62 results about "Stress intensity factor" patented technology

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 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 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 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 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.

The invention discloses a method for evaluating the corrosion fatigue crack growth rate of a steel member by fusing a physical model and data driving. The method comprises the following steps: firstly, acquiring data through pre-corrosion and fatigue tests, and calculating a stress intensity factor by adopting M-integral; and further, analyzing the characteristic correlation by using a Pearson coefficient and an SHAP-XGBoost method and quantifying the contribution degree of each parameter to crack propagation, thereby proposing a Paris correction formula. Then, a mixed loss function is constructed, data-driven artificial neural network loss and physical model loss based on a Paris correction formula are considered at the same time, and the data-driven artificial neural network loss and the physical model loss are harmonized through a physical influence coefficient; and finally, performing cycle training and hyper-parameter optimization on the mixed model by adopting a Bayesian optimizer until the prediction precision reaches a set threshold value, thereby realizing high-precision crack growth rate prediction. The prediction method has high precision and high reliability, and can be suitable for crack propagation prediction of actual engineering steel structures such as bridges, civil engineering and ocean engineering.

The present application relates to the field of ocean engineering and mechanical engineering technology, in particular to a fan blade crack propagation analysis method and device considering real marine environment. The method considers real marine environment working conditions, performs dynamic simulation analysis on the fan blade, determines the load distribution information borne by the fan blade and loads it on the finite element model of the fan blade, determines the fatigue hot spot area according to the finite element fatigue damage analysis result and performs crack arrangement. Through the finite element simulation result, the stress intensity factor of the crack tip is calculated and crack propagation simulation is performed to evaluate the fracture failure risk of the fan blade under real marine environment. The fan blade crack propagation analysis idea under complex stress conditions is proposed, which can prevent equipment failure and risk caused by blade fracture, provide a scientific basis for fan maintenance and operation, and thus reduce economic losses caused by fan blade failure.

The invention discloses a method and a system for calculating an I / III type mixed crack initiation mode and an in-plane crack initiation angle of isotropic rock. The method comprises the following steps: acquiring material attribute parameters to construct a geometric model; obtaining a stress intensity factor; obtaining a fitted I / III type geometrical shape factor; constructing an expression of a crack tip stress intensity factor under the new coordinate system; solving the maximum value of the I / III type crack tip stress intensity factor, and comparing the maximum value with the I / III type fracture toughness to obtain an isotropic rock I / III type mixed crack initiation mode; and an expression of the in-plane crack initiation angle is constructed, and the in-plane crack initiation angle of isotropic rock I / III type mixed crack initiation is obtained through calculation. According to the method, the isotropic rock I / III type mixed crack initiation mode and the in-plane crack initiation angle can be calculated more accurately, and the in-plane crack initiation angle can be determined only according to the geometrical shape factor and the fixed parameter under the condition that the crack tip stress intensity factor does not need to be obtained.

This application belongs to the field of fracture toughness testing under corrosive environments, and specifically discloses a method for calibrating the stress intensity factor loading rate in fracture toughness testing under corrosive environments. The method includes: preparing a specimen and creating a pre-crack; using a corrosive solution to create a pre-corrosive environment at the crack tip; establishing a corrosive environment on a testing machine and performing a three-point bending test on the specimen in the corrosive environment at a preset testing machine loading rate to obtain the specimen's yield strength; loading the specimen in the corrosive environment using multiple different testing machine loading rates to 60%-90% of the yield strength, and recording the force-time curves for each loading; calculating the corresponding stress intensity factor loading rate based on the force-time curves and performing linear fitting to obtain the corresponding functional relationship. This application solves the problem that when conducting fracture toughness testing under corrosive environments, it is impossible to directly set the stress intensity factor loading rate, and existing calibration methods cannot accurately reflect the coupling effect of the corrosive environment.

The application belongs to the field of fatigue life calculation, and particularly relates to a wheel disc crack propagation life calculation method based on a stress intensity factor critical value. The method comprises the following steps: obtaining stress or strain distribution of the wheel disc under a limit load working condition; pre-preparing an initial crack at a feature part of the wheel disc, and calculating a stress intensity factor distribution curve of a crack front under the limit load working condition; according to a first crack propagation plan, terminating the propagation when the stress intensity factor of the crack front reaches a material fracture toughness Kc, and obtaining a crack propagation morphology and a stress intensity factor distribution curve; obtaining stress or strain distribution of the wheel disc under a type I cyclic peak load working condition; calculating a maximum stress intensity factor K C ′ corresponding to the crack propagation morphology under the type I cyclic peak load working condition; and taking the maximum stress intensity factor K C ′ as a crack termination propagation condition, and calculating a crack propagation life. The crack propagation life is more conservative and has higher safety.

The present application belongs to the technical field of aero-engine, and particularly relates to a turbine guide vane temperature gradient crack propagation test method, which comprises determining a dangerous position of a real turbine guide vane; simulating the real turbine guide vane to obtain a first change rule of a stress intensity factor on a crack propagation path of the dangerous position; simultaneously acting on a simulation structure of the turbine guide vane through a plurality of independent electromagnetic induction heating modules and a plurality of cooling modules, so that the dangerous position of the simulation structure has a temperature gradient consistent with that of the real turbine guide vane; carrying out a crack propagation test to obtain a second change rule of the stress intensity factor on the crack propagation path of the dangerous position; comparing the first change rule and the second change rule; if the first change rule is consistent with the second change rule, ending the crack propagation test; and if the first change rule is inconsistent with the second change rule, adjusting a displacement load applied on the simulation structure. The present application improves the accuracy of obtained test data.

This invention discloses a method for calculating crack stress intensity factor based on a three-dimensional weighted function method, belonging to the field of reliability technology. Based on the Taylor series expansion method of complex functions, a complex variable finite element program is run to obtain the weighting function for a given crack geometry. Then, the stress intensity factor of the crack is obtained by integrating the stress on the crack surface with the weighting function. Specifically, a finite element model containing the crack is established and meshed; the nodes of the crack tip are perturbed on the imaginary axis; the imaginary part of the crack opening direction at the nodes on the crack surface is obtained by running the complex variable finite element program, thus obtaining the weighting function on the crack surface; the stress intensity factor at the nozzle corner is solved by integrating the weighting function and the stress on the crack surface. Compared to two-dimensional weighting functions, this method extends to three-dimensional elliptical cracks, broadening its application range; the method provides accurate calculation results for the stress intensity factor at the nozzle corner under complex loads, and is simple and effective to use.

The invention discloses a fatigue loading frequency sensitivity testing method for a bimetal composite pipe welded joint in a corrosion environment, and relates to the field of fatigue performance testing of the welded joint in the corrosion environment. The method comprises the following steps: preparing a bimetal composite pipe welding joint CT sample and prefabricating a fatigue crack; coating the non-notched surface of the sample with an anti-corrosion coating, and immersing the sample into a corrosion solution which is subjected to oxygen removal and is introduced with test gas for pre-soaking; a fatigue crack growth rate test is carried out in a corrosion environment and a constant stress intensity factor K control mode, and the loading frequency is gradually reduced along with crack growth; processing the crack propagation data under each frequency, and calculating da / dN of the crack in a stable propagation stage; d / d < N > under different frequencies are compared, when the variation amplitude of adjacent frequencies is smaller than a preset threshold value, it is judged that an environment-insensitive platform area is reached, and the larger value is the optimal loading frequency. According to the method, through step-by-step frequency reduction loading of a single sample, the test cost is remarkably reduced and the test period is remarkably shortened while the accuracy of a test result is ensured.

This invention relates to the field of metallurgical lifting equipment testing technology, specifically a method for predicting the fatigue crack propagation life of metal structures in metallurgical cranes. The method includes: collecting structural stress spectrum, strain monitoring time-series data of stress concentration areas, lifting operation spectrum, and temperature and humidity data under service conditions; constructing an initial crack parameter model; calculating the stress intensity factor variation spectrum, including the amplitude of the stress intensity factor at the crack tip corresponding to each load cycle; calculating the crack propagation increment per cycle and accumulating the crack size evolution data; setting a critical crack propagation size threshold based on structural integrity assessment criteria; and predicting the fatigue crack propagation life by comparing the evolution data with the threshold. This method refines the calculation dimensions of the stress intensity factor, restores the dynamic evolution process of crack size, closely matches the actual service load characteristics of metallurgical cranes, and optimizes the accuracy of crack propagation life prediction.

The present application belongs to the technical field of welded structure reliability evaluation, and particularly relates to a calculation method of stress intensity factor of gap defect weld under tensile shear load, comprising: selecting an automobile sheet part as a research object, and constructing a strip two-dimensional model of a gap defect weld containing an initial gap; based on the linear elastic superposition principle, the load borne by the gap defect weld is decomposed into multiple load types; based on the strip two-dimensional model of the gap defect weld containing the initial gap, the analytical solution of the stress intensity factor under the load generation mode corresponding to different load types is calculated respectively, and the analytical solution of the stress intensity factor under different load generation modes is calculated; a finite element model of the gap defect weld is constructed and finite element analysis is carried out, and the finite element solution of the stress intensity factor under different load generation modes is calculated; the analytical solution and the finite element solution of the stress intensity factor under different load generation modes are compared, and the accuracy of the analytical solution of the stress intensity factor is verified.

The invention discloses a transverse isotropic functionally graded material crack propagation analysis method and a service life prediction system, and relates to the field of civil engineering materials and structural safety, and the transverse isotropic functionally graded material crack propagation analysis method comprises the following steps: constructing a dual boundary integral equation set based on a transverse isotropic multilayer medium basic solution; calculating a crack tip mixed mode stress intensity factor with high precision by adopting a self-adaptive grid division technology; and realizing full-automatic prediction of a fatigue crack propagation path and a structural fatigue life by combining a crack propagation law and a virtual crack propagation strategy. By only automatically discretizing the boundary and the crack surface, the huge calculation burden of a traditional finite element method in global discretization and repeated grid division is avoided, and the method is particularly suitable for processing the fatigue problem of transverse isotropic functionally graded materials (such as layered rock mass, side slope foundation and oriented fiber reinforced composite materials) in a semi-infinite domain. And the calculation efficiency, the precision and the engineering practical level of durability analysis and life prediction of the civil engineering structure under the cyclic load are remarkably improved.