120 results about "Stress intensity factor" patented technology

The invention discloses an engine additive component service life prediction method based on modal polycondensation and expansion, and the method specifically comprises the steps: firstly, achieving the grid discretization of an initial defect structure based on a finite element method, and carrying out the local refinement of a defect region; performing modal polycondensation on the overall model to obtain a low-dimensional system model, and performing rapid calculation under the low-dimensional model to obtain modal response; establishing a conversion relation between a displacement vibration mode and a stress vibration mode, and obtaining full-field stress by utilizing modal response and based on modal extension; and solving a stress intensity factor-time history of the crack tip by adopting a stress extrapolation method, obtaining a delta K-R-n three-variable rain flow matrix by utilizing a rain flow counting method, and finally carrying out residual life evaluation through an iLAPS model. According to the method, system dynamics, fracture mechanics and modal order reduction technologies are fused, a new efficient and accurate fatigue life prediction path adapting to complex working conditions is provided for additive manufacturing components with defects, and the method has remarkable engineering application value and popularization potential.

The invention discloses a method and device for predicting the fatigue life of a high-temperature alloy vacuum electron beam welding structure, and belongs to the technical field of aero-engines. The method comprises the following steps: acquiring fatigue experiment data of a target high-temperature alloy standard sample; extracting the maximum area of an initial defect, a defect shape factor and crack source position information; obtaining a stress intensity factor range considering defect morphological characteristics and a fatigue crack propagation threshold value of a material structure containing initial defects, and correcting a damage tolerance theoretical formula to obtain simulation data; fatigue test data and simulation data are fused to form an initial data set, a fatigue limit is calculated and expanded to the data set, the expanded data set serves as input, training is conducted through a support vector regression method, hyper-parameters are determined through Bayesian optimization, and a fatigue life prediction result of the high-temperature alloy vacuum electron beam welding structure is output. The method provided by the invention can well consider the influence of different morphology defects on the fatigue performance of the welded joint.

The invention discloses an active learning and physical loss-based fatigue crack growth rate prediction method, which comprises the following steps of: splicing and fusing a preprocessed stress intensity factor, a stress ratio, pre-strain and stress amplitude, and taking the fused characteristics as the input of a model; embedding the Jones model into a loss function of the neural network, constructing a physical information time sequence model based on the Jones model, setting a parameter set, selecting a most valuable training sample from a training set by using active learning, retraining the model by using the selected most valuable training sample, selecting an optimal model, and evaluating the optimal model by using a test set; fusing the actually measured stress intensity factor, stress ratio, pre-strain and stress amplitude of the to-be-predicted material, and inputting into the obtained prediction model to obtain a predicted value of the fatigue crack growth rate. By adopting the technical scheme of the invention, the fatigue crack growth rate of the material in the whole life period can be efficiently and accurately predicted at low cost.

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 provides a method and system for evaluating fatigue crack life of a welding structure under a random load, and relates to the technical field of rail transit, and the method comprises the steps: recognizing a load peak value and a load valley value through a point-by-point extreme value extraction method, and generating an equivalent variable-amplitude load data set; initial crack propagation rate parameters C and m and stress intensity factor distribution are calculated, and then a deterministic crack propagation increment result is output; a hierarchical Bayesian framework is combined with an MCMC sampling method, and global parameter distribution considering material heterogeneity and observation noise is generated through a posterior distribution formula; predicting crack depth evolution curves under different confidence coefficients, and outputting fatigue life probability distribution and confidence intervals; and finally generating a fatigue life reliability evaluation report of the welding structure under the random load. The method has the beneficial effects that the problem of fatigue crack propagation of the railway vehicle welding structure under the action of the complex random load can be better solved, and more accurate and reasonable technical support is provided for reliability evaluation of the welding structure.

The application discloses a brake interface wear and fatigue crack prediction method based on complete thermal-mechanical coupling, comprising the following steps: S1, establishing a finite element model, and discretizing total analysis time into multiple time periods; S2, starting finite element analysis, and calculating interface node contact pressure and node slip rate; S3, performing transient thermal-mechanical coupling analysis; S4, calculating node wear depth and wear direction, and updating grid information by using ALE technology; S5, judging whether the interface contact state is stable convergence; S6, ending analysis, unloading brake load, and obtaining brake disc residual stress; and S7, presetting a crack at the maximum residual stress, simulating crack propagation behavior, calculating stress intensity factor and brake disc fatigue life. The application can simulate tribological behaviors such as contact stress, temperature and wear, and realizes brake disc fatigue life prediction by taking residual stress after the thermal-mechanical coupling process as load input.

The invention discloses a method for evaluating rock mass fracture freeze-thaw fracture damage risk based on surface temperature, which comprises the following steps: S1, carrying out data acquisition on a target area based on a multi-source sensor carried by an unmanned aerial vehicle platform, and obtaining fracture geometric parameters, daily surface minimum temperature, daily surface maximum temperature, daily temperature difference and fracture moisture conditions; s2, on the basis of the geometric parameters of the crack, constructing a crack frost heaving force analytical model; obtaining a quantitative relation between the stress intensity factor and the environment temperature; s3, the I-type fracture toughness of the target rock mass is measured, and the critical crack initiation temperature of the rock mass is determined; determining the number of critical freezing and thawing cycles; s4, on the basis of the daily earth surface minimum temperature, the daily temperature difference, the fracture moisture condition and the critical crack initiation temperature, the annual accumulated effective freezing and thawing cycle number is obtained; and calculating a freeze-thaw damage ratio, and carrying out risk quantification and grading. According to the invention, the problem of inaccurate evaluation caused by limitation to local monitoring and lack of an environment factor and material parameter integrated evaluation framework in the prior art is solved.

The invention discloses a method for predicting the service behavior of an oil and gas pipeline under a stress corrosion cracking condition, and belongs to the field of material performance analysis and prediction. Firstly, based on a convection diffusion equation, a real stress intensity factor of an oil and gas pipeline crack tip is used as an unknown quantity to obtain a stress distribution condition; then, applying boundary conditions and a crack propagation criterion in fracture mechanics, and performing preliminary calculation to obtain crack propagation behavior characteristics of the one-dimensional semi-analytical model; and finally, calibrating and calculating the diffusion coefficient of the material parameter in the one-dimensional semi-analytical model to obtain real full-life service time information of the oil and gas pipeline material. According to the method, the full-life behavior information of stress corrosion cracking can be quickly obtained, and a partial differential equation does not need to be solved; on the basis of fracture mechanics, the mechanism of repeated fracture and reconstruction of the passivation layer in the fracture process can be reproduced; the full-life service time of the oil and gas pipeline can be effectively predicted, and the parameter calibration method can be applied to other conditions and is wide in application range.

The invention belongs to the technical field of tunnel water inrush monitoring, and particularly relates to a tunnel water inrush monitoring and early warning method under a water-rock coupling effect, which comprises the following steps: S1, obtaining tunnel data and rainfall data of a historical time sequence, carrying out data processing, and training a preset logistic regression model; s2, acquiring a position cross-section diagram of the water-containing fracture of the tunnel by using a high-density electrical method; s3, selecting the maximum K water-containing fractures based on the position cross-section diagram in the S2, respectively calculating effective method corresponding force sigma'n and shear stress tau'n, and then calculating a stress intensity factor K II; corresponding cracking early warning judgment is carried out; s4, current tunnel data and rainfall data are obtained and processed, and the trained logistic regression model is used for predicting the current water inrush risk probability; and corresponding water inrush early warning judgment is carried out. According to the method, multi-source data can be fused, a water-rock coupling action mechanism is considered, and tunnel water inrush monitoring and early warning are efficiently carried out in real time.

The invention relates to a fatigue crack propagation simulation and life prediction method considering a crack closing effect. The method comprises the following steps: constructing a finite element model; assembling crack sizes in the finite element model according to user requirements, refining regional grids of the cracks, expanding the cracks in the finite element model, extracting a displacement field of the regional grids at the tips of the cracks, performing nonlinear calculation considering a crack closing effect on the basis of the displacement field, and calculating the crack closing effect. Obtaining an I-type stress intensity factor and an II-type stress intensity factor at the tip of the crack; calculating a crack propagation angle based on the I type stress intensity factor and the II type stress intensity factor and based on a maximum circumferential stress criterion, and calculating a new crack tip coordinate based on the crack tip coordinate, the crack propagation angle and a user-defined crack propagation increment; and updating historical crack tip coordinates based on the new crack tip coordinates to update the cracks, and assembling the finite element model until the I-type stress intensity factor is greater than the fracture toughness, and outputting a result in a table form.

The invention provides a stiffened wallboard life prediction method based on a data enhanced physical information neural network, which comprises the following steps: determining influence parameters of crack propagation fatigue life of a stiffened wallboard and a discourse domain of the influence parameters, obtaining sample points through sampling, calculating a stress intensity factor and fatigue life based on a finite element model, and constructing a training set; a double-layer physical information neural network is established, a first sub-model predicts a stress intensity factor by taking an influence parameter as input, a second sub-model combines the influence parameter and a stress intensity factor prediction value, a physical loss function based on a Paris crack propagation law is introduced, training is performed in combination with a data loss function, and fatigue life prediction is realized; and representing the influence parameters as fuzzy variables, obtaining a multi-level-cut set, and predicting the fuzzy response of the fatigue life by using the trained neural network. According to the method, a physical mechanism and data driving can be effectively fused, and efficient prediction of the crack propagation fatigue life of the stiffened wall plate under the uncertain condition is achieved.

The invention relates to the technical field of mechanical structure strength evaluation and structural design, and provides a safety evaluation and design method for a ship longitudinal welding structure, which comprises the following steps: determining a damaged key part; detecting the size of the minimum detectable crack in the ship longitudinal welding structure by adopting a nondestructive detection method; carrying out regularization and normalization processing on the crack obtained by detection; calculating a stress intensity factor amplitude corresponding to the current crack; judging whether the crack is expanded or not by combining a fatigue crack expansion threshold value predicted by a Zhu-Xuan model; based on a nondestructive testing result and a three-dimensional crack propagation analysis model, establishing a crack propagation digital twinborn body; and according to crack propagation prediction results and residual life evaluation results of the crack propagation digital twin under different structure schemes, safety and reliability of different welding structure forms, size parameters and process schemes are compared, and optimal design of the ship longitudinal welding structure is achieved.

The invention provides an LNG flexible pipeline water hammer-thermal shock coupling fatigue life evaluation method. The method comprises the following steps that an LNG flexible pipeline three-dimensional thermal-mechanical coupling model is established; transient fluid pressure fluctuation and temperature shock in the valve switching process are simulated, and a time-varying temperature field, a stress field and a crack tip stress intensity factor of the pipeline under the water hammer-thermal shock coupling effect are solved; a low-temperature test system is constructed, simulation results and experimental data are compared, and boundary condition parameters in the LNG flexible pipeline three-dimensional thermal-mechanical coupling model are corrected; cyclic load characteristics in the corrected stress response spectrum are extracted based on a rain flow counting method, and in combination with a corrected EPRG empirical model or an SES model, the accumulated fatigue damage amount of the crack-containing pipeline under the water hammer-thermal shock coupling cyclic load is calculated; and predicting the residual fatigue life of the pipeline. According to the method, the prediction precision of the fatigue life of the LNG flexible pipeline under the complex coupling action of the water hammer and the thermal shock is improved.

The application relates to a state evaluation method and device of an object, computer equipment and a system. The method comprises the following steps: acquiring a first crack image of an object to be evaluated; using a regression model to perform prediction based on a first crack parameter in the first crack image, so as to obtain a first stress intensity factor of the object to be evaluated; the regression model is a model for predicting the stress intensity factor, and the regression model is obtained by training a second crack parameter and a second stress intensity factor in a second crack image of a target object, and the second stress intensity factor is simulated based on the second crack parameter; and the state of the object to be evaluated is evaluated based on the first stress intensity factor, so as to obtain a state evaluation result of the object to be evaluated. The method can be used for state evaluation in multiple scenes.

The application discloses a method for determining the allowable damage scale of concrete based on a fracture extremum theory, which comprises the following steps: S1, carrying out a fracture test to obtain a peak load; S2, calculating a stress intensity factor generated by an external load and cohesive force according to a stress intensity factor manual; S3, establishing a crack tip stress intensity factor balance equation according to a crack propagation criterion, and then deducing an expression of the external load; S4, determining a critical effective crack length of the concrete according to the fracture extremum theory; and S5, calculating the allowable damage scale according to the critical effective crack length. The method for determining the allowable damage scale of concrete based on the fracture extremum theory is adopted, the fracture extremum characteristics of the concrete are fully considered, the peak load of the fracture test needs to be measured only when the method is applied to analyze the crack propagation of the concrete, the test operation is simple, the calculation result is high in accuracy, and the method is suitable for test pieces of different sizes and types.

The invention provides an LNG (Liquefied Natural Gas) conveying flexible pipeline crack initiation and extension prediction method, which comprises the following steps of: constructing a multilayer composite structure geometric model, and defining thermal parameters and mechanical parameters of each layer of material in the model; presetting an initial crack in the model, and establishing a thermal-mechanical coupling control equation containing an interface thermal resistance effect; applying an internal ultralow temperature boundary condition, an external environment temperature boundary condition and a mechanical load boundary condition; solving the thermal-mechanical coupling control equation to obtain temperature field distribution of the section of the pipeline, applying a temperature field as a body load to the multilayer composite structure geometric model, and calculating to obtain a stress field and a stress intensity factor of a crack tip; constructing a crack propagation criterion considering the interface thermal resistance effect; and comparing the stress intensity factor obtained by calculation with a crack propagation criterion, and judging whether the crack is propagated or not. According to the method, the physical authenticity and calculation precision of crack initiation and propagation prediction of the LNG flexible pipeline in the ultralow temperature environment are improved.

The invention relates to a nuclear power plant main pipeline damage tolerance establishment method. The method comprises the following steps: S1, determining the critical crack size of the main pipeline of the nuclear power plant at the end of the life; and S2, performing finite element calculation based on the established finite element model of the crack-free structure of the main pipeline so as to obtain stress distribution of the crack-free structure under each load working condition. S3, according to the initial crack size and the finite element calculation result, stress intensity factor calculation, transient pairing, elastic-plastic correction and fatigue crack propagation calculation are conducted in sequence, and the life end crack size of the main pipeline is obtained. And S4, when it is judged that the life end crack size of the main pipeline is smaller than the critical crack size, the step S3 is executed again to conduct iterative calculation on the initial crack size. And when the final crack size of the service life of the main pipeline is judged to be greater than the critical crack size, taking the initial crack size updated by the last iteration as the structural damage tolerance. The nuclear power pipeline defect evaluation period can be shortened, and the evaluation efficiency is improved.

The application discloses a kind of crack propagation prediction method and system of water turbine runner under transient hydraulic excitation, belong to the technical field of water conservancy and hydropower engineering, to solve the technical problem that existing prediction method cannot simulate crack propagation under transient hydraulic excitation.The application is by constructing finite element grid and level set field, encryption grid, identify enhanced node and solve runner time sequence displacement field, then calculate the stress intensity factor and energy release rate of crack front node, and calculate crack propagation direction and rate based on this, thereby update and correct level set field, to obtain the crack after expansion, to realize the accurate simulation of crack propagation under transient hydraulic excitation, provide reliable basis for runner crack monitoring, expansion trend prediction and fracture life assessment.Further, the application can track the crack propagation process from the current small condition to the penetration by multiple iterations, and accurately predict the fracture life of the runner according to the propagation law.

This invention discloses a rapid generation method for rectangular disks suitable for structured meshes. This method simplifies crack propagation calculations of the disk into a parametric fracture mechanics model, enabling the calculation of stress intensity factor and crack propagation life. Specifically, finite element modeling is employed to extract the geometric boundaries of the disk and its partitions, considering the influence of geometric dimensions and boundary effects on crack propagation. Based on coordinate system transformation, using the crack initiation point and stress gradient direction as a reference, the rectangular plate can be accurately located, improving modeling efficiency. This invention simplifies the crack propagation plane into a finite-size rectangular plate. Based on boundary intersection point capture, it achieves high-fidelity equivalence between the rectangular plate model and the actual complex contour of the disk, reducing calculation errors in the boundary region using traditional methods. Furthermore, by extracting the crack-free stress distribution along the crack propagation direction on the rectangular plate, the stress intensity factor at the crack tip and crack propagation life can be calculated using the weighted function method.

The invention discloses a method for determining stress intensity factors of mechanical connection orifice cracks of a metal structure, and belongs to the field of structural strength analysis. The method mainly comprises the following steps: step 1, determining the characteristics of an analyzed metal mechanical connection structure, and determining the width of a batten and the diameter of a nail hole; 2, determining geometric characteristics of the crack; 3, determining the actual stress condition of the flat plate model; and 4, substituting the parameters and the determined condition into an orifice crack stress intensity factor analysis formula correspondingly deduced by the patent to calculate a corresponding stress intensity factor. An existing stress intensity factor manual is only provided with an ideal model of infinite plate rigid nails, many things and conditions are greatly simplified, and the error between a calculation result and an engineering actual result is large.

The invention discloses a fatigue crack propagation life prediction method for a laser shock peening titanium alloy lug, and belongs to the technical field of fatigue crack propagation life prediction of a metal structure, and the method comprises the following steps: carrying out laser shock peening on a target lug structure, and testing to obtain a residual stress field of the target lug structure after laser shock peening; carrying out a fatigue test by adopting an identification load method, and interpreting a fracture; stress intensity factors caused by external loads and residual stress of all points of the front edge on the marking line are calculated in finite element numerical simulation software; correcting the fatigue crack growth rate model; calculating a crack propagation amount corresponding to each point of the preset crack front edge based on the fatigue crack propagation rate model, fitting to obtain a new crack front edge, and recording a corresponding cycle index; and calculating to obtain the fatigue crack propagation life. By adopting the method, accurate prediction of the three-dimensional fatigue crack propagation life under the action of the laser shock peening residual compressive stress field is realized.

This invention relates to a method for testing the fracture toughness of anisotropic eccentrically loaded single-sided notched tensile specimens, comprising: S1, establishing a two-dimensional plane stress model of anisotropic material ESET specimens; S2, mesh generation; S3, calculating displacement, strain, and stress field to obtain the stress intensity factor K and compliance C under different initial crack lengths and anisotropic material parameters; S4, establishing crack length calculation formulas and stress intensity factor calculation formulas based on compliance under different eccentric loading rates, initial crack lengths, and anisotropic material parameters. This invention allows for rapid and accurate measurement of crack length simply by measuring the deformation of the material under external force; it reliably extends the application range of standardized eccentrically loaded single-sided notched tensile specimens from traditional isotropic metals to modern advanced materials such as composite materials, additive manufacturing alloys, and rolled plates, while ensuring the calculation accuracy under anisotropic conditions.

The invention belongs to the technical field of structural health monitoring, and particularly provides a fiber grating displacement sensing-based crack propagation real-time monitoring and early warning method and system, and the method comprises the steps: carrying out the real-time monitoring and early warning of crack propagation on the basis of strain wavelength signals collected by a fiber grating sensor array which is arranged on a miter gate in a fan shape, and employing a finite element digital twin database and a signal matching algorithm; and multi-dimensional characteristic values such as crack length, opening displacement and stress intensity factors are extracted, and the accuracy of crack state recognition is improved by combining multi-measuring-point signal fusion and fracture mechanical analysis. Through combination of gate operation load characteristics and crack propagation rules, a mapping relation between sensor data characteristics and a database is matched, and accurate identification of crack initiation, propagation paths and danger levels is realized. The monitoring and early warning system provided by the invention can realize full-life-cycle online automatic diagnosis, quantitative evaluation and early warning positioning of gate cracks from microscopic expansion to macroscopic failure, and is expected to solve the problem that the hydraulic metal structure cracks are difficult to quantitatively monitor and safely predict in real time.

The invention relates to the technical field of material testing, and discloses a method for testing hydrogen induced cracking of a material in a high-pressure hydrogen environment, which comprises the following steps: firstly, preparing an extended compact tensile sample based on size data of a standard wedge-shaped opening loading sample and a standard compact tensile sample; then carrying out fatigue crack prefabrication on the extended compact tensile sample through a fatigue testing machine, and carrying out shape conversion to obtain a standard wedge-shaped opening loading sample with fatigue cracks, and taking the standard wedge-shaped opening loading sample as a target wedge-shaped opening loading sample; applying a load to the tail end of the fatigue crack on the target wedge-shaped opening loading sample, and placing the target wedge-shaped opening loading sample in a high-pressure hydrogen environment to determine the length of the current hydrogen-induced crack; and finally, determining a stress intensity factor threshold value of the to-be-tested material according to the initial applied stress intensity factor, the current hydrogen-induced crack length and the standard value of the hydrogen-induced crack length. According to the method, not only can a more accurate hydrogen-induced delayed cracking stress intensity factor threshold value be obtained, but also the test cost can be effectively reduced.

The present application relates to the technical field of strength evaluation, in particular to a method for intelligent evaluation of residual strength of a marine low-temperature tank box outer container based on deep learning, comprising the following steps: collecting three-direction acceleration pressure wall temperature strain and outer container images, identifying crack angle, weld direction, crack depth and weld projection section, determining dangerous anchor points according to load principal vector method direction angle difference and strain peak value, extracting pressure temperature strain drop characteristics and calculating equivalent stress retention, and combining wall thickness stress intensity factor and fracture toughness threshold to output residual strength results. In the present application, the low-temperature lagging pressure peak stress retention of ship motion and the crack geometry are unified and mapped to the dangerous anchor points through the linkage of multi-source time sequence load and image crack information, the weld neighborhood risk is separated from the overall working condition, the timeliness of dangerous crack identification and the adaptability of residual strength judgment to low-temperature continuous action transient impact are improved, and the risk of conservative or dangerous evaluation is reduced.

The invention discloses a weight function method for calculating a stress intensity factor of a circumferential weld surface crack of a pipeline. The method comprises the following steps: constructing a point load weight function for calculating the stress intensity factor of the circumferential weld surface crack of a pipeline structure; establishing a pipeline structure finite element model containing the circumferential weld surface cracks, and calculating a stress intensity factor reference solution under a reference load based on an M integral method; solving a weight coefficient of a calculation point of the front edge of the surface crack of the circumferential weld in the point load weight function, and optimizing a back propagation neural network through a genetic algorithm to establish a weight coefficient prediction model; and carrying out double integral operation on the product of the point load weight function and the stress distribution load on the circumferential weld surface crack surface to realize calculation of a stress intensity factor. The method solves the problems that an existing method is only suitable for the situation that the stress distribution load changes unidirectionally along the crack depth and is not suitable for stress distribution which changes bidirectionally along the crack depth and the crack length frequently occurring in an actual structure, the calculation cost is increased, and the calculation precision is reduced.

The application discloses a kind of based on fissure expansion's rock slope excavation unloading failure path analysis method, belong to slope stability analysis technical field, including the following steps: S1, fissure equivalent simulation;S2, stress intensity factor calculation and expansion type judgment;S3, fissure cracking judgment;S4, fissure expansion calculation;S5, fissure expansion section generation.The fissure expansion's rock slope excavation unloading failure path analysis method in the application, by the originally complex fissure expansion environment is divided into multiple sub fissure dynamic expansion model, then single sub fissure expansion model is analyzed one by one, then the fissure expansion situation of single sub fissure expansion model is combined with other sub fissure expansion model and is analyzed, such as step by step calculation, obtain the fissure expansion situation of rock slope under overall complex environment, overall calculation logic is clear, avoid complex redundant calculation, improve fissure expansion situation analysis efficiency.

The application provides a kind of water turbine component crack operation and maintenance method, belongs to water turbine crack maintenance technical field.The method includes: obtaining water turbine component operating parameter, crack characteristics and far field stress, and determining weight distribution coefficient, stress intensity factor and the like by stress analysis.Screen out the components to be evaluated whose weight distribution coefficient, stress intensity factor and the like meet specific conditions, obtain their treatment measures and cost-benefit net present value, determine the risk level score of each measure, and select the minimum risk level score and cost-benefit net present value exceeding the threshold value as the target treatment measure.Finally, the target treatment measure is issued to the user terminal, so that the user can maintain the component.The application accurately evaluates the condition of water turbine component by obtaining relevant parameters and stress analysis, provides a scientific basis for decision-making, also screens key components according to various parameter standards, improves operation and maintenance efficiency, and can also determine the target treatment measure by comprehensively considering risk and cost-benefit, to avoid over-treatment or insufficient treatment.

The application belongs to the field of aircraft design, and particularly relates to a stress intensity factor acquisition method, device, equipment and storage medium, which comprises the following steps: determining a crack initiation mode of a hole edge crack, calculating a stress intensity factor correction coefficient beta1 of a single hole edge crack by calling a finite element software and using a fitting function method; calculating a stress intensity factor correction coefficient beta2 of a double hole edge crack by calling the finite element software and using the fitting function method; obtaining a crack tip stress intensity factor correction coefficient beta3 under the influence of a side hole according to an analytical method; obtaining left and right crack tip stress intensity factor correction coefficients beta4 and beta5 under the influence of a side crack according to the analytical method; and calculating a stress intensity factor of the hole edge crack according to a combined multiplication formula stress intensity factor. The application is aimed at solving the stress intensity factor of a multi-hole and multi-crack structure of an aircraft, and different solving methods are respectively given for different boundary conditions.

The application provides a gear fatigue crack propagation life calculation method and system considering random dynamic load, and the method is as follows: a local plane coordinate system is established at a crack tip, and a crack propagation equation is constructed; time-varying mesh stiffness containing a tooth root crack feature is calculated; a vibration differential equation of a gear mesh pair is constructed and solved, and dynamic meshing forces of the gear pair under different crack states are obtained; the dynamic meshing forces of the gear pair under different crack states are processed, and a load spectrum is prepared, and variable amplitude load data with multi-periodicity are obtained; the variable amplitude load data are taken as boundary conditions, crack propagation is simulated, gear fatigue crack propagation data are read from a finite element data file; stress intensity factors are calculated based on the gear fatigue crack propagation data; and fatigue crack propagation life is estimated based on the Paris formula and the stress intensity factors. The method can improve the reliability and fatigue crack propagation life of the gear, improve the safety of equipment, and reduce maintenance costs.