87 results about "Creep strain" patented technology

The invention discloses a large-span box girder bridge time-varying reliability evaluation method considering concrete fatigue creep. The method comprises the steps that concrete static creep and shrinkage strain are calculated; calculating concrete fatigue creep strain generated by the vehicle load; constructing a concrete unified constitutive model considering a multi-factor coupling effect; establishing a long-term performance fine analysis numerical model of the large-span box girder bridge; establishing a large-span box girder bridge time-varying reliability calculation method; establishing a limit state equation of reliability analysis; and evaluating the structural time-varying reliability considering the concrete fatigue creep effect. According to the method, the time-varying reliability of the large-span box girder bridge under the coupling action of factors such as concrete static creep, cyclic creep and shrinkage can be accurately evaluated, and technical support can be provided for health diagnosis, maintenance and reinforcement of bridges of the same type.

The invention discloses a concrete nonlinear creep explicit modeling method and system, and relates to the technical field of concrete structures and materials.The concrete nonlinear creep explicit modeling method comprises the steps that concrete creep test data under all conditions are collected, and a test data set is constructed; preprocessing the concrete creep test data of the test data set; a DBO algorithm is adopted to optimize hyper-parameters of the LGBM model, and the LGBM model is constructed and trained through the test data set and the optimal hyper-parameters; the input features of the trained LGBM model are screened through an SHAP additive interpretation method, and key feature parameters are obtained; and establishing a concrete nonlinear creep explicit calculation formula by using a PySR symbol regression tool and taking the key characteristic parameters as input and the creep strain as output. The concrete nonlinear creep explicit modeling method provided by the invention has both calculation precision and engineering practical value.

The invention relates to a MATLAB working condition prediction and ANSYS matching surface creep analysis method, and belongs to the technical field of mechanical engineering structure connection analysis and monitoring and computer-aided engineering software integration. The method comprises the following steps that a user inputs geometric parameters and typical working conditions through an MATLAB GUIDE interaction interface, and a system can generate a theoretical response curve of the matching surface pressure changing along with the magnitude of interference, the load and the rotating speed in real time and is used for evaluating the maximum allowable working parameter range. And then ANSYS is called to carry out batch finite element simulation, and actual contact pressure distribution and a creep strain cloud picture are obtained, so that the influence of different working condition combinations on the creep behavior of the matching interface is quantified. The method supports visual comparative analysis under the combination of multiple working conditions, and a user can intuitively master the evolution law and the creep development trend of the pressure distribution of the matching surface. The interactive critical failure discrimination module integrated in the system can automatically identify typical contact failure situations and perform significant annotation in images.

The application discloses a creep deformation statistical analysis method, and specific steps are as follows: step 001, obtaining creep deformation and time relationship of not less than three same size samples of same batch material or same batch parts under the same condition; step 002, selecting some typical time and corresponding creep strain, selecting a suitable statistical distribution function to statistically analyze the creep strain under the typical time, and fitting the distribution parameters; step 003, calculating the survival rate of the tested sample or part not more than a certain creep strain or the creep strain of the tested sample or part under a certain survival rate under the selected statistical distribution function, and drawing a P-C-T curve; through the method, the creep deformation of the material or the part can be statistically analyzed, and then the survival rate of the material or the part not more than a certain creep strain under a given condition can be calculated, which has important significance for accurately evaluating the creep performance of the material or the part.

The invention provides a method for constructing a constitutive model of compression creep of a metal material. The method comprises the following steps: 1) constructing the constitutive model of the metal material under nominal compression stress; 2) determining a creep time threshold value of the metal material; 3) determining creep characteristic constants A and B and creep time influence parameters n and m of the material; and 4) substituting the determined material parameters A, n, m and B into the constitutive model under the nominal compression stress to obtain the compression creep constitutive model of the metal material. According to the method, the change relation of the creep strain of the metal material under the constant compression load along with time can be described, and the creep deformation behavior of the metal material under the long-term compression load can also be predicted, so that the design of a structural member is optimized, and the service reliability of the structural member is improved.

The invention discloses an equal-life design method for an engine rotor and stator blade structural member based on an isochronous stress-strain relationship, which is suitable for creep / endurance life design of the engine rotor and stator blade structural member. Acquiring a tensile stress-strain curve and a creep curve of the material at different temperatures and stresses; according to the target design life of the engine, extracting a stress-creep strain relation at the target life moment from the creep curve, and superposing the stress-creep strain relation with the tensile stress-strain curve to construct an isochronous stress-strain relation under the target life; inputting the isochronous stress-strain relationship into a rotor and stator blade finite element model, and calculating stress-strain distribution at a target life moment; and based on the comparison of the calculation result and the failure criterion, carrying out the weight reduction or local thickening optimization design of the blade until the target life requirement is met. The life prediction precision can be improved, the calculation cost is reduced, and the method has important engineering application value.

The invention constructs a fracture conductivity evaluation method considering shale hydration. The method mainly comprises the following steps: 1, carrying out a triaxial hydration creep mechanics experiment, establishing an elastic-viscoelastic-viscous plastic multi-stage creep constitutive equation based on triaxial experiment data, and analyzing shale elastic and viscous deformation mechanisms; 2, secondly, constructing a shale creep constitutive model by stages according to a stress threshold value, describing a viscoelastic stage by adopting an improved Burgers model, and establishing a viscoplastic strain equation based on an overstress theory; 3, coupling hydration action parameters to correct a shale creep equation, and quantifying the influence of hydration on rock modulus, viscosity coefficient and yield stress; 4, the creep strain and the crack dynamic width are correlated through a mathematical model, and a multi-field coupling relation is established in combination with a permeability evolution rule; and 5, finally constructing a fracture conductivity prediction model when the hydration effect is considered, and realizing fracture conductivity dynamic analysis under the hydration-creep synergistic effect. According to the method, the shale hydration-creep coupling effect is creatively fused into fracture conductivity prediction, and a quantitative tool is provided for shale reservoir long-term productivity evaluation.

The application discloses a kind of prediction methods of high-strength steel wire high temperature creep behavior of rust, belong to bridge cable safety assessment technical field.The method is first obtained by test the material intrinsic material parameters of rust high-strength steel wire test piece and un-rust high-strength steel wire test piece;Then three-dimensional scanning quantization corrosion morphology is used, the maximum pit depth of rust high-strength steel wire surface and the pit root radius of pit bottom are extracted, and then the stress concentration coefficient and the effective bearing area decay function after net section loss are calculated, and the corrosion damage index is introduced;On this basis, the creep strain rate prediction model considering local stress concentration, section loss and material damage is established.The prediction method of the application realizes the quantitative prediction from pit micro-morphology to macro creep behavior, and has great engineering application value for evaluating the safety and residual life of in-service bridge cable.

The application discloses a kind of bridge structure in concrete shrinkage and creep calculation method, equipment and storage medium, the method includes using initial strain method to calculate stress increment and creep strain increment in different period, and then calculate stress and creep strain at different time;According to the stress increment of different period, stress-strain relationship and creep coefficient fitting function calculation period Δt n+1 Internal concrete creep caused by unit equivalent node load increment;According to concrete shrinkage strain increment calculation period Δt n+1 Internal concrete shrinkage caused by unit equivalent node load increment.The application can accurately calculate the shrinkage and creep effect of concrete in the structure when applied to bridge structure analysis, greatly improves the calculation efficiency and saves storage space.

The invention provides a method for analyzing time-history stress relaxation of anchoring force of a pre-stressed anchor cable under high-pressure stress, and relates to the technical field of geotechnical engineering. According to the method, engineering geological investigation, ground stress testing and indoor triaxial rheological testing are systematically combined, a potential high-stress area is accurately recognized, key rheological parameters of a rock-soil body are obtained, and then the stress self-adaptive creep coupling constitutive model with the long-term strength of the rock body as the criterion is constructed; and finally, accurately predicting the time-history creep strain of the rock-soil body and the anchoring force loss of the anchor cable under the high stress condition through numerical calculation. According to the method, the defect that a traditional creep theory describes a nonlinear creep behavior in a high-pressure stress state and a prestress loss coupling mechanism is effectively overcome, and the prediction precision and reliability of mechanical response of an anchoring system are remarkably improved; a basis is provided for long-term stability evaluation and safety control of prestressed anchoring engineering under complex geological conditions, and geotechnical engineering anchoring design and safety early warning are developed towards the refined and intelligent direction.

This invention discloses a method and system for predicting the creep fatigue behavior of martensitic heat-resistant steel, relating to the field of high-temperature creep fatigue performance evaluation technology. The method includes: acquiring the microstructure evolution of copper-containing martensitic heat-resistant steel during the test process, obtaining the cyclic strength change rate based on the microstructure evolution, and calculating the creep rate of the copper-containing martensitic heat-resistant steel in the dislocation climb hard phase, as well as the dislocation density under cyclic loading conditions; based on the cyclic strength change rate, creep rate, and dislocation density, obtaining the elastic strain tensor, plastic strain tensor, and creep strain tensor of the copper-containing martensitic heat-resistant steel, and predicting the stress-strain evolution of the copper-containing martensitic heat-resistant steel under cyclic loading conditions based on the elastic modulus tensor; this invention overcomes the limitations of macroscopic creep fatigue behavior prediction methods and provides a new approach to revealing the influence of microstructure on creep fatigue performance.

The invention belongs to the technical field of bearings, and discloses a foil dynamic pressure radial gas bearing bump foil creep test method, which is characterized in that a miniature rubber block is inserted between a top foil and a rigid substrate, and the miniature rubber block is used as a flexible element, is in direct contact with the top foil, and deforms under the action of a compression load transmitted by the top foil; a monocrystalline silicon semiconductor strain gauge is pasted on the side face of the miniature rubber block, and the direction is perpendicular to the direction of the compression load; in the running process of the bearing, the output strain value of the strain gauge is monitored in real time through a data acquisition system; the semiconductor strain gauge is a sensitive element manufactured based on the piezoresistive effect of semiconductor monocrystalline silicon, the resistivity of a semiconductor crystal material is changed when the semiconductor crystal material is stressed in a certain direction and deforms, and strain, stress and the like are indirectly measured. The device has the beneficial effect that the problem that the creep strain is difficult to test in real time due to the tiny structure of the bump foil is solved.

The present invention relates to a stress intensity limit S t A failure probability assessment method is provided, comprising: obtaining creep rupture test data of specimens under different working conditions, including creep rupture life and creep strain-time curves; determining the standard error of the logarithmic creep rupture life; determining the average stress required for the total strain to reach 1%, the minimum stress at the onset of the third stage of creep, and the minimum stress causing creep rupture under each working condition, as the first criterion stress, the second criterion stress, and the third criterion stress, respectively; determining creep life models corresponding to the first, second, and third criterion stresses; determining creep life models considering safety factors corresponding to the first, second, and third criterion stresses; determining probability parameters corresponding to the first, second, and third criterion stresses based on the creep life model after introducing probability parameters and the creep life model considering safety factors for each criterion; and calculating the failure probabilities of the first, second, and third criterion stresses under different working conditions.

The application discloses a structure suitable for creep supervision of P91 pipeline containing a soft area, which comprises a plurality of creep supervision measuring points fixedly installed on the outer wall of the P91 pipeline containing the soft area, wherein the creep supervision measuring points comprise a creep supervision measuring point upper layer and a creep supervision measuring point lower layer which are stacked together, and at least one of the creep supervision measuring points is located on the soft area of the P91 pipeline. The structure suitable for the creep supervision of the P91 pipeline containing the soft area can carry out the creep supervision on the soft area with the worst creep performance, the supervision object is more targeted, the creep strain law of the soft area of the pipeline can be accurately reflected, lossy detection such as hardness detection and metallographic detection does not need to be frequently carried out, no damage is caused to the pipeline, and more data support can be provided for the supervision and evaluation and life assessment of the pipeline. The application also discloses an evaluation method suitable for the creep supervision of the P91 pipeline containing the soft area, which has the same advantages as the structure suitable for the creep supervision of the P91 pipeline containing the soft area.

The present invention relates to a method for testing the uniaxial creep threshold of a metal material, comprising: step 1, setting a nominal stress and performing a creep test on the metal material sample based on the nominal stress; step 2, if the creep strain within a preset time is greater than 1 / 10,000, reducing the nominal stress and re-performing the creep test for the preset time using a new sample; and re-performing step 2 or step 3; step 3, if the creep strain within the preset time is less than or equal to 1 / 10,000, increasing the nominal stress and continuing the creep test for the same preset time until the creep strain within the preset time is greater than 1 / 10,000, and then stopping the test; and step 4, obtaining the creep threshold of the sample. The present invention can quickly measure the uniaxial creep threshold of a metal material, saving testing costs.

The invention relates to a method for constructing a rock salt nonlinear damage creep constitutive model considering a temperature effect. The method comprises the following steps: constructing an element combination model formed by connecting an elastomer, a nonlinear viscous body and a generalized Kelvin body in series as a basic framework of the rock salt nonlinear damage creep constitutive model considering the temperature effect; introducing a damage variable related to time and temperature; establishing a constitutive equation of the nonlinear viscous body of the salt rock; based on the constitutive equation of the salt rock nonlinear viscous body, deducing a total creep strain expression of a salt rock nonlinear damage creep constitutive model considering the temperature effect in a one-dimensional stress state; and carrying out uniaxial compression creep tests on the salt rock sample at different temperatures by adopting a graded loading mode to obtain strain-time data and a corresponding creep curve of the salt rock sample at the corresponding temperature, and carrying out inversion to determine model parameters in the total creep strain expression. The invention also provides a long-term deformation prediction method of the salt-cavern underground gas storage cavern structure.

The application discloses a fuel rod cladding rupture failure modeling calculation method, system, equipment and medium. The material of the cladding is Zr-4, and the method comprises the following steps: determining initial conditions, inputting fuel rod geometric dimensions and corresponding fuel, cladding material properties and boundary conditions; calculating the temperature distribution of fuel and cladding at each time based on the physical properties of fuel, cladding and the gap between fuel and cladding; calculating the thickness and mass of the oxidation layer, calculating the volume fraction of Zr-4 converted from alpha phase to beta phase through a crystal phase change model; calculating the high-temperature creep strain rate of the cladding through a high-temperature creep model, calculating the hoop creep strain of the cladding and the hoop stress of the cladding, and updating the gas volume in the cladding and calculating the gas pressure; based on the high-temperature creep strain rate of the cladding, calculating the hoop creep strain of the cladding or the hoop stress of the cladding, evaluating whether the cladding ruptures through a cladding rupture failure criterion and obtaining the rupture time. The application can accurately determine the time of cladding rupture.

The present application relates to the technical fields of high temperature creep test, in particular to a method for obtaining high temperature creep parameters of iron-nickel based alloy, which mainly determines the creep strain model of iron-nickel based alloy, obtains the creep strain rate calculation formula from the creep strain model, implements two creep tests of target test material under two different creep stresses at target temperature, respectively obtains the creep curves corresponding to creep time and creep strain, selects two creep times at the first stage and the second stage of the two creep curves respectively, obtains the creep strain and creep strain rate under the creep stress corresponding to the two creep times respectively, substitutes into the creep strain model and the creep strain rate calculation formula, and calculates the variable parameters of the creep strain model. The evaluation process of the creep model is greatly simplified, the required number of creep tests and test time are reduced, and the test cost is reduced.

The present invention relates to a method for predicting creep damage in high-temperature, pressure-bearing structures. The creep damage of high-temperature structures is assessed using a creep deformation prediction model. The creep damage value D is the ratio of the creep strain value ε of the equipment at time t to the creep ductility parameter εD of the pressure-bearing equipment material. The creep ductility parameter is the creep strain value corresponding to the intersection of the extended deformation curve of the material in creep stage II and the material's fracture life at time t. The creep deformation prediction model provided by the present invention can accurately predict the entire creep deformation process of a material within a wide stress range. The model parameter identification process is simple, and the evaluation results are safe and reliable. The model is suitable for evaluating the creep damage state of key high-temperature structural components.

The invention provides an indoor creep test analysis method for underground cavern rocks. Creep behaviors of underground plant granite are researched by adopting a creep test. According to test results in multiple stress states, expressions of instantaneous strain and creep strain are established by using the ratio Rd of confining pressure, deviatoric stress and peak strength. Then, the confining pressure is introduced into a Nishihara model, and an expression which can accurately describe deformation of granite along with time under the action of different confining pressures and deviatoric stresses is obtained. Instantaneous and creep parameter changes under various applied stresses can be completely explained.

The present invention discloses a control method for reaming while drilling based on the creep characteristics of salt rock, which relates to the technical field of automatic control. The method includes: Step 1: Considering the effects of effective stress, temperature, creep duration, and pore pressure on the creep deformation of salt rock, establishing a constitutive equation for the creep strain rate of salt rock, and calculating the creep strain rate of salt rock; Step 2: Establishing a salt rock dissolution-creep coupling model according to the creep strain rate; Step 3: Establishing a dynamic wellbore stability evaluation model to judge in real time whether the salt rock wellbore is stable during the reaming operation; Step 4: Establishing a reaming parameter optimization model, and calculating the corrected operation parameters and the corrected reaming trajectory vector according to the initial trajectory tangential unit vector and the initial drilling operation parameters. The present invention can effectively improve the wellbore stability, reduce the risk of non-uniform borehole expansion caused by creep, optimize the reaming trajectory control, reduce the potential safety hazards during construction, and improve the reaming efficiency.

A method for maintaining a physical asset based on recommendations generated by analyzing operational data and a composite model of a plurality of models representing the physical asset includes analyzing an error indicator associated with the composite model to determine that the error indicator exceeds a tolerance level and increases a number of basis functions in the port-reduced static condensation reduced basis element approximation accordingly. The computing device receives, from a sensor associated with the physical asset, first operational data associated with a region of the physical asset and updates the model, the operational data including data relating to a measurement of temperature and to a pressure load. The computing device determines a structural response of the physical asset to the thermal load and to the pressure load, including a determination of a level of creep strain. The computing device provides a recommendation for maintaining the physical asset.

The invention discloses a small deformation mechanical analysis system and method based on a reactor numerical calculation framework and related products, and relates to the technical field of nuclear reactor fuel performance analysis. On the basis of a reactor numerical development framework, a unified tangent modulus and stress data interface is constructed according to a finite element theory and mechanical constitutive models such as elasticity, plasticity and creep; a radial regression algorithm is used for calculating the plasticity / creep strain of a nonlinear material, consistent tangent modulus and stress data are updated and transmitted into a nonlinear solver, a small deformation mechanical analysis system of a reactor numerical development framework is formed, and theoretical model support is provided for a fuel performance analysis program based on small deformation.

The present invention discloses a method for analyzing the scale effect of creep strain measurement of metal materials, comprising the following steps: Step 001, dividing a creep specimen test section S under a certain stress state into reference test sections C composed of multiple materials and the same process under the same stress state, assuming that the creep strain of the test section S at a given creep time is approximately n S The method of the present invention is used to quantify the difference between creep strains or creep curves measured on specimens of different sizes under the same stress state, thereby better understanding the creep properties of materials.

The application discloses a kind of high-temperature bolt creep deformation measurement methods, simply summarized, including the following steps: step 1) correction is carried out to measuring micrometer;Step 2) the initial length of high-temperature bolt before operation ( L 初 ) is measured; Step 3) the original length of high-temperature bolt when converting to 0 ℃ ( L 初1 );Step 4) the length of high-temperature bolt after operation ( L 运 ) is measured;Step 5) the length of high-temperature bolt after operation when converting to 0 ℃ ( L 运h );Step 6) the absolute creep deformation amount (△L) of high-temperature bolt is calculated;Step 7) the relative creep strain (ε) of high-temperature bolt is obtained.The creep measuring point of high-temperature bolt is simple and reasonable to install, and measurement error is not easy to produce.The measurement operation is simple, fast, and the measurement result is high in precision and small in error, the creep deformation of high-temperature bolt can be accurately measured by micrometer, which is convenient for industry promotion and conducive to the development of high-temperature bolt creep supervision work.

The present invention discloses a method for predicting the creep deformation of a turbine disk based on a coupled creep constitutive model. Aiming at the creep deformation of the turbine disk under a complex multi-stress field, the relationship curve between creep strain and time at different stress levels is obtained by means of a uniaxial creep test of a standard test bar. According to the combined time-hardening creep constitutive model and the θ-parameter method creep constitutive model, the material creep characteristic parameters at different stress levels are obtained. In the CREEP user subroutine provided by the finite element software ABAQUS, the two constitutive models are coupled and calculated by applying environmental stress to each integration point. The creep strain and creep deformation of each integration point are calculated within each time increment step to predict the creep deformation of the turbine disk under different stresses. This method overcomes the problem of being unable to accurately predict the creep deformation behaviors of both the low-stress and high-stress parts in an aero-engine turbine disk simultaneously, and can predict the creep deformation under a complex stress field.

This invention discloses a method for constructing a fractional-order creep damage constitutive model, relating to the field of geotechnical engineering technology. The method includes: conducting creep tests on a geogrid under different types of soil constraint stress to obtain creep curves; calculating the creep strain of the geogrid at different time points based on the creep curves and plotting the curve of the geogrid's creep strain versus time; introducing the Khachanov damage variable according to the creep damage law to determine the damage variables during the geogrid creep process; constructing an initial fractional-order creep damage constitutive model based on the damage variables, and determining the parameters of the initial fractional-order creep damage constitutive model through the curve of the geogrid's creep strain versus time, thus obtaining the fractional-order creep damage constitutive model. The fractional-order creep damage constitutive model constructed by this invention can accurately reflect the variation law of the geogrid at different creep stages.

This invention discloses a high-temperature creep-resistant die-cast magnesium alloy material with the following mass percentages: Al 4.0-8.0%, La 0-2.5%, Ce 0-3.5%, Pr 0-1.0%, and Nd 0-1.5%, wherein the total mass percentage of La, Ce, Pr, and Nd is ≤4.0%, and Ca 0.05-1.0%, Sr 0.05-3.0%, Mn 0.2-0.6%, and Si 0.01-0.1%. The ratio of Al content to (RE+Sr+Ca) content is (1-2.5):1, and the ratio of RE content to (Sr+Ca) content is (1-2):1. The balance is Mg and unavoidable impurities. The microstructure is uniformly distributed with a grain size of 10-20 μm, containing Al2La phase, AlMnLa ternary phase, and Al... 11 La3 phase and Al4Sr phase. The preparation method includes the following steps: 1. Calculation of the alloy's thermodynamic properties; 2. Preparation of the alloy melt; 3. Refining and modification of the alloy melt; 4. High-pressure casting of the alloy. The tensile strength is 240-250 MPa; the yield strength is 120-130 MPa; the elongation is 9.5-12.5%; under the conditions of a test temperature of 175℃, an applied stress of 85 MPa, and a test duration of 100 h, the creep strain is less than 0.1%.

The invention provides a method and system for predicting shrinkage and creep deformation of high-performance concrete of an early-age loaded steel pipe, and belongs to the field of concrete. The problem that self-constriction of steel pipe high-performance concrete is underestimated is solved The problem that the creep deformation prediction result of the steel pipe high-performance concrete is not accurate due to the fact that different influences of loading periods on the creep deformation of the component under different water-binder ratios are not considered is solved. The method comprises the following steps: carrying out shrinkage and creep tests of different loading ages on steel tube high-performance concrete with different concrete water-binder ratios to obtain shrinkage strain and creep strain experimental results; performing nonlinear regression analysis on shrinkage and creep test results of the steel tube high-performance concrete with different concrete water-binder ratios in different loading periods, introducing influence coefficients of the concrete water-binder ratios on shrinkage and creep, and establishing a high-performance concrete shrinkage and creep model; and adopting a step-by-step integral method to consider the shrinkage and creep deformation after the stress redistribution of the high-performance concrete of the steel pipe.

This invention discloses a method for evaluating the creep life of high-temperature pipelines based on a physical information neural network. The method includes: obtaining the three-dimensional residual stress distribution of the welded joint region of the high-temperature pipeline based on welding thermo-mechanical coupled finite element simulation or residual stress measurement, and using this as the initial stress field for creep analysis; based on the initial stress field, constructing a stress redistribution model considering service temperature, internal pressure, structural constraints, and material creep effects to obtain the stress field distribution evolving over time; based on the evolved stress field, constructing a physical information neural network model incorporating creep constitutive relations and stress balance constraints to predict the creep strain or creep damage evolution process in key areas of the welded joint, and determining the creep life of the high-temperature pipeline by combining creep failure criteria. This invention can reasonably reflect the relaxation and redistribution behavior of welded residual stress during long-term high-temperature service, thereby improving the reliability of creep life evaluation of high-temperature pipeline welded joints.