivalent Value) of the fractured rock mass creep characterization unit; obtaining the equivalent viscoelastic creep parameters and equivalent viscoplastic creep parameters of the fractured rock mass; and applying the obtained parameters to long-term slope deformation analysis. This method provides a more reliable theoretical basis for the long-term stability assessment and safety prediction of hydropower, mining, and tunnel projects.

The application discloses a kind of based on the prediction method of cyclic creep deformation behavior of unified viscoplastic theory, specific implementation is at the same test temperature, carry out cyclic creep test under different conditions, obtain corresponding data;Unified viscoplastic constitutive model is established, including the establishment of main control equation, flow rule, movement hardening criterion, isotropic hardening criterion;A group of strain control creep-fatigue tests at the above temperature is carried out, and corresponding data is obtained, including each cycle hysteresis loop, each cycle peak stress, strain amplitude;The initial material parameters of the constitutive model are determined using the creep-fatigue test data, and the optimal material parameters are obtained by fitting a group of cyclic creep deformation curves through trial parameter method;The final constitutive model is determined using the obtained optimal material parameters, and the deformation behavior of the material under cyclic creep load is predicted by the constitutive model.The application has the advantages of strong applicability and high precision, and can predict the deformation behavior of the material under cyclic creep.

This invention relates to a displacement prediction method for landslides with stick-slip characteristics, comprising the following steps: Step S1: Obtaining calculation parameters of the landslide to be measured; Step S2: Obtaining rainfall intensity, duration, groundwater level, and volumetric water content parameters of the slope surface at the monitoring point of the landslide to be measured; Step S3: Based on the parameters obtained in Steps S1 and S2, calculating the rainwater infiltration of an infinite slope under different rainfall intensities, and calculating the migration depth of the wetting front; Step S4: Establishing the relationship between effective rainfall and groundwater level fluctuations, and calculating pore water pressure; Step S5: Constructing an infinite viscoplastic slope model based on the pore water pressure, and calculating the landslide displacement rate. This invention can provide efficient and high-quality displacement prediction for landslides with stick-slip characteristics.

The application discloses an elasto-plastic constitutive parameter calculation method, comprising the following steps: S1, performing uniaxial tension experiment, obtaining a true stress-true strain curve of the experiment, and performing intercept processing near the maximum stress to obtain an intercepted curve; S2, based on the intercepted curve, extracting data points according to an equal arc length method, and performing data compression; S3, through a selected elastic model and a plastic model, performing nonlinear analysis on each data point, obtaining the proportion of elasticity and plasticity in the strain increment at each data point, and calculating the true stress-true strain curve of the model. According to the application, data points are extracted according to the arc length, the operation speed is improved under the condition that appropriate data points are selected, the elasto-plasticity of the data points is decomposed, the rationality of the mechanical calculation is ensured, the global optimization of the elasto-viscoplastic constitutive parameter is performed by constructing an optimization objective function, the coordination of the elastic and plastic constitutive parameters is ensured, and the calculation precision is improved.

The invention discloses a compaction pile hole shrinkage space-time change rule prediction method and system, and relates to the technical field of foundation treatment and geotechnical engineering.The method comprises the steps that data such as the depth of a to-be-measured pile hole is obtained; establishing a function relationship of the peak cohesion, the peak internal friction angle, the residual cohesion and the residual internal friction angle with respect to the water content based on the test data; establishing a softening constitutive relation of the strength evolved from a peak value to a residual value according to the accumulated plastic shear strain; determining far-field lateral stress by combining the depth, the soil weight and the static soil pressure coefficient, and constructing a three-zone stress field of a residual zone, a softening zone and an elastic zone around the pile hole according to the far-field lateral stress; further constructing a system shrinkage coefficient according to the relationship between the stress state at the hole wall and the viscoplastic strain rate, and establishing an evolution equation of the hole radius about time, depth and water content; and calculating a change result of the radius of the pile hole along with time and depth in the target time period according to the evolution equation. According to the method, unified calculation of the shrinkage process under the combined action of multiple factors is realized.

The present application relates to the field of structural fatigue fracture prediction and computational fracture mechanics, and particularly relates to a high-temperature notched fracture phase field life prediction method based on cyclic plastic zone calibration. In view of the fact that significant viscoplastic flow occurs at the root of the notch under high-temperature cyclic loading, and the fact that the value of the characteristic scale parameter in the existing fatigue phase field model lacks physical basis, leading to high sensitivity of life prediction to parameters, the method obtains the local stress-strain response at the root of the notch based on a unified viscoplastic cyclic constitutive model, quantifies the characteristic size of the inelastic process zone at the root of the notch by using the cyclic plastic zone theory, and establishes a quantitative mapping between the characteristic size and the regularization length of the fracture phase field to determine the characteristic scale of the phase field; in the finite element framework, the alternating iterative solution of the displacement field and the phase field variables is realized by coupling the UMAT and UEL user subroutines, so that the crack initiation, propagation and branching can be simulated without presetting the crack path, and the crack evolution process and fatigue life prediction results of the notched component under high-temperature working conditions are output.

The application discloses a simulation method of elastic-viscoplastic material phase transition based on a material point method, which is characterized by the following steps: 1) a unified numerical model for describing the elastic-viscoplastic material and non-Newtonian fluid phenomenon is established for simulating the material in the phase transition process; 2) Allen-Cahn and Cahn-Hilliard phase field equations are discretely modeled and introduced into the material point method; and 3) an elastic-viscoplastic material control strategy driven by phase field evolution is introduced to eliminate the discontinuity in performance caused by the change of physical properties of the mixed contact surface in the process. Compared with the prior art, the application has the advantages that the simulation of the three states of solid, intermediate and liquid of the complex elastic-viscoplastic material is simulated, the details generated by the evolution between phases are simulated, a new flexible phase field evolution based on the material point method and the corresponding material performance can be seamlessly and controllably displayed, and thus a realistic phase transition simulation effect is realized, and the application has a unique advantage in the generation of complex phase transition animation.

The invention provides a continuous feeding friction extrusion deposition additive manufacturing device and method for improving the performance uniformity of a metal-based material component. The additive manufacturing device comprises a deposition module and a feeding module. The material adding method comprises the steps that a wire rod raw material is conveyed into a center groove of a static sleeve of the deposition device through the feeding device, and a non-rotating raw material abuts against the bottom face of a rotating mold of the deposition device and is in relative rotating friction with the bottom face. Raw materials reach a viscoplastic rheological state under the action of friction and deformation heat, are extruded out of a discharging hole of the rotary mold under the driving of the feeding device and are deposited on the surface of a base plate, and after the deposition device moves along a preset material adding path and reciprocates for multiple times, the material adding component is obtained. According to the method, the wire rod material serves as the raw material, the length of the single raw material is increased, the number of connection points in a deposition layer is greatly reduced, continuous, efficient and stable machining of friction extrusion deposition additive manufacturing is achieved, and the structure property uniformity of an additive component is greatly improved.

The invention provides a lithium strip extrusion forming finite element simulation method and system. The method comprises the steps that S1, a model is built based on a Lagrange description method and an Euler description method, and grid division is conducted; s2, defining material attributes of the lithium metal and the model, and setting a viscoplastic constitutive relation of the lithium metal; s3, establishing a dynamic display analysis step, setting a contact mode and a constraint condition, and simulating an extrusion process; and S4, evaluating the stress distribution uniformity and fluctuation characteristics of lithium strip forming according to the stress nephogram output by the model and the stress fluctuation data of the preset fixed point of the extrusion port. Based on the coupling Euler-Lagrange method, the plastic deformation behavior of the lithium metal in the mold and the internal stress distribution and fluctuation characteristics of the lithium strip are simulated; material attributes are defined by introducing a viscoplastic constitutive model, and the hardening behavior of the lithium strip in a mold runner is described; a symmetric modeling method is adopted and a local mesh refinement technology is combined, so that the model calculation efficiency and the simulation precision are improved.

The application discloses a rubber part vulcanization deformation prediction and mold compensation method based on multi-field coupling data and belongs to the technical field of rubber component vulcanization data processing. In view of defects such as simplification of a traditional simulation dynamics model, multi-field step-by-step decoupling, fixed material parameters, and mold relying on experience for mold modification, the application first constructs a standardized data set through multi-dimensional testing, trains a temperature and vulcanization degree double-factor machine learning model, establishes a multi-field finite element model containing a high-order viscoelastic and viscoplastic coupling constitutive relation, adopts a segmented multi-factor correction Kamal equation, introduces pressure, auxiliary agent, heating rate, and thermal oxygen aging correction factors, realizes synchronous coupling solution of four fields of temperature, vulcanization dynamics, mechanics and shrinkage, can expand flow and damage fields, extracts deformation, residual stress, plastic strain and internal damage data through simulation, reversely maps and differentially compensates a mold surface according to different zones, and iterates multiple indexes in a closed loop until tolerances reach the standard.

The invention relates to a method for constructing a viscoplastic constitutive model of a binding material of an MEMS (Micro Electro Mechanical System) device in a deep space environment. The method comprises the following steps: acquiring irradiation-temperature coupling experiment data, simulating atomic displacement and molecular chain change under irradiation damage, and establishing a defect-mechanical property mapping relation; constructing a viscoplastic constitutive equation considering irradiation-temperature nonlinearity; model parameters are calibrated in combination with experiment and simulation data, and finite element verification is passed; finally, the model is embedded into MEMS device multi-physical field simulation, residual stress evolution is predicted, and damage parameters are dynamically corrected through an annealing experiment. According to the method, the viscoplastic behavior of the binding material in the deep space environment can be accurately represented, and the reliability evaluation precision of the MEMS device is improved.

This invention relates to a method for simulating waveforms and predicting the remaining service life of high-temperature components under overload damage, belonging to the field of material life prediction technology under complex high-temperature loads. The steps are as follows: under the same temperature and load-holding stress conditions, the creep fatigue cycle life of the material is determined through two sets of repeated stress-strain mixed-controlled creep fatigue interactive tests; a creep fatigue damage evolution equation considering the overload effect is constructed based on the proportion of the creep fatigue cycle life; a viscoplastic constitutive model coupled with continuous damage mechanics is established; the viscoplastic constitutive model coupled with continuous damage mechanics is solved in the UMAT subroutine of the ABAQUS platform; and the remaining creep fatigue life of the component is calculated using the viscoplastic constitutive model in the ABAQUS platform. This invention, through the designed HCFIO overload damage simulation waveform, accurately reproduces the entire overload-holding-recovery service process of high-temperature components under single-failure conditions, solving the problem that existing tests cannot simulate real overload scenarios.

The invention relates to a method, a device, a medium and equipment for predicting annulus pressure and lining buckling of a flexible hose for oil and gas gathering and transportation. The method comprises the following steps: establishing a multi-component gas permeation continuity equation; constructing a gas phase concentration dynamic modulation model, correcting boundary conditions, and correcting the concentration of each gas component in the fluid in the pipe according to the liquid phase retention rate; constructing an annular gas mass balance equation; carrying out simultaneous solution on the multi-component gas permeation continuity equation and the annular gas mass balance equation to obtain gas concentration distribution of each node, and calculating annular gas pressure and total permeation pressure through an ideal gas state equation; and constructing a lining buckling displacement calculation model, inputting total permeation pressure into the lining buckling displacement calculation model, and iteratively calculating and outputting annular pressure and radial buckling displacement of the lining layer. According to the method, the modeling problem of the viscoplasticity and dynamic pressure boundary of the lining material is solved, and the buckling behavior is accurately predicted.

In the crystal plasticity finite element method, it was necessary to represent the crystal orientation in the data in order to determine the anisotropy caused by differences in crystal orientation. Furthermore, many finite element methods using yield functions exhibit isotropic hardening. [Solution] The crystal orientation was changed to represent the Taylor factor M. In other words, for a face-centered cubic lattice, the data for the 12-slip system could be rewritten in terms of the Taylor factor M. Furthermore, by including the deviated back stress, the Bauschinger effect could be expressed. This is not possible for rigid-plastic properties.

This application discloses a method and system for predicting the spatiotemporal variation law of borehole shrinkage in compaction piles, relating to the fields of foundation treatment and geotechnical engineering. The method includes: acquiring data such as the depth of the pile borehole to be tested; establishing functional relationships between peak cohesion, peak internal friction angle, residual cohesion, and residual internal friction angle with respect to water content based on experimental data; establishing a softening constitutive relationship based on the evolution of strength from peak to residual based on cumulative plastic shear strain; determining the far-field lateral stress by combining depth, soil weight, and at-rest earth pressure coefficient, and constructing a three-zone stress field around the pile borehole comprising a residual zone, a softened zone, and an elastic zone; further constructing a system shrinkage coefficient based on the relationship between the stress state at the borehole wall and the viscoplastic strain rate, and establishing an evolution equation for the borehole radius with respect to time, depth, and water content; and calculating the variation of the pile borehole radius with time and depth within a target time period based on the evolution equation. This method achieves unified calculation of the shrinkage process under the combined action of multiple factors.

A method for sintering dimension compensation in binder jet additive manufacturing is disclosed. This method constructs a thermoelastic-viscoplastic constitutive model of the green body sintering process using binder jet additive manufacturing, employs the finite element method (FEM) for numerical simulation, and predicts deformation data. The deformed node coordinates output from the FEM simulation are extracted to form a deformed coordinate point cloud. Simultaneously, the original design model is discretized into an original design coordinate point cloud, achieving matching between the original and deformed coordinate point clouds. A GA-BP neural network is used to learn the nonlinear mapping relationship between the original design coordinate point cloud and the compensation model coordinate point cloud, generating a compensated geometric model. Three indicators—curvature change energy, Fourier high-frequency energy ratio, and straightness linearity error—are introduced to evaluate the contour quality of the compensation model. The compensation model is then used for binder jet additive manufacturing printing, and the green body undergoes curing and sintering to obtain the finished part. This invention improves the manufacturing precision of parts and belongs to the field of metal 3D printing technology.

The invention discloses a high-bearing-capacity backing bearing with a multi-layer composite wall thickness outer ring, and relates to a bearing, a dynamic blocking transition layer of the high-bearing-capacity backing bearing is composed of polyhedral rigid microparticles and a viscoplastic matrix, and the volume fraction of the microparticles is limited in a critical blocking threshold value interval. When the micro-particles bear quasi-static radial heavy load, the micro-particles are in a blocked state to form a rigid force chain to transmit hydrostatic pressure stress; when high-frequency transverse shear stress wave excitation is borne, transient superplastic rheology happens to a base body, a force chain enters a local unblocking state to generate micro rheology, and sudden reduction of transverse shear rigidity is triggered. Based on the stress state orthogonal decoupling double-state phase change characteristic, the subsurface standing wave resonance condition is actively destroyed, the contradiction between macroscopic compression resistance and microcosmic dissipation is solved, deep stripping failure under the high-speed heavy-load working condition is effectively restrained, and the energy-saving and efficient concept of green manufacturing is fully embodied through material selection and process design.

The invention discloses a packaging system reliability evaluation method and device considering viscoplastic behaviors, and relates to the technical field of electronic packaging reliability simulation analysis, and the method comprises the steps: converting an original impact response spectrum into a power spectrum based on a stable random vibration process hypothesis; generating an initial time domain signal according to the power spectrum and a randomly generated phase spectrum; performing iterative correction on the initial time domain signal to obtain a time domain impact vibration signal consistent with the original impact response spectrum in energy distribution; establishing a finite element model of the packaging system, and describing viscoplastic mechanical behaviors of a welding spot material in the finite element model by adopting a unified creep-plastic constitutive model; according to the method, the time-domain impact vibration signal is used as a load to be input into the finite element model, time-domain nonlinear dynamic simulation is carried out, the mechanical response of the packaging system under impact vibration is obtained, the uncertainty of a nonlinear simulation result caused by inaccurate input is reduced, and therefore the impact vibration reliability of the packaging system is accurately evaluated.